From: Technotranscendence (neptune@mars.superlink.net)
Date: Sun May 25 2003 - 08:12:48 MDT
On Sunday, May 25, 2003 4:33 AM Anders Sandberg asa@nada.kth.se wrote:
>> NASA and USM are considering going out and moving smaller rocks in
>> the asteroid belt which may collide with earth. What is the biggest
rock
>> you think could be moved around by modern rockets?
>
> It is all a matter of how much time you take. Even a fireworks rocket
> can, if it fires long enough, impart enough delta-v on an object to
> change is orbit completely. Also, if you have plenty of lead time you
> can impart a small delta V into the object - the displacement will
grow
> at least linearly with time.
Yep. Also, most of these rocks would be hit/pushed where it makes the
biggest impact: at apohelion (for the ones with noncircular orbits,
which means all of them, IIRC:).
The big problem is not so much getting the right amount of energy to the
right spot -- a nuke would do fine in most cases -- but being able to
finely control the outcome. This requires more knowledge of asteroid
composition, shape, and structure. For example, if the asteroid in
question is more like a floating dirt pile, then it might harder to
manuever since it might break up under manipulation with most of the
fragments still heading where you don't want them -- even worse, the
fragments might be distributed over a larger range of impact sites. It
won't be like in that asteroid movie -- two chunks, but many thousands
of chunks, many of which might survive atmospheric entry or sweep Near
Earth Space of all spacecraft.
To learn about asteroid composition and structure, perhaps the current
best way is to do more flybys, orbits, and landings -- many more, since
asteroids probably vary a lot. (Earthbound observations have certainly
led to a range of classifications that indicate differences in
composition and perhaps structure.) Such missions need not be high
cost, especially if we can get the SpaceWatch crowd to join efforts with
the would be asteroid mining people. They seem like natural allies, yet
I don't see them even talking to each other. (Sadly, inside space
activism circles, this sort of isolation between groups is typical.)
Cheers!
Dan
http://uweb.superlink.net/neptune/
This archive was generated by hypermail 2.1.5 : Sun May 25 2003 - 08:15:55 MDT