Hayabusa2 Landers

Program pages DLR: MASCOT JAXA: Hayabusa2

DLR. CC BY 3.0.

Overview

Hayabusa2 carried three small surface vehicles to asteroid 162173 Ryugu [1]: the twin MINERVA-II1 rovers Rover-1A and Rover-1B, built at JAXA/ISAS, and MASCOT, built by DLR with CNES. All three are hoppers. MINERVA-II is the program name, successor to the single MINERVA carried by Hayabusa; MINERVA-II1 is the first of its containers, the one holding Rover-1A and Rover-1B.

Specifications

Parameter	MINERVA-II1 Rover-1A / 1B	MASCOT	Source
Body	18 cm diameter, 7 cm high	30 x 30 x 20 cm	[1], [7]
Mass	1151 g / 1129 g	about 10 kg	[1], [7]
Mobility	hopping, single DC motor driving a flywheel	hopping, eccentric tungsten swing arm driven by a stepper motor	[1], [7], [5]
Hop performance	about 10 cm/s for a 1 kg rover in microgravity, from simulation and drop tower test	up to about 100 m in a single hop	[1], [5]
Power	solar cells on every face, 2 W maximum	none; 200 Wh primary battery sized for 16 h	[1], [7]
Energy storage	3 electric double layer capacitors in series, charged above 6 V, computer stops below 4 V	primary battery only	[1], [7]
Processor	44 MHz, no floating point unit, 256 kB program limit	not published	[1]
Telemetry	32 kbps maximum to the spacecraft relay, over 20 km range	not published	[1]
Cameras	4 (Rover-1A), 3 (Rover-1B)	MasCam, plus MARA, MicrOmega and MasMag	[1], [2]

Mission profile

Parameter	Value	Source
Host	Hayabusa2	[1]
Target	asteroid 162173 Ryugu	[1]
MINERVA-II1 separation	21 September 2018 at 04:06 UTC, from about 50 m altitude, the spacecraft translating north so that its own motion canceled the separation velocity	[1]
MASCOT separation	3 October 2018, from about 51 m	[7]
MASCOT time to first contact	about 6 min	[7]
MASCOT achieved lifetime	17 h 07 min, about two asteroid day and night cycles	[7]
MASCOT final resting position	22.32 +/- 0.05 deg S, 317.16 +/- 0.05 deg E	[2]

Operating environment

Quantity	Value	Source
Volume-equivalent diameter	850 to 880 m	[3]
Rotation period	7.6326 h	[3]
Day and night at the surface	3.8 h each	[1]
Surface gravity	about 1e-4 m/s2, about 10 micro-g	[1]
Local gravity at the Rover-1A site	1.3e-4 m/s2 from the shape model	[1]
Modeled surface acceleration used pre-encounter	1.8e-4 m/s2	[3]
Escape velocity	about 35 cm/s	[1]
Global thermal inertia	225 +/- 45 J/m2/K/s^0.5	[6]
Geometric albedo	0.049	[3]

The pre-encounter prediction from remote thermal inertia of 150 to 300 J/m2/K/s^0.5 put the typical regolith particle size at 3 to 30 mm, with 6 to 10 mm most likely [3]. With an assumed 50 percent porosity, lunar-analogue relations give a cohesion near 300 Pa and a friction angle near 37 degrees, falling to perhaps 100 Pa if the grains are 1 mm to 1 cm. That set of numbers, not a fine dust regolith, is what the landers were designed against.

Wheels are not usable here. Available traction scales with normal force, which scales with weight, and at 1e-4 m/s2 the weight of a 1 kg rover is on the order of 0.1 mN; cohesion between surface grains exceeds their weight across the whole relevant size range [8]. All three vehicles therefore react internally rather than against the surface.

MINERVA-II1 rovers

Beyond the parameters in the comparison table above:

Parameter	Value
Navigation sensors	photodiodes, thermometers, gyro, accelerometer
Observation sensors beyond the cameras	thermometers, potentiometers

Source: [1].

Hopping mechanism

A single internal DC motor drives a flywheel. Spinning it up generates a reaction torque on the body, and because the point of application of the force between rover and surface is offset from the center of mass, friction converts part of that torque into a lateral force, so the rover leaves the surface with horizontal velocity [1]. Larger normal force gives larger friction for a short time and therefore a faster hop. Numerical simulation and drop tower testing give about 10 cm/s for a 1 kg rover in microgravity [1].

The motor must be turned while the rover is at rest on the surface. Firing it in free flight only changes attitude and produces no translation [1]. The friction the method depends on is itself uncertain at this gravity, because interparticle cohesion rather than weight sets the shear response of the surface layer [8], and the pre-encounter estimate spanned 100 to 300 Pa of cohesion with a friction angle near 37 degrees [3].

