Astrobiology: Photochemistry on ice

The delivery of extraterrestrial organic molecules is a possible alternative or complement to their generation on early prebiotic Earth. Amino acids have been found on several meteorites and the usual explanation for their presence is that they formed in liquid water reactions on parent bodies such as comets or asteroids. Two independent studies now identify ice photochemistry in the interstellar medium as a possible source of meteorite-borne amino acids. Ultraviolet irradiation of ice mixtures containing known 'interstellar' molecules (such as CO, NCN and NH₃) in the conditions of vacuum and low temperature found in the interstellar medium generates amino acids including glycine, alanine, serine and proline.

letters to nature
Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues
MAX P. BERNSTEIN, JASON P. DWORKIN, SCOTT A. SANDFORD, GEORGE W. COOPER & LOUIS J. ALLAMANDOLA
Nature 416, 401–403 (28 March 2002)
| First Paragraph | Full Text | PDF (146 K) |

letters to nature
Amino acids from ultraviolet irradiation of interstellar ice analogues
G. M. MUÑOZ CARO, U. J. MEIERHENRICH, W. A. SCHUTTE, B. BARBIER, A. ARCONES SEGOVIA, H. ROSENBAUER, W. H.-P. THIEMANN, A. BRACK & J. M. GREENBERG
Nature 416, 403–406 (28 March 2002)
| First Paragraph | Full Text | PDF (182 K) |

news and views
Astrobiology: Seeds of life?
EVERETT L. SHOCK
Amino acids, a basic constituent of life, can form in dust grains that are similar to those found in the space between stars. But how much does this tell us about the origins of life on Earth?
Nature 416, 380–381 (28 March 2002)
| Full Text | PDF (323 K) |

28 March 2002 table of contents