Japan will launch the first spacecraft designed to travel to Mars and return to Earth on Monday, bringing back soil from one of the planet's potato-shaped moons.
The Japan Aerospace Exploration Agency, known as JAXA, leads the Martian Moons Exploration mission, or MMX, with NASA as a partner. The rocket lifts off from Tanegashima Space Center at 3:41 p.m. ET on Oct. 19, or 4:41 a.m. Tuesday in Japan.
MMX should reach Mars next August and survey the planet's two small moons, Phobos and Deimos. No earlier than December 2028, it will land on Phobos, scoop up a sample, and turn for home, reaching Earth in 2031.
"MMX will be the first spacecraft ever to return to Earth from the Mars system," said Tom Statler, NASA's program scientist for the mission. "That says a lot."
Scientists hope that the sample will reveal how the Red Planet got its moons. Mars' gravity may have captured passing asteroids, or a large object may have slammed into Mars and blasted debris into orbit, where it clumped together into moons. Learning which story is likely true will give scientists new insight into both Mars and Earth, including events that shaped both planets billions of years ago.
Getting there depends on the trip home. JAXA has brought samples back from asteroids before. Its Hayabusa spacecraft returned tiny particles of the asteroid Itokawa, and Hayabusa2 brought back a bit more than 5 grams from the asteroid Ryugu.
NASA's OSIRIS-Rex has also collected more than 120 grams from the asteroid Bennu. What sets this mission apart is that it will be the first to collect from a moon other than Earth's. NASA, which supplied the mission's Megane instrument and one of its two soil samplers, will keep at least 15 percent of the returning specimens. The U.S. space agency estimates its investment in the mission to be around $87 million over 14 years.
The Japanese space agency will livestream the launch beginning at 2:45 p.m. ET / 11:45 a.m. PT on Monday. You can watch it lift off in the video mini player below.
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So far, the origin of the moons remains elusive. In visible light, Phobos and Deimos resemble a type of asteroid that generally orbits in the outer part of the main asteroid belt, the ring of rocky objects that circles the sun between Mars and Jupiter. But both moons follow nearly circular paths lined up with Mars' equator, a pattern that fits debris from a giant collision.
Megane, which means "eyeglasses" in Japanese, will take the first measurements of the chemical elements that make up Phobos. The instrument measures gamma rays, a powerful form of light, and neutrons, tiny particles emitted from the moon's surface.
After a nail-biting landing on Phobos, the spacecraft will stay about 2 ½ hours. Honeybee Robotics' sampler, which sits on one of the lander's four legs, will fire ultrapure nitrogen gas to blow loose soil into a container, like a vacuum cleaner.
"You blink, and it's all done," said Kris Zacny, Honeybee's vice president.
The spacecraft's other sampler pushes a tube into the top 2 inches of the surface. The spacecraft also carries a small rover from the French and German space agencies.
Astronomers say Phobos' weak gravity and lack of air make it far easier to land on than Mars. Still, the mission could point the way there.
"The ability to make such round trips could be interesting for future robotic missions that bring back samples from Mars itself and potentially even visiting Mars with humans in the future," the European Space Agency, another MMX partner, said in a statement.
The spacecraft has three modules: one to reach Mars, one to land on Phobos, and one to return the sample home. When the return module reaches Earth, it will send down a capsule carrying at least 10 grams — roughly one-third of an ounce — of Phobos soil. The capsule will land in Australia, and the sample will then travel to Japan, where scientists will catalog it and share it with the mission's partners.