Mars’ moons: Japan’s space agency preps pioneering mission

Japan’s space agency (JAXA) has received the green light for a pioneering mission to the two moons of Mars.

The government’s science ministry this week allowed the Martian Moons Exploration (MMX) project to enter the development phase.

It means JAXA is on course to launch a Mars-bound spacecraft in 2024 aboard a new H-3 rocket being developed by Mitsubishi Heavy Industries. The spacecraft will arrive close to the Red Planet’s moons, Phobos and Deimos, a year later in 2025.

At the start, the spacecraft will spend time surveying Mars’ moons from a distance, making detailed maps of their surfaces, before attempting to become the first-ever mission to make a landing on one of them.

But that’s not all.

The team also wants to take a sample during its time on the surface, bringing it to Earth in 2029 for analysis.

The moons

Phobos has been selected for surface operations, JAXA said this week, with the spacecraft expected to stay on the surface for several hours while it gathers a sample weighing at least 10 grams from just below the moon’s surface. The team also wants to put down a rover to gather additional data during a close-up exploration.

Mars’ moons are among the smallest in the solar system, according to NASA. Phobos has a diameter of 14.3 miles (23 km), making it slightly larger than Deimos, which has a diameter of 7.5 miles. The larger moon orbits only 3,700 miles (6,000 km) above the Martian surface, closer than any other known moon. It makes a complete trip around Mars three times a day, while the more distant Deimos (14,573 miles/23,460 km) takes 30 hours for each orbit.

Mission objectives

JAXA says its mission could tell us more about water arrival in the inner Solar System and settle debates about whether the moons are asteroids captured by Mars’ gravity or were formed during a giant impact with the Martian planet.

It will also help scientists to determine if either of the moons could act as a viable base for humans ahead of making a landing on Mars.

“Humans can realistically explore the surfaces of only a few objects and Phobos and Deimos are on that list,” said Jim Green, NASA chief scientist. “Their position orbiting about Mars may make them a prime target for humans to visit first before reaching the surface of the Red Planet, but that will only be possible after the results of the MMX mission have been completed.”

The MMX spacecraft will carry eleven scientific instruments, four of them provided by NASA, ESA (Europe), CNES (France), and DLR (Germany). JAXA’s devices will include a telescopic camera for observing detailed terrain, a wide-angle camera to identify hydrated minerals and organic matter, and the all-important sampling device and sample return capsule.

There’s plenty of confidence in Japan’s ability to achieve its mission aims as it has past form when it comes to landing on distant space rocks, gathering samples, and getting them back to Earth. In 2010, for example, Hayabusa returned with a capsule containing tiny particles taken from the surface of a faraway asteroid.

More recently, Hayabusa2 visited another asteroid and is currently on its way back to Earth with samples from that one, too. It is expected to arrive toward the end of 2020. JAXA said it’s further developing the Hayabusa technology for use in the MMX mission.

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