Tokyo: Japan is set 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, expected to take five years, will provide clues about how Phobos and its smaller sibling, Deimos, formed and potentially shed light on the origins of life in the solar system.
The Japan Aerospace Exploration Agency (JAXA) is scheduled to launch the spacecraft on Tuesday aboard its H-3 rocket, which is emerging as a mainstay of Japan’s space programme. The mission comes as the United States, China and other countries consider sending astronauts to Mars.
Samples from Phobos could provide useful data for scientists assessing the possibility of using a Martian moon as a base for future crewed missions to the planet, said Yasuhiro Kawakatsu, manager of the Martian Moons eXploration (MMX) project.
“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 the 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 remain largely unexplored. Phobos and Deimos take their names from the Greek mythological personifications of fear and terror, the sons of the war god Ares, whose Roman counterpart is Mars.
Multiple Russian attempts to land on Phobos, including one in 2011, have failed.
A key question for scientists is how the two moons formed and what they are made of. Some researchers believe the irregular, crater-pocked bodies are remnants of debris created when a large celestial object crashed into Mars. Others suggest they could be asteroids that originated elsewhere in the solar system.
JAXA officials believe samples from Phobos will help answer these questions.
“We can almost certainly come to a conclusion by analyzing (Phobos) soil samples,” said Kiyoshi Kuramoto, the MMX mission’s principal investigator.
Scientists selected Phobos for sample collection mainly because it is closer to Mars than Deimos and may therefore contain more information about the planet. JAXA officials estimate that material originating from Mars could account for about 0.1% of the material collected from Phobos.
Phobos measures about 20 to 30 kilometres (10 to 20 miles) in diameter and orbits Mars at a distance of approximately 6,000 kilometres (3,700 miles), completing three orbits a day.
Samples from Phobos could also provide insights into the origins of Deimos, as the two moons are believed to have similar roots, Kuramoto said. The mission also includes plans to fly past Deimos and collect observations.
The journey to Mars will be long, with the planet about 55 million kilometres (34 million miles) from Earth at their closest point.
After launching aboard the H-3 rocket, the spacecraft is expected to reach the Mars region a year later. It will then spend three years flying near and around Phobos, collecting data and gathering samples before returning to Earth in 2031.
The MMX spacecraft comprises three modules — propulsion, exploration and return — and weighs about five tonnes. Only the return module will travel back to Earth, carrying the samples in a capsule.
The spacecraft will carry 13 instruments, including a rover jointly developed by France and Germany that will land on Phobos. Its equipment will also include a NASA sampling device, an instrument to measure gamma rays, and the European Space Agency’s deep-space communications device. A Japanese radiation monitor will gather data that could support future crewed exploration of Mars.
The French-German rover, Idefix, is scheduled to land on Phobos first. During a 100-day mission expected around 2029, it will explore the moon’s surface and help prepare for the subsequent Japanese soil-sampling operation.
After landing at a later stage, the MMX spacecraft will aim to collect at least 10 grams (0.35 ounces) of soil through two sampling attempts using US and Japanese methods.
NASA’s sampling device uses pressurised gas to lift surface dust into a container, while JAXA’s coring method will collect material from a depth of about 2 centimetres (less than 1 inch).
During the first attempt, the MMX spacecraft will use both devices to collect surface and underground samples. A second landing will be used to gather additional underground material.
Scientists say collecting samples from multiple locations increases the chances of finding potential traces of past microbial life originating from Mars.
The samples will be stored in a heat-protected capsule designed to withstand re-entry into Earth’s atmosphere. The capsule is expected to land in Australia before being transported to Japan.
Japan’s two Hayabusa missions have previously returned asteroid samples, first in 2010 and again in 2020.
The spacecraft must select a relatively smooth, level landing site using topographical data provided by the rover. It will then have to collect samples within two hours.
Landing on the heavily cratered moon is challenging because its gravity is only one two-thousandth of Earth’s.
To minimise bouncing on touchdown, the MMX exploration module is equipped with four-legged landing gear featuring shock absorption.
The rover has wheels designed to gain traction in low gravity. It can also right itself if it tips over and move “at a snail’s pace”, JAXA said.