Astronomers annually register hundreds of tiny celestial bodies passing in close proximity to the Earth. Some are of interest to science, others can be a potential threat to the planet. But why are hundreds of thousands of these objects still not listed in the catalogs and directories of scientists?
Objects approaching the Earth: what is it and what does humanity face
This diagram shows orbits of all the largest NEOs known to scientists
Near-Earth objects (NEOs) are small bodies drifting in the Solar System, whose orbits sometimes approach the Earth at a distance representing the danger of collision. NEOs are also a kind of indicator of the composition, dynamics and global processes occurring in the system or in its individual regions. These include, for example, the majority of meteorites, exploring which astronomers and learn a variety of details about the cosmos and the structure of other planets. The main advantage of NEOs is that reaching them is sometimes much easier (and cheaper) than the Moon or other planets.
The total number of known NEOs today exceeds 18,000, many of them potential candidates for small NASA missions. Over the past couple of decades, the speed of discovering new objects has increased, and the US policy played a big role in this – since even small NEOs were recognized as a significant threat, the minimum diameter of such an object was reduced from 1 km to 140 meters.
Of course, all celestial bodies claiming a dangerous proximity to the Earth need careful study – but, as always, there is one problem. Since NEOs are in constant motion, the process of discovering new celestial bodies requires a constant comparison with previously discovered objects, which, under conditions of their impressive amount, is often not possible. Astronomers admit that many NEOs manage to track, but their subsequent observations are not carried out – there are not enough resources.
From 2013 to 2016, a team of astronomers from the Minor Planet Center submitted 170,000 new objects as candidates for NEOs, 18% of which still remain unconfirmed.
Of course, even taking into account the power of modern telescopes, it is very difficult to track the mass of small celestial bodies, and therefore scientists insist on closer attention to these undesirable neighbors of the Earth – eventually, sooner or later an asteroid will fall to the planet.