Japan's MMX spacecraft to launch to Mars's moon Phobos to bring back samples

Mixed · 2Japan's space agency JAXA is about to launch the Martian Moons eXploration (MMX) spacecraft towards Phobos, the larger of Mars's two moons, with the aim of bringing back a sample. 1 2 Mixed · 2The launch is on an H3 rocket from the Tanegashima Space Center in southern Japan. The Conversation gives the time as Monday 19 October at 20:41 BST, while New Scientist gives 20 October (the two are consistent if the latter uses Japanese local time). 2 1 Mixed · 2MMX should reach Mars in August 2027 and enter an orbit alongside Phobos to map its surface, also observing Deimos along the way. One Conversation article instead says it arrives in 'late 2027'. 1 2 3

Left · 1The mission is led by JAXA with the US, France, Germany and the European Space Agency. It carries a small rover called Idefix, developed by JAXA, the French space agency Cnes and the German Aerospace Center (DLR). The Conversation describes it as microwave-oven-sized, and another Conversation article says it weighs 25kg. 2 3 Mixed · 2According to The Conversation, the rover is due to be dropped in early 2029 and operate for about 100 days, and the main module lands in 2030 for about 2.5 hours. New Scientist says the spacecraft will make one or two brief landings, and that the rover is the first placed on so small a body, so part of its purpose is to test whether a wheeled rover works in such low gravity. 2 1 Mixed · 2Two sampling devices are carried. One blasts gas at the surface to blow dust and pebbles into a container. The other drives a hollow cylinder into the ground to take a core. The Conversation calls the coring device the C-sampler, says it takes a core up to 2cm deep, and calls the gas device the P-sampler, a back-up with a small risk of toppling the spacecraft; New Scientist says the core is several centimetres deep. 1 2

Mixed · 2The spacecraft aims to gather at least 10 grams, which would be the first sample return from a Martian moon, and bring it back to Earth in 2031. The Conversation says the capsule will land by parachute in Australia and be taken to Japan. 2 1 Mixed · 2The science goal is to settle how Phobos and Deimos formed, a question researchers have debated for more than a century. One hypothesis is that they are captured asteroids. The other is that they formed from debris thrown out when an object hit Mars, as Earth's Moon is thought to have formed. 1 3 Mixed · 2The moons' shapes and surfaces resemble asteroids, but their near-circular orbits around Mars's equator fit the impact idea better. The captured-asteroid idea also needs an extremely dense early Martian atmosphere to trap them. A composition resembling known asteroid meteorites would favour capture, while a lot of Martian material would favour a giant impact. 1 3

Mixed · 2The samples might also contain material from Mars itself, thrown up by impacts and preserved on Phobos. The Conversation calls MMX a 'lite-version' of the Mars Sample Return programme, which it says was effectively cancelled by US Congress over budget pressures. 1 2 Mixed · 2The Conversation notes that Russia's 2011 Phobos-Grunt mission failed to leave Earth orbit, while JAXA has already returned asteroid samples with Hayabusa and Hayabusa 2. NASA's Tom Statler, whose team collaborates on MMX, said the answer would help illuminate the early era when the inner planets may have acquired much of their water and organic compounds. 2 1