From D. L. GILES
A doomsday Swift-Tuttle comet arriving in 130 years (This Week, 24 October
and 14 November) and bodies more than 100 metres across once every 5000
years (‘How to destroy the doomsday asteroid’, 6 June)!
Before we accept that nuclear missiles can protect us from the doomsday
asteroid or comet, could we please consider the following points: If the
warhead impacts before initiation it won’t go critical.
If a nuclear explosion occurs a tenth of a second before impact it will
have no effect – it will be 3 kilometres away.
If it could be made to explode less than a hundredth of a second before
impact there would be no blast but the radiation would cause a comet (and
probably an asteroid) to explode. However, the centre of gravity of the
irradiated debris would still be travelling on exactly the same path towards
earth.
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If a missile actually impacted without causing any division, the path
of the asteroid would be only minutely deflected – not enough to save us.
I suspect that the close explosion as above would be very difficult
to achieve. Both the timing and the aim would have to be perfect.
Not exactly a fail-safe situation . . . Are there any other ideas?
D. L. Giles Broadford, Victoria Australia
