The silent missiles that flit between the planets have been blamed for some of the largest exterminations that life on Earth has had to endure: However you like your mass extinctions, high on the list of potential triggers is usually a close encounter with a meteorite.
Recently, however, a remarkable discovery has cast these aerial assaults into a surprising new light — because, as well as destroying life, it now seems that ancient collisions might also have helped create it.
In September 2013, a study appeared in the journal Nature Geoscience that set out to test an extraordinary theory regarding life's deep roots. Researchers had previously hypothesized that, through a process known as shock synthesis, the extreme conditions generated by meteorite impacts — specifically ones involving comets — might be able to forge the fundamental chemicals of biology. With the shock as a catalyst, the theory went, the organic (carbon-bearing) molecules present in the ice of comets — such as ammonia and methanol, a simple alcohol — could be transformed into amino acids, the crucial components of proteins, and therefore of life. [Did Comet Impacts Spur Life on Earth? ]