Did life on Earth come from a comet?
An icy comet collision billions of years ago might have spurred life on Earth, a new British study suggests.
Researchers found that amino acids – the building blocks of life – can be produced when an icy comet collides with a planet. The shock wave from the collision produces molecules that transform into amino acids under the heat of impact, the study finds.
Imperial College London scientist Zita Martins, a co-author of the paper, said in a news release that the research shows that amino acids can form anywhere in the solar system.
"Excitingly, our study widens the scope for where these important ingredients may be formed in the Solar System and adds another piece to the puzzle of how life on our planet took root," Dr. Martins said.
The team recreated a collision by firing steel projectiles out of a gun at more than 15,000 miles per hour into ice mixtures that mimicked the composition of comets.
The discovery is the latest evidence that supports the theory that basic ingredients for life on Earth came from space.
Scientists speculate that some 3.8 billion years ago, Earth was showered with asteroids and comets during what is known as the Late Heavy Bombardment (LHB) period. Some theories suggest that life began at the end of the LHB.
In 2005, NASA's "Deep Impact" mission launched a spacecraft to crash into a comet named Tempel 1, with the goal of discovering the composition of comets. Scientists found organic chemicals under the surface of Tempel 1's core, a discovery suggesting that comets might have delivered the necessary ingredients for early life on Earth.
Earlier this month, Deep Impact researchers announced that they lost communication with the probe as it studied another comet named ISON, but are working to fix the problem.
Recent findings from a biochemist in Florida also suggest that chemicals essential for life arrive on Earth via a meteorite from Mars.
Dr. Steven Benner of the Weistheimer Institute for Science and Technology told Space.com that three billion years ago, oxidized molybdenum – an element that might have been crucial to life – existed on Mars but not on Earth. The evidence makes it more likely that life came from a Martian meteorite, Benner said.
The new "cosmic factory" study also found that amino acids are produced when a rocky meteorite hits an icy planet surface, giving importance to future space missions to Saturn and Jupiter's icy moons in search of life.
Dr. Mark Price, another co-author from the University of Kent, said in the release that the process reveals how simple molecules, such as water and carbon-dioxide ice, can be transformed into more complicated molecules such as amino acids.
"This is the first step towards life," Price said. "The next step is to work out how to go from an amino acid to even more complex molecules such as proteins."
