Yuichi Tsuda

Yuichi Tsuda
Japan Aerospace Exploration Agency | JAXA · Institute of Space and Astronautical Science (ISAS)

PhD

About

299
Publications
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Introduction
Field of Interests: Astrodynamics, Orbital Mechanics, Spacecraft System, Spacecraft Guidance Navigation Control, Solar Sail, Small Satellite Technology, Formation Flying, Solar System Explorations, Small Body Explorations, Sample Return Mission

Publications

Publications (299)
Article
Full-text available
Abstract: Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements fr...
Preprint
Full-text available
Asteroid 162173 Ryugu has numerous craters. The initial measurement of impact craters on Ryugu, by Sugita et al. (2019), is based on Hayabusa2 ONC images obtained during the first month after the arrival of Hayabusa2 in June 2018. Utilizing new images taken until February 2019, we constructed a global impact crater catalogue of Ryugu, which include...
Preprint
Full-text available
Asteroid 162173 Ryugu is a rubble-pile asteroid, whose top-shape is compatible with models of deformation by spin up. Rims of major craters on Ryugu have an east-west asymmetric profile; their western crater rims are sharp and tall, while their eastern crater rims are rounded and low. Although there are various possible explanations, we theoretical...
Preprint
Sample-return missions allow the study of materials collected directly from celestial bodies, unbiased by atmospheric entry effects and/or Earth alteration and contamination phenomena, using state-of-the-art techniques - but only if the collected material stays pristine. The scarcity of outer-space unaltered material recovered until now makes this...
Article
Over a broad size range, the shapes of impact fragments from catastrophic disruptions are distributed around the mean axial ratio 2: √2: 1, irrespective of experimental conditions and target materials. Although most blocks on asteroids are likely to be impact fragments, there is not enough quantitative data for reliable statistics on their three-ax...
Article
Full-text available
The characterization of objects that have best preserved the mineralogical and molecular phases formed in the earliest stages of the Solar System evolution is key to understanding the processes that led to the formation of the planets in their diversity. The Hayabusa2 mission of the Japan Aerospace Exploration Agency has returned for the first time...
Conference Paper
Full-text available
This work presents the development of a statistical ejecta model to predict the ejecta characteristics due to the impact of a small kinetic impactor onto asteroids surfaces. The distribution of the ejecta in terms of particle size, ejection velocity, and ejection direction is obtained. The procedure followed to compute the parameters defining the s...
Chapter
Hayabusa2 is an asteroid sample return mission by Japan Aerospace Exploration Agency. After the first touchdown to the asteroid Ryugu, the nadir-viewing wide-angle optical navigation camera (ONC-W1) of Hayabusa2 experienced significant degradation in sensitivity that are likely caused by dust adhesion to its optical system. Images of the asteroid a...
Chapter
Hayabusa2, the Japanese interplanetary probe, arrived at asteroid 162173 (Ryugu) on June 27, 2018. During its 1.4 year-long proximity phase, the probe made various remote sensing observations in preparation for performing an artificial cratering experiment and collecting surface/sub-surface samples. This chapter describes the initial remote sensing...
Chapter
This chapter describes the operation strategy of the deployable payload, Rover2 of MINERVA II, and the target marker (TM) installed on the Hayabusa2 spacecraft. The operation team conducted a technical experiment wherein MINERVAII2 and TM were orbited around Ryugu as MINERVA II2 did not have a surface exploration capability. This study investigates...
Chapter
The asteroid explorer Hayabusa2 was launched by Japan Aerospace Exploration Agency (JAXA) on December 3, 2014. The spacecraft's main mission is to sample asteroid fragments and return them to Earth for more sophisticated scientific analysis. Hayabusa2 carried multiple rovers and lander, separated them, and landed on the surface of the asteroid. One...
Chapter
The Japan Aerospace Exploration Agency (JAXA) has conducted an asteroid sample return mission, Hayabusa2. The spacecraft was launched in 2014 and arrived at the asteroid Ryugu on June 27, 2018. During the asteroid approach phase, the spacecraft successfully completed several key operations, including two touchdown operations. These were based on an...
Chapter
Hayabusa2, the asteroid explorer launched by Japan Aerospace Exploration Agency (JAXA) on December 3, 2014, brought Asteroid Ryugu's sample back to Earth on December 6, 2020. After releasing the capsule containing the sample, the spacecraft departed from Earth to start its new journey. All the mission operations went successful so far, and the spac...
Chapter
The Japan Aerospace Exploration Agency developed and operated the asteroid sample return mission Hayabusa2 which is the world's second asteroid sample return mission. The sample from the asteroid was collected and the spacecraft came back to Earth in December 2020. In the reentry phase, several trajectory correction maneuvers of the spacecraft were...
