NEO Coordination Centre


Precursor services


Please note that all SSA-NEO Services are under development

Last update: 2015-11-26 14:46:00 UTC
Current number of known NEOs:
Current number of NEOs in risk list:


NEOCC Newsletter: November 2015
02 November 2015
The ESA SSA-NEO Coordination Centre has released the November newsletter summarising the most relevant data and events on asteroids and comets approaching the orbit of the Earth.
Please, feel free to forward it to potentially interested people.
You can download the newsletter by clicking on the button below; for subscribing to it please send a message to


WT1190F comes back: ESA NEOCC watching rare reentry

22 October 2015



An object discovered on 3 October 2015, temporarily designated WT1190F by the observers, will enter the Earth's

atmosphere on 13 November. It was discovered by the Catalina Sky Survey (

The object is in Earth orbit, with a period of about three weeks. Its orbit is quite well known because it was also observed twice in 2013 by the same survey team. This long observational coverage is sufficient to model its trajectory with good accuracy and obtain two interesting results.

First, the object is likely man made. The motion of this body over about two years can be modelled in detail only if the effects of solar radiation pressure are taken into account. The intensity of this solar push is proportional to the object's area-to-mass ratio, which can therefore be estimated, providing an indirect clue to its density. It turns out that this body has a mean density that is about 10% that of water. This is too low to be a natural space rock, but it is compatible with being a hollow shell, such as the spent upper stage of a rocket.

The second, and even more interesting result, is that the object will re-enter Earth's atmosphere in a few weeks, around 06:20 UT on 13 November 2015. The object is quite small, at most a couple of meters in diameter, and a significant fraction if not all of it can be expected to completely burn up in the atmosphere. Whatever is left will fall into the ocean about 100 km off the southern coast of Sri Lanka. Its mass is not sufficient to cause any threat to the area, but the show will still be spectacular, since for a few seconds the object will become quite bright in the noon sky.

During the next few weeks ESA's NEOCC will organize observational campaigns to collect as much data as possible on this object. The goal is twofold; first, the object is interesting to better understand the re-entry of satellites and debris from high orbits. Second, it provides us with an ideal opportunity to test our readiness for any possible future events involving an asteroid, since the components of this scenario, from discovery to impact, are all very similar.

WT1190F observed on 9 October 2015 with the University of Hawaii 2.2 meter telescope on Mauna Kea, Hawaii. [Credits: B. Bolin, R. Jedicke, M. Micheli]


NEOCC Newsletter: October 2015
01 October 2015
The ESA SSA-NEO Coordination Centre has released the October newsletter summarising the most relevant data and events on asteroids and comets approaching the orbit of the Earth.
Please, feel free to forward it to potentially interested people.
You can download the newsletter by clicking on the button below; for subscribing to it please send a message to


NEOCC Newsletter: September 2015
01 September 2015
The ESA SSA-NEO Coordination Centre has released the September newsletter summarising the most relevant data and events on asteroids and comets approaching the orbit of the Earth.
Please, feel free to forward it to potentially interested people.
You can download the newsletter by clicking on the button below; for subscribing to it please send a message to


NEOCC Newsletter: August 2015
07 August 2015
The ESA SSA-NEO Coordination Centre has released the August newsletter summarising the most relevant data and events on asteroids and comets approaching the orbit of the Earth.
Please, feel free to forward it to potentially interested people.
You can download the newsletter by clicking on the button below; for subscribing to it please send a message to


Going faint
31 July 2015
One of the major goals of the ESA NEO Coordination Centre is to focus observations on objects with non-zero impact probabilities. When an asteroid quickly becomes very faint just after discovery and stays that way for decades, the only option is to use telescopes that can see faint objects. It is essential then to be ready to catch a favourable opportunity when the object, although faint, is slightly brighter than average.
This is the case for 2008 LG2, a small asteroid with a diameter of about 30 meters, not much larger than the one that fragmented over Chelyabinsk in 2013. It was discovered in 2008 by the LINEAR survey in New Mexico, USA, during a particularly close fly-by when it reached magnitude 18. But such a good observational opportunity will not happen again at least until year 2056, and by that time the uncertainty in its position would have increased so much that nobody would be able to locate it. On the other hand, it had a non-negligible possibility of impacting our planet between year 2070 and year 2090. Is it possible to do something sooner?
Fortunately, a big 8-meter telescope is theoretically capable of detecting a 30 meter object more or less anywhere in the Earth neighbourhood. We just need to wait for a time when our object is not very far from Earth, and we may be still able to detect it. During the past few months 2008 LG2 got into this favourable geometry, and reached a peak magnitude of 26.6. That's when we successfully observed it with the ESO Very Large Telescope on Cerro Paranal, Chile.
2008LG2 [VLT]
These observations were made possible by a very fruitful collaboration that was established between the ESA NEOCC and the European Southern Observatory (ESO), which allows us to use their 8.2 meter Very Large Telescope (VLT) to chase faint asteroids with impact possibilities. We routinely observe objects as faint as magnitude 26, but the case of 2008 LG2 was exceptional, because it allowed us to push the limits of the telescope below a visual magnitude of 26.5, a threshold that was never surpassed in an NEO observation.
We repeated the same observation on two nights, on 16 June and 7 July 2015, to confirm that the candidate we detected was indeed the correct one, as required for these recovery observations. Although the object was so faint, both observations were successful, the object was identified and its position carefully measured. These data led to a significant improvement in our knowledge of the object's orbit (about 400 times), sufficient to exclude any chance of impact with our planet at least for the next century.


Telescopes focus on target of ESA's asteroid mission

06 July 2015

AIM monitors DART impact

Telescopes around the globe recently homed in on one point in the sky, observing the paired Didymos asteroids – the target for ESA’s proposed Asteroid Impact Mission.

The 800 m-diameter main body is orbited by a 170 m moon, informally dubbed Didymoon. The duo were more favourably placed from March until early June for studies.

The goal was to help with planning not only ESA’s Asteroid Impact Mission (AIM) but also the NASA-led Double Asteroid Redirection Test, or DART, which will crash into Didymoon in late 2022 as ESA’s craft looks on.

The two candidate missions together are known as the Asteroid Impact & Deflection Assessment (AIDA) mission.

The very best observations turned out to be from Flagstaff, Arizona, USA – part of the observatory that famously discovered Pluto back in 1930 – as the conditions proved optimal there.

Andy Rivkin from the John Hopkins University’s Applied Physics Laboratory explained: “The most important question we were trying to answer was how much tilt is present between the orbit of the satellite around the primary and the orbit of the Didymos system around the Sun.”

The orientation of Didymoon’s orbit is one of the key factors involved in planning the mission. It is important, for example, in calculating the approach of the spacecraft to the binary system, as well as to know when the asteroid moon will fall into shadow – needed for scheduling payload operations.

Sharpening our estimates of the mass of the two Didymos bodies is also crucial, not least because the outcome of the DART impact will be influenced by the asteroids’ density.

Petr Pravec, from the Astronomical Institute of the Academy of Sciences of the Czech Republic, commented: “Unfortunately, we had bad weather on many of the nights that we were planning to get data. However, we were able to obtain some data and are using it in combination with older optical and radar data to refine the orbital period for the system and the density of Didymos.”

Nicholas Moskovitz, of Lowell University, Flagstaff, reveals: “The next observations of the Didymos binary system will be in the spring of 2017. We should be able to obtain time on larger telescopes as we hope AIM will be a fully approved mission by then. In addition, the asteroid system will be about 30% brighter than it was this time round, which will make the observations somewhat easier."

“There are additional opportunities for pre-impact observations in 2019 and 2021, but we expect to have cleared up any lingering questions in 2017 and will just use the later observations to update our orbit calculations.”

“The observers did a great job,” says ESA’s Detlef Koschny. “Despite the bad weather conditions, they managed to collect good data. This is a nice demonstration of how well collaboration between an Agency and the science community can work.”


NEOCC Newsletter: July 2015
01 July 2015
The ESA SSA-NEO Coordination Centre has released the July newsletter summarising the most relevant data and events on asteroids and comets approaching the orbit of the Earth.
Please, feel free to forward it to potentially interested people.
You can download the newsletter by clicking on the button below; for subscribing to it please send a message to


Helping Europe prepare for asteroid risk

30 June 2015


Chelyabinsk sky rendering


Each year, astronomers worldwide discover over 1000 new asteroids or other space rocks that could strike our planet. And if one is spotted heading towards Earth, experts working in ESA and national emergency offices need to know who should do what, and when.

A critical factor in protecting lives and property in the event of an object being discovered en route to Earth is civil response, and how national authorities can best inform their citizens of what to do. In turn, this requires ESA to know how best to compile, analyse and distribute scientific information on an impending object to those national authorities.

A workshop sponsored by ESA at the end of June saw delegates from six ESA Member states meeting with the Agency's Space Situational Awareness team to discuss asteroids – and to exercise the reactions that each would foresee in the event of a real near-Earth object, or NEO, threat.

National emergency response offices in Switzerland, Germany, Luxembourg, Romania, Sweden and the UK learned how the flow of information during an alert would run from ESA's NEO Coordination Centre to national authorities and then into national alert and warning systems.

Delegates contributed crucial information about their countries' response networks – think of those used for severe weather or flood warning – aimed at the general public, businesses and communities.

ESA's Optical Ground Station

"Every year, more than 1000 new NEOs are discovered," notes ESA's Gerhard Drolshagen. "Most of them are some tens of metres in size and have the potential to cause damage on the ground. Sooner or later, one will actually hit Earth. These workshops are helping us to prepare for such an event."

Of the more than 600 000 known asteroids in our Solar System, more than 12 000 are classified as NEOs because their orbits bring them relatively close to our path.

While the likelihood of any real event remains small, understanding them and devising the best response is more important than ever since the Chelyabinsk strike in February 2013. Global awareness spiked after the event, and governments began to become aware of the kind of information they needed to provide to people on the ground – such as staying away from windows to avoid flying glass. 

In this third workshop, the UN-mandated International Asteroid Warning Network (IAWN) and its relationship to ESA was highlighted.

Detecting space hazards

"Establishing interfaces to the various emergency response offices is now a much clearer process," says ESA's Detlef Koschny. "We also learned which information needs to be made available at what time, and to whom."

Delegates are now aware of the channels through which ESA could inform countries about threats, so that they could prepare culturally and geographically appropriate responses for their countries.

"In the event of a threat, we need to clearly establish roles and responsibilities for the impact zone," said Nicolas Bobrinsky, Head of ESA's Space Situational Awareness. "Clear planning is the key to improved public safety."


