Japan's MMX spacecraft begins five-year Phobos sample mission

Baroukh says Idefix will scout for safety during a 100-day survey

Japan launched the MMX spacecraft before dawn Tuesday from the country’s main spaceport on Tanegashima Island, beginning a five-year mission to explore Mars’ two moons and bring samples back to Earth if the mission succeeds. Officials declared success an hour later when the spacecraft separated as planned from the rocket’s upper stage. Flight controllers burst into applause and jumped to their feet, shaking hands and embracing.

The Japan Aerospace Exploration Agency leads the $578 million effort, joined by NASA, the French Space Agency, the German Space Agency and the European Space Agency. The five partners are attempting to place a rover and lander on Phobos, the larger and closer of Mars’ two small moons. Dubbed MMX for Martian Moons Exploration, the mission features a 5-ton spacecraft that should reach Mars by late next summer, match Phobos’ tight orbit and eject the rover.

No spacecraft has reached Phobos or Deimos, and no country has returned samples from Mars or either moon. NASA has successfully landed nine spacecraft on Mars over the past 50 years, while China achieved a touchdown in 2021, but those milestones did not include the Martian moons or sample return. If MMX succeeds, its Phobos material will reach Earth in 2031.

The French-German rover, named Idefix after the white terrier in the Asterix comics, is no bigger than a microwave oven. It is designed to land on Phobos by itself, bounce for several minutes in the moon’s extraordinarily low gravity and stop. The four-wheeled vehicle can right itself if it lands upside down, but Julien Baroukh of the French Space Agency said it could sink into soft soil or become wedged between rocks.

Once Idefix deploys its solar panels, the rover can no longer right itself, which is why it will move at 1 millimeter per second, or 0.04 inches per second. According to Baroukh, Idefix will serve as a “scout for safety” during a 100-day survey. Japanese flight controllers want to avoid powdery soil and rough terrain when the mothership — a four-legged stationary lander — descends to the surface to gather samples in late 2028 or 2029.

Japan’s mothership will spend just two hours on Phobos in late 2028 or 2029, drilling and vacuuming up at least 10 grams, or one-third of an ounce, of soil and rock. It will launch back into space, study Deimos during a series of flybys and leave the Martian neighborhood in 2030. The plan calls for a 2031 sample delivery in the Australian desert if the mission succeeds.

Phobos is a lumpy, potato-shaped rock about 22 kilometers, or 14 miles, across. Scientists hope samples of it can explain how Mars’ moons formed, including whether Phobos and Deimos arose after an ancient collision between Mars and a large space rock or are stray asteroids ensnared by Martian gravity. Examining Phobos could also help explain how moons elsewhere formed. Scientists also anticipate finding traces of Mars in Phobos; the samples should help demystify planetary and moon formation and, perhaps, the recipe for life.

Japan brings experience from two asteroid sample returns. NASA astrophysicist Tom Statler, who is involved with the project, said, “There’s a lot of adrenaline and a lot of excitement and a lot of wow.”

The undertaking has a history of failed attempts, and wreckage litters the mission path. Russia failed in all three of its Phobos attempts as well as many other Mars endeavors. In its only other Mars mission, Japan failed to get a spacecraft into orbit around Mars. NASA has also had failed Mars efforts in its search for evidence about whether life ever existed on Mars.

Phobos means fear in Greek, and Deimos means dread. The moons are twin sons of the god of war Ares — Mars in Roman mythology.

NASA’s acting planetary science director Lindsay Hays said the findings will help shape future Mars missions, including astronaut missions. German Space Agency rover chief Markus Grebenstein said, “It is a once-in-a-lifetime chance. We are part of the first sample return mission from the Martian system.”

The $578 million mission draws $350 million from Japan, $87 million from NASA, about $68 million from the French Space Agency, about $56 million from the German Space Agency and some $17 million from the European Space Agency.

Japan is not the only country pursuing Martian-system samples. China plans to launch a sample-return mission to Mars in 2028, while NASA is still debating how to retrieve the more than 30 sample tubes collected by the Perseverance Mars rover. Japan and China could be neck-and-neck in getting samples back from the Martian system; both are targeting 2031.