What we can learn...

[SierraRocks]

Have things gone back & forth between Mars & Earth before?

 

[Lynne]

Have things gone back & forth between Mars & Earth before?

Interesting question. It seems we have a lot of meteor rocks from there already.
One source of Mars samples is what are thought to be Martian meteorites, which are rocks ejected from Mars that made their way to Earth. Of over 61,000 meteorites that have been found on Earth, 132 wereidentified as Martian as of 3 March 2014.

 

[SierraRocks]

Interesting question. It seems we have a lot of meteor rocks from there already.
One source of Mars samples is what are thought to be Martian meteorites, which are rocks ejected from Mars that made their way to Earth. Of over 61,000 meteorites that have been found on Earth, 132 wereidentified as Martian as of 3 March 2014.[/QU

Oh wow. That 132 sounds like a lot of "cross contamination" of microscopic flora /which could live -dormant or not- in space are already here. Another rock? Another bit of flora? Just go ahead! What could it matter? (Famous last words, right)