[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Dinosaurs in space?



In a message dated 5/17/01 3:17:36 PM EST, kinman@hotmail.com writes:

<< The most likely planets with Earth rocks would therefore be Venus and 
 Mercury, but their extreme environments aren't very conducive to rocks lying 
 around unchanged like they would on the Moon (which also has the advantage 
 of being so close to us). >>

It is much more difficult to reach Mercury than Mars via meteorite from 
earth. Mercury is deep within the sun's gravitational well, and a meteorite 
would have to lose quite a bit of the earth's orbital velocity in order to 
reach that planet, considerably more than would have to be added to earth's 
velocity to reach Mars. Spacecraft from earth to Mercury (e.g., Mariner 10) 
have to use Venus for precise gravity-assisted slowdown to accomplish this, 
but random meteorites from earth would be much more likely to simply hit 
Venus than to be slowed down enough to go all the way to Mercury.