Japan is about to try something no spacecraft has done: fly to the Mars system, land on one of its moons, and come home with a piece of it. The Martian Moons Exploration mission, MMX, is led by the Japan Aerospace Exploration Agency, with NASA as a partner. Liftoff from Tanegashima Space Center is set for 3:41 p.m. ET on Oct. 19, which is 4:41 a.m. on Oct. 20 in Japan.
Practice on asteroids
Why would JAXA expect to pull it off? It has done a version of this before. The agency’s Hayabusa probe returned tiny particles of the asteroid Itokawa in 2010, and Hayabusa2 brought back a bit more than 5 grams from the asteroid Ryugu. NASA’s OSIRIS-REx has also collected more than 120 grams from Bennu. What sets MMX apart is its target. It will be the first mission to collect material from a moon other than Earth’s.
“MMX will be the first spacecraft ever to return to Earth from the Mars system,” said Tom Statler, NASA’s program scientist for the mission. “That says a lot.”
How the sampling works
The spacecraft is made of three modules: one to reach Mars, one to land on Phobos, and one to carry the sample back. It should arrive at Mars in August 2027 and survey Phobos and Deimos. The landing comes no earlier than December 2028, and the stay will be short, about two and a half hours.
Two samplers share the job. JAXA’s C-Sampler pushes a tube into the top few inches of the surface to pull out a core. NASA’s contribution, built by Honeybee Robotics, is a pneumatic sampler on one of the lander’s four legs. It fires ultrapure nitrogen gas to blow loose soil into a container, a bit like a vacuum cleaner. “You blink, and it’s all done,” said Honeybee vice president Kris Zacny. A small rover from the French and German space agencies also rides along.
Phobos has weak gravity and no air, so landing there is far easier than landing on Mars. Even so, the European Space Agency, another partner, said such round trips could be useful for future missions that fetch samples from Mars itself, and perhaps for human visits.
The question about the moons
Nobody knows where Phobos and Deimos came from. In visible light, they look like a kind of asteroid usually found in the outer main belt. But both circle Mars on nearly round paths lined up with its equator, a pattern that fits debris from a giant impact. Statler said the moons may be the remains of a massive impact, or ancient asteroids captured by Mars’ gravity, and settling it will shed light on the era when Earth and the other inner planets may have picked up much of their water and organic compounds.
NASA supplied MEGANE, short for Mars-moon Exploration with Gamma rays and Neutrons, and the name is also the Japanese word for eyeglasses. It measures gamma rays and neutrons coming off the surface to work out which chemical elements make up Phobos. NASA also provides Deep Space Network support and funds U.S. scientists on the team, and puts its investment at around $87 million over 14 years.
Bringing it home
The return capsule is due on Earth in 2031, carrying at least 10 grams of Phobos soil, roughly a third of an ounce. It will land in Australia, then travel to Japan, where scientists will catalog the sample and share it with partners. NASA will keep at least 15 percent at the Astromaterials Lab at its Johnson Space Center in Houston.
Sources
- JAXA's Martian Moons Exploration mission launch: how to watch live
- JAXA
- NASA to Help Unlock Mysteries of Mars’ Moons in Upcoming Mission – NASA Science
Photo: Osamu Iwasaki (CC BY-SA 2.0)