Flight results for the Rover-1A hop of 22 September 2018, at about 30 degrees south [1]:

Quantity	Value
Motor drive	75 percent duty
Time from hop to return, from gyro history	1024 +/- 7.5 s
Assumed initial speed	6 to 8 cm/s
Assumed hop angle from drop tower results	30 to 45 degrees from vertical
Predicted flight time for that range	700 to 1100 s
Ballistic range	25 to 50 m

Rover-1B hopped on asteroid day 7, 23 September 2018, imaged the asteroid six times from above during the flight, and returned to the surface 24 minutes later, bouncing several times before coming to rest [1]. Multiple bounces on arrival are the expected behavior for a body whose surface is a poorly sorted boulder field rather than a fine deposit [2].

Autonomy

The rovers cannot localize themselves. The processor has no floating point unit and cannot evaluate imagery to determine rover state, so state estimation runs on the photodiodes or the gyro instead [1]. A rover at rest on the surface has near-zero angular rate and a photodiode signal that does not change; one in ballistic flight has a non-zero angular rate, because after a hop it necessarily carries angular momentum, and its photodiode readings vary as it tumbles. The estimator classifies the rover as in ballistic flight or at rest, and only in the second state does it fire the motor, image in stereo, and measure surface temperature and surface potential relative to the rover.

Because images during flight are taken at random attitudes, most contain no asteroid. Onboard screening rejects them before transmission [1]. Uncompressed images are screened by four tests on the luminance histogram of a decimated Y channel: too many pixels near 0 is a black image, too many near 255 is a white-out, and a luminance variance below threshold is a featureless image. All thresholds are settable by command from Earth. JPEG compression is done in software in spare processor time and takes 6 to 7 minutes per image [1], so the initial configuration transmits uncompressed; when compression is used, an insufficient size reduction is itself the rejection criterion.

Three further autonomous functions run on state: protection in a high temperature environment, transition to a low power mode, and transmit power control [1]. Nothing in this chain depends on knowing where the rover is on the body, which is the design response to a surface whose shape model was only built after arrival [3].

Duty cycle and thermal

The rovers only work in daylight. The capacitors charge after sunrise, the computer starts, and as evening approaches the power balance goes negative, the capacitor voltage falls and the computer stops until the next sunrise [1]. This repeats on the 7.6 h asteroid day.

A protection function cuts power to the equipment above 80 C; it was never triggered [1]. The pre-encounter thermal model put Ryugu at a geometric albedo of 0.049 with an infrared emissivity of 0.9, which is what drove the expectation of a hot surface [3]. Ryugu was expected to run hot because its albedo is very low and it absorbs nearly all incident sunlight, but the short rotation period keeps the surface from reaching that level, and the highest instrument temperature recorded was 45 C on 16 October 2018, asteroid day 82 [1]. On the same day the autonomous voltage watchdog switched the transmitter off late in the day, which restored the power balance and let the voltage recover before the transmitter was restarted.

Results

Rover-1A kept communicating with the spacecraft for 113 asteroid days, until 26 October 2018, and returned 609 images [1]. Rover-1B was last heard on asteroid day 10, 24 September 2018, having returned 39 images. The cause of loss is not established for either, but Rover-1B’s capacitor voltage collapsed immediately beforehand, which is consistent with it having entered permanent shadow. Weak signals earlier in the mission are attributed to the rovers’ own autonomous transmit power control.

MASCOT

Beyond the parameters in the comparison table above:

Parameter	Value
Structure	carbon fiber reinforced plastic laminate, 0.125 mm thick
Structure mass	450 g

Source: [7].

The eccentric swing arm is both the hopping actuator and the uprighting mechanism, which matters because the instruments face one direction [7]. It is driven by a stepper motor and can move the lander up to about 100 m in a single hop [5]. There is no solar array; lifetime is fixed by the primary battery.

Payload and what it measured

MARA is a six-channel thermal infrared radiometer covering about 10 to 15 cm2 within the MasCam field of view [2]. It operated from separation through the whole 17 h mission and, after landing, measured the emitted flux of one rock over a full 7 h 38 min asteroid rotation. Two channels are dedicated to low night-time temperatures, an 8 to 12 micrometer bandpass and a long pass above 3 micrometer [2]; four further bandpasses at 5.5 to 7, 8 to 9.5, 9.5 to 11.5 and 13.5 to 15.5 micrometer resolve emissivity against wavelength. The six channels are designated SiLP (3.5 to 100 micrometer), W10 (8 to 12), B06, B08, B09 and B13 [4].

MARA result	Value	Source
Surface temperature range at the landing site	210 to 300 K	[2]
Rock thermal inertia, first analysis	282 (+93 / -25) J/m2/K/s^0.5	[2]
After data assimilation re-analysis	295 +/- 18 J/m2/K/s^0.5	[2]
After shape model and MASCOT self-reflection correction	256 +/- 34 J/m2/K/s^0.5	[2]
Derived rock porosity	0.46 to 0.56	[2]
Favored porosity from Ryugu bulk density constraints	0.50 +/- 0.02	[2]
Best-fit thermal inertia in the final MARA analysis	256 (+4 / -3) J/m2/K/s^0.5	[4]
Best-fit porosity in the final MARA analysis	46.7 (+0.3 / -0.4) percent	[4]
Broadband emissivity	0.97 +/- 0.01	[4]
Emissivity, 5.5 to 7 micrometer	0.87 +/- 0.01	[4]
Emissivity, 8 to 9.5 micrometer	0.98 +/- 0.01	[4]
Implied grain density	2848 +/- 152 kg/m3	[2]

There was no evidence of a masking dust layer, so the low thermal inertia is a property of the rock itself rather than of a coating [2]. Emissivity across the MARA channels matches the most aqueously altered carbonaceous chondrites, CI, CM and CR, which places Ryugu as strongly aqueously altered before dehydration [4].

