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Last update: 2021-03-05 10:57:27 UTC


NEOCC Newsletter: March 2021

05 March 2021

The ESA S2P-NEO Coordination Centre has released the March 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; to subscribe to the service, please fill in the form on page




Impact monitoring for Apophis computed including the Yarkovsky effect

22 January 2021

Thanks to new observations collected since December 2020, the well-known non-gravitational phenomenon known as "Yarkovsky effect" has now become clearly detectable on (99942) Apophis. The effect manifests itself in the motion of the asteroid as an additional tangential acceleration. This can be included in the orbit determination process as an additional parameter of the fit, usually labelled A2.

As a consequence of the improved orbit determination that now includes the estimation of A2, ESA's NEOCC, in agreement with JPL's CNEOS and NEODyS, has performed a revision of the Apophis impact hazard assessment.

The new results have been generated considering all the available measurements up to 17 January 2021, including both optical and radar observations, and the Yarkovsky parameter in the process. The coefficient of the Yarkovsky acceleration can now be estimated as (-2.65 ± 0.23) 10-14 au/d2.

Once the orbit determination was completed, the impact monitoring process could be executed based on a generalised "line of variations" method, where, beyond the six orbital parameters, also the Yarkovsky parameter is included. As a result, the updated impact probability for the possible impact of Apophis in 2068 is about 1 in 900 000, corresponding to a Palermo Scale value of -3.86.

The new computation has been released on the NEOCC website on 21 January, and the revised table of possible impacts is available here.



1998 KY26 - recovering the target of the Hayabusa2 extended mission

23 December 2020

Asteroid 1998 KY26, the target of the extended mission of Hayabusa2. Image stack obtained with the Very Large Telescope of the European Southern Observatory. Credit: ESO / ESA NEOCC

On 6 December 2020, JAXA's Hayabusa2 spacecraft successfully completed its primary mission with the delivery of the sample container to Earth. Despite the great success of the project, the probe's mission might not be over yet. An extended mission is currently being considered: it will allow both a fly-by of a numbered asteroid, (98943) 2001 CC21, and more importantly a rendezvous with 1998 KY26, a small ~30 metre near-Earth asteroid first discovered in 1998 by the US-funded Spacewatch survey.

This target is particularly interesting, for a variety of reasons. It will, for example, be the first rendezvous with a tiny and fast-rotating asteroid. It is also an object that has been well observed with radar during its discovery apparition in 1998. This has allowed astronomers to derive an accurate tridimensional model of its shape.

However, despite the excellent characterisation effort back in 1998, the orbit of this asteroid was not known well enough to safely navigate the spacecraft. A recovery was needed, and the perfect opportunity was happening right now.

Our team, in the framework of our collaboration with ESO on near-Earth asteroids, was able to use ESO's VLT to target 1998 KY26 on 10 December 2020. At the time of the observation, the object was expected to reach magnitude 25.5, thus requiring very large telescopes. Recovering an object only observed 22 years earlier might appear challenging but, in this particular case, we could take advantages of the excellent radar detections obtained during the discovery apparition. This allowed the determination of a reasonably accurate ephemeris, with an uncertainty that could fit inside VLT's field of view. The object was successfully detected in the first set of frames, and then confirmed with an independent set of images collected two nights later. Around the same time, a Japanese team at the Subaru telescope also observed the target, providing an independent confirmation of the detection.

With the addition of our new observations, it is now possible to plan the mission in more detail. The object will become visible again in 2024, and observations collected during that apparition will be crucial to ensure the successful navigation of the spacecraft to the target, which should be reached in 2031.



NEOCC Close Approach Fact Sheet: 2020 SW

22 September 2020

The ESA S2P-NEO Coordination Centre has released a Close Approach Fact Sheet (CAFS) for asteroid 2020 SW, passing by Earth on 24 September. Please, feel free to forward it to potentially interested people.

You can download the CAFS by clicking on the button below; for subscribing to our releases, please fill in the form on page