Rocks floating in space may have brought life to Earth, but they can also be killers. NASA’s current exploration of the asteroid belt is revealing that there are fewer asteroids than previously thought (they still number in the hundreds of thousands). But there are still dozens of dangerous ones that could hit us – with catastrophic consequences. Great extinctions have been caused by asteroid impacts, and unless we can work out how to deflect these loose cannons we could suffer the same fate as the dinosaurs.
One of the theories about asteroids and their cousins the comets is that during the “era of bombardment” of the planets about 4.3 billion years ago, these chunks of rock and ice brought the Earth’s water. They also may have contained the building blocks of life, the amino acids that go into DNA. This theory of “panspermia” holds that life did not begin on Earth but was brought here from space. It suggests that life may be widespread in the universe, though as yet we have no scientific confirmation of that. The search for life in space has been going on for decades without positive results – and anyway, even if we found it, it could be too far away, or too alien, for us to communicate with it!
For more on these topics:
- NASA Finds Fewer Near-Earth Asteroids Than Previously Thought
- Did Life Begin In Space? New Evidence From Comets
- SETI – the search for life in space
See the evidence of impacts, early life and asteroid traces on a visit to the Vredefort Dome! – Graeme Addison