Radio astronomers have found the first evidence of an amino acid-like molecule in outer space, floating in a dust cloud 25,000 light-years away. Although the discovery doesn't prove that complex organic structures originated in space, it does present strong evidence that the basic ingredients for living organisms exist elsewhere in the galaxy--and that they could be seeding many young planets with life's building blocks.
There's much more to outer space than empty space. In the gaps between the stars, astronomers have detected not only dust and gas but also molecules that constitute basic organic substances. They found these molecules not with optical telescopes but by tuning in with exquisitely sensitive antenna dishes that can receive the extremely faint radio signals generated by molecular clouds.
The Large Molecule Heimat (LMH) is a favorite place to search. This unusually compact cloud of dust and gas near the center of the Milky Way in the direction of the constellation Sagittarius is energized by a hot young star at its core, and it's a veritable alphabet soup of molecules. Most of the 140 types of molecules found in space have been discovered here, including some common on Earth: acetic acid (vinegar), ethylene glycol (the chief ingredient in antifreeze), and a basic sugar known as glycol aldehyde. Until now, however, no one had found a link to the building blocks of life.
Using radio telescopes in Spain, France, and Australia, a team headed by researchers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, scanned the LMH for signals in the precise wavelengths that would reveal the presence of more complex molecules. They eventually collected 3700 separate spectral lines, and 51 of them, the team reports in an article in press in Astronomy and Astrophysics, were unmistakably amino acetonitrile, a molecule that resembles a primitive amino acid.
It's unlikely the molecule is unique to the LMH. Other star-forming regions should also harbor the right conditions to produce amino acetonitrile, and possibly even proper amino acids, says lead author Arnaud Belloche. The next generation of radio telescopes, such as the Atacama Large Millimeter Array, under construction in Chile, should have an easier time finding these molecules, adds co-author Karl Menten.
Discovering molecules like amino acetonitrile is a big deal, because it's not easy for them to materialize in the extreme temperatures of space, says radio astronomer Anthony Remijan of the National Radio Astronomy Observatory in Charlottesville, Virginia: "Too hot and they are destroyed, too cold and they can't form." So the finding shows that the chemistry needed to create molecules giving rise to life on Earth "is present in space and the molecules themselves are abundant," Remijan says.
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