NEOCC Newsletter: June 2015
03 June 2015
The ESA SSA-NEO Coordination Centre has released the June newsletter summarising the most relevant data and events on asteroids and comets approaching the orbit of the Earth.
Please, feel free to forward it to potentially interested people.
You can download the newsletter by clicking on the button below; for subscribing to it please send a message to


NEOCC newsletter: May 2015
04 May 2015

The ESA SSA-NEO Coordination Centre has released the May newsletter summarising the most relevant data and events on asteroids and comets approaching the orbit of the Earth.
Please, feel free to forward it to potentially interested people.
You can download the newsletter by clicking on the button below; for subscribing to it please send a message to


NELIOTA: ESA's new lunar monitoring project in collaboration with the National Observatory of Athens
23 April 2015
Credit: J. Madiedo / MIDAS
NELIOTA is an activity initiated by the European Space Agency (ESA), which was recently launched at the National Observatory of Athens. The project aims to count and characterise the number and distribution of near-earth objects (NEOs). NEOs are meteoroids, comets or asteroids found in the neighbourhood of the Earth. Large NEOs can pose a threat to humans, as some have the potential to impact the Earth. The Earth's atmosphere protects us from impacts of small NEOs, most of which burn up as they enter the atmosphere at great speeds. Only the largest ones have the potential to reach the surface. On the Moon, however, the absence of an atmosphere means that all NEOs that enter the Moon's gravity will impact the surface. Impacts on the non-illuminated side of the Moon cause a visible flash that lasts about 1 second and results in a crater. Scientists are interested in understanding the size distribution and frequency of NEOs in order to assess the threat of small NEO collisions to orbiting spacecraft and to future ESA Moon missions.
The NELIOTA project will use existing facilities at the National Observatory of Athens to establish an operational system that will monitor the Moon, looking for faint NEO impacts. The project involves upgrading the 1.2m Kryoneri telescope, located in the Northern Peloponnese, in Greece, as well as procuring two specialised fast-frame cameras. Specialised software will be developed to control the telescope and cameras, as well as process the resulting images to detect the impacts automatically. The NELIOTA system will then publish the data on the web so it can be made available to the scientific community and the general public.
The objective of this three and a half year activity is to design, develop and implement a highly automated lunar monitoring system. The system will conduct an observing campaign for 2 years searching for NEO impact flashes on the Moon. The impact events will be verified, characterised and recorded. The 1.2m Kryoneri telescope will be capable of detecting flashes far fainter than telescopes currently monitoring the Moon. It is expected that NELIOTA will be able to record NEOs weighing just a few grams. 
This activity is being undertaken by a team led by Dr. Alceste Bonanos at the Institute for Astronomy, Astrophysics, Space Applications & Remote Sensing at the National Observatory of Athens, Greece. The upgrade of the 1.2m Kryoneri telescope will be undertaken by DFM Engineering, Inc. The project website can be found here
This project forms part of many activities initiated and/or sponsored by the European Space Agency to help have a better understanding of our Space environment. In parallel to this exciting new venture, the Agency is also examining our space weather and the detrimental impact of space debris.  


ESA's AIM webpage

15 April 2015

A dedicated webpage for ESA's Asteroid Impact Mission study is now online here.


Call for media: ESA hosts IAA Planetary Defence Conference 2015

10 April 2015


ESA will host the International Academy of Astronautic's 4th Planetary Defence Conference (PDC 2015), entitled ‘Assessing Impact Risk & Managing Response', at the Agency's ESRIN establishment, near Rome, 13–17 April 2015. A media briefing will be held on 16 April 2015.
PDC 2015 will provide a forum for the world's top experts from space agencies, academia and industry to present the latest research and discuss current scientific understanding of the risk posed by asteroids that could potentially strike our planet.
Topics to be discussed at PDC 2015 include planetary defence, the continuing international search for undiscovered NEOs, the state of scientific knowledge of asteroids and their physical characteristics, mitigation techniques, future deflection missions, impact warning and effects, civil response and education. The conference will include an exercise where participants will simulate the decision-making process for developing deflection and civil defence responses to a hypothetical asteroid impact threat.
Media are invited to take part in the PDC2015 press briefing, Thursday, 16 April, to include presentations from agency experts and the release of summary findings from the week-long conference.

Assessing the threat

 Chelyabinsk asteroid vapour trail seen by Meteosat
Of the more than 600 000 known asteroids in our Solar System, more than 12 000 are classified as near-Earth objects, or NEOs, because their orbits bring them relatively close to our path.
Dramatic proof that any of these can strike Earth came on 15 February 2013, when an unknown object thought to be 17–20 m in diameter arrived at 66 000 km/h and exploded high above Chelyabinsk, Russia, with 20–30 times the energy of the Hiroshima atomic bomb.
The resulting shock wave caused widespread damage and injuries, making it the largest known natural object to have entered the atmosphere since the 1908 Tunguska event, which destroyed a remote forest area of Siberia.
Coordinating Europe's efforts
International cooperation to address the NEO threat is coordinated at ESA by the Space Situational Awareness (SSA) Programme office.
In addition to coordinating Europe's asteroid-hunting activities, the SSA Programme office represents ESA at the International Asteroid Warning Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG), technical fora with a mandate from the UN Committee on the Peaceful Uses of Outer Space (UNCOPUOS) to develop a strategy on how to react to a possible asteroid impact threat.
Press briefing 16 April
The media briefing will be held at ESRIN, ESA's Centre for Earth Observation, in Frascati, near Rome, on 16 April 2015.
Doors open at 10:00 CEST (08:00 GMT)

CREOP Room, Building 11, ESRIN

10:00 Doors open; registration
The Planetary Defence Conference: Global cooperation against asteroid threats
Dr Detlef Koschny, Head of NEO Segment, ESA Space Situational Awareness Programme
Finding asteroids & avoiding impacts: space agencies taking action to prevent future catastrophe
Dr Lindley Johnston, NEO Programs Executive, Science Mission Directorate, HQ NASA
Responding to asteroid threat scenarios - The importance of impact simulation exercises
Debbie Lewis, Director, Resilience Planning at Axiom (Alderney) Ltd.
Presentation of findings PDC 2015
Dr William Ailor, Distinguished Engineer, The Aerospace Corporation, PDC 2015 co-chair
Richard Tremayne-Smith, Advisor, The Secure World Foundation, PDC 2015 co-chair
11:45 Open Q&A
End of briefing; opportunities for individual interviews; small group visits to ESA's NEO Coordination Centre
Media representatives wishing to attend the 16 April press briefing are requested to register hereAny media who have already registered for full access to the PDC 2015 conference are automatically registered for this briefing and need take no further action.
For further information, please contact:
ESA Media Relations Office
Tel: +33 1 53 69 72 99
ESA Space Situational Awareness
Programme Communication Officer
Jocelyne Landeau-Constantin
Tel: +49 6151 90 0
International Academy of Astronautics
Fabrice Dennemont,
Jean-Michel Contant,

Tel.: +33 1 47 23 82 15


Our NEO newsletter
03 April 2015
The ESA SSA-NEO Coordination Centre has started to publish a monthly newsletter summarising the most relevant data and events on asteroids and comets approaching the orbit of the Earth. The newsletter wishes to provide information useful to experts, journalists and the public at large. You can download the first issue by clicking on the button below; for subscribing to it please send a message to


ESA's planetary defence test set for 2020
31 March 2015 
Asteroid collision
If an asteroid were spotted headed towards Earth, what could humanity do about it? ESA's latest mission is part of a larger international effort to find out.
This month marked the start of preliminary design work on ESA's Asteroid Impact Mission, or AIM. Intended to demonstrate technologies for future deep-space missions, AIM will also be the Agency's very first investigation of planetary defence techniques.
Launched in October 2020, AIM will travel to a binary asteroid system – the paired Didymos asteroids, which will come a comparatively close 11 million km to Earth in 2022. The 800 m-diameter main body is orbited by a 170 m moon, informally called ‘Didymoon'.
This smaller body is AIM's focus: the spacecraft will perform high-resolution visual, thermal and radar mapping of the moon to build detailed maps of its surface and interior structure. 
Laser link
AIM will also put down a lander – ESA's first touchdown on a small body since Rosetta's Philae landed on a comet last November.
Two or more CubeSats will also be dispatched from the mothership to gather other scientific data in the vicinity of the moon. AIM's findings will be returned by high-capacity laser link to ESA's Optical Ground Station on Tenerife in the Canary Islands.
AIM should gather a rich scientific bounty – gaining valuable insights into the formation of our Solar System – but these activities will also set the stage for a historic event to come.
Target: Didymoon
For AIM is also Europe's contribution to the larger Asteroid Impact & Deflection Assessment mission: AIDA. In late 2022, the NASA-led part of AIDA will arrive: the Double Asteroid Redirection Test, or DART, probe will approach the binary system – then crash straight into the asteroid moon at about 6 km/s.
"AIM will be watching closely as DART hits Didymoon," explains Ian Carnelli, managing the mission for ESA. "In the aftermath, it will perform detailed before-and-after comparisons on the structure of the body itself, as well as its orbit, to characterise DART's kinetic impact and its consequences.
"The results will allow laboratory impact models to be calibrated on a large-scale basis, to fully understand how an asteroid would react to this kind of energy. This will shed light on the role the ejecta plume will play – a fundamental part in the energy transfer and under scientific debate for over two decades.
AIM and Didymos binary system
"In addition, DART's shifting of Didymoon's orbit will mark the first time humanity has altered the Solar System.
"It will also give us a baseline for planning any future planetary defence strategies. We will gain insight into the kind of force needed to shift the orbit of any incoming asteroid, and better understand how the technique could be applied if a real threat were to occur."


Preparing for an asteroid strike
18 December 2014
ESA and national disaster response offices recently rehearsed how to react if a threatening space rock is ever discovered to be on a collision course with Earth.
Last month, experts from ESA's Space Situational Awareness (SSA) programme and Europe's national disaster response organisations met for a two-day exercise on what to do if an asteroid is ever found to be heading our way.
In ESA's first-ever asteroid impact exercise, they went through a countdown to an impact, practising steps to be taken if near-Earth objects, or NEOs, of various sizes were detected.
The exercise considered the threat from an imaginary, but plausible, asteroid, initially thought to range in size from 12 m to 38 m – spanning roughly the range between the 2013 Chelyabinsk airburst and the 1908 Tunguska event – and travelling at 12.5 km/s.
Critical times to take action
ESA Space Situational Awareness: detecting space hazards
Space Situational Awareness - Near Earth Objects
Teams were challenged to decide what should happen at five critical points in time, focused on 30, 26, 5 and 3 days before and 1 hour after impact.
"There are a large number of variables to consider in predicting the effects and damage from any asteroid impact, making simulations such as these very complex," says Detlef Koschny, head of NEO activities in the SSA office.
"These include the size, mass, speed, composition and impact angle. Nonetheless, this shouldn't stop Europe from developing a comprehensive set of measures that could be taken by national civil authorities, which can be general enough to accommodate a range of possible effects.
"The first step is to study NEOs and their impact effects and understand the basic science."
How should Europe react
Participants came from various departments and agencies of the ESA member states Germany and Switzerland, including Germany's Federal Office of Civil Protection and Disaster Assista
ESA's Optical Ground Station (OGS) is 2400 m above sea level on the volcanic island of Tenerife.
Tenerife station
They studied questions such as: how should Europe react, who would need to know, which information would need to be distributed, and to whom?
"For example, within about three days before a predicted impact, we'd likely have relatively good estimates of the mass, size, composition and impact location," says Gerhard Drolshagen of ESA's NEO team.
"All of these directly affect the type of impact effects, amount of energy to be generated and hence potential reactions that civil authorities could take."


