Late in the last century, researchers calculated that an asteroid impact on Mars could jettison rocks towards Earth in a way that preserved bacterial life within them; the implication being that life could have evolved first on a warmer wetter Mars and later seeded life on Earth.
Now Mauri Valtonen from Turku University in Finland and colleagues have worked out whether bacteria might have been able to make a similar journey from a planet orbiting another star.The answer is probably not.
But there is with one important caveat.The sun almost certainly formed in a star-birthing nursery with various other stars which later dispersed. It’s quite possible, say the team, that bacteria could have passed from one system to another while all these star systems were close together.
Nobody knows which stars are the sun’s sisters and brothers but various groups are looking to solve this conundrum. In particular, the European Space Agency’s Gaia observatory (launch date 2011) is designed to create a 3D map of our galaxy that should allow us to work out what came from where. Studying these stars will then become an obsession for various astronomers.
Equally likely, of course, is the possibility that Earth seeded planets around these stars with life.So if you work on Gaia, don’t be surprised to find somebody staring right back at us.
Ref:arxiv.org/abs/0809.0378 : Natural Transfer of Viable Microbes in Space from Planets in the Extra-Solar Systems to a Planet in our Solar System and Vice-Versa