Japan is to launch a spacecraft on the world’s first mission to bring back samples from Phobos, one of the two small, potato-shaped moons orbiting Mars.
Scientists hope the mission, which is expected to take five years, will provide clues to how Phobos and its smaller sibling Deimos formed, and hopefully even shed light on the origins of life in the solar system.
The Japan Aerospace Exploration Agency (Jaxa) is aiming to launch the spacecraft on Tuesday on a new Japanese mainstay H3 rocket.
Yasuhiro Kawakatsu, project manager for the Martian Moons eXploration (MMX) mission, said samples from Phobos would provide useful data for scientists to consider using a Martian moon as a base for a future manned mission to the planet. The US, China and others are hoping to send astronauts to Mars.
“Despite their potential importance, Martian moons have never been fully investigated,” Kawakatsu said. “They are known as the most important unclimbed mountains in the solar system.”
Japan is leading an international mission, which includes equipment and communications support from Nasa and other national space agencies.
Since the 1960s, dozens of missions have been sent to Mars, but its moons largely remain a mystery. Multiple Russian attempts to land on Phobos, including one launched in 2011, have failed.
Phobos and Deimos take their names from the Greek mythological personifications of fear and terror, sons of the war god Ares, whose Roman counterpart is Mars.
A key question is how they formed and what they are made of. Some scientists think the two irregular crater-pocked bodies could be remnants of debris formed after a large celestial object crashed into Mars. Others say the moons could be asteroids that have come from elsewhere.
Jaxa officials think samples from Phobos will provide answers. “We can almost certainly come to a conclusion by analysing soil samples,” said Kiyoshi Kuramoto, principal investigator on the mission.
Scientists chose to collect samples from Phobos mainly because the moon is closer to Mars than Deimos, and therefore may have more information about the planet. Material from Mars is expected to make up about 0.1% of the material collected from Phobos, Jaxa officials say.
Phobos is about 27km (17 miles) in diameter at its widest point, and orbits Mars at a distance of about 6,000km (3,700 miles) three times a day.
Samples from Phobos could also shed light on the origin of Deimos as the two moons were believed to have similar roots, Kuramoto said. The mission includes plans to fly by Deimos and collect observations.
It will be a long journey to reach the red planet, which is 55m km away from Earth at its closest point. The actual flight distance would be 500-600m km, Kawakatsu said.
After launching on the H3 rocket, the spacecraft will arrive at the Mars region in around August 2027. It will then fly near and around Phobos for three years to collect data and samples from the moon, before returning home in 2031.
MMX is made up of three modules, for propulsion, exploration and return. Only the third module will return home with the samples.
The spacecraft will carry 13 instruments, including a rover jointly developed by France and Germany that will land on the moon, as well as a Nasa sampling device and instrument to measure gamma rays, and the European Space Agency’s deep space communication device. A Japanese radiation monitor will collect data that can help a future manned Mars exploration.
The French-German rover Idefix is due to on Phobos first. During a 100-day mission in around 2029, it will explore the surface to help the subsequent Japanese soil-sampling. The spacecraft will choose a relatively smooth and level site for its landing based on topographical data provided by the rover.
Once the MMX mission lands, Jaxa scientists aim to collect at least 10g (0.35oz) of soil from the moon from two sampling attempts using US and Japanese methods.
Nasa’s sampling device uses pressurised gas to lift surface dust into a container, and Jaxa’s coring method will collect samples from a depth of about 2cm. In the first attempt, the MMX will collect surface and underground samples using both devices, and take additional underground samples in the second landing.
Scientists say collecting samples from multiple locations increases the chances of obtaining any potential traces of past microbial life from Mars.
Landing on the pockmarked moon, which has just one two-thousandths of Earth’s gravity, is a challenge. To minimise bouncing at touchdown, the MMX’s exploration module is equipped with four-legged landing gear with shock absorption features.
The rover has wheels that can get traction in low gravity, right itself if it tips over, and move “at a snail’s pace”, according to Jaxa.
The samples will be stored in a heat-protected capsule designed to survive reentry into Earth’s atmosphere. The module is expected to land in Australia before being sent back to Japan.
