"Malcolm Street" wrote:

All you need to do is get a dinosaur-killer-sized
asteroid into orbit closer than the moon without
risking it hitting the earth.

No, and no. You don't have to start with something
10 km in diameter, 200 m in diameter is a huge good
start for just getting a lot of mass available that
isn't at the bottom of (quite so deep) a gravitational
well, and you don't have to get it physically closer
than the material on the moons surface, just
energetically closer, which any stable Lagrangian
point orbit would suffice to accomplish.

Now that Smart-1 has proved humankind capable of doing
space the slow and steady way, what _are_ the
implications for robotically shipping a "rock" from
the asteroid belt to L5, probably (I have no clue how
to do the math) simpler than diverting something in a
profoundly non-circular solar orbit, like an earth's
orbit transiting asteroid, if one is willing to be
patient.

And, what constitutes a big enough "rock" to be worth
the effort?

xanthian.


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