2014 UR116 is no threat
11 December 2014
The recent claim that asteroid 2014 UR116 may be threatening the Earth shows how difficult it is to convey the right message about the NEO hazard.
The no-news spread after statements from the discoverers: the asteroid was no imminent threat but if, in a not yet foreseeable distant future, it hit the Earth then due to its large size (400 m) the effects would be devastating. Of course this is true for many NEOs, highlighting that the real challenge in communicating the asteroid hazard is to correctly handle the dangerous mix between reassuring and threating information. There is the need for authoritative sources, not only of NEO data but also for disseminating unambiguously to the public and the press the related information. 
This is why the International Astronomical Union has appointed as reference sources for NEO impact monitoring data the NEODyS and Sentry systems (running at the University of Pisa, Italy and at JPL, USA, respectively). It also motivates the establishment of the NEO Coordination Centre of the European Space Agency: relying on the NEODyS computational engine it disseminates data and provides services on the NEO hazard toward a wide range of different users and stakeholders. 
The more experienced user can rule out any short-term threat by simply displaying the 2014 UR116 Summary Page of ESA's NEO web portal at the MOID (Minimum Orbit Intersect Distance) value of 0.0288 au of the asteroid implies that the closest approaches could now occur only at a safe distance of nearly 5 million km. A fact that can also be visualised by opening the Orbit Visualization Tool, which allows to move the orbit in space and understand the underlying orbital geometries.


LBT detects one of the faintest NEOs ever observed thanks to a collaboration between INAF and ESA

2 December 2014

The Large Binocular Telescope (LBT), of which the Italian National Institute for Astrophysics (INAF)  is a main partner, has successfully observed asteroid 2014 KC46 in one of the faintest Near-Earth Object (NEO) recoveries ever performed. This challenging observation, which pushed the limits of the telescope down to a visual magnitude of 26.3, was carried out on the nights of 28 and 30 October 2014 by a new collaboration between the Italian LBT team and the NEO Coordination Centre of the European Space Agency. LBT spotted the 100-metre-sized object while it was just beyond the orbit of Mars. The corresponding measurement of its position was sufficient to decrease the uncertainties associated to its orbital path to the point of safely dismissing any possible threat that the asteroid may hit the Earth in the near future.

The successful observation of 2014 KC46 has been made possible by the unique performances of LBT: a large field of view to entirely cover the uncertainty in the position of the target asteroid, coupled with the ability to spot very faint objects thanks to the twin 8.4-meter mirrors of the telescope. This result highlights the importance of rapid response for securing NEO orbits and the effectiveness of LBT in detecting faint large-uncertainty objects.

The data have been accepted by the IAU Minor Planet Center, the official organisation in charge of collecting astrometric data for small bodies of the solar system, and published in the electronic circular MPEC 2014-V35. Both the European NEODyS system and the JPL-based Sentry system updated their orbit determination and impact monitoring using the new LBT observations, and confirmed the removal of all impact solutions for the next century.

The Large Binocular Telescope is a facility consisting of two 8.4-meter mirrors on a common mount, located at an altitude of 3200 m on Mt. Graham (Arizona, USA). This telescope is equivalent in light-gathering power to a single 11.8 meter instrument.  LBT is a collaboration between the Instituto Nazionale di Astrofisica (INAF), The University of Arizona, Arizona State University, Northern Arizona University, the LBT Beteiligungsgesellschaft in Germany, The Ohio State University, Research Corporation in Tucson, and the University of Notre Dame.

The NEO Segment of ESA's Space Situational Awareness (SSA) aims to coordinate and combine information from different sources, analyse them to predict possible impact with the Earth, assess danger, and analyse possible mitigations, including the deflection of a menacing asteroid. Within this framework, the ESA NEO Coordination Centre provides data and services on the NEO hazard and coordinates follow-up astronomical observations.


Final presentation day at ESRIN - Computing the risk of NEOs, impact scenarios, the future of NEO activities, and more
19 November 2014

The SSA-NEO and NEOCC-Team in front of the Coordination Centre (from left to right: Gerhard Drolshagen, Philipp Maier, Detlef Koschny, Joaquim Correia de Oliveira, Marco Micheli, Fabrizio Bernardi, Barbara Borgia, Ettore Perozzi, Ana Maria Teodorescu)

On 18th November, ESRIN and the heart of ESA's NEO activities, the NEO Coordination Centre (NEOCC), welcomed an elaborate group of people involved in NEO activities in Europe. About 40 NEO scientists, technical, and political experts followed the final presentations and status reports of four activities carried out for ESA over the last two years.
The presentations ranged from the everyday work at the NEOCC, providing the expert community and the public with most up-to-date data on NEOs, all the way to the calculation of NEO impact effects and possible mitigation missions for Earth-threatening objects. In a concluding discussion, possible future activities for Europe were discussed.
All presentations as well as a video recording of the event are publically available. The presentations can be downloaded in the proceedings section of the event webpage at
The video recordings are available here:


Focus on: ESA OGS
30 October 2014
The ESA Optical Ground Station has quickly become a major asset for the NEO Coordination Centre, thanks to the many nights devoted to observing asteroids. It is located at an altitude of 2400 m on the slope of a volcano, in Tenerife, hosted at the Observatorio del Teide - Instituto the Astrofisica de Canarias. The telescope has been originally committed to advanced optical communication experiments on board the ESA geostationary satellite Artemis, and it is therefore equipped with a state-of -the-art laser equipment, still operational. During the SSA social media event on 7 October a spectacular transit of the International Space Station had been organised: a laser link with the ISS was established while the telescope provided incredibly clear images of the Space Station as shown in the image below (,
Once the Artemis mission was over, OGS became available for supporting other programs. The Space Debris office of ESA installed a focal reducer and a wide-field CCD camera for observing space debris and satellites. In the meantime, the telescope has turned out extremely useful for fulfilling the ESA Space Situational Awareness observing needs. Over the past few years the SSA-NEO programme has been allocated approximately four nights per month, around new moon, entirely dedicated to asteroid observations. These observations are managed by the NEOCC. As can be seen from the image, laser communication is still part of the activities at the OGS.
The main focus of these activities is to collect follow-up observations of NEOs. A significant fraction of the targets are the so-called "NEOCP objects", recently discovered asteroids whose preliminary ephemerides are posted by the IAU Minor Planet Center on the NEO Confirmation Page (
In most cases these recent discoveries have been observed only for a very short amount of time and it is therefore impossible to determine their orbits and carefully assess if they are indeed dangerous NEOs. In most cases, this same lack of knowledge results in very large positional uncertainties in the sky, thus requiring a telescope with a large field of view to be certain that the object is going to be visible in the image. The OGS, with its 47 arcminutes square field, is ideal for these searches; over the last year, about a dozen candidates per night were successfully targeted and approximately half of them were confirmed to be NEOs thanks to our observations.
The second main focus of follow-up activities is guided by the Priority List published on the NEOCC website. At any given time, the list highlights about a dozen objects in urgent need of observations, plus many lower priority ones. We therefore try to observe as many of them as possible down to at least a visual magnitude of 22, which is the practical limit of the instrument. This activity is essential in order to prevent most of these targets from being lost because of a too large orbital uncertainty at their next apparition.
At any given time some of the older, known objects also come back in the vicinity of the Earth and become visible again. These observations are often particularly challenging, because the long timespan between the last observation and the current time could result in large positional uncertainties, which need to be covered entirely to make sure the object is located.
From the beginning of 2014 we have observed almost 200 NEOs, with a success rate above 80 % (i.e. the fraction of targets that were effectively located when observed). Most of the targets are in the magnitude range between 20 and 22, which is accessible only to very few follow-up sites in the world, giving us an advantage and a very useful niche of capabilities that we can successfully exploit.

Every night a few hours are also devoted to a survey project named TOTAS (Teide Observatory Tenerife Asteroid Survey). 
So far TOTAS has discovered 10 NEOs in a total of 300 hours search time. Among them, 2014 QN266 is an interesting Virtual Impactor in an Earth-like orbit. Last February a comet now named P/2014 C1 (TOTAS) was spotted – as reported in our early news "Totas survey finds its first comet". 
We always stay alert for any exceptional target or event on which we may provide observations. An interesting case was the recent close fly-by of comet C/2013 A1 (Siding Spring) with Mars (above: our image of comet C/2013 A1 (Siding Spring) taken at 20:20 UT on 19 October 2014, with the ESA OGS telescope. The comet, marked with the red dashes, was just emerging from its closest approach and heading North. The vertical and horizontal features emerging from the saturated disk of Mars are artefacts of the telescope. The comet's tail is just barely visible in the image, pointing toward the planet.).
After some tests on the previous night, on October 19 we were ready to collect observations of the comet right around the time of closest approach. The weather was very uncooperative: winds up to 65 km/h, blowing right from the direction of the comet, plus humidity constantly hovering between 90 % and 100 %, forced us to keep the dome closed. However, luck assisted us for about 30 minutes, when conditions improved enough to allow us a peek at the event. And it was worth it: below is a nice picture of this unique event, taken when the objects were only 17° above the horizon.
It was definitely a challenging observation: in addition to the unfavourable atmospheric conditions, we had to deal with imaging a faint object sitting next to a huge source tens of thousands of times brighter. But that's the real job for asteroid hunters!


Lost NEOs (part 2): how to find them… online!
02 Oct 2014
The Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. The images of 2008 CK70 taken used for the precovery discussed in the text were taken with this telescope, and located thanks to the Solar System Object Image Search tool of the Canadian Astronomy Data Centre. (Image credit: M. Micheli)
This post discusses a second component of our observational effort at the NEO Coordination Centre.
After discussing what to do to ensure that an important NEO is adequately monitored, we will now present a possible strategy to improve the orbit of old objects, that have not been properly observed in the past.
In the previous story we talked about how a large fraction of near-Earth objects are effectively lost. This term means that, even if they were discovered and observed in the past, our knowledge of their orbit is not sufficient to allow us to find them again with a telescope the next time they will become observable. This is clearly a concern particularly for the ones that have possible future collisions, because it prevents us from getting additional observations. These observations would be needed to refine the knowledge of their future trajectory to a level sufficient to exclude them from the risk list of dangerous asteroids.
We already discussed the cases where an object can be monitored or recovered with existing optical telescopes, either because it has been discovered recently, or because the uncertainty of its position is not too large. But what can we do if neither option is available?
Fortunately, there is a possibility. Every night, all over the planet, there are dozens of large professional telescopes observing the sky. Some of them may be taking very specific data on individual targets (e.g. performing spectroscopy, polarimetry, or using so-called adaptive optics to obtain high-resolution image data).  However, a large fraction will likely be operating in the most basic mode of astronomical observations of our time, namely taking images of a section of the sky with a digital camera. The goals of these observations can be very diverse, ranging from extragalactic astronomy to stellar astrophysics or cosmology, but the final product will often be the same: images of the sky taken in a particular filter, and with a given exposure time. After these images have been analyzed by the scientists requesting them, they are often made available to the public on the telescope's website. From there, anybody can download them for whatever additional purpose. 
However, there is a high chance that nobody paid attention to asteroids which may be visible in the field. If we have access to these large archives, with a tool which is capable of identifying the appropriate frames, then we may have a chance to find additional observations of an asteroid taken when the object was not yet lost. If that's the case we may be able to locate it, use these data to extend the observed arc, and "save" the object from getting lost. In other cases, these additional observations may at least be sufficient to determine that the object is not a danger for our planet, which is already an important result. This process is called "precovery", a combination of the word "recovery" and the prefix "pre", to suggest that it is based on existing data, and not on new images.
An interesting example of it is represented by an object precovered by our team a few months ago. Found in February 2008 and named 2008 CK70, it was at the time considered as one of the most dangerous known NEOs. It would have multiple chances of impact starting from the year 2079. Unfortunately, the available observations had all been obtained on only five days around the time of discovery, an arc far too short to successfully extrapolate its position to the current time, more than 6 years later. It was therefore effectively considered a lost object, and would probably have remained in such a state until somebody had rediscovered it by chance.
However, after a search in the databases of some large telescopes, we noticed a set of images taken by the Canada-France-Hawaii Telescope (CFHT) in Hawaii. These were taken almost one month before the object had been discovered and covered the area where the object could be. An accurate inspection of the frames allowed us to locate the asteroid, which was extremely faint (magnitude 24.5) at that time, but nevertheless clearly visible in the exposures thanks to the large aperture of the telescope and excellent sky quality of the site. We could accurately measure its position, and add this information to the orbital determination. The resulting significant improvement was sufficient to exclude all possible future impacts for the next century. At the same time it reduced the uncertainty of the sky position for the object to a level small enough to make it recoverable the next time it will come close to the Earth, in 2017.
2008 CK70
An animation of 2008 CK70 as seen in the precovery frames from CFHT. Can you spot the moving asteroid? Hint: it is very faint, but near the centre. (Image credit: CFHT Legacy Survey)
The chance of finding a situation like this, with good images taken at the right time with the right telescope, may not seem large. But, given the number of professional observatories in the world, it is still significant.  Over the past few months we were able to locate precovery observations for at least a dozen asteroids with non-zero impact probability with Earth. For most of them, this resulted in either a reduction of their impact probability or a total removal of the object from the risk list.
Moreover, with the increase of the number of survey telescopes that scan the sky every night, such as the Catalina Sky Survey, or the Pan-STARRS project, the number of exposures available to look for new data is growing fast. And, even if these survey telescopes are designed to look for asteroids, and their images are carefully searched for anything that moves, there is still a chance that something may have been missed. This is especially true if the object is faint, or slow. This is the reason why we need to keep looking into these archives, and why every telescope, big or small, at professional or amateur level, should consider making their data available to the community. You never know what may be hidden in your images, until you look at them from the right perspective!
A more formal discussion of the follow-up and precovery efforts organized by the NEOCC can be found in an abstract presented at the ACM 2014 conference held last month in Helsinki (, and in a related paper soon to be published in the journal "Earth, Moon, and Planets" (


