The closest approach distance is not the only important parameter for assessing the asteroid hazard. The velocity plays a crucial role in shaping the outcome of a close encounter as well as in evaluating the consequences of an impact. The speed at which an asteroid flies by the Earth results from geometrical and dynamical considerations characterizing its pre-encounter orbit.

Near-Earth asteroid 3122 Florence will have a close pass by Earth on1 September when it will be at a closest distance of 0.0472 au (18.4 LD), which makes it a Potentially Hazardous Asteroid (PHA). This Amor object, named after nurse Florence Nightingale (1820-1910), has an estimated diameter of ~4.35 km and was discovered in March 1981 by S.J. Bus at Siding Spring Observatory.

The Fly-Eye Telescope is an innovative project of ESA‘s SSA-NEO Segment that will focus on survey and follow-up of NEOs. Another important milestone on the way to build the telescope was achieved: from 30 July to 1 August ESA attended the acceptance test of the equatorial mount at its production site in Verona, Italy.

Over the past few weeks some media outlets discussed the future impact possibilities of asteroid (101955) Bennu, the target of the ongoing NASA mission Osiris-REx. Bennu is indeed ranked near the top of our risk list, but the earliest year when an impact is possible is 2175, not 2135 as some reports stated.

Asteroid 52768 1998OR2

Just a few days before the edition of the present newsletter a large bolide crossed the Italian northern sky. The event was observed by many people and in particular by a newly installed fireball network PRISMA (see next page). Such images have been used to determine the trajectory of the entering object.

For the first time in the history of NEA observations more than 2 000 new NEAs have been discovered in one calendar year, resulting in a monthly average of nearly 170 new asteroids. In addition, 2017 was the fifth year in a row with NEA discoveries above a thousand.

During 2015-2016 ESA funded the development of two small robotic observatories, called the Test-Bed Telescopes (TBTs). The main goal is to develop and test a fully automated telescope control system to observe NEOs and space debris.

In October 2017 the Pan-STARRS survey discovered the first known interstellar object transiting through our Solar System. Named ‘Oumuamua by the discoverers, it soon became the focus of numerous observations by the world's largest professional telescopes.

In the acronym "NEO"the final letter O stands for "Object", because the group is generally understood to include both asteroids and comets that come close to Earth. It is however interesting to note that most aspects of the NEO discovery process we commonly associate with asteroids happened first for comets

On 25 April 2018 ESA’s Gaia Data Processing and Analysis Consortium published the second release of the mission data products (known as Data Release 2, or DR2 for short). For the first time, Gaia astrometry of more than 14 000 known asteroids was made public, showing that the spacecraft can achieve astrometric precisions at the milliarcsecond level.

Current NEO statistics During the last month the global numbered asteroid catalogue (including main belt asteroid) surpassed the threshold of half million objects. The number of known NEOs surpassed 17 000, thanks to more than 300 discoveries in a single month.

Asteroid 2012 TC4, discovered five years ago by the Pan-STARRS survey,will come back close to Earth on 12 October 2077.It will fly-by at 44 000 km from the surface, providing a rare chance to carefully observe a small known object during its entire approach to our planet.

Asteroid 2012 TC4is the target of an international observing campaign that will culminate this month during its close fly-by with Earth. The object will safely fly at about 44 000 km from the Earth surface, with no chance of collision with our planet.

Whenever a new set of observations for an object is published, our Impact Monitoring routines perform a new search for possibly impacting orbits compatible with such set of observations. The system is capable of detecting all possibly impacting orbits down to an impact probability threshold, named “generic completeness level”.

A new release of our NEO Web Portal is on-line at http://neo.ssa.esa.int/. It represents a major update of the SSA-NEO system since it includes a number of new functionalities and an improved graphics. The possibility of visualizing the actual trajectory of an NEO including gravitational perturbations and an enlarged plot at close encounter has been implemented.

2016 NA39 is a newly-discovered asteroid that for a few days in mid-July deserved attention. Because of its large size, around one kilometre, it became the highest rated object with possible impacts in the current century, scoring as high as Palermo Scale of —2.6.

November was a month of close approaches of many small objects. A particularly interesting case was 2015 VY105, which came to less than 30 000 km from the Earth’s surface on 15 November.

The NEO Coordination Centre is collaborating with the European Commission project NEOShield-2 on the dissemination of NEO physical properties. Our EARN-based physical properties database will be enhanced to host additional data.

December 2024 Newsletter

The month ofApril saw two very important international meetings on NEOs taking place at the ESA ESRIN establishment in Frascati. On g—10 April the Space Mission Planning Advisory Group (SMPAG) met for two days for their third regular meeting.

On 9 May the planet Mercury will transit the Sun as seen from Earth. Although not an asteroid event, this gives us a chance to talk about how transits have been used in the past to probe the population of small asteroids extremely close to the Sun (the so-called Vulcanoids).

This month, while reading this newsletter, you will find an object designated with a “non-standard” name: XDg2F93. Labels like this, not following the standard form of year + letters + numbers,are called “temporary designations”.

March 2023 Newsletter

A small size asteroid will approach the Earth on 12 October 2017. The expected minimum distance is just above the geostationary ring, thus being a good target for radar observations.

2024MK

During the past year ESA funded the refurbishment and modernization of the 0.8 m Schmidt reflector located at the Calar Alto Observatory in Spain. The telescope, identified with the MPC code Z84,is now operational and can be remotely controlled.

In the month of December, (29075) 1950 DA, an old NEA, entered the risk list in a peculiar way: the addition is not based on new observations but it is the combined result of an already existing good observational coverage for this object, together with a newly implemented dynamical model now available at NEODYS.

The newly discovered asteroid (469219) 2016 HO3 has been attracting the interest of the NEO community becauseof its peculiar orbital path. Having the same period of revolution of the Earth but a higher eccentricity and being properly phased, this object appears to circle our planet in a retrograde “quasi-satellite” orbit with period one year.

In recent years, it has become increasingly common for ground-based surveys to discover small objects that seem to be in distant Earth-centred orbits. Most of them turn out to be man-made spacecraft or upper stages of spent rockets residing in Earth’s region.