September 13, 2013
Could Life On An Asteroid Survive Impact With Earth?
John P. Millis, PhD for redOrbit.com - Your Universe Online
Where did life come from? It is a fundamental question that has consumed scientific inquiry for centuries. And naturally, theories abound. While some believe that life as we know it arose naturally from Earth, others believe that if may have come from outer space.It sounds almost like something out of science fiction, but panspermia – the theory that life can naturally transplant from one from planet, comet, or asteroid, to another – remains a serious scientific position. The challenge is that it is difficult to prove or disprove. In fact, it has been difficult to demonstrate that it is even possible, much less the solution to the question of life’s proliferation here on planet Earth.
One of the more popular iterations of the theory suggests that life actually originated on Mars, and that microscopic organisms were carried away to Earth after a large meteorite impact sent them hurdling across the solar system aboard a Martian rock. But could life have survived such an ordeal?
First of all, there is the question of the initial collision. A meteorite slamming in the Red Planet would have likely killed much of the life around the impact site. The life would then also have to survive the trip to Earth, and then find protection from the immense heat of entry into our planet’s atmosphere.
To test the feasibility of such a theory, Dina Pasini from the University of Kent conducted an experiment where frozen samples of Nannochloropsis oculata – a species of single-celled algae – were fired from a high velocity gas gun into a vat of water.
“As you might expect, increasing the speed of impact does increase the proportion of algae that die,” Pasini explain in a statement. "But even at 6.93 kilometres per second (about 4.3 miles per second), a small proportion survived. This sort of impact velocity would be what you would expect if a meteorite hit a planet similar to the Earth.”
This is actually a major victory for panspermia models, as the initial impact is thought to be the most brutal. If, for instance, the life were incased in ice or rock, it would probably have little trouble making the trip from Mars to Earth. Furthermore, if the sample were also embedded in a meteorite, for example, the high temperatures of atmospheric friction would have had virtually no effect on the life within.
“Our research raises several questions,” Pasini says. “If we find life on another planet, will it be truly alien or will it be related to us? And if so, did it spawn us or did we spawn it? We cannot answer these questions just now, but the questions are not as farfetched as one might assume.”