MasCam uses a Scheimpflug optic so that the whole scene from 150 mm to infinity is in focus, and carries 4 by 36 monochromatic LEDs in four spectral bands for night imaging [2]. Surface image scale reaches 0.1 mm per pixel. It resolved two boulder types, brighter smooth ones with non-dendritic fractures and darker cauliflower-textured ones consistent with thermal fatigue, with sizes from a few millimeters to a few tens of meters and poor sorting. No accumulation of fine dust was found anywhere in the images. Shadow tracing on the LED-lit night images gives the rock surface a fractal dimension of 1.16 +/- 0.04 and an RMS slope of 36.6 +/- 1.4 degrees, about 6 percent less rough than material imaged on comet 67P [2].

MasMag is a triaxial fluxgate magnetometer.

MasMag parameter	Value
Sensor mass	89 g
Electronics mass	180 g
Total mass	about 280 g
Power	about 0.5 W
Electronics envelope	109 x 94 x 20 mm
Dynamic range	+/- 12,000 nT
Noise at 1 Hz	below 15 pT/sqrt(Hz)
Resolution	2 pT
Sampling rate	10 Hz
Data rate	1010 bit/s
Excitation frequency	about 9.6 kHz

Source: [5].

It acquired data from the start of descent, through the bounces, at touchdown and at the final resting position, and after calibration and de-spinning showed no detectable change above background: the field vector fluctuates within +/- 1 nT with no systematic trend on approach down to about 10 cm from the surface [2].

MicrOmega is a near-infrared hyperspectral microscope intended to determine the mineralogical composition of the regolith, but MASCOT came to rest on a depression that prevented it from returning its intended measurement, and an identical instrument was subsequently applied to the returned samples in the curation facility instead [2], [7].

Site context

The MASCOT landing area was characterized from orbit by Hayabusa2. Regional average thermal inertia there is 181 +/- 102 J/m2/K/s^0.5 and the individual rock MASCOT rested against gives 180 (+65 / -40) [6], against a global average of 225 +/- 45 and a thermal infrared imager estimate of 200 +/- 7. Multi-band orbital imagery of the region depends on image registration across the ONC-T filter set, which is a separate processing problem for a rotating irregular body [10].

Surface strength at depth was constrained independently by the Hayabusa2 Small Carry-on Impactor experiment, whose crater is reproduced by numerical simulation only for very weak material [9].

Radiation

No lander-specific radiation design data is published for either vehicle. The interplanetary environment over the four-year cruise is that of the Badhwar-O’Neill galactic cosmic ray model [14].

Technologies developed

MINERVA-II1 demonstrated that a torque-reaction hop is a workable mobility method at 1e-4 m/s2, and that a 44 MHz processor with no floating point unit can support useful autonomy if the state estimator is built on photodiodes and a gyro rather than on imagery [1]. The image screening filter is the same idea applied to the downlink: a rover that cannot point its camera usefully instead discards its own bad frames.

MASCOT demonstrated an instrumented, uprighting, battery-only lander at asteroid gravity, and produced the only in-situ thermal and magnetic measurements made on an asteroid surface [2]. Hayabusa2 itself continues in extended mission, with a flyby of near-Earth asteroid 98943 Torifune [11], and the mission remains the reference for small-body surface delivery [13].

References

Yoshimitsu, T. and Kubota, T. (2020). Engineering Challenges and Results by MINERVA-II Asteroid Surface Rovers . Journal of the Robotics Society of Japan, 8. Source

BibTeX

@article{yoshimitsu2020engineering,
  title = {Engineering Challenges and Results by MINERVA-II Asteroid Surface Rovers},
  author = {Yoshimitsu, Tetsuo and Kubota, Takashi},
  journal = {Journal of the Robotics Society of Japan},
  volume = {38},
  number = {8},
  pages = {754--761},
  year = {2020},
  doi = {10.7210/jrsj.38.754},
  abstract = {Hayabusa2 is a Japanese asteroid explorer which aims to get some fragments from the C-type asteroid ``Ryugu'' and bring them back to the Earth. It was launched in December 2014 and arrived at the target asteroid at the end of June 2018 after 3.5 years' interplanetary cruise using an Ion engine propulsion system. The authors developed two tiny twin rovers for Hayabusa2 spacecraft. The objectives of the rovers were performing two technical experiments on the asteroid surface. They had hopping capability fitted for the microgravity environment of small planetary bodies, which was to be evaluated on the asteroid surface. The rovers had full autonomy to move to as many different places as possible and make some observations such as taking images and directly measuring the surface properties. The fully autonomous capability was to be demonstrated on the asteroid surface. The rovers were deployed onto the Northern hemisphere of the target asteroid on 04:06, 21 September 2018 (UTC) at the altitude of approximately 50 meters above the surface. Both rovers made autonomous surface explorations by hopping as planned, which were evidenced by the status and image data transmitted from the rovers. This was the World first surface mobile exploration on small planetary body in our Solar System attained by unmanned robot, as well as the first surface mobile exploration on extraterrestrial body in our country. This paper describes the technical aspects of MINERVA-II rovers, followed by some actual behaviors of the rovers on the asteroid surface which illustlated the great achievments of the two technical challenges by the rovers.}
}

