Martian Debris May Also Be Found On Phobos
November 12, 2013

Samples From Upcoming Phobos Mission Could Also Shed Light On Mars

[ Watch the Video: Phobos Mission Could Return With Bonus Martian Material ]

redOrbit Staff & Wire Reports - Your Universe Online

Call it the geological equivalent of a buy-one, get-one free special: a planned Russian mission to collect samples from the Martian moon Phobos could also net debris from the Red Planet itself, according to research appearing in the journal Space and Planetary Science.

The study, which was authored by Brown University professor of geological sciences James Head and colleagues, helps confirm the research that the surface of Phobos contains copious amounts of dust, soil and rock blown off the surface of Mars by large projectile impacts.

Since the moon’s orbital path occasionally travels through plumes of planetary debris, it has been collecting rock, soil and other particles from Mars for millions of years, according to the researchers. For that reason, the mission (which is currently scheduled to take place in 2020) could result in the collection of samples from both celestial bodies.

“The mission is scheduled to be flown early in the next decade, so the question is not academic,” Head explained in a statement. “This work shows that samples from Mars can indeed be found in the soil of Phobos, and how their concentration might change with depth. That will be critical in the design of the drills other equipment.”

According to the researchers, their work was inspired by the preparations for a previous, failed Russian Federal Space Agency (Roscosmos) attempt to reach Phobos in 2011. While experts have long predicted that the satellite contained materials that were Martian in origin, Roscosmos officials wanted to know how much such debris might be there and exactly where it could be located.

They recruited Head and Ken Ramsley, a visiting researcher in the university’s planetary geosciences group. The duo first used a model based on the Earth’s moon in order to estimate how much of the loose dust and rock on the surface of Phobos (also known as regolith) originated from projectiles, then they used orbital and gravitational data to figure out exactly how much of that projectile material was Martian in origin.

“When an impactor hits Mars, only a certain of proportion of ejecta will have enough velocity to reach the altitude of Phobos, and Phobos' orbital path intersects only a certain proportion of that,” explained Ramsley. “So we can crunch those numbers and find out what proportion of material on the surface of Phobos comes from Mars.”

Based on their calculations, the regolith of Phobos should consist of approximately 250 parts per million of Martian material. Furthermore, that material is believed to be distributed fairly evenly all across the moon’s surface, primarily in the upper layers of the regolith. The reason for that, according to Ramsley, is that Phobos’ orbit around Mars has only been close enough to receive the debris for the past several 100 million years.

“While 250 parts per million doesn't sound like a lot, the possibility of returning even a little Martian material to Earth gets planetary scientists excited. It's a nice bonus for a mission primarily aimed at learning more about Phobos, a mysterious little rock in its own right,” the university explained. “Scientists are still not sure where it came from… [and] there are also questions about whether its interior might hold significant amounts of water.”