Mars's tiny moons – one small step for mankind?

Forget Mars – the Red Planet's moons Phobos and Deimos could be the next stop in the solar system for humanity, according to planetary scientists. During a recent conference at the Ames Research Center in Moffett Field, in California, Scientists speculated that astronauts could make their first footprints on one of them within 10 years. As a counterpoint to a return mission to Earth's moon, some scientists believe that a manned mission returning to the moon is counter productive. Plus a robotic mission to either of Mars' moons is easier than one to Luna.

Granted, the Moon is only a short three-day spaceflight from Earth, whereas Phobos and Deimos are several months away using current propulsion methods.

But the Moon's gravity is one-sixth Earth's, strong enough that a landing craft has to fire retrorockets to slow its descent to the surface, and again to leave. This wastes tonnes of heavy, expensive fuel and adds millions of dollars to the cost of a mission.

Mars' two potato-shaped worlds, on the other hand, are tiny – Phobos is the size of Manhattan and Deimos is about a third as large, just 6.3 kilometres wide. So their gravitational pull is only one-thousandth that of Earth, making landing on them more like docking with another spaceship.

Estimates put a robotic or manned mission to Mars' moons at a tenth of the cost of a moon or Mars mission. Plus there are many unknowns about the makeup and origins of both of Mars' moons that such missions could help answer. Scientists have theorised that the moons may be asteroids captured by Mars's gravity, or that they may be remnants of a single moon that was blasted apart by a massive impact. But until we have missions that target these bodies, we will always have questions.

This image of Phobos, taken by Europe's Mars Express spacecraft from a distance of less than 200 km, shows the Mars-facing side of the moon (Image: ESA/DLR/FU Berlin/G Neukum)

Thanks to Shaun A. Saunders for the post