Otto, K., Ho, T.-M., Ulamec, S., Bibring, J.-P., Biele, J., Grott, M., Hamm, M., Hercik, D., Jaumann, R., Sato, M., Schröder, S. E., Tanaka, S., Auster, U., Kitazato, K., Knollenberg, J., Moussi, A., Nakamura, T., Okada, T., Pilorget, C., Schmitz, N., Sugita, S., Wada, K. and Yabuta, H. (2023). MASCOT's in situ analysis of asteroid Ryugu in the context of regolith samples and remote sensing data returned by Hayabusa2 . Earth, Planets and Space. Source

BibTeX

@article{otto2023mascot,
  title = {MASCOT's in situ analysis of asteroid Ryugu in the context of regolith samples and remote sensing data returned by Hayabusa2},
  author = {Otto, Katharina and Ho, Tra-Mi and Ulamec, Stephan and Bibring, Jean-Pierre and Biele, Jens and Grott, Matthias and Hamm, Maximilian and Hercik, David and Jaumann, Ralf and Sato, Masahiko and Schröder, Stefan E. and Tanaka, Satoshi and Auster, Ulrich and Kitazato, Kohei and Knollenberg, Jörg and Moussi, Aurelie and Nakamura, Tomoki and Okada, Tatsuaki and Pilorget, Cedric and Schmitz, Nicole and Sugita, Seiji and Wada, Koji and Yabuta, Hikaru},
  journal = {Earth, Planets and Space},
  volume = {75},
  pages = {51},
  year = {2023},
  doi = {10.1186/s40623-023-01805-8},
  abstract = {Abstract The Hayabusa2 mission provided a unique data set of asteroid Ryugu that covers a wide range of spatial scale from the orbiter remote sensing instruments to the returned samples. The MASCOT lander that was delivered onto the surface of Ryugu aimed to provide context for these data sets by producing in situ data collected by a camera (MasCam), a radiometer (MARA), a magnetometer (MasMag) and a spectrometer (MicrOmega). In this work, we evaluate the success of MASCOT as an integrated lander to bridge the gap between orbiter and returned sample analysis. We find that MASCOT’s measurements and derivatives thereof, including the rock morphology, colour in the visible wavelengths, possible meteorite analogue, density, and porosity of the rock at the landing site are in good agreement with those of the orbiter and the returned samples. However, it also provides information on the spatial scale (sub-millimetres to centimetres) at which some physical properties such as the thermal inertia and reflectance undergo scale-dependent changes. Some of the in situ observations such as the presence of clast/inclusions in rocks and the absence of fine particles at the landing site was uniquely identified by MASCOT. Thus, we conclude that the delivery of an in situ instrument like MASCOT provides a valuable data set that complements and provides context for remote sensing and returned sample analyses. Graphical Abstract}
}

Wada, K., Grott, M., Michel, P., Walsh, K. J., Barucci, A. M., Biele, J., Blum, J., Ernst, C. M., Grundmann, J. T., Gundlach, B., Hagermann, A., Hamm, M., Jutzi, M., Kim, M.-J., Kührt, E., Le Corre, L., Libourel, G., Lichtenheldt, R., Maturilli, A., Messenger, S. R., Michikami, T., Miyamoto, H., Mottola, S., Nakamura, A. M., Müller, T., Nittler, L. R., Ogawa, K., Okada, T., Palomba, E., Sakatani, N., Schröder, S., Senshu, H., Takir, D. and Zolensky, M. E. (2018). Asteroid Ryugu Before the Hayabusa2 Encounter . arXiv preprint. Source

