Japan's space agency, JAXA, is set to launch its Martian Moons eXploration mission, known as MMX, which aims to bring back the first samples from Phobos, a moon of Mars, the BBC and The Associated Press reported. The spacecraft will launch from Japan on an H3 rocket, The Associated Press reported.

JAXA has set the launch for 4:41 AM Japan time on Tuesday, October 20, which is 3:41 PM ET on Monday, according to JAXA. The agency has a backup launch period through November 9.

The spacecraft is due to reach the Mars area in August 2027, the BBC and The Associated Press reported. A small rover built by France and Germany will land on Phobos first and help pick a landing site, The Associated Press reported. The main spacecraft will then touch down and collect about 10 grams of material, the BBC and The Associated Press reported. The sample is set to return to Earth in 2031, landing in Australia, the BBC and The Associated Press reported.

Scientists hope the sample will show how Phobos and the smaller moon, Deimos, formed, the BBC and The Associated Press reported. One idea is that they formed from debris after a large object hit Mars. Another is that they are asteroids that came from elsewhere, the BBC and The Associated Press reported.

The sample may also hold tiny grains from Mars itself, the BBC and The Associated Press reported. "They are known as the most important unclimbed mountains in the solar system," Yasuhiro Kawakatsu, the MMX project manager, said of the Martian moons, The Associated Press reported.

The mission includes equipment from NASA and other space agencies, The Associated Press reported. A separate NASA and European plan to return samples from Mars has been effectively canceled after its funding was halted, the BBC reported.

What we know: JAXA plans to launch MMX to collect and return samples from Phobos.
What we don't: Whether the launch will go ahead on time.