ESA's bug-eyed telescope to spot risky asteroids

22 Sep 2014

Situational awareness

Spotting Earth-threatening asteroids is tough partly because the sky is so big. But insects offer an answer, since they figured out long ago how to look in many directions at once.
As part of the global effort to hunt out risky celestial objects such as asteroids and comets, ESA is developing an automated telescope for nightly sky surveys.
This telescope is the first in a future network that would completely scan the sky and automatically identify possible new near-Earth objects, or NEOs, for follow up and later checking by human researchers.
But a web of traditional telescopes would be complex and expensive because of the number required. Adding to the problem, the system must be able to discover objects many times fainter than the naked eye can perceive.
While no network can spot all potentially hazardous objects, under favourable conditions it should detect everything down to about 40 m in diameter at least three weeks before impact.
Fly-eye Telescope
One telescope, 16 lenses
The answer is a new, European telescope nicknamed ‘fly-eye' that splits the image into 16 smaller subimages to expand the field of view, similar to the technique exploited by a fly's compound eye.
The design is modular, and allows for mass and cheaper production and lower maintenance costs. It will be used to build the prototype, to be fielded by ESA's Space Situational Awareness (SSA) programme early next year.
"This novel technology is key to the future NEO survey network," says Gian Maria Pinna of the SSA office.
Performance equivalent to large telescope
These fly-eyed survey telescopes offer performance equivalent to a 1 m-diameter telescope, and provide a very large field of view: 6.7° x 6.7° or about 45 square degrees; 6.7° is about 13 times the diameter of the Moon as seen from the Earth.
"The new telescopes would provide the resolution necessary to determine the orbits of any detected objects," says Gian Maria Pinna.
"If the prototype confirms the expected performance, it will pave the way to full procurement and deployment of the operational network of telescopes."
This summer, ESA signed a contract for about €1 million with a consortium led by CGS S.p.A (Italy), comprising Creotech Instruments S.A. (Poland), SC EnviroScopY SRL (Romania) and Pro Optica S.A. (Romania) for the detailed design of the advanced telescope.
It is expected that the detailed design will be followed by several additional contracts with European companies valued at up to €10 million for building and deploying the first survey prototype telescope.
"The development of the first optical sensor specific to ESA's NEO search and discovery activities is a fundamental step toward Europe's contribution to safeguarding our planet from possible collisions by dangerous objects," notes Nicolas Bobrinsky, Head of the SSA Programme.

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Lost NEOs (part 1): how to find them in the sky


15 Sep 2014

2014 DN112

A star field containing the near-Earth asteroid 2014 DN112, imaged by the ESO Very Large Telescope in Chile in March 2014. (Image credit: ESA/ESO)

The observational component of NEO science is an extremely important part of the impact mitigation effort, since observations are the input data for all the computational models used to predict future collisions. This post will summarize our effort to ensure that enough data are obtained, especially on the most important and challenging objects, during the short time when they are observable.

At the top of this page there is a counter with the number of objects in the current NEO risk list (their names and details are accessible via the "Risk Page" menu to the left). These are the most important objects to study if you are interested in the danger that asteroids can pose to our planet. This is because they have a non-zero chance of colliding with it over the next century.

However, only a small fraction of them are observable at any given time. And there is more: If you want to point a telescope and collect more data on any of them, you need to know precisely where they are in the sky. In most cases that is a big problem. Of all the known objects which could possibly impact the Earth in the future, approximately 90 % are lost again. This means that the next time they will come close enough to be observable from Earth, we will not know where they will be in the sky. This is  because the uncertainty with which their future position is known increases dramatically with time.

How can we address this problem? There are basically two approaches: we should first do our best to prevent the newly discovered NEOs from getting lost by collecting additional observations to improve the orbit determination process. Secondly, we should make an effort to "recover" some of the old objects the next time they come back, even if their position in the sky is poorly constrained. Because of the importance of these problems, ESA's NEO Coordination Centre organizes a systematic effort to involve multiple observatories and astronomers, in Europe and all over the world, in observing these dangerous asteroids.

Let us start with the most direct way of changing this situation of lost asteroids. On average, one new NEO is discovered every 8 hours. Most of them are found when they are close to us, quite bright and easy to see. Therefore many observations are performed around the time of discovery, both by professional and amateur astronomers worldwide. However, within a few weeks, the objects start receding from the Earth, becoming progressively fainter. When this happens it becomes very likely that no additional data will be obtained, because larger telescopes would be needed. It is not easy to obtain access to these, especially on short notice. This, in turn, means that no additional information may become available, and our evaluation of the danger of the object will not improve anytime soon.

To address this problem, we have or are developing agreements with various professional telescopes, including the ESO Very Large Telescope (VLT) in Chile. The VLT, with its 8.2 meter primary mirror, is one of the most powerful telescopes on the planet. It can easily detect asteroids down to magnitude 26, 100 times fainter than what even the most advanced amateur astronomers can do. Over the last six months we have obtained observations of about 15 such objects. For most of them our detections were sufficient to either clarify that they will not hit the Earth anytime soon, or at least ensure that we will be able to observe them again the next time they come close to the Earth.. Without our observations, most of them would have become new entries in the list of lost objects.

animation of our VLT images of 2014 GY44

An animation of two VLT images of 2014 GY44, when it had a visual magnitude of approximately 26. The object is the faint round dot moving diagonally between the two frames. The stars in the image appear as long trails, because the telescope was moving following the expected motion of the asteroid in the sky. (Image credit: ESA/ESO)

2014GY44 OVT

Plot of the relative position of 2014 GY44 and the inner planets at the time of the VLT observation (1 May 2014), generated using the ESA Orbit Visualization Tool (accessible via this website). The object has an estimated diameter of only 50 meters in diameter and was already more than 36 million kilometers away from Earth. (Image credit: ESA)

But what can we do when the problem arises from a large uncertainty in their position? If the area of the sky where they can be found is reasonably small, say up to a few degrees in size, one can attempt to use telescopes with a large field of view. These can image a significant fraction of this sky area in a short time, with multiple exposures. The object will likely be visible somewhere in these images. If we can locate it we can then measure its position and improve the orbit enough to make it observable again for years to come. This process, called "recovery", is another one of the goals we are  pursuing from the NEOCC, with the help of many cooperating observatories*.

Animation of our VLT images of 2012 HP13

An animation of our VLT images of 2012 HP13, an NEO with a large uncertainty that we recovered two years after its discovery. The moving object at the center of the frame is a real asteroid, but it was not the target of our search. Can you spot the fainter one (which is the NEO we were looking for)? Hint: it is fainter than the central one, and near the bottom of the frame. (Image credit: ESA/ESO)

Unfortunately, there are some objects which are now too faint and too far to observe with even the most powerful telescopes on Earth. Next time they will become bright enough to see, their uncertainties will be huge, too large for even the largest cameras in the world. Some of them, such as the large asteroid 1979 XB, are so hopelessly lost that at their next apparition they can literally be anywhere in the sky!

Fortunately, at least in some cases, there is a way out. More on this in our next story… stay tuned!


*If you have access to a large telescope (anything that can reach magnitude 21 or fainter), and want to collaborate with us, please let us know.


2014 RC - a close fly-by coming up
04 Sep 2014
In the evening of 07 September 2014, the newly discovered asteroid 2014 RC will have a very close fly-by of just above 30000 km to our planet. The object is estimated to be between 10 and 30 m in size. While the fly-by is very close, there is no chance that the object will hit the Earth.
2014 RC was announced as a newly discovered object by the Minor Planet Center in the US on 02 September 2014. Its fly-by velocity will be fairly slow, just around 11 km per second. The European NEODyS system finds a nominal fly-by distance to the Earth's surface of 33587 km, which is just inside the geostationary ring.
The close approach time will be between 18:00 and 18:15 UTC on 07 September 2014 (Update: the revised close approach time was 18:02 UTC).
The object will reach a magnitude of 11 which would make it in principle observable with a pair of binoculars or a small telescope. Unfortunately the object will not be visible over Europe.
This object is comparable in size to the object that entered the Earth's atmosphere over Chelyabinsk in Russia on 15 February 2013. Luckily it will fly by our planet safely.

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Happy Birthday NEOCC!


22 May 2014

AZT-24 Telescope at Campo Imperatore Observing Station

The AZT-24 Telescope at Campo Imperatore Station used for infrared observations of NEAs. (Image credit: INAF)

Today the NEO Coordination Centre (NEOCC) celebrates its first year of activities. On 22 May 2013 the Centre was formally inaugurated at ESRIN by Thomas Reiter, ESA Director of Human Spaceflight and Operations.
Since then, the Centre has regularly provided information and data on NEOs through its main services updated on a daily basis (Risk list, Priority list, Close Approaches and Physical Properties) and through its technical news service.

In addition, several campaigns for astrometric and physical observations of NEAs have been organized and successfully completed. A network of collaborating observatories has been created.

A good example for an astrometric and physical observation campaign was the case of 2013 QW1, a candidate NEO in an Earth-bound orbit whose nature, either natural or artificial, needed to be quickly determined. An observing alert triggered by the NEOCC resulted in rapid spectroscopic observations from the 3.5-metre Italian Telescopio Nazionale Galileo (TNG) in the Canary Islands, which contributed to exclude that 2013 QW1 was  a natural object because of the "artificial" appearance of its reflectance spectrum. We acknowledge Davide Perna, Antonella Barucci (Observatoire de Paris Meudon) and Elisabetta Dotto (INAF – Osservatorio di Roma) for having responded to our call.