BibTeX

@article{wada2018asteroid,
  title = {Asteroid Ryugu Before the Hayabusa2 Encounter},
  author = {Wada, Koji and Grott, Matthias and Michel, Patrick and Walsh, Kevin J. and Barucci, Antonella M. and Biele, Jens and Blum, Jürgen and Ernst, Carolyn M. and Grundmann, Jan T. and Gundlach, Bastian and Hagermann, Axel and Hamm, Maximilian and Jutzi, Martin and Kim, Myung-Jin and Kührt, Ekkehard and Le Corre, Lucille and Libourel, Guy and Lichtenheldt, Roy and Maturilli, Alessandro and Messenger, Scott R. and Michikami, Tatsuhiro and Miyamoto, Hideaki and Mottola, Stefano and Nakamura, Akiko M. and Müller, Thomas and Nittler, Larry R. and Ogawa, Kazunori and Okada, Tatsuaki and Palomba, Ernesto and Sakatani, Naoya and Schröder, Stefan and Senshu, Hiroki and Takir, Driss and Zolensky, Michael E.},
  journal = {arXiv preprint},
  year = {2018},
  doi = {10.7892/boris.122706},
  abstract = {Asteroid (162173) Ryugu is the target object of Hayabusa2, an asteroid exploration and sample return mission led by Japan Aerospace Exploration Agency (JAXA). Ground-based observations indicate that Ryugu is a C-type near-Earth asteroid with a diameter of less than 1 km, but the knowledge of its detailed properties is very limited prior to Hayabusa2 observation. This paper summarizes our best understanding of the physical and dynamical properties of Ryugu based on ground-based remote sensing and theoretical modeling before the Hayabusa2’s arrival at the asteroid. This information is used to construct a design reference model of the asteroid that is used for the formulation of mission operation plans in advance of asteroid arrival. Particular attention is given to the surface properties of Ryugu that are relevant to sample acquisition. This reference model helps readers to appropriately interpret the data that will be directly obtained by Hayabusa2 and promotes scientific studies not only for Ryugu itself and other small bodies but also for the solar system evolution that small bodies shed light on.}
}

Hamm, M., Grott, M., Senshu, H., Knollenberg, J., de Wiljes, J., Hamilton, V. E., Scholten, F., Matz, K. D., Bates, H., Maturilli, A., Shimaki, Y., Sakatani, N., Neumann, W., Okada, T., Preusker, F., Elgner, S., Helbert, J., Kührt, E., Ho, T.-M., Tanaka, S., Jaumann, R. and Sugita, S. (2022). Mid-infrared emissivity of partially dehydrated asteroid (162173) Ryugu shows strong signs of aqueous alteration . Nature Communications. Source

BibTeX

@article{hamm2022mid,
  title = {Mid-infrared emissivity of partially dehydrated asteroid (162173) Ryugu shows strong signs of aqueous alteration},
  author = {Hamm, Maximilian and Grott, Matthias and Senshu, Hiroki and Knollenberg, J. and de Wiljes, J. and Hamilton, Victoria E. and Scholten, Frank and Matz, K. D. and Bates, H. and Maturilli, Alessandro and Shimaki, Yuri and Sakatani, Naoya and Neumann, W. and Okada, Tatsuaki and Preusker, Frank and Elgner, S. and Helbert, J. and Kührt, Ekkehard and Ho, Tra-Mi and Tanaka, Satoshi and Jaumann, Ralf and Sugita, Seiji},
  journal = {Nature Communications},
  volume = {13},
  pages = {364},
  year = {2022},
  doi = {10.1038/s41467-022-28051-y},
  abstract = {Abstract The near-Earth asteroid (162173) Ryugu, the target of Hayabusa2 space mission, was observed via both orbiter and the lander instruments. The infrared radiometer on the MASCOT lander (MARA) is the only instrument providing spectrally resolved mid-infrared (MIR) data, which is crucial for establishing a link between the asteroid material and meteorites found on Earth. Earlier studies revealed that the single boulder investigated by the lander belongs to the most common type found on Ryugu. Here we show the spectral variation of Ryugu’s emissivity using the complete set of in-situ MIR data and compare it to those of various carbonaceous chondritic meteorites, revealing similarities to the most aqueously altered ones, as well as to asteroid (101955) Bennu. The results show that Ryugu experienced strong aqueous alteration prior to any dehydration.}
}

Herčík, D., Auster, H.-U., Blum, J., Fornaçon, K.-H., Fujimoto, M., Gebauer, K., Güttler, C., Hillenmaier, O., Hördt, A., Liebert, E., Matsuoka, A., Nomura, R., Richter, I., Stoll, B., Weiss, B. P. and Glassmeier, K.-H. (2016). The MASCOT Magnetometer . Space Science Reviews. Source

BibTeX

@article{hercik2016mascot,
  title = {The MASCOT Magnetometer},
  author = {Herčík, David and Auster, Hans-Ulrich and Blum, Jürgen and Fornaçon, Karl-Heinz and Fujimoto, Masaki and Gebauer, Kathrin and Güttler, Carsten and Hillenmaier, Olaf and Hördt, Andreas and Liebert, Evelyn and Matsuoka, Ayako and Nomura, Reiko and Richter, Ingo and Stoll, Bernd and Weiss, Benjamin P. and Glassmeier, Karl-Heinz},
  journal = {Space Science Reviews},
  volume = {208},
  pages = {433--449},
  year = {2016},
  doi = {10.1007/978-94-024-1538-4_22},
  abstract = {The Mobile Asteroid Scout (MASCOT) is a small lander on board the Hayabusa2 mission of the Japan Aerospace Exploration Agency to the asteroid 162173 Ryugu. Among the instruments on MASCOT is a fluxgate magnetometer, the MASCOT Magnetometer (MasMag). The magnetometer is a lightweight ( $\sim280~\mbox{g}$ ) and low power ( $\sim0.5~\mbox{W}$ ) triaxial fluxgate magnetometer. Magnetic field measurements during the landing period and during the surface operational phase shall provide information about any intrinsic magnetic field of the asteroid and its remanent magnetization. This could provide important constraints on planet formation and the thermal and aqueous evolution of primitive asteroids.}
}

