"A sample from the moon Phobos, which is much easier to reach than the Red Planet itself, would almost surely contain martian material blasted off [Mars] from large asteroid impacts," Purdue University Professor Jay Melosh said.
"If life on Mars exists or existed within the last 10 million years, a mission to Phobos could yield our first evidence of life beyond Earth," he said in a university release Friday.
"We are talking little green microbes, not little green men," Melosh said.
Melosh led a team chosen by NASA's Planetary Protection Office to evaluate if a sample from Phobos could contain enough recent material from Mars to include viable martian organisms.
The team concluded a 200-gram sample scooped from the surface of Phobos could contain, on average, about one-tenth of a milligram of Mars surface material launched in the past 10 million years.
"Approximately one ton of martian material lands on Earth every year," Melosh said. "There is a lot more swapping back and forth of material within our solar system than people realize."
There is ongoing international interest in a Phobos mission, he said, and such a possibility will likely be a recurring topic as NASA reformulates its Mars Exploration Program.
A NASA report issued June 26 said the martian moons are "important destinations that may provide much of the value of human surface exploration at reduced cost and risk."