MASCOT—The Mobile Asteroid Surface Scout Onboard the Hayabusa2 Mission
TL;DR: In this paper, a mobile asteroid surface SCOuT (MASCOT) was developed by the German Aerospace Centre (DLR) in collaboration with the Centre National d'Etudes Spatiales (CNES).
Abstract: On December 3rd, 2014, the Japanese Space Agency (JAXA) launched successfully the Hayabusa2 (HY2) spacecraft to its journey to Near Earth asteroid (162173) Ryugu. Aboard this spacecraft is a compact landing package, MASCOT (Mobile Asteroid surface SCOuT), which was developed by the German Aerospace Centre (DLR) in collaboration with the Centre National d’Etudes Spatiales (CNES). Similar to the famous predecessor mission Hayabusa, Hayabusa2, will also study an asteroid and return samples to Earth. This time, however, the target is a C-type asteroid which is considered to be more primitive than (25143) Itokawa and provide insight into an even earlier stage of our Solar System. Upon arrival at asteroid Ryugu in 2018, MASCOT will be released from the HY2 spacecraft and gently descend by free fall from an altitude of about 100 m to the surface of the asteroid. After a few bounces, the lander will come to rest at the surface and perform its scientific investigations of the surface structure and mineralogical composition, the thermal behaviour and the magnetic properties by operating its four scientific instruments. Those include an IR imaging spectrometer (MicrOmega, IAS Paris), a camera (MASCAM, DLR Berlin), a radiometer (MARA, DLR Berlin) and a magnetometer (MASMAG, TU Braunschweig). In order to allow optimized payload operations the thermal design of MASCOT is required to cope with the contrasting requirements of the 4-year cruise in cold environment versus the hot conditions on the surface of the asteroid. Operations up to 2 asteroid days (∼16 hours) based on a primary battery are currently envisaged. A mobility mechanism allows locomotion on the surface. The mechanism is supported by an attitude and motion sensing system and an intelligent autonomy manager, which is implemented in the onboard software that enables MASCOT to operate fully independently when ground intervention is not available.
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TL;DR: The Hayabusa2 mission as mentioned in this paper was the first mission to explore a C-type near-Earth asteroid (162173) Ryugu (1999 JU3) to observe and explore the 900 m-sized object, and return samples collected from the surface layer.
Abstract: The Hayabusa2 mission journeys to C-type near-Earth asteroid (162173) Ryugu (1999 JU3) to observe and explore the 900 m-sized object, as well as return samples collected from the surface layer. The Haybusa2 spacecraft developed by Japan Aerospace Exploration Agency (JAXA) was successfully launched on December 3, 2014 by an H-IIA launch vehicle and performed an Earth swing-by on December 3, 2015 to set it on a course toward its target Ryugu. Hayabusa2 aims at increasing our knowledge of the early history and transfer processes of the solar system through deciphering memories recorded on Ryugu, especially about the origin of water and organic materials transferred to the Earth’s region. Hayabusa2 carries four remote-sensing instruments, a telescopic optical camera with seven colors (ONC-T), a laser altimeter (LIDAR), a near-infrared spectrometer covering the 3-μm absorption band (NIRS3), and a thermal infrared imager (TIR). It also has three small rovers of MINERVA-II and a small lander MASCOT (Mobile Asteroid Surface Scout) developed by German Aerospace Center (DLR) in cooperation with French space agency CNES. MASCOT has a wide angle imager (MasCam), a 6-band thermal radiator (MARA), a 3-axis magnetometer (MasMag), and a hyperspectral infrared microscope (MicrOmega). Further, Hayabusa2 has a sampling device (SMP), and impact experiment devices which consist of a small carry-on impactor (SCI) and a deployable camera (DCAM3). The interdisciplinary research using the data from these onboard and lander’s instruments and the analyses of returned samples are the key to success of the mission.
210 citations
German Aerospace Center1, Kobe University2, Centre national de la recherche scientifique3, University of Münster4, Chiba Institute of Technology5, Japan Aerospace Exploration Agency6, University of Stirling7, University of Tokyo8, Heinrich Hertz Institute9, University of Potsdam10, University of Paris-Sud11, Centre National D'Etudes Spatiales12
TL;DR: In this article, in situ thermal infrared observations of a boulder on the C-type asteroid Ryugu were reported, indicating high boulder porosities as well as a low tensile strength in the few hundred kilopascal range.
