DNA in Space? Biological Building Blocks Found in Meteorites

By MICHAEL D. LEMONICK Thursday, Aug. 11, 2011

Meteorites contain a large variety of nucleobases, an essential building block of DNA.

Chris Smith / NASA's Goddard Space Flight Center

• COMMENTScientists have been finding evidence of life inside meteorites for well over 100 years — that, or the building blocks of life. The claims of life have been debunked every time, most recently just this past March. It always turns out to be a wishful interpretation of chemicals, minerals and tiny structures inside the meteorite that couldbe the fossilized husks of long-dead bacteria, but almost certainly aren't.

The building blocks, though, have proven a lot more convincing. As far back as the 1960's, it was clear that amino acids, which link up to form proteins, can and do form in space. And now, scientists at NASA's Goddard Space Flight Center in Greenbelt, Maryland, are claiming that another set of molecules crucial to life have also rained down on Earth: adenine and guanine, two of the four so-called nucleobases that, along with cytosine and thymine, form the rungs of DNA's ladder-like structure./.../(See pictures of meteors that fell from the sky.)