The observing campaign of 2002 GT fits along the second type of activities done by the NEOCC, namely to coordinate observations. The observing campaign was organised by the Centre to characterise the target selected for the NASA EPOXI (formerly Deep Impact) mission during its last apparition before the then planned encounter with the spacecraft. A large community promptly responded: photometric and light-curve observations were performed from the 1-metre diameter C2PU telescope at the Observatoire de la Cote d'Azur, which allowed the calculation of the rotation period of the object (3.77 hours). Spectra and photometric data were collected from the Asiago Observatory (University of Padova and Observatory of Padova) allowing the determination of the asteroid type (Sq); infrared observations were provided from the Campo Imperatore Station of the INAF Rome Astronomical Observatory. Finally, several astrometric measurements were provided by six telescopes belonging to the Gaia Follow-up Network for Solar System objects (Gaia-FUN-SSO).

Deep Impact Launch

Deep Impact lifts off from pad 17-B at Cape Canaveral Air Force Station, Fla., bound for Comet Tempel 1. (Image credit: NASA/KSC)

Building up on these early experiences, a framework agreement with ESO's Very Large Telescope (VLT) has been established, which has allowed the Centre to start a focused observational effort to obtain astrometric observations of high-risk objects. This collaboration allowed the NEOCC team to obtain critical observations of almost a dozen dangerous objects, which in most cases led to their removal from the list of possible future impactors; a few recent examples have been the early recovery of 2009 FD (currently the highest-rated known possible impactor) and the challenging follow-up observations of 2014 AF16.

The regular availability of the ESA Optical Ground Station (OGS) Telescope for ESA's NEO programme turned out to be extremely useful to perform routine observations of newly discovered objects, with a specific focus on the urgent targets suggested by the NEOCC Priority List.

ESA OGS Telescope

The ESA Optical Ground Station (OGS).  (Image credit: ESA)

The Centre keeps growing. The technical and scientific team behind the NEOCC is working on the implementation of new services and on the improvement of the existing ones, which will be soon available.  Meanwhile, a well-timed gift is already on the way for celebrating the second birthday of the NEOCC: the 4th IAA Planetary Defence Conference will be hosted at ESA/ESRIN on 13 - 17 April 2015. See you then!

External links:

ESA/ESO Collaboration Successfully Tracks Its First Potentially Threatening Near-Earth Object. ESO Announcement, 21 January 2014.
Target Asteroid Tracked by European Teams. ESA SSA News, 18 July 2013.
Space Oddity: The Mystery of 2013 QW1. ESA SSA News, 19 September 2013.

Publications related to NEOCC activities:

E. Perozzi, D. Koschny, R. Dominguez-Gonzalez, G. Drolshagen, N. Sanchez-Ortiz. The SSA NEO Segment and Gaia: present opportunities and future developments. In proc. ‘2nd Gaia-Follow-Up Network for Solar System Objects'. P. Tanga and W. Thuillot eds. IMCCE/Observatoire de Paris, 2013.

E. Perozzi. The Near Earth Object Hazard and Mitigation. In proc. ‘Mathematical Methods for Planet Earth'.A. Celletti, U. Locatelli, E. Strickland eds, Springer. 2013 (in press).

E. Perozzi, F. Bernardi, A. Milani, G.B. Valsecchi. "Vicini ma non troppo". Le Scienze, July 2013.
E. Perozzi, F. Bernardi, E. Foschi, G. Drolshagen, D. Koschny, G.B. Valsecchi: Observing small and accessible NEOs: the importance of newly discovered objects. Stardust Virtual Workshop, Glasgow 6-9 May 2014.

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A good year to find a comet


12 February 2014
Comet P/2014 C1 seen from Argentina
Comet P/2014 C1 seen from Argentina's Pierre Auger Observatory on 4 February 2014 (Image credit: FRAM/GLORIA/Martin Masek)
A team of European astronomers has found a previously unknown comet, detected as a tiny blob of light orbiting our Sun deep in the Solar System.
The comet was unexpectedly discovered on 1 February during a routine set of observations using the 1 m-diameter telescope at ESA's Optical Ground Station, Tenerife, Spain.
The confirmation was announced by the International Astronomical Union's Minor Planet Center, the international clearing house for all such discoveries, on 4 February, after eight other observatories confirmed the sighting.
The tiny object is extremely faint, and its orbit was determined to lie between Jupiter and Mars – it will not come close to Earth.
Comet year
"All comets are interesting especially as they are thought to have played a role in bringing water to Earth in the distant past," says Detlef Koschny, responsible for near-Earth object (NEO) activities at ESA's Space Situational Awareness (SSA) programme office.
Orbit of comet P/2014 C1 TOTAS
Orbit of comet P/2014 C1 TOTAS (Image credit: TOTAS) 
"Later this year, Rosetta will meet up with another comet, 67P/Churyumov–Gerasimenko, and study its nucleus and surrounding gas and dust, so it's especially fitting that a European team has found a new comet this year."
This latest discovery was, in fact, made by software, which compares successive images to find ‘movers' – objects that move against the star field background. The find was confirmed by Rafal Reszelewski, working as part of the team to verify possible new objects automatically flagged by the  software.
Since 2010, the TOTAS team has been working in collaboration with ESA's SSA office to conduct periodic sky surveys to find and confirm asteroids and other NEOs that orbit close to Earth. In 2011, it found asteroid 2011 SF108, which does orbit much closer to Earth.

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TOTAS survey finds its first comet


6 January 2014

In a fruitful collaboration between ESA and a group of amateur astronomers, the first comet was discovered by the so-called TOTAS survey. The comet is called P/2014 C1 (TOTAS) and has an orbit between Jupiter and Mars.

TOTAS stands for 'Tenerife Observatory Teide Asteroid Survey'. The survey name is derived from the name SOHAS = Starkenburg Observatory Heppenheim Asteroid Survey. SOHAS was initiated by M. Busch, a software developer and active amateur astronomer at the public observatory in Heppenheim, Germany (called Starkenburg-Sternwarte). Already in 2009, M. Busch adapted his telescope control and asteroid search software to work with the 1-m telescope of ESA on Tenerife, the Optical Ground Station, and renamed it TOTAS.

When the SSA-NEO programme learned about this, a long and fruitful collaboration started in March 2010. During a survey test campaign very close to the morning horizon on 01 February 2014, the automatic processing software picked up a special object. R. Reszelewski, one of the team of amateur astronomers who check the images generated by the computer software, was the first to detect the cometary nature
(Figure 1).


Image of Comet P/2014 C1 (TOTAS)

Figure 1: Animation of the comet (Image credit: TOTAS/ESA)

The observations were immediately submitted to the Minor Planet Center. On 04 February, after confirming messages of eight other observatories securing the orbit, the Minor Planet Center announced the discovery of comet TOTAS (

The comet orbits the Sun between Jupiter and Mars and will not come close to the Earth. Its orbit is shown in Figure 2.


Comet P/2014 C1 (TOTAS) orbit

Figure 2: Comet P/2014 C1 (TOTAS) orbit (Image credit: M. Bush/EasySky)

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Getting ready for asteroids


31 January 2014
Asteroids passing Earth 
With a mandate from the UN, ESA and other space agencies from around the world are about to establish a high-level group to help coordinate global response should a threatening asteroid ever be found heading towards Earth.
For the first time, national space agencies from North and South America, Europe, Asia and Africa will establish an expert group aimed at getting the world's space-faring nations on the ‘same page' when it comes to reacting to asteroid threats.
Its task is to coordinate expertise and capabilities for missions aimed at countering asteroids that might one day strike Earth.
Of the more than 600 000 known asteroids in our Solar System, more than 10 000 are classified as near-Earth objects, or NEOs, because their orbits bring them relatively close to our path.
Asteroid trace over Chelyabinsk
Dramatic proof that any of these can strike Earth came on 15 February 2013, when an unknown object thought to be 17–20 m in diameter arrived at 66 000 km/h and exploded high above Chelyabinsk, Russia, with 20–30 times the energy of the Hiroshima atomic bomb.
The resulting shock wave caused widespread damage and injuries, making it the largest known natural object to have entered the atmosphere since the 1908 Tunguska event, which destroyed a remote forest area of Siberia.
Coordinating global efforts
The Space Mission Planning and Advisory Group (SMPAG – pronounced ‘same page') was established by Action Team 14, a technical forum with a mandate from the UN Committee on the Peaceful Uses of Outer Space (UNCOPUOS) to develop a strategy on how to react on a possible asteroid impact threat.
It will coordinate the technological knowhow of agencies to recommend specific efforts related to asteroid threats, including basic research and development, impact mitigation measures and deflection missions.
Control room of ESA's observatory on Tenerife
"SMPAG will also develop and refine a set of reference missions that could be individually or cooperatively flown to intercept an asteroid," says Detlef Koschny, Head of the NEO Segment in ESA's Space Situational Awareness (SSA) programme office.
"These include precursor missions or test and evaluation missions, which we need to fly to prove technology before a real threat arises."
The first-ever meeting will be hosted by ESA on 6–7 February at its operations centre in Darmstadt, Germany.
Thirty-plus representatives from 13 agencies, seven government ministries and the UN will share knowledge and the latest research related to impact case studies, and will develop a work plan for the next two years.
"As a first step, the group will study each agency's organisational and operational capabilities, specific technologies and scientific abilities, and propose options that make best use of who can do what, the best," says Detlef.
ESA Space Situational Awareness: detecting space hazards
The group will work in close cooperation with another Action Team 14-mandated committee: the International Asteroid Warning Network (IAWN).
Each will study and recommend specific actions to deal with different aspects of the asteroid threat – IAWN to coordinate the global search for threatening NEOs, understand their effects in case of a collision, and interface with disaster preparation and civil response agencies; and SMPAG for the technology and space mission aspects.
Current threats, future scenarios
The critical first step is to spot potential threats in the sky with as much advance warning as possible.
"ESA is already doing a great deal to support the global effort to address the asteroid threat," says Nicolas Bobrinsky, ESA's SSA Programme Manager.
The Agency is now developing the capability to integrate Europe's current NEO tracking assets – as well as new technology such as automated, wide-field-of-view telescopes – into a coordinated and more efficient NEO system that can provide nightly sky surveys and advanced warnings.
Among other recent developments, starting in late 2013, ESA will make use of observing time at the European Southern Observatory in Chile to conduct quick and accurate confirmations of the most hazardous NEOs.

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The Recovery of 2009 FD, a Potentially Hazardous Asteroid


21 January 2014

VLT Telescopes

The VLT telescopes on the Paranal mountain in Chile (credit: ESO).

The first recovery campaign carried out by the ESA NEO Coordination Centre in coordination with ESO, using the Very Large Telescope (VLT) turned out to be a success. Before the campaign, asteroid 2009 FD was ranked among the top five objects in the risk list. Now the associated value on the so-called Palermo scale ( has dropped by almost a factor of ten to a value of -2.6 (from -1.8 on the logarithmic scale).

The observations were performed by a team including Olivier Hainaut (ESO), Detlef Koschny (ESA), and Marco Micheli (NEOCC team, ESA/Serco), with the FORS2 camera on the 8.2-meter VLT telescope on Cerro Paranal in Chile. Images of the area of the sky where the object was located were obtained on five different nights, between 30 November and 5 December 2013.