Abstract: C-type asteroids are among the most pristine objects in the Solar System, but little is known about their interior structure and surface properties. Telescopic thermal infrared observations have so far been interpreted in terms of a regolith-covered surface with low thermal conductivity and particle sizes in the centimetre range. This includes observations of C-type asteroid (162173) Ryugu1–3. However, on arrival of the Hayabusa2 spacecraft at Ryugu, a regolith cover of sand- to pebble-sized particles was found to be absent4,5 (R.J. et al., manuscript in preparation). Rather, the surface is largely covered by cobbles and boulders, seemingly incompatible with the remote-sensing infrared observations. Here we report on in situ thermal infrared observations of a boulder on the C-type asteroid Ryugu. We found that the boulder’s thermal inertia was much lower than anticipated based on laboratory measurements of meteorites, and that a surface covered by such low-conductivity boulders would be consistent with remote-sensing observations. Our results furthermore indicate high boulder porosities as well as a low tensile strength in the few hundred kilopascal range. The predicted low tensile strength confirms the suspected observational bias6 in our meteorite collections, as such asteroidal material would be too frail to survive atmospheric entry7. The MASCOT lander observed a boulder on the surface of asteroid Ryugu up close. The boulder’s low thermal inertia is closer to fine regolith or comets rather than stony boulders, indicating high porosity and low tensile strength. Orbit measurements confirm that Ryugu’s surface is covered with similar boulders.
131 citations
Japan Aerospace Exploration Agency1, University of Tokyo2, Rikkyo University3, Graduate University for Advanced Studies4, Chiba Institute of Technology5, University of Aizu6, Hokkaido University of Education7, National Institute of Advanced Industrial Science and Technology8, Hokkaido Kitami Hokuto High School9, National Institute for Environmental Studies10, German Aerospace Center11, Max Planck Society12, University of Stirling13, University of Potsdam14, Centre national de la recherche scientifique15, Kobe University16, Seoul National University17, Kōchi University18, Kindai University19, Spanish National Research Council20, Hiroshima University21, NEC22, Mitsubishi Electric23, Nagoya University24
TL;DR: Thermal imaging data obtained from the spacecraft Hayabusa2 reveal that the carbonaceous asteroid 162173 Ryugu is an object of unusually high porosity, which constrain the formation history of Ryugu.
Abstract: Additional co-authors: Tsuneo Matsunaga, Takeshi Imamura, Takehiko Wada, Sunao Hasegawa, Jorn Helbert, Thomas G. Muller, Jens Biele, Matthias Grott, Maximilian Hamm, Marco Delbo, Naru Hirata, Naoyuki Hirata, Yukio Yamamoto, Seiji Sugita, Noriyuki Namiki, Kohei Kitazato, Masahiko Arakawa, Shogo Tachibana, Hitoshi Ikeda, Masateru Ishiguro, Koji Wada, Chikatoshi Honda, Rie Honda, Yoshiaki Ishihara, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Akira Miura, Tomokatsu Morota, Hirotomo Noda, Rina Noguchi, Kazunori Ogawa, Kei Shirai, Eri Tatsumi, Hikaru Yabuta, Yasuhiro Yokota, Manabu Yamada, Masanao Abe, Masahiko Hayakawa, Takahiro Iwata, Masanobu Ozaki, Hajime Yano, Satoshi Hosoda, Osamu Mori, Hirotaka Sawada, Takanobu Shimada, Hiroshi Takeuchi, Ryudo Tsukizaki, Atsushi Fujii, Chikako Hirose, Shota Kikuchi, Yuya Mimasu, Naoko Ogawa, Go Ono, Tadateru Takahashi, Yuto Takei, Tomohiro Yamaguchi, Kent Yoshikawa, Fuyuto Terui, Takanao Saiki, Satoru Nakazawa, Makoto Yoshikawa, Seiichiro Watanabe & Yuichi Tsuda Output Status: Forthcoming/Available Online
110 citations
German Aerospace Center1, Free University of Berlin2, University of Tokyo3, Centre national de la recherche scientifique4, Centre National D'Etudes Spatiales5, University of Paris6, Rikkyo University7, Japan Aerospace Exploration Agency8, Nagoya University9, Hiroshima University10, Kōchi University11, National Institute of Advanced Industrial Science and Technology12
TL;DR: Images from the Mobile Asteroid Surface Scout lander show that rocks on asteroid Ryugu are similar to carbonaceous chondrite meteorites, and close-up images of a rock reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration.
Abstract: The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu's surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.
101 citations
TL;DR: The hopping rover is a promising solution for small celestial body surface mobility but how to predict its locomotion and landing area is challenging when considering the complex dynamical environment.
Abstract: The hopping rover is a promising solution for small celestial body surface mobility. How to predict its locomotion and landing area is challenging when considering the complex dynamical environment...
74 citations
References
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TL;DR: During the interval from September through early December 2005, the Hayabusa spacecraft was in close proximity to near-Earth asteroid Itokawa, and a variety of data were taken on its shape, mass, and surface topography as well as its mineralogic and elemental abundances.
