The Mobile Asteroid Surface Scout (MASCOT), a lander carried by JAXA’s Hayabusa-2 spacecraft, successfully completed its historic exploration of the near-Earth asteroid Ryugu on October 3, 2018, as its battery ran out.
An artist’s impression of MASCOT during landing. Image credit: DLR.
MASCOT was developed by the German Aerospace Center (DLR) and built in close cooperation with the French space agency CNES (Centre National d’Etudes Spatiales).
“With MASCOT, it has been possible to, for the first time, explore the surface of an asteroid directly on site so extensively,” said Dr. Hansjörg Dittus, DLR Executive Board Member for Space Research and Technology.
“A mission like this can only be done working in close cooperation with international partners — bringing together all their expertise and commitment.”
MASCOT landed safely on the 3,117-foot (950 m) diameter asteroid Ryugu in the early morning of October 3. The lander had no propulsion system and landed in free fall.
Six minutes after separating from Hayabusa-2, and following the end of a ballistic trajectory, the module made its first contact with the asteroid.
On the surface, MASCOT moved through the activation of a tungsten swing arm accelerated and decelerated by a motor. This made it possible for the lander to be repositioned to the ‘correct’ side or even perform hops across the asteroid’s surface.
The gravitational attraction on Ryugu is just 1/66,500th of the Earth’s, so the little momentum provided was enough.
JAXA’s Hayabusa-2 spacecraft acquired images of the MASCOT lander as it approached Ryugu on October 3, 2018. MASCOT can be seen at the top. Image credit: JAXA / Tokyo University / Kochi University / Rikkyo University / Nagoya University / Chiba Institute of Technology / Meiji University / Aizu University / AIST.
“After a first automated reorientation hop, it ended up in an unfavorable position. With another manually commanded hopping maneuver, we were able to place the lander in another favorable position thanks to the very precisely controlled swing arm,” said MASCOT operations manager Dr. Christian Krause, from DLR.
“From that position, MASCOT completed a measurement sequence with all instruments over one asteroid day and an asteroid night.”
“Later, we were able to continue the activities on Ryugu with a special maneuver,” said MASCOT scientific director Dr. Ralf Jaumann, a planetary scientist at DLR.
“With a ‘mini-move’ we recorded image sequences that will be used to generate stereo images of the surface once they have been analyzed.”
In addition to the images acquired by the MASCAM camera, a DLR radiometer, a magnetometer from TU Braunschweig and a spectrometer from the Institut d’Astrophysique Spatiale provided a variety of measurements on the temperature, magnetic properties and the composition of Ryugu.
“This success was possible thanks to state-of-the-art robotic technology, long-term planning and intensive international cooperation between the scientists and engineers of the three space nations Japan, France and Germany,” said Dr. Hansjörg Dittus, DLR Executive Board Member for Space Research and Technology.
“We are proud of how MASCOT was able to master its way across the asteroid Ryugu over boulders and rocks and send so much data about its composition back to Earth,” said DLR Chair Dr. Pascale Ehrenfreund.
This image of Ryugu was captured by the ONC-T camera aboard the Hayabusa-2 spacecraft on September 21, 2018, from a distance of 210 feet (64 m). Image credit: JAXA / Tokyo University / Kochi University / Rikkyo University / Nagoya University / Chiba Institute of Technology / Meiji University / Aizu University / AIST.
The scientists are now busy analyzing the acquired data and images.
“What we saw from a distance already gave us an idea of what it might look like on the surface,” Dr. Jaumann said.
“In fact, it is even crazier on the surface than expected. Everything is covered in rough blocks and strewn with boulders. How compact these blocks are and what they are composed of, we still do not know.”
“But what was most surprising was that large accumulations of fine material are nowhere to be found — and we did not expect that. We have to investigate this in the next few weeks, because the cosmic weathering would actually have had to produce fine material.”
“This will be of enormous importance for the characterization of this class of asteroids.”
MINERVA-II1 Rover-1A (back) and Rover-1B (foreground) explore the surface of Ryugu. Image credit: JAXA.
Almost two weeks before the MASCOT landing, the Hayabusa-2 mission team successfully landed two unmanned MINERVA-II1 rovers on Ryugu.
“The MINERVA-II1 consists of two small rovers, Rover-1A and Rover-1B,” the researchers said.
“They are the world’s first rovers to land on the surface of an asteroid. This is also the first time for autonomous movement and picture capture on an asteroid surface.”
“We are also delighted that the two rovers both achieved this operation at the same time.”
“I cannot find words to express how happy I am that we were able to realize mobile exploration on the surface of an asteroid,” said Hayabusa-2 project manager Dr. Yuichi Tsuda.
“I am proud that Hayabusa2 was able to contribute to the creation of this technology for a new method of space exploration by surface movement on small bodies.”
“I was so moved to see these small rovers successfully explore an asteroid surface because we could not achieve this at the time of Hayabusa, 13 years ago. I was particularly impressed with the images taken from close range on the asteroid surface,” said Hayabusa-2 project manager Dr. Makoto Yoshikawa.
This image was taken by MINERVA-II1 Rover-1B just before hopping on the surface of Ryugu. Image credit: JAXA.
“Although I was disappointed with the blurred image that first came from the rover, it was good to be able to capture this shot as it was recorded by the rover as the Hayabusa-2 spacecraft is shown,” said MINERVA-II1 manager Dr. Tetsuo Yoshimitsu.
“Moreover, with the image taken during the hop on the asteroid surface, I was able to confirm the effectiveness of this movement mechanism on the small celestial body and see the result of many years of research.”
“The good news made me so happy. From the surface of Ryugu, MINERVA-II1 sent a radio signal to the Earth via Hayabusa-2,” added Dr. Takashi Kubota, spokesperson for the Hayabusa-2 project.
“The image taken by MINERVA-II1 during a hop allowed me to relax as a dream of many years came true. I felt awed by what we had achieved in Japan. This is just a real charm of deep space exploration.”