It was a challenging recovery. Although it was possible in the first night to locate the asteroid position with good accuracy, the following two nights the observing conditions were worse. The faint "clump of pixels" indicating the position of 2009 FD was still detectable but the quality of the astrometric data degraded. In the following nights bad seeing and technical reasons prevented further improvements. Nevertheless, a detailed re-examination of the data resulted in good-quality astrometric data which has been accepted by the Minor Planet Center, the central clearing house for asteroid astrometry. The object's observations were finally taken into account in their 'daily orbit update' of 11 December 2013.

Screenshot of asteroid 2009 FD, at a magnitude of ~24.

Both the European NEODyS system and the JPL-based Sentry system performed orbit determination and impact monitoring using the new observations. These computations showed that there are still some low-probability impact solutions, ranging from the years 2185 to 2198. Yet they are likely to disappear within the next few months, when 2009 FD will become progressively brighter, peaking at a magnitude of V=19 in mid-March 2014, thus ensuring a proper astrometric coverage.

The successful recovery of 2009 FD shows that having access to a large telescope such as the VLT is a great opportunity for the NEO Coordination Centre, since it gives a chance to obtain astrometric observations of very faint objects (down to visual magnitude 25.5) which only very few people and instruments in the world can do.  


Palermo scale:

The Very Large Telescope:

ESA's SSA-NEO Coordination Centre:

European Southern Observatory:

ESA/ESO Collaboration Successfully Tracks Its First Potentially Threatening Near-Earth Object:


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Observing 2013 NJ: A study case


4 December 2013

Pan-STARRS of 2013 NJ
Discovery images of 2013 NJ, obtained on 1 July 2013 by the NASA-funded Pan-STARRS telescope in Hawaii.
If an asteroid is discovered which could come very close to Earth, it is important to coordinate observational activities quickly to better know its precise flyby distance.This is illustrated by the following case of near-Earth asteroid (NEA) 2013 NJ.
2013 NJ is a 100-meter class object (absolute magnitude H = 22) discovered in early July 2013. It had a close encounter with the Earth on 26 November 2013, 1 million kilometers away from our planet. Even if the object was carefully tracked by observers around the time of discovery, its observational geometry then kept it close to the Sun for the past few months, making it unobservable from the ground until after its current close encounter with the Earth.
As a result, when the object became observable a few days ago from the Southern hemisphere, its position in the sky was poorly known. Without immediate additional astrometric observations the asteroid position in the sky would not have been constrained enough to allow pointing narrow-field instruments devoted to physical characterization (i.e. spectrometers, polarimeters) to the asteroid. Luckily, with a peak visual magnitude of 14 this object was bright enough to be easily reobserved even with small telescopes. It was actually recovered from Cerro Tololo in Chile, less than 24 hours after its close approach, providing the astrometric information needed to significantly improve its orbit and predict its path in the sky for the following days. But what would have happened if 2013 NJ were a much smaller object?
Things would not have proceeded as smoothly as they did. Such an asteroid would have been at risk of being lost, unless the object would have been recovered when still on the southern hemisphere - difficult, as there are not so many telescopes there. Physical characterization needed also to be planned in a timely manner and attempted quickly. The asteroid would be going through a much fainter magnitude range, thus implying more demanding observational requirements in terms of time scale and telescope performances.
This "study case" scenario demonstrates that a quick coordinated response, able to ensure challenging astrometric and physical follow-up of small objects, is essential for the future developments of NEA research and mitigation. Even more since the US and European NEO space programmes are increasingly focused on small accessible asteroids, which are likely to be discovered in circumstances resembling that of 2013 NJ, forcing astronomers to react on short timescales and organize their observations during very short visibility windows.

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09 November 2013

On 8 November 2013 asteroid 2013TV135 has been removed from the Risk Page. The non-zero impact probability spotted by monitoring systems just after its discovery (on 8 October 2013) dropped essentially to zero. The bulk of astrometric data collected by astronomers during exactly one month of observations helped to improve our knowledge of its orbit, that eventually turned out to be a safe one.

With respect to the impact monitoring analysis, the case of 2013TV135 is a very typical one. Statistically speaking, almost every NEA initially found to have non-zero impact probability will eventually turn out to be actually safe for the Earth. And this is even more true for the bigger ones.

Every time new astrometric data become available from observations, the characterization of the asteroid orbit improves and the estimated impact probability is re-computed. This may happen in the days, weeks, months or even years following the discovery date, depending on the availability of observational data.

A typical pattern is that as the orbit becomes more precisely determined, impact probability often increases initially, or shows a quite erratic behaviour (see, for instance, the table in "2013TV135, A newly discovered object at the top of the impact risk list"), but then decreases until it falls to zero, or some very low number. This is exactly what happened with 2013TV135.

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23 October 2013

Crimean Astrophysical Observatory

Crimean Astrophysical Observatory (Credit: Wikipedia)

Soon after having been spotted in the sky on 8 October 2013 from the Crimean Astrophysical Observatory (Ukraine), asteroid 2013TV135 topped the Risk Page.

Being a relatively large object (500 m in size) it quickly gained the headline news having ramped up the Palermo Scale value for a possible impact in August 2032.

The object has an absolute magnitude of 19.6 and it is currently easily observable. Although the many observations performed worldwide for orbit improvement, the impact probability and Palermo Scale continue to change with no clear pattern.

"We need more data, and also higher quality data with very accurate astrometry; we do not need too many observations, 3-5 observations per night is optimal" suggests Andrea Milani, on behalf of the NEODyS consortium.

Additional information can be extracted from the past history of 2013TV135: computing backwards ephemeris one notices that its brightness peaked at about 16th magnitude in mid-September, well before discovery, when it was observable from the southern hemisphere. Uncertainty analysis reveals that were the object first spotted at that time, its orbit would have been quickly well constrained thus avoiding any further concern.

Thus 2013TV135 is telling us the importance of both, a well coordinated follow-up campaign and the importance of extending the NEO sky surveys to the southern skies.

For the time being, stay tuned: the values of the impact probability (IP) and  Palermo Scale (PS) are reported daily in the table below:

 impact date            IP         PS    computation date

 2032/08/26.371  2.02E-5  -1.73    2013/10/16
 2032/08/26.364  2.74E-5  -1.62    2013/10/17
 2032/08/26.355  4.34E-5  -1.41    2013/10/18
 2032/08/26.352  2.65E-4  -0.62    2013/10/19
 2032/08/26.355  1.34E-4  -0.86    2013/10/20
 2032/08/26.354  1.19E-4  -0.88    2013/10/21
 2032/08/26.355  1.22E-4  -0.86    2013/10/22
 2032/08/26.355  1.97E-4  -0.65    2013/10/23
 2032/08/26.357  1.62E-4  -0.74    2013/10/24
 2032/08/26.357  1.02E-4  -0.95    2013/10/25
 2032/08/26.358  7.38E-5  -1.07    2013/10/26
 2032/08/26.358  7.70E-5  -1.06    2013/10/27
 2032/08/26.358  7.43E-5  -1.08    2013/10/28
 2032/08/26.358  9.42E-5  -0.97    2013/10/29
 2032/08/26.358  1.50E-4  -0.77    2013/10/30
 2032/08/26.359  2.31E-4  -0.58    2013/10/31
 2032/08/26.359  2.20E-4  -0.60    2013/11/01
 2032/08/26.359  6.46E-5  -1.14    2013/11/02
 2032/08/26.358  7.58E-6  -2.07    2013/11/03
 2032/08/26.358  5.25E-9  -5.49    2013/11/04
 2032/08/26.358  8.36E-8  -4.03    2013/11/05
 2032/08/26.359  2.79E-7  -3.51    2013/11/06
 2032/08/26.358  1.82E-7  -3.69    2013/11/07

Update: on 8 November 2013 asteroid 2013TV135 has been removed from the Risk Page. The non-zero impact probability spotted by monitoring systems just after its discovery dropped essentially to zero. The bulk of astrometric data collected by astronomers during one month of observations helped to improve our knowledge of its orbit, that eventually turned out to be a safe one.

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19 September 2013

Artificial object 2013 QW1 as imaged by Telescopio Nazionale Galileo/TNG.

Artificial object 2013 QW1 as imaged by Telescopio Nazionale Galileo/TNG (Copyright TNG/Telescopio Nazionale Galileo)

Last month, ESA's near-Earth asteroid coordination centre triggered a series of European observations that confirmed an unknown object was, in fact, of human origin. The confirmation was the Centre's second such success in recent months and demonstrates the effectiveness of the Agency's asteroid-monitoring activities.

On 23 August, a rather unusual object was spotted in the sky by the US PanSTARRS asteroid survey and provisionally named 2013 QW1. The suspected near-Earth object (NEO) was moving in an Earth-centred orbit, leading astronomers to ask: was it natural or artificial?

If artificial, it would not be the first time that an asteroid-hunting survey had rediscovered a lost rocket stage wandering in space close to the edge of our planet's gravitational reach.

Apollo 12 on the launch pad

Apollo 12 at Pad A, Launch Complex 39, Kennedy Space Center (Copyright NASA)

Another object found in 2002

For example, when the third stage of the Apollo 12 mission failed to crash on the Moon as planned (NASA used such impacts to generate ‘Moonquakes' that could be studied by lunar seismographs to gain information on the Moon's interior), its subsequent orbital evolution was alternatively dominated by the attraction of the Sun and Earth.

The object was eventually rediscovered in 2002 as a temporary satellite of Earth, and its manmade origin was revealed by analysing the light reflected by the rocket body, which did not resemble that of an asteroid but rather revealed the titanium-enriched white paint used at that time for the Apollo rockets.

However, for the mysterious 2013 QW1, things were not that simple, and further observations were needed to determine whether it was artificial or natural.

That's when ESA's NEO Coordination Centre became involved, sending an alert to a number of collaborating observatories in Europe to trigger additional observations that might help to confirm the object's identity.

2012 QW1 Spectrum

2013 QW1 Spectrum (Copyright Observatoire de Paris/D. Perna and Maria Antonietta Barucci)

European astronomers up to challenge

The challenge was taken up by a team led by Elisabetta Dotto at INAF–Osservatorio di Roma, and Davide Perna and Maria Antonietta Barucci at the Observatoire de Paris, Meudon, who obtained time on the Italian Telescopio Nazionale Galileo to capture light reflected from the object.

"It was a bit of a challenge, because the object was moving fast with respect to a typical suspected NEO," said Dr Perna.

"But despite the difficulties, observations were made with an instrument called DOLORES, for ‘Device Optimized for the LOw RESolution', which allowed us to obtain the object's spectrum."

The result was a spectrum that does not resemble any asteroid. Instead, it bore strong similarities with the spectra of previously observed space junk such as discarded rocket stages, abandoned boosters or defunct satellites.

These measurements provided convincing evidence of the artificial nature of 2013 QW1 – it is possibly a booster stage – and supported it being removed from ESA's NEO catalogue and included, under the name 2010-050B, in the Minor Planet Center's Distant Artificial Satellite Observations list.

ESA's coordinating role

The event highlights the coordination role that ESA's new NEO Coordination Centre is playing in addition to its primary function of providing information on all known NEOs, including their orbits, impact risk and close approaches to Earth.

"The observations by European astronomers coordinated by ESA demonstrated a very quick reaction in getting high-quality data that conclusively identified the object as artificial, and hence no threat," says Detlef Koschny, responsible for NEO activities at ESA's Space Situational Awareness programme office.

"Our Centre has again shown it is serving as a focal point for coordinating observations which are vital for the European and international community involved in asteroid science, impact monitoring and mitigation."