Schröder, S., Sakatani, N., Honda, R., Tatsumi, E., Yokota, Y., Domingue, D., Cho, Y., Kameda, S., Kitazato, K., Kouyama, T., Matsuoka, M., Miura, A., Morota, T., Okada, T., Sawada, H., Senshu, H., Shimaki, Y., Sugita, S., Tanaka, S., Yabuta, H., Yamada, M., Grott, M., Hamm, M., Ho, T.-M., Jaumann, R., Mottola, S., Otto, K., Schmitz, N. and Scholten, F. (2022). Characterization of the MASCOT landing area by Hayabusa2 . Astronomy & Astrophysics. Source

BibTeX

@article{schroder2022characterization,
  title = {Characterization of the MASCOT landing area by Hayabusa2},
  author = {Schröder, Stefan and Sakatani, Naoya and Honda, Rie and Tatsumi, Eri and Yokota, Yasuhiro and Domingue, Deborah and Cho, Yuichiro and Kameda, Shingo and Kitazato, Kohei and Kouyama, Toru and Matsuoka, Moe and Miura, Akira and Morota, Tomokatsu and Okada, Tatsuaki and Sawada, Hirotaka and Senshu, Hiroki and Shimaki, Yuri and Sugita, Seiji and Tanaka, Satoshi and Yabuta, Hikaru and Yamada, Manabu and Grott, Matthias and Hamm, Maximilian and Ho, Tra-Mi and Jaumann, Ralf and Mottola, Stefano and Otto, Katharina and Schmitz, Nicole and Scholten, Frank},
  journal = {Astronomy & Astrophysics},
  volume = {666},
  pages = {A164},
  year = {2022},
  doi = {10.1051/0004-6361/202244059},
  abstract = {Context. After landing on C-type asteroid Ryugu, MASCOT imaged brightly colored, submillimeter-sized inclusions in a small rock. Hayabusa2 successfully returned a sample of small particles from the surface of Ryugu, but none of these appear to harbor such inclusions. The samples are considered representative of Ryugu. Aims. To understand the apparent discrepancy between MASCOT observations and Ryugu samples, we assess whether the MASCOT landing site, and the rock by implication, is perhaps atypical for Ryugu. Methods. We analyzed observations of the MASCOT landing area acquired by three instruments on board Hayabusa2: a camera (ONC), a near-infrared spectrometer (NIRS3), and a thermal infrared imager. We compared the landing area properties thus retrieved with those of the average Ryugu surface. Results. We selected several areas and landforms in the landing area for analysis: a small crater, a collection of smooth rocks, and the landing site itself. The crater is relatively blue and the rocks are relatively red. The spectral and thermophysical properties of the landing site are very close to those of the average Ryugu surface. The spectral properties of the MASCOT rock are probably close to average, but its thermal inertia may be somewhat higher. Conclusions. The MASCOT rock can also be considered representative of Ryugu. Some of the submillimeter-sized particles in the returned samples stand out because of their atypical spectral properties. Such particles may be present as inclusions in the MASCOT rock.}
}

(2026). DLR: MASCOT. dlr.de/en/research-and-transfer/projects-and-missions/hayabusa2

BibTeX

@misc{dlrmascot,
  title = {DLR: MASCOT},
  organization = {dlr.de},
  year = {2026},
  url = {https://www.dlr.de/en/research-and-transfer/projects-and-missions/hayabusa2}
}

Scheeres, D. J., Hartzell, C. M., Sánchez, P. and Swift, M. (2010). Scaling forces to asteroid surfaces: The role of cohesion . Icarus. Source

BibTeX

@article{scheeres2010scaling,
  title = {Scaling forces to asteroid surfaces: The role of cohesion},
  author = {Scheeres, Daniel J. and Hartzell, C. M. and Sánchez, Paul and Swift, M.},
  journal = {Icarus},
  volume = {210},
  pages = {968--984},
  year = {2010},
  doi = {10.1016/j.icarus.2010.07.009}
}

Jutzi, M., Raducan, S. D., Zhang, Y., Michel, P. and Arakawa, M. (2022). Constraining surface properties of asteroid (162173) Ryugu from numerical simulations of Hayabusa2 mission impact experiment . Nature Communications. Source

