The current NASA thinking concerning the Journey to Mars program envisions a visit to the Martian moon Phobos in the early 2030s before attempting a landing on the Martian surface in the late 2030s, as Popular Mechanics noted on Wednesday. The idea of a practice run that takes astronauts almost but not quite to Mars is similar to what the space agency did during the 1960s Apollo program. Apollo 8 and Apollo 10 each orbited the moon but did not land on it before the Apollo 11 mission went all the way to the lunar surface, fulfilling President John. F. Kennedy’s challenge.
The idea of a Mars orbit mission, including a visit to Phobos, actually originated with the Planetary Society, a private group that supports science-oriented space exploration. The theory is that everything involved in going to and from Mars except the landing would be tested, including propulsion and life support systems. While the astronauts are in Mars orbit, they could do some useful science by landing on Phobos and using it as a base.
Phobos orbits Mars every seven hours from an altitude of 9,380 kilometers. The moon of Mars is just 17 by 12 miles wide and is composed of carbon-rich rock with likely some ice beneath the surface similar to a C-type asteroid. One theory posits that Phobos and its companion moon Deimos are asteroids from the main belt that were captured into Mars orbit billions of years ago. Some scientists dispute this theory, however.
Phobos is heavily cratered, with a huge basin gouged out of it called the Stickney Crater. Mars’ gravity is slowly pulling the moon closer to its surface. In about 10 million years, Phobos will break up in the skies over Mars, torn apart by tidal forces.
Besides exploring Phobos itself, a tricky proposition because of its low gravity, the astronauts will be able to control rovers and other robots on the Martian surface in real time, without waiting the 20 or so minutes it takes for radio signals to travel from Earth to Mars.
The argument against going to Phobos before going to Mars stems from the great expense such a voyage would entail. Why not go all the way if one is already in orbit around the Red Planet? But NASA likes to take small, incremental steps when conducting a challenging program of space exploration. It served the space agency well during the Apollo program.
However, if some private group that is a little less risk adverse, say Elon Musk’s SpaceX, gets its own Mars program off the ground, it might decide to go for broke and go all the way the first time.
Mark R. Whittington is the author of Why is it so Hard to Go Back to the Moon? and The Man from Mars: The Asteroid Mining Caper