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14 August 2013

The number of known Near-Earth Asteroids has just overcome 10,000 units! This result represents an important achievement if one thinks that over the one hundred years between 1898 (when the first NEA, 433 Eros was discovered) and 1998 only about 500 NEAs had been found, while the current NEA discovery rate is about 1,000 per year.

Out of the 10,000 discoveries, roughly 10 percent are larger than one kilometer in size, while the vast majority of NEAs are smaller than that, with the number of objects of a given size quickly increasing as the size decreases.

The first and most important step to protect our planet from NEAs is to discover all objects potentially at risk of collision with the Earth and in doing so the present wide-field, high-sensitivity sky surveys have proven extremely effective, putting astronomers are on the right track.

Eros Dicovery Plate

The elongated track left by 433 Eros is clearly visible in the discovery plate of the first NEA taken by Gustav Witt from the Observatory of Berlin. More details on the story behind Eros discovery at

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18 July 2013

In a recent close-ish flyby, asteroid 2002 GT was studied in detail for the first time by a network of European astronomers. The observations were coordinated by ESA's asteroid centre in Italy, and should prove crucial for a future spacecraft rendezvous.

Asteroid 2002 GT, a relatively large object a few hundred metres across, made a somewhat close flyby of Earth on 26 June, passing us at almost 50 times the distance of the Moon.

Asteroid 2002GT passes Earth 26 June 2013 (More about this video)

The encounter sparked intensive worldwide observations because the asteroid is the target of NASA's Epoxi mission in January 2020.

Last month's flyby was the last chance before then to study the object's diameter, rotation, composition and other physical characteristics.

Ideal opportunity to coordinate response

"The flyby presented an ideal opportunity to exercise the unique ‘coordinating function' of ESA's new Near-Earth Object Coordination Centre," says Ettore Perozzi, project leader for NEO services at Deimos Space.

Asteroid in infrared

"By alerting and then collating observations from diverse European teams, the Centre was able to provide a comprehensive set of results back to the scientific and space exploration communities, a cycle that wasn't happening before. This is really a first for Europe."

Deimos Space leads a project team that operates the Centre at the Agency's ESRIN site near Rome.

The gathered information will enable a very good characterisation of the asteroid's surface composition, thermal properties, shape and rotation. All of these features are crucial for any spacecraft visit.

Moreover, analysis of its changing brightness indicates the possible presence of a small moon.

 Focal point: ESA's NEO Coordination Centre

Gerhard Drolshagen, co-manager of the NEO segment at ESA's Space Situational Awareness programme office, says the 2002 GT event highlighted the potential coordination role that the Centre can play in addition to its primary function of providing information on all known NEOs, including their orbits, impact risk and close approaches to Earth.

"Traditionally, Europe's asteroid community reliably delivered world-class observations and has been credited with many significant discoveries and findings. What was lacking, however, was a central point to coordinate and synthesise data that could function across national and organisational boundaries.

Asteroid 2002 GT

"Our Centre has proven it can act as a driving force and a focal point for the European and international community involved in asteroid science, impact monitoring and mitigation."

Ettore adds: "We now know 2002 GT is a rocky body, belonging to a peculiar transition class that astronomers refer to as ‘Sq-type'.

Asteroid type

"It's also a potentially hazardous object, as its orbit crosses that of Earth, so it's certainly a very interesting object, well worth watching."

More about the NEO Coordination Centre, SSA and contact information

About 2002GT observations

ESA's Near-Earth Object Coordination Centre (NEO-CC) received well-documented observations of 2002GT as follows:

- Photometry and light-curve data from the 1 m-diameter C2PU telescope at the Observatoire de la Cote d'Azur, which allows calculation of the rotation period (3.77 hours). The shape of the light curve is also compatible with the presence of a satellite.

- Spectra and photometric data from Asiago Observatory (University of Padova and Observatory of Padova) which allows determination of the asteroid type (Sq), in agreement with other observations.

- Infrared observations from the Campo Imperatore Station of the INAF Rome Astronomical Observatory. Even under bad weather conditions, teams there were able to spot the asteroid 20 days before Earth flyby.

- Astrometry from Gaia-FUN-SSO. Six telescopes observed 2002 GT providing more than 1000 astrometric measurements. These were sent to the Minor Planet Centre and processed at the Institut de Mécanique Céléste et de Calcul des Ephémérides for computing orbital elements.

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24 June 2013

A new series of images from Gemini Observatory shows Comet C/2012 S1 (ISON) heading toward an extremely close rendezvous with the Sun. The images have been takenbetween February and May 2013 and show the comet's remarkable activity despite its current great distance from the Sun and Earth (730-580 million kilometers; or 4.9-3.9 A.U. from the Sun, just inside the orbital distance of Jupiter). Each image in the series is taken with the Gemini Multi-Object Spectrograph at the Gemini North telescope on Mauna Kea, Hawaii.

Discovered in September 2012 by two Russian amateur astronomers, Comet ISON will come to perihelion on 28 November 2013 at a distance of 0.012 AU (1,800,000 km) from the center point of the Sun. Accounting for the solar radius, the comet will pass approximately 1,100,000 km above the Sun's surface. This will be a very close pass. With a fairly large nucleus, estimated in the 1 to 10 km range, the comet will surely undergo strong radiation and tidal stresses and a tidal breakup is not an improbable outcome of the graze. But if Comet ISON survives that close encounter, the comet may appear in the morning sky before dawn in early December and become one of the greatest comets in the last 50 years or more.

Images of Comet ISON obtained using the Gemini Multi-Object Spectrograph at Gemini North on February 4, March 4, April 3, and May 4, 2013 (left to right, respectively; Comet ISON at center in all images). Credit: Gemini Observatory/AURA.

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17 June 2013

An interesting connection between Earth Observation and NEO monitoring activities has been unveiled through the NEO Coordination Centre participation at the "Big Data From Space" meeting, held at ESRIN from 5 to 7 june 2013 (

The meeting aims to timely face the challenge of the huge increase in the images flow coming from space which will characterise the next generation of Earth Observation missions. The study case presented by the NEOCC refers to the discovery and characterization of the Kamil crater, a rayed impact crater with 45 m in diameter located in southern Egypt and first identified on Google Earth in 2008.

The Kamil crater floor depth is 16 m and is overlain by a 6 m-thick crater-fill material, which is consistent with a crater generated by an iron meteorite 1.3 m in diameter impacting at a velocity between 3 and 4 km/s. QuickBird Image 2009, Courtesy of Telespazio.

A geophysical expedition was undertaken in February 2010, which collected several hundred kilograms of nickel-enriched iron meteorites and performed in-situ measurements. Prior to the expedition extensive analysis of the impact site was performed by both high resolution optical images and by radar acquisitions from the Italian COSMO-SkyMed satellites, allowing detailed geo-morphological analysis of the features surrounding the crater and the search for secondary impacts.

The possibility of setting up an extended survey of small impact craters in inaccessible regions by using multispectral high resolution images appears then an appealing opportunity and a novel application within the "Big Data" initiative. The utilisation of Earth Observation data for developing and implementing new services at the NEO Coordination Centre and their contribution to operations has been also discussed. The NEOCC presentation can be found here.

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22 May 2013

SSA NEO-CC inauguration

ESA today inaugurated a new hub that will strengthen Europe's contribution to the global hunt for asteroids and other hazardous natural objects that may strike Earth.

Near-Earth Objects, or NEOs, are asteroids or comets with sizes ranging from metres to tens of kilometres that orbit the Sun and whose orbits come close to that of Earth. There are over 600.000 asteroids known in our Solar System, and almost 10.000 of them are NEOs.

Dramatic proof that some of these could strike Earth came on 15 February, when an unknown object thought to be 17–20 m in diameter exploded high above Chelyabinsk, Russia, with 20–30 times the energy of the Hiroshima atomic bomb. The resulting shock wave caused widespread damage and injuries, making it the largest known natural object to have entered the atmosphere since the 1908 Tunguska event.

The NEO Coordination Centre will serve as the central access point to a network of European NEO data sources and information providers being established under ESA's Space Situational Awareness (SSA) Programme.

This is the second centre to be opened under SSA leadership after the Space Weather Coordination Centre that opened in Brussels last month.

Asteroid trace over Chelyabinsk, Russia, on 15 February 2013

Located at ESRIN, ESA's centre for Earth observation, the centre was formally inaugurated today by Thomas Reiter, ESA Director of Human Spaceflight and Operations, together with Augusto Cramarossa, Italian Delegate to the ESA Council, and Claudio Portelli, Italian Delegate to the SSA Programme, both of ASI, the Italian space agency.

The event was hosted by Volker Liebig, ESA Director of Earth Observation Programmes and Head of the ESRIN Establishment.

The new centre will support experts in the field by federating new and existing European assets, systems and sensors into a future NEO system. It will support the integration and initial operation of ESA's NEO information distribution network.

Asteroid 2012DA14

The Centre is also the focus point for scientific studies needed to improve NEO warning services and provide near-realtime data to European and international customers, including scientific bodies, international organisations and decision-makers.

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8 May 2013

Asteroid trace over Chelyabinsk, Russia, on 15 February 2013

In February, a speeding asteroid slammed into our atmosphere and exploded high over Russia's Ural region, injuring hundreds and causing millions of euros of damage. What should we do if we have a similar – or even bigger – strike in the future?

Of the more than 600.000 known asteroids in our Solar System, almost 10.000 are classified as near-Earth objects, or NEOs, because their orbits bring them relatively close to Earth's path.

Dramatic proof that any of these can strike Earth came on 15 February, when an unknown object thought to be 17–20 m in diameter arrived at 66 000 km/h and exploded high above Chelyabinsk, Russia, with 20–30 times the energy of the Hiroshima atomic bomb.

The resulting shock wave caused widespread damage and injuries, making it the largest known natural object to have entered the atmosphere since the 1908 Tunguska event, which destroyed a remote forest area of Siberia.

"It's important that we become aware of the current and future position of NEOs, develop estimates on the likelihood of impacts and assess the possible consequences," says Detlef Koschny, Head of NEO activities in the Agency's Space Situational Awareness (SSA) Programme Office. 

Artist's impression of asteroids passing Earth

"More importantly, we must consider whether and how warning, mitigation and possible deflection actions can be taken. It's important not only for Europe, but for the rest of the planet, too."

One aspect of ESA's four-year-old SSA activity requires the development of an integrated system to scan the sky nightly for as-yet-undiscovered NEOs.

Another important element is studying how mitigation measures can be applied in the case of smaller NEOs, and how to deflect any larger ones that may seriously threaten our home planet.

This week, Deimos Space, an industrial partner working for ESA on SSA, has invited top researchers from universities, research institutes, national space agencies and industry in Europe and the USA to discuss the state of the art in NEO impact effects and threat mitigation.

The meeting is taking place in Tres Cantos, Spain, near Madrid.

"A great deal of work remains to be done, for example, in computer modelling of impact effects, how airbursts differ from ground strikes, kinetic versus explosive deflection strategies and much more," says Gerhard Drolshagen, of the SSA Programme Office.

"The aim is to develop plans that will guide us in current and future NEO research and development."

Ultimately, ESA aims to develop the capability to integrate Europe's current and new assets – such as automated telescopes – into a coordinated and more efficient NEO system that can provide nightly sky surveys and advanced warning.

"With this, we can work with our partner agencies, scientists, industry and international bodies like the UN to offer firm options to national governments and political decision-makers," says Nicolas Bobrinsky, Head of ESA's SSA Programme.