BibTeX

@article{jutzi2022constraining,
  title = {Constraining surface properties of asteroid (162173) Ryugu from numerical simulations of Hayabusa2 mission impact experiment},
  author = {Jutzi, Martin and Raducan, Sabina D. and Zhang, Yun and Michel, Patrick and Arakawa, Masahiko},
  journal = {Nature Communications},
  volume = {13},
  pages = {7134--7134},
  year = {2022},
  doi = {10.1038/s41467-022-34540-x},
  abstract = {Abstract The Hayabusa2 mission impact experiment on asteroid Ryugu created an unexpectedly large crater. The associated regime of low-gravity, low-strength cratering remained largely unexplored so far, because these impact conditions cannot be re-created in laboratory experiments on Earth. Here we show that the target cohesion may be very low and the impact probably occurred in the transitional cratering regime, between strength and gravity. For such conditions, our numerical simulations are able to reproduce the outcome of the impact on Ryugu, including the effects of boulders originally located near the impact point. Consistent with most recent analysis of Ryugu and Bennu, cratering scaling-laws derived from our results suggest that surfaces of small asteroids must be very young. However, our results also show that the cratering efficiency can be strongly affected by the presence of a very small amount of cohesion. Consequently, the varying ages of different geological surface units on Ryugu may be due to the influence of cohesion.}
}

Kouyama, T., Tatsumi, E., Honda, C., Honda, R., Morota, T., Yokota, Y., Kameda, S., Yamada, M., Suzuki, H., Sakatani, N., Hayakawa, M., Cho, Y., Matsuoka, M., Yoshioka, K., Sawada, H. and Sugita, S. (2021). Image registration for multi-band images taken by ONC-T onboard Hayabusa2 . arXiv preprint. Source

BibTeX

@article{kouyama2021image,
  title = {Image registration for multi-band images taken by ONC-T onboard Hayabusa2},
  author = {Kouyama, Toru and Tatsumi, Eri and Honda, Chikatoshi and Honda, Rie and Morota, Tomokatsu and Yokota, Yasuhiro and Kameda, Shingo and Yamada, Manabu and Suzuki, Hidehiko and Sakatani, Naoya and Hayakawa, Masahiko and Cho, Yuichiro and Matsuoka, Moe and Yoshioka, Kazuo and Sawada, Hirotaka and Sugita, Seiji},
  journal = {arXiv preprint},
  year = {2021},
  url = {https://arxiv.org/abs/2112.09404}
}

Hirabayashi, M., Hayakawa, M., Mimasu, Y., Hirata, N., Iwaki, T., Kamata, S., Kitazato, K., Kouyama, T., Sakatani, N., Yano, H., Yumoto, K., Fujiwara, M., Shimomura, S., Saiki, T., Takeuchi, H., Tatsumi, E., Tsuda, Y., Yokota, Y., Yoshikawa, M., Tanaka, S. and Hayabusa2 Extended Mission Torifune Flyby Working Group. (2026). Overview of Hayabusa2 extended mission's flyby of Near-Earth Asteroid (98943) Torifune . The Planetary Science Journal. Source

BibTeX

@article{hirabayashi2026overview,
  title = {Overview of Hayabusa2 extended mission's flyby of Near-Earth Asteroid (98943) Torifune},
  author = {Hirabayashi, Masatoshi and Hayakawa, Masahiko and Mimasu, Yuya and Hirata, Naru and Iwaki, Takuya and Kamata, Shunichi and Kitazato, Kohei and Kouyama, Toru and Sakatani, Naoya and Yano, Hajime and Yumoto, Koki and Fujiwara, Masahiro and Shimomura, Sumito and Saiki, Takanao and Takeuchi, Hiroshi and Tatsumi, Eri and Tsuda, Yuichi and Yokota, Yasuhiro and Yoshikawa, Makoto and Tanaka, Satoshi and {Hayabusa2 Extended Mission Torifune Flyby Working Group}},
  journal = {The Planetary Science Journal},
  volume = {7},
  pages = {121},
  year = {2026},
  doi = {10.3847/psj/ae5f79},
  abstract = {Abstract The Hayabusa2 extended mission, nicknamed Hayabusa2# ( # is pronounced SHARP, which stands for the Small Hazardous Asteroid Reconnaissance Probe), is JAXA’s small body explorer to conduct science and engineering investigations in space. After the successful return to the Earth with the samples from the carbonaceous asteroid (162173) Ryugu on 2020 December 6, Hayabusa2 diverted away from Earth to start its decade-long extended mission. The major scope includes an engineering demonstration of long-term maintenance strategies for spacecraft and operation systems and scientific investigations during various mission phases. Major scientific investigations include spacecraft-based telescopic observations of exoplanets and zodiacal dust observations during the cruise phase, flyby observations of the near-Earth asteroid (98943) Torifune in 2026 July, and rendezvous observations of near-Earth asteroid 1998 KY26 in 2031. This study overviews Hayabusa2#’s flyby and the physical properties of Torifune. Although the flyby operation planning is still ongoing, the mission will attempt to fly by the target at a distance (from the asteroid’s center) of 1–10 km. The flyby speed is planned to be 5.25 km s −1 , while the encounter location is 0.81 au from the Sun. The mission plans to fix the spacecraft’s orientation during the flyby, only allowing for a very limited pointing change to attain higher-resolution imaging. The mission will attempt to obtain science and engineering returns during the flyby. The planned investigations will offer stronger insights into material transport mechanisms in the inner solar system and a demonstration of planetary defense technologies.}
}

