Posted: Tue, Jan 30, 2007, 8:01 AM ET (1301 GMT)
If the planet Mars still harbors any living organisms, they must exist well below the surface to avoid being killed by radiation, scientists concluded in a new study. In a paper published in Tuesday's edition of the journal Geophysical Research Letters, scientists said a model of the solar and galactic radiation that reaches the surface of Mars showed that such radiation would kill any life on the surface and to a depth of at least several meters. At deeper levels, though, life could exist if it has access to liquid water and organic material. The best place to look, the study concluded, would be within what scientists believe to be a frozen sea in the Elysium region of the planet.

Related Links:

•  BBC article
•  SPACE.com article
•  The Guardian article
•  Cosmos Magazine article
•  AGU press release