Earth-Impactor Mitigation Methods

by Germano D'Abramo (*) - copyright TumblingStone 2001

The need to avoid the impact of an asteroid with the Earth has led to what is now known as mitigation strategy. There are two basically different approaches to the problem: the change of the asteroid's orbit (deflection) or the asteroid fragmentation and its dispersal.

The fragmentation procedure appears to be risky and in some cases even impossible for at least two reasons:

Moreover, the fragmentation procedure is impossible in some cases, for example:

Concerning the deflection procedure, it suffices to aptly modify the orbital velocity of the impacting body along its revolution around the Sun. For the sake of simplicity, we could say that the velocity change must lead the asteroid gain ground (or lose it, depending on if we increment or decrement its orbital velocity) with respect to the motion of the Earth during the time span between the application and the predicted epoch of collision of an amount of at least one Earth radius. Therefore, it is clear that the longer the warning time before the epoch of the impact, the less the magnitude of the velocity change required for the same deflection. Namely, in most cases it is exactly an inverse proportion between warning time and magnitude of velocity change, if we obviously ignore such peculiar cases like that described by A. Carusi in this issue of T.S..

The velocity change can be impulsive or steady. It is impulsive if it is delivered "instantaneously'', in one solution. The velocity change is steady when a constant thrust is applied to the asteroid for a longer time span, which could be even equal to the warning time before the impact.
Within the known mitigation strategies there are the following impulsive methods:

Among the steady mitigation methods there are:

Solar panels, a mean of deflection?

By the way, all these methods were never tested or applied for mitigation actions. They were only theoretically handled. Besides, as already mentioned, the actual accomplishment of some of these mitigation methods seems out of reach even in the distant future, due to their insurmountable technical problems. Obviously, the hope is that we would never need such remedies, but, as the old saying goes, hope the best, get ready for the worse!



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