"Events like the Chelyabinsk strike show that the NEO hazard is not just theoretical, and we need to invest in practical measures today to address tomorrow's threats."

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19 February 2013

In the last observing slot the TOTAS survey found another NEO. This is the fifth NEO found in about 300 hours of survey time, which is a good result considering the field of view of the telescope. The lucky 'clicker' who identified the object as a real object was Felix Hormuth. Congratulations!

The object was announced by the Minor Planet Center here:

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18 February 2013

On 15 Feb 2013, a very large fireball was reported over Chelyabinsk, Russia. Peter Brown from the University of Western Ontario, Canada, analyzed infrasound measurements of the event and deduced the following parameters:

Time of impact: 03:20:26 UT on 15-FEB-2013
Entry angle: 20 degree from surface
Entry velocity: below 20 km/s
Trajectory direction: North to South
Asteroid diameter before entry in the atmosphere: about 15 m
Kinetic energy: 500kt TNT equivalent (corresponding to 30 times the energy of the Hiroshima bomb)
Explosion altitude: 15-25 km

The direction of the trajectory and the large distance in time indicate that the object was unrelated to asteroid 2012DA14, which had a very close flyby in the evening of the same day.

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7 February 2013

Artist's impression of asteroids passing Earth

A little-known asteroid will skim past Earth on 15 February, passing just 28 000 km from our planet. The 50 m-diameter chunk of space rock was discovered last year by ESA-sponsored amateur astronomers in Spain.

Details of the ancient asteroid, 2012 DA14, are sketchy – no direct measurements of its size are available. From its brightness, scientists estimate its diameter at 50–80 m. Its composition is unknown and its mass is thought to be of the order of 130 000 tonnes.

What is known is that it will not impact Earth anytime soon.

"Its orbit can be computed quite accurately using Europe's NEODyS asteroid database," says Detlef Koschny, responsible for near-Earth objects at ESA's Space Situational Awareness office.

"These computations show that a collision with Earth can be excluded quite safely at least for this century."

Asteroid 2012 DA14

On 15 February, the asteroid will make its closest pass to our planet this century when it flies by at 7.8 km/s at a distance of just within 28 000 km.

"This is well inside the geostationary ring, where many communication satellites are located," says Detlef. "There is no danger to these satellites, however, as the asteroid will come ‘from below' and not intersect the geostationary belt."

The asteroid will make its closest approach at around 19:40 GMT (20:40 CET) on Friday evening next week. While tiny against the vastness of our Solar System, it should be visible in Europe to anyone with a good pair of binoculars and an idea of where to look (see link to details below).

The asteroid was discovered by the La Sagra Sky Survey, which is supported by ESA's Space Situational Awareness programme, on 22 February 2012. The observatory is in southeast Spain, near Granada, at an altitude of 1700 m, one of the darkest, least light-polluted locations on the European mainland.

The small size and previously unknown orbit of 2012 DA14 meant that it was spotted only after it had flown past Earth at about seven times the distance of the Moon.

"If this object were made of iron and it were to hit our planet, it could create a crater comparable to the 1.5 km Meteor Crater near Flagstaff, Arizona, for example," says Detlef. "However, it won't."

Asteroid 2012 DA14 orbit

Finding near-Earth objects (NEOs) like these – passing close to our planet and large enough to do damage if they were to enter our atmosphere – is a major goal of ESA's Space Situational Awareness (SSA) programme.

The SSA office sponsors a number of astronomer groups in Europe, supporting their local surveys or allocating observation time at ESA's own telescope on Tenerife, Spain.

The discovery of 2012 DA14 was particularly significant for the Agency's SSA office because it is typical of the estimated half a million undiscovered NEOs up to 30 m across.

"Our SSA programme is developing a system of automated optical telescopes that can detect asteroids just like this one," says ESA's Nicolas Bobrinsky, SSA programme manager.

"In cooperation with survey efforts worldwide, our goal is to spot NEOs larger than 40 m in size at least three weeks before closest approach to Earth."

To achieve this, ESA teams supported by European industry are developing a system of automated 1 m-diameter telescopes capable of imaging the complete sky in one night. 

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17 January 2013

During the last observing run with the ESA 1-m telesope on Tenerife (the OGS = Optical Ground Station) the SSA-NEO programme successfully recovered three 'lost' NEOs. In addition, one new NEO was discovered. The new object has the designation 2013 AS76:

From the brightness of the object the size can be estimated to be around 40 - 100 m. With a minimum flyby distance to the Earth of just above 0.05 AU or 7.5 Million km it just falls outside the definition of a 'Potentially Hazardous Object'. Thus it will not pose any threat to our planet in the near future.

Three so-called NEO candidates observed with the OGS are still on the NEO Confirmation Page of the Minor Planet Center (

This discovery was possible because of the dedication and support of the TOTAS team ( The lucky person who first saw this object was amateur astronomer Gerhard Lehmann.

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7 January 2013

The orbital path of 2011 AG5 has been carefully analyzed in the past year, due to its 1-in-550 probability to pass, during the moderately close approach to the Earth that will take place in early February 2023, through a 365 km wide keyhole leading to a resonant return with impact on the Earth on 5 February 2040.

As it is customary in these cases, observing opportunities, useful to refine the orbit and possibly remove the collision possibilities, have been looked for; the first of these opportunities has occurred in October 2012, and has been put to good use by a team of the Institute for Astronomy of the University of Hawaii, using the Gemini North telescope.

Given the difficulty of the observations, the analysis of the collected data has taken some time. The astrometry so obtained has been fed to the CLOMON2 impact monitoring robot, and the results have been carefully cross-checked with those of JPL Sentry.

The result is that no impact with the Earth is possible between now and 2100. It is anyway desirable that the next observing opportunities for this object be exploited, so as to further refine our knowledge of its motion and especially of the circumstances of its encounter with the Earth in 2023, when physical observations would be possible. (Source: NEODyS)

Gemini Multi-Object Spectrograph image of 2011 AG5. The asteroid is the point at the center of the image -circled. (Image credit: Gemini Observatory)

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15 November 2012

In the last observing slot at ESA's 1-m telescope on Tenerife, the previously 'lost' object 2009 XZ1 has been recovered. E. Schwab (Germany) has planned and analyzed the observations. The Minor Planet Electronic Circular announcing the recovery can be found here: The animation shows a 4' x 4' cutout of the original image, showing five stacks of images following the asteroid. The object is the dot moving upwards close to the center of the images between the trailed stars.

Image credit: ESA/Schwab

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17 October 2012

In the last SSA-NEO observing run on Tenerife, we have imaged an object on the NEO Confirmation Page called SW40nU (now called comet C/2012 T5), discovered by the Spacewatch survey. It turned out to be a comet. This image shows a stack of all obtained images on 15 Oct 2012 at 23:29 UT, tracked on the object. The new comet is in the center of the image, the short tail is clearly visible arching to the right of the object. Because the image was tracked on the comet, the stars are trailed lines. Data for this object has been submitted to the Minor Planet Center and the Central Bureau for Astronomical Telegrams.

Image credit: ESA/Knöfel

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12 October 2012

A potentially hazardous asteroid once found but then lost has been rediscovered and its orbit confirmed by a determined amateur astronomer working with ESA's space hazards programme. The half-kilometre object will not threaten Earth anytime soon.

Asteroid 2008SE85

Amateur astronomer Erwin Schwab, from Germany, conducted his asteroid hunt in September during a regular observation slot at ESA's Optical Ground Station in Tenerife, Spain, sponsored by the Agency's Space Situational Awareness programme.

He was determined to rediscover the object, known by its catalogue name as 2008SE85.

Potentially Hazardous Asteroid 2008SE85 was discovered in September 2008 by the Catalina Sky Survey, and observed by a few observatories to October 2008. 

Asteroid considered lost

Since then, however, nobody had observed the object and predictions for its current position had become so inaccurate that the object was considered to be ‘lost'.

Orbit of 2008SE85

Erwin planned his observing sequence to look for the object within the area of uncertainty of its predicted position. After only a few hours, he found it about 2° – four times the apparent size of the Moon – away from its predicted position.

"I found the object on the evening of Saturday, 15 September, while checking the images on my computer," says Erwin.

"I then saw it again at 01:30 on Sunday morning – and that was my birthday! It was one of the nicest birthday presents."

These new observations of the roughly 500 m-diameter asteroid will allow a much more accurate determination of its orbit and help confirm that it will not be a threat to Earth anytime soon.

Potentially Hazardous Asteroids approach Earth closer than about 7 million km; about 1300 are known.

When a new asteroid is discovered, follow-up observations must be done within a few hours and then days to ensure it is not subsequently lost.

USA-based Minor Planet Center acknowledges the find

Asteroid position measurements are collected from observers worldwide by the US-based Minor Planet Center, which acknowledged the rediscovery of 2008SE85 by releasing a Minor Planet Electronic Circular announcing the new observations.

1m telescope at ESA's Optical Ground Station

"These observations were part of the strong collaboration that we have with a number of experienced backyard observers," says Detlef Koschny, Head of the Near-Earth Object segment of ESA's Space Situational Awareness programme.

"It's not the first time our collaboration with amateurs has scored such a success. Members of the Teide Observatory Tenerife Asteroid Survey started by Matthias Busch from Heppenheim, Germany, discovered two new near-Earth objects during the last year while working with our observing programme."

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While the sky becomes more and more continuously scanned by ground and space-based NEO surveys, discovering objects in unusual orbital configurations represents the new frontier. Their dynamics translates into peculiar visibility conditions thus calling for smart observation strategies. Tunguska-class (i.e. 30-60 meter size) objects in orbits closely resembling that of the Earth turn out particularly elusive due to their faint appearance and the long synodic period. The only chance to spot them in the sky is when they, from time to time, come close to our planet, crossing the night sky at high declinations. This is the case for asteroid 2012 DA14, discovered from the La Sagra Observatory, in southern Spain, on 23 February 2012 (a detailed account is posted at the observatory web site 2012DA14 is a 45 meter NEO which exhibit an interesting dynamical behaviour characterized in the 2001-2013 timeframe by yearly close approaches to our planet ( down to distances smaller than the geostationary ring where most telecommunication satellites reside. Even if 2012 DA14 will not impact the Earth it poses the challenge of how to discover these objects with a warning time large enough for mitigation. A space-based observatory in a "strange" orbital configuration has been proposed to this end.

Image: The discovery plates of 2012DA14 (credits: La Sagra Sky Survey)

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The data gathered by the US WISE mission have been released as public domain on 14 March 2012 ( This release provides improved calibration and processing algorithms. After the successful detection of 2010TK7, the first Earth Trojan Asteroid, which resulted from post-processing archived WISE data, new discoveries are expected in the future.

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Although Gaia's primary mission goal is the precise measurement of star positions and not observing NEOs, nevertheless it is likely to produce a significant contribution to NEO detection. This is due to the peculiar way its on-board telescopes will scan the sky, reaching solar elongations as low as 45 degrees. Yet without a robust ground-based network of follow-up telescopes Gaia's detections would lose much of their value because of the poor quality of the computed orbits. The Gaia working group devoted to moving objects detection, led by the Institut de Méchanique Céleste et de Calcul des Éphémérides (IMCCE) of the Observatory of Paris, is taking up the challenge. After a successful kick-off meetig in 2010 a second workshop is planned in Paris from 19 to 21 September 2012.

Image: Logo of the Gaia Follow-Up-Network of Solar System Objects