Any Chance Of Future Impact Is 'Extremely Remote', Agency Says
Asteroid 2006 QV89, a small object 20 to 50 metres (approx. 65-165 feet) in diameter, was in the news lately because of a very small, 1-in-7000 chance of impact with Earth on September 9, 2019.
In the first known case of ruling out an asteroid impact through a ‘non-detection’, ESA and the European Southern Observatory have concluded that asteroid 2006 QV89 is not on a collision course this year – and the chance of any future impact is extremely remote.
Asteroids come and go, quite literally, often frustrating astronomers. You can catch sight of a hurtling space rock, take some measurements to narrow down its orbit, and days later it's gone – potentially remaining unobservable for decades.
In general, when an asteroid is found to have even a tiny chance of impacting Earth, further observations and measurements are taken. These ‘astrometric’ data refine our understanding of the asteroid’s path, improving our understanding of the risk it poses and often excluding any chance of collision altogether. However, the case of asteroid 2006 QV89 is peculiar. The object was discovered in August 2006 and then observed for only ten days. These observations suggested it had a 1-in-7000 chance of impacting Earth on September 9, 2019.
After the tenth day, the asteroid was unobservable and has not been seen since. Now, after more than a decade, ESA says it can predict its position with only very poor accuracy. As a result it is extremely difficult for astronomers to re-observe it, as no one knows exactly where to point a telescope.
Nevertheless, there is a way to obtain the information needed.
While the exact trajectory of 2006 QV89’s is not known, what is known is where it would appear in the sky if it were on a collision course with our planet. Therefore, simply observing this small area of the sky allows astronomers to check that the asteroid is indeed, hopefully, not there.
This way, any risk of an impact can be indirectly excluded even without actually seeing the asteroid.
This is precisely what ESA and the European Southern Observatory (ESO) did on July 4 and 5 as part of the ongoing collaboration between the two organizations to observe high-risk asteroids using ESO's Very Large Telescope (VLT).
Teams obtained very ‘deep’ images of a small area in the sky, where the asteroid would have been located if it were on track to impact Earth in September.
Nothing was seen, so at least for this object, Earth can breathe easy.
(Image provided with ESA news release)