Abstract: During the interval from September through early December 2005, the Hayabusa spacecraft was in close proximity to near-Earth asteroid 25143 Itokawa, and a variety of data were taken on its shape, mass, and surface topography as well as its mineralogic and elemental abundances. The asteroid9s orthogonal axes are 535, 294, and 209 meters, the mass is 3.51 × 1010 kilograms, and the estimated bulk density is 1.9 ± 0.13 grams per cubic centimeter. The correspondence between the smooth areas on the surface (Muses Sea and Sagamihara) and the gravitationally low regions suggests mass movement and an effective resurfacing process by impact jolting. Itokawa is considered to be a rubble-pile body because of its low bulk density, high porosity, boulder-rich appearance, and shape. The existence of very large boulders and pillars suggests an early collisional breakup of a preexisting parent asteroid followed by a re-agglomeration into a rubble-pile object.
874 citations
University of Maryland, College Park1, Max Planck Society2, Jet Propulsion Laboratory3, University of Hawaii4, University of Arizona5, Brown University6, Science Applications International Corporation7, Cornell University8, Space Telescope Science Institute9, Johns Hopkins University Applied Physics Laboratory10
TL;DR: A large increase in organic material occurred during and after the event, with smaller changes in carbon dioxide relative to water, and a thermal map indicates a surface in equilibrium with sunlight.
Abstract: Deep Impact collided with comet Tempel 1, excavating a crater controlled by gravity. The comet's outer layer is composed of 1- to 100-micrometer fine particles with negligible strength ( 1000 kelvins). A large increase in organic material occurred during and after the event, with smaller changes in carbon dioxide relative to water. On approach, the spacecraft observed frequent natural outbursts, a mean radius of 3.0 ± 0.1 kilometers, smooth and rough terrain, scarps, and impact craters. A thermal map indicates a surface in equilibrium with sunlight.
751 citations
TL;DR: The ROSETTA mission as discussed by the authors will rendezvous in 2014 with comet 67P/Churyumov-Gerasimenko close to its aphelion and will study the physical and chemical properties of the nucleus, the evolution of the coma during the comet's approach to the Sun, and the development of the interaction region of the solar wind and the comet, for more than one year until it reaches perihelion.
Abstract: The ROSETTA Mission, the Planetary Cornerstone Mission in the European Space Agency’s long-term programme Horizon 2000, will rendezvous in 2014 with comet 67P/Churyumov-Gerasimenko close to its aphelion and will study the physical and chemical properties of the nucleus, the evolution of the coma during the comet’s approach to the Sun, and the development of the interaction region of the solar wind and the comet, for more than one year until it reaches perihelion. In addition to the investigations performed by the scientific instruments on board the orbiter, the ROSETTA lander PHILAE will be deployed onto the surface of the nucleus. On its way to comet 67P/Churyumov-Gerasimenko, ROSETTA will fly by and study the two asteroids 2867 Steins and 21 Lutetia.
543 citations
Max Planck Society1, University of Padua2, Aix-Marseille University3, International Space Science Institute4, Spanish National Research Council5, European Space Research and Technology Centre6, Uppsala University7, German Aerospace Center8, Braunschweig University of Technology9, University of Maryland, College Park10, Pierre-and-Marie-Curie University11, Centre national de la recherche scientifique12, INAF13, University of Trento14, Planetary Science Institute15, Macau University of Science and Technology16, National Central University17, European Space Agency18, NASA Lunar Science Institute19, Instituto Nacional de Técnica Aeroespacial20, University of Bern21, University of Cologne22
TL;DR: Images from the OSIRIS scientific imaging system onboard Rosetta show that the nucleus of 67P/Churyumov-Gerasimenko consists of two lobes connected by a short neck, which raises the question of whether the two Lobes represent a contact binary formed 4.5 billion years ago, or a single body where a gap has evolved via mass loss.
Abstract: Images from the OSIRIS scientific imaging system onboard Rosetta show that the nucleus of 67P/Churyumov-Gerasimenko consists of two lobes connected by a short neck. The nucleus has a bulk density less than half that of water. Activity at a distance from the Sun of >3 astronomical units is predominantly from the neck, where jets have been seen consistently. The nucleus rotates about the principal axis of momentum. The surface morphology suggests that the removal of larger volumes of material, possibly via explosive release of subsurface pressure or via creation of overhangs by sublimation, may be a major mass loss process. The shape raises the question of whether the two lobes represent a contact binary formed 4.5 billion years ago, or a single body where a gap has evolved via mass loss.
421 citations
TL;DR: The Giotto space probe's neutral mass spectrometer experiment has determined the abundances and the chemical, elemental and isotopic compositions of gases and low energy ions in the coma of comet Halley.
Abstract: The Giotto space probe's neutral mass spectrometer experiment has determined the abundances and the chemical, elemental and isotopic compositions of gases and low energy ions in the coma of comet Halley. Preliminary results show water predominating, at about 80 percent by volume, with a density of 4.7 x 10 to the 7th molecules/cu cm at 1000 km and a photodestruction scale length of 39,000 km. Limits on the abundances of CO2, NH3 and CH4 relative to H2O are also obtained. An ion temperature change observation indicates a contact surface location at 47,000 + or - 200 km.
395 citations