Japan Launches a Mission to Bring Home a Piece of the Martian Moon Phobos

Japan’s space agency launched a spacecraft toward Mars on Tuesday morning local time on a mission to collect soil from the Martian moon Phobos and bring it back to Earth, an attempt no space program has made before.

The Martian Moons eXploration spacecraft, known as MMX, lifted off on an H3 rocket from the Tanegashima Space Center in southern Japan at 4:41 a.m. Japan time, which was Monday afternoon in the eastern United States. The German Aerospace Center, or DLR, described the launch as successful, and Space.com and Reuters reported the spacecraft on its way.

The mission is led by the Japan Aerospace Exploration Agency with partners including NASA, the French space agency CNES, DLR and the European Space Agency. According to ESA, MMX would be the first mission to return a sample from Phobos, the first to fly in a special looping orbit around that moon, and the first to collect material from the surface of any moon other than our own.

The spacecraft is expected to take about a year to reach Mars, entering orbit around the planet in August 2027 and beginning to circle Phobos about a month later. After studying Phobos and the smaller moon Deimos from a distance, it is scheduled to release a rover, descend to Phobos in late 2028 or 2029 to collect samples, leave Mars orbit in 2030 and send a capsule carrying at least 10 grams of material back to Earth in 2031. The capsule is to land in Australia before the samples are taken to Japan for analysis.

The rover, named Idefix, was built by DLR and CNES. It weighs about 25 kilograms on Earth but would weigh only about 15 grams in Phobos’s feeble gravity, ESA said. It is to be dropped from roughly 40 to 100 meters above the surface, bounce to a stop, turn itself upright, unfold its solar panels and explore for about 100 days while enduring temperature swings of more than 200 degrees Celsius. Markus Grebenstein, DLR’s project manager for the rover, called driving on Phobos uncharted territory for robotics.

The central scientific question is where Mars’s moons came from. One idea holds that Phobos and Deimos are asteroids captured by Mars’s gravity. Another holds that they formed from debris thrown into orbit when a large object struck the planet. Samples studied in laboratories on Earth could help decide between those explanations and shed light on the early history of Mars, including whether it was once habitable, ESA said.

Yasuhiro Kawakatsu, JAXA’s project manager for MMX, described MMX as a world-class effort built on international collaboration, and German officials praised the European robotics and precision technology on board, DLR said. ESA has said its Mars Express orbiter, expected to keep operating until at least 2029, may support MMX observations.