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The MASCOT lander, released from the Japanese shuttle Hayabusa 2 this week, made three jumps in different locations of the Ryugu asteroid before emptying its battery, surviving its useful life and returning the data of his four instruments, according to German and French officials who developed the surface. robot.
The tiny LG, no bigger than a microwave oven, was released from the Hayabusa 2 space shuttle at 0157:20 GMT Wednesday (9:57 pm EDT Tuesday) while the Japanese mothership maneuvered to a point at only 51 meters from Ryugu.
Six minutes later, the tumbling lander made his first contact with the surface of the asteroid – at 0:03 UTC (10:03 HNT) – and bounced several times, as expected, before stopping and throwing a automated scientific campaign.
The mobile surface asteroid scout lasted more than 17 hours, exceeding mission expectations. The lifespan of the LG was limited by the capacity of its lithium battery and designers did not install solar panels on the boat to save weight and money.
"According to our estimate, we thought it would last 12 hours if it was a success, maybe 15 or 16 hours if we were really above it," said Aurélie Moussi, MASCOT project manager at CNES, the French aerospace agency. French space agency, which supplied the battery. "We lasted 17 hours. It's amazing. "
"In our best dreams, we did not expect so much joy," said Moussi.
Some of MASCOT's instruments, as well as many members of his ground crew, come from the Philae mission, which landed on comet 67P / Churyumov-Gerasimenko in 2014 after being separated from the orbiter of Rosetta comets of the European Space Agency.
Like Philae, MASCOT bounced off the surface of his new home. But Philae was carrying anchor equipment and other landing aids to prevent such movements, while the MASCOT lander did not have any such equipment.
Nevertheless, Philae collected images and other scientific data throughout his stay around the comet.
"We used (battery) cells from the same batch as Philae," Moussi said Friday during a presentation at the International Astronautical Congress in Bremen, Germany. "It seems that this lot is really good."
The Hayabusa 2 satellite, managed by the Japan Aerospace Exploration Agency, directed the MASCOT lander to a destination area in the southern hemisphere of Ryugu. Once on the surface, MASCOT had an internal oscillating arm capable of moving like a pendulum, which allowed it to generate momentum and to jump at different places of the asteroid, which is about 1 km in diameter and has a gravity field 80,000 times weaker than the Earth.
Ryugu encircles the sun on a path mainly between the orbits of Earth and Mars. The asteroid plunges briefly inside the earth's orbit at every trip around the sun, making Ryugu a potentially dangerous asteroid, likely to pose a threat to our planet.
Stephan Ulamec, MASCOT Payload Manager at DLR, the German space agency, congratulated the Hayabusa 2 spacecraft for the tricky descent maneuver to an asteroid more than 200 million kilometers from Earth.
"The Hayabusa 2 space shuttle worked so well, like a clock," he said. "We are tempted to assume that all this is easy and trivial because it worked very well. It's not at all.
"Our role was relatively easy," joked Ulamec, who was project manager on Philae's comet Landae. "We were dropped. We fell to the ground and landed. The problem is that we had to straighten and operate for the time allowed by the main battery. "
The engineers at DLR's landing gear control center in Cologne, Germany, detected that the robot was facing the wrong way once it settled on the surface. This forced the controllers to abandon the original scientific plan and to send emergency orders to MASCOT, routed through the Hayabusa 2 Control Center in Sagamihara, Japan, to retreat with the assistance of its integrated recovery mechanism.
"After this very first touchdown, we noticed pretty quickly that the undercarriage was upside down," said Ulamec.
The switchover worked as expected and the robot traveled about 1 or 2 meters and the four instruments began collecting data from the surface of the asteroid, Ulamec said.
Ryugu turns once on his axis every 7 hours and 36 minutes. MASCOT experienced three sunsets before emptying its battery of the asteroid.
The LG collected day and night measurements. His camera was equipped with four LEDs to illuminate neighboring rocks with red, green, blue and infrared light. A radiometer instrument measured the temperatures of Ryugu's surface material during a complete day-night cycle, data that can help scientists better understand the physical properties of asteroid rocks and dust, thus giving future missions an interaction with asteroid surfaces, according to Matthias Grott, principal investigator for the MASCOT Radiometer at DLR.
"What we have learned so far from images is that it seems that the surface is made up of more consolidated rocks covered with a thin layer of particles," Grott said. .
MASCOT's magnetometer measured the spin of the undercarriage as it descended to the asteroid, confirming its successful deployment from Hayabusa 2 and informing the controllers of the robot's motion on the surface. The instrument has also been designed to search for any residual magnetic field on the asteroid.
"Later, we were able to continue the Ryugu activities with a special maneuver," said Ralf Jaumann, DLR Global Scientist and MASCOT Scientific Director. "With a mini-move, we recorded sequences of images that will be used to generate stereoscopic images of the surface once analyzed."
On the second day of MASCOT's three-and-a-half hours on the asteroid Ryugu, the lander made a small movement to put the materials on the surface at the sight of a tiny microscope designed to elucidate the mineral composition of the rocks. the asteroid, looking for the chemical signatures of carbon and molecules that could once interact with water.
"For the first time, we are trying to measure the composition of the carbon-rich material of an asteroid," said Jean-Pierre Bibring, scientific lead of the MicrOmega spectrometer from MASCOT. "To do this, we built an instrument supposed to be in contact (with the surface)."
As always, in exploration, you never know where you are going, "said Bibring, a scientist at the Institute of Space Astrophysics in Orsay, France. "We landed there for the first time trying to measure the composition and, of course, we discovered a lot of things that we had not planned."
MASCOT once again made a jump before his mission ended up going several meters to get to another site, and the controllers lost their radio link with the LG at 19:04 GMT (15:04 EDT) on Wednesday then that he was entering his third night on the asteroid.
After deploying MASCOT, Hayabusa 2 climbed to a position about 3 kilometers from the asteroid to relay data between the Earth and the lander. However, Hayabusa 2, who was to remain in the sun to generate electricity, was unable to contact MASCOT when the landing area swung out of the mother ship's field of view and into the night.
By the time MASCOT returned to daylight, Hayabusa 2 heard no signal from the LG.
"The evaluation of valuable data is just beginning," said Tra-Mi Ho, MASCOT project manager at DLR's Space Systems Institute. "We will learn a lot about the past of the solar system and the importance of near-Earth asteroids such as Ryugu."
Ryugu's exploration by MASCOT took place less than two weeks after Hayabusa 2 released two Japanese construction robots, even smaller than MASCOT's, which bounced around the surface of the asteroid.
The landers deployed by Hayabusa 2 were not the first to touch an asteroid and return data. This distinction goes to NASA's NEAR-Shoemaker spacecraft that landed on the asteroid Eros in 2001. But they are the first to render images of the surface of an asteroid, and the first missions to move to different places on an asteroid.
"With MASCOT it was possible, for the first time, to explore the surface of an asteroid as directly as possible on site," says Hansjörg Dittus, DLR's director for research and development. space technology. "A mission like this can only be achieved by working in close cooperation with international partners – bringing together all their expertise and commitment."
The mission of Hayabusa 2 is far from over.
The main purpose of the probe is to collect up to three samples of Ryugu and bring them back to Earth. The first attempt at sampling is scheduled for late October, followed by two more next year.
Hayabusa 2 will also launch an additional robot around the asteroid next year, before leaving Ryugu in time to drop his return capsule samples for a comeback and a landing in Australia in December 2020.
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Follow Stephen Clark on Twitter: @ StephenClark1.
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