Astronomers annually record 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 included in the catalogs and reference books of scientists?
This diagram shows the orbits of all of the largest NEOs known to scientists.
Near-Earth objects (NEOs) are small bodies that drift in the solar system, whose orbits sometimes approach the Earth at a distance that presents a collision hazard. NEOs are also a kind of indicators of the composition, dynamics and global processes occurring in the system or in its individual regions. These include, for example, most of the meteorites, studying which astronomers and learn various details about space and the structure of other planets. The main advantage of NEOs is that they are sometimes much easier (and cheaper) to reach than the Moon or other planets.
The total number of known NEOs to date exceeds 18,000, with many of them being potential candidates for small NASA missions. Over the past couple of decades, the rate of detection of new objects has increased, and US policy has played a large 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 that claim to be dangerously close to 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 constant comparison with previously discovered objects, which is often not possible given their impressive number. Astronomers admit that many NEOs can be tracked, but follow-up observations are never carried out due to lack of resources.
From 2013 to 2016, a team of astronomers from the Minor Planet Center submitted 170,000 new objects as NEO candidates, 18% of which are still 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 unwanted neighbors of the Earth - in the end, sooner or later, some asteroid will still fall on the planet.
Vasily Makarov
