Watching Asteroids and Comets to Avoid Impact

Dangers posed by asteroids are among the issues discussed during the third international meeting of the top-level representatives in charge of security currently underway in Saint-Petersburg.

The report on countering asteroid and meteorites threats is to be made by Russian Federal Space Agency (Roscosmos) representative.

Space strikes back… and again

While today asteroids do not bother Earthlings as they did only a few billions of years ago, encounters still occur. Thanks to their tiny dimensions, the impact is almost always a short flash in the upper atmosphere. Very rarely the remnants of the space bodies reach the Earth, and thanks to the uneven density of Earth’s population, only a tiny share of them land in the vicinity of humans. Still, asteroids are regarded today as one of the most serious global threats.

Perhaps the reason is this: for the first time the real number of asteroids in the vicinity of the Earth was assessed and found uncomfortably great – tens of thousands, with some of them travelling on the orbits that might unfortunately intersect the Earth’s one in a very unlucky moment when the collision might prove unavoidable.

Then, the effects of the possible rendezvous were estimated. According to the calculations, the most destructive celestial bodies are comets since they travel with high velocities and their trajectories are hard to predict. Then, there are asteroids.

It was estimated, that a body with only several hundred meters in diameter could bring significant regional destructions (Tunguska event in 1908 was driven presumably by relatively small body less than 100 m in diameter). Further on, the collision with 1 to 10 km body might lead to a global catastrophe.

The problem is that the number of near-Earth objects (whose orbits lie in the vicinity of the Earth’s) is great, but they are sometimes hard to observe due to dark surface and their trajectories are not that simple to calculated, as one should take into account the gravity influence of the Earth, the Sun and other bodies.

For example, the most famous until now, Apophis (350 m) is expected to pass near the Earth in 2029. Dependent on the details of the first encounter, the second, to follow in 2036, might have different outcome.

While the threat is already known, the possible remedy is only being discussed. The solutions proposed encompass all sorts of ideas including ‘explosive’ ones, best described by the Armageddon sci-fi movie (even though its creators did not think that it is far more dangerous to have multitude of space debris with chaotic trajectories than the only one), to more peaceful ideas to paint the asteroid therefore changing its response to solar light, which would eventually make it to change the initial trajectory.

One may think of all of these ideas as of rather bizarre ones, but as the danger itself seems to come from science fiction books, the counteractions are bound to be unconventional, too. The question is, whether the asteroid threat is approached seriously enough.

Count, touch, and strike

Up till now, the activities on the space threat prevention were rather passive. Many countries and scientific organizations are driving observational programs for asteroid detections, kind of ‘early warning’. The most well-known is NASA’s Near Earth Object (NEO) Program whose aim was to map all the bodies in the Earth’s neighborhood big and close enough to pose threat for the planet.

Currently there are 1311 known potentially hazardous asteroids. Both the ground-based and space facilities are engaged in the search, for example, NASA’s WISE (Wide-field Infrared Survey Explorer).

In Russia, there is a special expert working group on space threat driven by the Institute of Astronomy of the Russian Academy of Sciences, which has an aim to closely watch both the natural and artificial threats, namely ‘space junk’ from abandoned out of service satellites. This group is engaged in development of a new program stipulating necessary measures against asteroids and comets.

Since this might be one of the Russian space policy priorities (according to the vice prime minister Dmitry Rogozin), this program might get a fresh boost in the very near future.

Still, there are no approved missions to test any of the methods to withstand the asteroid threat, at least for the very moment. The mission to the asteroid Apophis suggested by Russian space community (developed by Lavochkin design bureau) is by far mostly scientific spacecraft and its future is not determined yet.

It is unlikely that the current meeting in Saint-Petersburg will bring any changes, but it’s interesting that space issues are being discussed regardless of military use.

While private companies declare their intention to mine the asteroids, thus rising debates over whose property this asteroid actually will be, the state bodies are considering the most impersonal threat from space. Might it be the beginning of real space expansion or the idea is only an attempt to follow general trend? While the latter seems to be more realistic, the first option is far more interesting.

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