Hayabusa2's mission to destroy the asteroid Ryugu was delayed until 2019

The Japan Aerospace Exploration Agency (JAXA) has postponed the hit of the main section of the Hayabusa2 probe on the Ryugu asteroid to January 2019, Nature reported, after the mission scientists had determined that Ryugu's surface was rougher than expected and that landing needs more planning time.

While Hayabusa2 carries a number of small rovers, some of which have already been deployed on Ryugu's surface, the spacecraft's mother ship must land on the surface of the asteroid to collect samples. According to nature, scientists at JAXA determined that there were few sites on the asteroid without rocks and that the best of them was very small:

For the sample collection phase, the project team was hoping to identify an area at least 100 meters wide that would be relatively free of blocks, that is to say without rocks over 50 centimeters. Otherwise, higher rocks could hit the main body of the device as it deploys its one meter arm to take a sample, says a JAXA release.

But detailed maps of the surface have shown that the best of these areas is only about 20 feet wide. The agency now wants to make sure that it can hit such a narrow target on the rotating surface.

Hayabusa2 will collect samples via various methods; the first descent, which corresponds to the delayed descent in question, will be made by flying the craft on the surface to fire a tantalum ball at Ryugu. After that, the bulk materials will be recovered by a sampling horn and the craft will fire with its thrusters to escape the surface of the asteroid. A final collection of samples scheduled for 2019 will involve firing a kinetic impactor to the remote asteroid and detonating a remotely fired charge inboard. (According to Popular Science, the 10 kg of explosives it contains will throw a copper disc on Ryugu in a similar way to military anti-tank weapons). After approximately two weeks of avoiding the impactor debris, the impactor will descend to the surface to collect samples from the impact site.

"Although the spacecraft can be controlled with a 10-meter position error at an altitude of less than 50 meters, it remains to be seen whether this accuracy can be maintained as the spacecraft descends to the surface," said JAXA. to Nature in a statement. However, Makoto Yoshikawa, head of the JAXA mission at Sagamihara Institute of Space Science and Astronautics, told the paper that the delay should not affect the date of Hayabusa2's return to Earth in 2020, that's fine.

Depending on the nature, the JAXA will organize a rehearsal in October to check if the boat is able to get to the surface safely:

The JAXA has announced that it will perform a ground contact repetition from October 14 to 16, bringing the craft back to an altitude of about 25 meters – the lowest to date – to test the altitude measurements of the aircraft. the probe at short distance.

Hayabusa2 has already made a close approach, less than 25 meters, this week.

Last week, JAXA called for delaying landings. Project leader Yuichi Tsuda told Agence France-Presse: "The mission … is to land without hitting the rocks". It would be "very difficult", he added, because I expected the surface to be smooth … but it seems that there is no flat surface. "

In late September, Hayabusa2's MINERVA-II1A and MINERVA-II1B rovers (using the torque generated by the internal engines rather than the wheels) managed to land in Ryugu and began to monitor the surface. They quickly began to transmit fascinating images of the surface of the meteor. Ten days later, Hayabusa2 successfully deployed its Mobile Asteroid Surface Scout (MASCOT) mobile observation robot, which contains a camera, a spectrometer, a magnetometer and a radiometer. However, its non-rechargeable lithium-ion battery failed as expected just over 17 hours after touch.