: Planetary Defence <- from SpaceRef Newsletter - 12 March 2007
Russell McMahon email (remove spam text)
Reports from the second trienniel Planetary Defence Conference.
Sounds good ! :-).
In this case the baddies are large "Near Earth Objects" over 140m in
diameter that pass within 1.3 earth-sun distances from the sun.
"One of the complications is just getting to the asteroid,
which is much harder when it chooses us, as opposed to us
choosing it. "
Some interesting material.
Outline material only but no doubt enough information for Gargoyle to
Various methods of interception and deflection are discussed.
" ...On the question of how to protect against an identified
threat, the opinions seemed to fall toward using the gravity tractor
or the ballistic impact in preference to nuclear explosives. ..."
" All three of these deflection technologies need to be
developed, however, since they have very different capabilities, and
we are dealing here with a huge range of NEA sizes and orbits. One of
the complications is just getting to the asteroid, which is much
harder when it chooses us, as opposed to us choosing it. The gravity
tractor must match orbits (rendezvous) with the target. In contrast,
the kinetic impactor does not need to slow down near the asteroid, but
it does have to hit a small target at high speed. Nuclear charges
would normally be used from a rendezvous spacecraft, but in extreme
cases might be deployed like kinetic impact, with a high-speed
intercept. There is no "one size fits all" solution. "
" Mark Boslough (Sandia) discussed interesting simulations of
atmospheric explosions such as Tunguska. Noting that the fireball from
a meteor explosion has considerably downward momentum (unlike the
classic mushroom cloud from a nuclear explosion), he concludes that
the Tunguska impactor exploded higher and was smaller (energy of order
5 megatons) than usually inferred."
From: <mail.aterra.com> spaceref-daily
See also: www.piclist.com/techref/index.htm?key=planetary+defence
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