Zappin' Aphosis

The Register reports: [edited]

NASA plans to deal with killer comets or asteroids on collision courses with Earth are more advanced than many analysts had thought. Flight International reported on Friday that the agency's Marshall Space Flight Centre has developed designs for an asteroid-buster spacecraft which could be launched using the future Ares V cargo rocket.

According to Flight, Marshall engineers based their design study around the 99942 Apophis asteroid, which rounds the Sun eccentrically, veering in and out between the orbits of Mercury and Mars.

Apophis is estimated to be perhaps 270 metres across and it will pass close to Earth in 2029, well inside the orbit of the Moon and closing in to the same sort of distance as geosynchronous satellites.

There was initially some concern following Apophis' discovery in 2004 that it might strike the Earth devastatingly in 2029 or 2036 - hence the name ("Apophis is the Egyptian god of evil and destruction who dwelled in eternal darkness," says NASA.)

Further observations have refined the data and it is now known that the likelihood of a collision with Apophis in the foreseeable future is extremely small.

Disappointingly for fans of Armageddon, the NASA asteroid-defence mission included no role for any eccentric oil-drilling experts, nor even any straight-arrow astronauts. The human race would rely on robots to sacrifice themselves for our survival.

Initially, a recce probe would be sent out in order to make sure of a threat asteroid's composition and flightpath; then the main mission would follow, blasting off in 2020 or 2021 in the case of Apophis.

Rather than smashing any troublesome space rock to pieces, it seems the plan would be to give it a relatively gentle nudge while it was still far away, so that it missed the Earth cleanly. Of course, a 20 million tonne boulder would need a hefty nudge - and under the headline-grabbingest NASA plan this would be delivered by a volley of up to six nuclear missiles packing 1.2 megaton B83 warheads.

These would detonate a hundred metres or so from the asteroid, and the heat of the explosions would cause part of it to vapourise and shove the remainder to one side.

There was also an alternative design for the boulder-buster mission, in which the shunting missiles would use only their own kinetic energy.

There was a third, more groovy option in which a solar powerplant craft would fly alongside the menacing meteor and focus the sun's rays to boil off asteroidal material, which would have the effect of gradually easing it off the path of danger.

Apparently, the three different plans are each optimised for different types of asteroid. Once the composition of a dangerous space object was known, the design of the interceptor would be selected.

NASA reportedly assessed that the nuclear option could push 100 metre to 500 metre sized boulders safely off course given two years' warning, and larger ones with a five year heads-up.
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