Tagging an Asteroid — how hard can it be?

So a massive asteroid is coming our way… And, yes, I’m serious. As SatNews Daily reminds us this morning, in just 22 years, Apophis-99942 will be at its closest distance to the Earth (in about 200 years).

At its worst, the asteroid—identified as Apofiz-99942—should smash into the Earth by 2036. At the least, it should wipe out practically all civilian and military satellites in geostationary orbit, which is about 42,000km above the planet. […] Apofiz (spelled Apophis in the West) will pass the Earth at a distance of 30,000 to 40,000 km. Whatever happens, the Earth will suffer from the effects of the close encounter with this asteroid.

Before we start to panic, the odds of a 2036 collision are very small—about 1 in 24,000. But scientists want to know more. That’s why the California-based non-governmental group, The Planetary Society, has launched the "Apophis Mission Design Competition." The contest offers $50,000 in prize money for the winner who designs a mission to "tag" the asteroid. So far, more than 100 teams and individuals from 25 nations are developing plans.

You may be wondering: how will tagging the asteroid help?image of Apophis in orbit

Tagging may be necessary to track Apophis accurately enough to determine whether it will impact Earth, and thus help decide whether to mount a deflection mission to alter its orbit. Apophis is a Near Earth object (NEO) some 400 meters in size. If Apophis passes through a several hundred-meter wide "keyhole" in 2029, it will impact Earth in 2036. While current estimates rate the probability of impact as very low, Apophis is being used as an example to enable design of a broader type of mission to any potentially dangerous asteroid. Very precise tracking may be needed to determine the probability of a collision. Such precise tracking could require "tagging" the asteroid, perhaps with a beacon, transponder, reflector — or some other method. Exactly how an asteroid could best be tagged is not yet known, nor is it obvious.

What if we find out that the worst case scenario is taking shape? While NASA currently has no plans to study methods of asteroid deflection, Russia has made some claims:

Russia, however, has said it is prepared to repel asteroids to save the Earth. Viktor Remishevsky, deputy head of the Russian Federal Space Agency (Roscosmos) was reported to have said that if necessary, Russia’s rocket-manufacturing complex can create the means in space to repulse asteroids threatening Earth. He also noted that saving the Earth from the threat of asteroids demands international cooperation.

Rest easy. We have at least 22 years to figure it out.

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