On September 14th, the unmanned Foton 3 mission launched from Baikonur Cosmodrome in glorious Kazakhstan. One of the 43 experiments it carried was designed by John Parnell, Chair in Geology and Petroleum Geology at the University of Aberdeen to test whether life can survive the microgravity, radiation and reentry burn of a trip through space to Earth.
It can.
Parnell had a faux meteorite created out of rock from a quarry in Orkney, Scotland. The Orkney rock is full of organic material and fossils. Parnell said in a U-Aberdeen press release, "The Orkney rock is a very robust material but it will be interesting to see if organic matter in the rock is robust enough to survive the harsh conditions endured during re-entering the Earth's atmosphere."
The fist-sized rock was protected during launch, but uncovered during reentry, to feel the full blast of the atmospheric burn at 8 kilometers per second. Parnell’s team was specifically interested in what are called fossil biomarkers, indications of the presence of life rather than life itself. Certain molecules, such as steranes and hopanes, are thought to form only when living matter decays. Parnell told New Scientist, “Unlike things like DNA that decompose quite quickly, these have long-term stability over millions or even billions of years. ... This experiment is really designed to look at fossil biomarkers rather than living ones. But the more you know about the survival of organic molecules in general, the more you can understand whether living [things] could survive as well." This will test such theories as the 1996 claim that researchers had found fossil traces of life in a rock from Mars.
"In the bit of rock we got back, some biological compounds have survived," said Parnell told National Geographic News. He added that his preliminary findings indicated that it was possible for simple organisms to survive, and that they would have a better chance of survival in a bigger rock, because the Orkney rock lost about three-quarters of its mass. In addition, in a bigger meteorite, the reentry temperatures of about 392 degrees Fahrenheit (200 degrees Celsius) wouldn’t penetrate to the center of the rock. But, Parnell added, "There's a sort of window of opportunity in terms of size, between being too small and too big," because a much larger meteorite would vaporize on impact.
If life did travel to Earth via meteorite, it most likely came from Mars. Studies suggest that fully 5% of meteorites from Mars land on Earth. Of these meteorites, Parnell said, "A very few will make [the trip from Mars to Earth] in a year or so. Those are the ones which could conceivably bring something interesting with them."
“[W]e should be open to the possibility that there is microbial life on Mars that shares a common ancestor with Earth life," David Morrison, a senior scientist at the NASA Astrobiology Institute in Moffett Field, California, told National Geographic News. "It may not be likely, but we cannot exclude the possibility that we are, in effect, all Martians."