Grimm, C. D., Lange, C., Lange, M., Mierheim, O., Sasaki, K., Meyer, M., Kroth, W., Ulamec, S. and Ho, T.-M. (2020). The MASCOT Separation Mechanism: A Reliable, Low-Mass Deployment System for Nano-Spacecraft . CEAS Space Journal, 3. Source

BibTeX

@article{grimm2020mascot,
  title = {The {MASCOT} Separation Mechanism: A Reliable, Low-Mass Deployment System for Nano-Spacecraft},
  author = {Grimm, Christian D. and Lange, Caroline and Lange, Michael and Mierheim, Olaf and Sasaki, Kaname and Meyer, Michael and Kroth, Wolfgang and Ulamec, Stephan and Ho, Tra-Mi},
  journal = {CEAS Space Journal},
  volume = {12},
  number = {3},
  pages = {343--365},
  year = {2020},
  doi = {10.1007/s12567-020-00302-y},
  abstract = {Abstract The Mobile Asteroid Surface Scout (MASCOT), an Asteroid Lander carried by the Hayabusa2 spacecraft, successfully landed on the Near-Earth Asteroid (162173) Ryugu on October 03, 2018. Thereby accomplishing the first-ever landing of a European spacecraft on the surface of this type of celestial body. MASCOT was a prototype design of a new class of nano-size surface science packages for the exploration of small solar system bodies. The very low gravity (thus, very low escape velocity) of the target body required the design of a miniaturized deployment mechanism with a relatively small, well-reproducible separation velocity. In addition, the mechanism also had to safely restrain the lander to the mother spacecraft during the launch and its 3.5-year cruise phase. In this paper, we describe in detail the design, numerical analysis and test of this newly developed separation mechanism. Furthermore, we compare the mechanism to other existing deployment systems and verify its performance with two independent analysis methods using actual flight data taken during the ultimate flight activation event, which initiated the successful delivery and surface operation of the MASCOT asteroid lander.}
}

Ho, T.-M., Baturkin, V., Grimm, C., Grundmann, J. T., Hobbie, C., Ksenik, E., Lange, C., Sasaki, K., Schlotterer, M., Talapina, M., Termtanasombat, N., Wejmo, E., Witte, L., Wrasmann, M., Wübbels, G., Rößler, J., Ziach, C., Findlay, R., Biele, J., Krause, C., Ulamec, S., Lange, M., Mierheim, O., Lichtenheldt, R., Maier, M., Reill, J., Sedlmayr, H.-J., Bousquet, P., Bellion, A., Bompis, O., Cenac-Morthe, C., Deleuze, M., Fredon, S., Jurado, E., Canalias, E., Jaumann, R., Bibring, J.-P., Glassmeier, K. H., Hercik, D., Grott, M., Celotti, L., Cordero, F., Hendrikse, J. and Okada, T. (2017). MASCOT: The Mobile Asteroid Surface Scout Onboard the Hayabusa2 Mission . Space Science Reviews, 1-4. Source

BibTeX

@article{ho2017mascot,
  title = {{MASCOT}: The Mobile Asteroid Surface Scout Onboard the {Hayabusa2} Mission},
  author = {Ho, Tra-Mi and Baturkin, Volodymyr and Grimm, Christian and Grundmann, Jan Thimo and Hobbie, Catherin and Ksenik, Eugen and Lange, Caroline and Sasaki, Kaname and Schlotterer, Markus and Talapina, Maria and Termtanasombat, Nawarat and Wejmo, Elisabet and Witte, Lars and Wrasmann, Michael and Wübbels, Guido and Rößler, Johannes and Ziach, Christian and Findlay, Ross and Biele, Jens and Krause, Christian and Ulamec, Stephan and Lange, Michael and Mierheim, Olaf and Lichtenheldt, Roy and Maier, Maximilian and Reill, Josef and Sedlmayr, Hans-Jürgen and Bousquet, Pierre and Bellion, Anthony and Bompis, Olivier and Cenac-Morthe, Celine and Deleuze, Muriel and Fredon, Stephane and Jurado, Eric and Canalias, Elisabet and Jaumann, Ralf and Bibring, Jean-Pierre and Glassmeier, Karl Heinz and Hercik, David and Grott, Matthias and Celotti, Luca and Cordero, Federico and Hendrikse, Jeffrey and Okada, Tatsuaki},
  journal = {Space Science Reviews},
  volume = {208},
  number = {1-4},
  pages = {339--374},
  year = {2017},
  doi = {10.1007/s11214-016-0251-6}
}

Hayabusa2 Landers

Overview

Specifications

Mission profile

Operating environment

MINERVA-II1 rovers

Hopping mechanism

Autonomy

Duty cycle and thermal

Results

MASCOT

Payload and what it measured

Site context

Radiation

Technologies developed

References

Further reading