Chapter
Hayabusa2 successfully accomplished a round-trip flight to asteroid Ryugu after 6 years of the interplanetary cruise. The target asteroid Ryugu was selected from C-type (carbon-rich) Near-Earth Asteroids that were reachable with readily available ion engine technology in JAXA. A combination of the low and continuous thrust trajectory design and an...
Chapter
Hayabusa2, a Japanese asteroid-sampling probe, arrived at asteroid Ryugu on June 27, 2018. During 1.5 years of the Ryugu proximity phase, we performed various science observations to investigate the properties of Ryugu. We also succeeded in lots of critical descent operations, including two rovers/a lander landing, two sample collections, a kinetic...
Chapter
This paper focuses on the touchdown and sampling dynamics of the Hayabusa2 mission with near-Earth asteroid 162,173 Ryugu. Hayabusa2 successfully contacted on the asteroid's surface and ejected a projectile for sample collection on February 22, 2019. Hayabusa2 later contacted near a crater formed by an impactor and repeated the sampling sequence on...
Chapter
Hayabusa2 was a mission with a series of challenging operations and a scientific goal that related to the origins of life. These attributes presented an opportunity to engage with a wide range of people beyond the scientific community who might be inspired by the difficulty of the engineering or relate to a search for how life on Earth began. The m...
Chapter
Hayabusa2 is a sample-return mission from the asteroid Ryugu. The spacecraft was launched in 2014 and accomplished its mission by returning to Earth in 2020. The spacecraft performed two touchdown operations for soil sample collection in 2019. The accuracy requirements for the guidance, navigation, and control (GNC) of the spacecraft were challengi...
Chapter
The asteroid explorer Hayabusa2 is a compact spacecraft designed for small-body sample return. The technology used was based on the former Hayabusa mission, with many improvements and upgrades in terms of reliability and capability. It weighs 609 kg and is equipped with 14 scientific payloads. It can land, perform a kinetic impact experiment, and e...
Chapter
A sub-surface investigation is one of the desired missions in small body exploration. Since the surface materials that have been exposed for a long time to space have been potentially altered by space weathering and heat processes, investigating underground materials and conditions is very important to clarify the “true nature” of the asteroid. Hay...
Chapter
The Hayabusa2 mission is designed to touch down on the asteroid Ryugu for material sampling. The landing site selection (LSS) is a key for a successful touchdown from engineering and scientific standpoints. This paper outlines the LSS processes and results for the two touchdown operations of Hayabusa2. In addition, pre-arrival LSS training to valid...
Chapter
On November 23, 2018, the Hayabusa2 spacecraft entered in superior solar conjunction. Thus, the spacecraft, in hovering around Ryugu, was in the Sun's shadow as seen from Earth. It is the first time, that a spacecraft experiences solar conjunction while in hovering at a minor celestial body. The solar corona caused a 21-day disruption in the Hayabu...
Chapter
The Hayabusa2 explorer arrived at the asteroid Ryugu in June 2018. During its operational phase, Hayabusa2 performed several challenging activities. One was deploying several “hopping” rovers to the surface: the MINERVA-II-1A and -B. The MINERVA-II-1A/B were successfully deployed on September 21, shortly after which they landed on the surface of Ry...
Chapter
The most challenging aspects for the navigation of Hayabusa2 toward its target asteroid (16273) Ryugu were the limited a priori knowledge of the Ryugu's trajectory and the need for precise orbit determination (OD) during its ion-engine thrusting periods. Ryugu's ephemeris had to be simultaneously determined with the orbit of Hayabusa2 through optic...
Chapter
Hayabusa2 is the second Japanese small body sample return exploration mission, targeting the carbonaceous asteroid (162173) Ryugu. The spacecraft was launched with Japan's H2A launch vehicle from the Tanegashima Space Center in December 2014 and arrived at Ryugu in June 2018. After completing detailed remote sensing observations, two sampling opera...
Chapter
The Japan Aerospace Exploration Agency developed and performed an asteroid sample return mission: Hayabusa2. Hayabusa2 is a Japanese, second-in-the-world asteroid sample return mission. Hayabusa2 visited the C-type asteroid Ryugu in 2018, stayed in the proximity of the asteroid for 1.5 years, and returned to Earth in 2020. During the asteroid proxi...
Chapter
Hayabusa2 made its first touchdown (TD) on February 22, 2019, and its second TD on July 11, 2019. The operation for each TD was a round trip from the home position, where the spacecraft stands by at an altitude of 20 km, to the surface of the asteroid Ryugu. For each TD, the outward trip lasted approximately 24 h. This chapter discusses the first a...
Chapter
Hayabusa2 has completed its exploration of the asteroid Ryugu and successfully returned samples to Earth. During its rendezvous with Ryugu, radio science experiments were conducted to estimate the gravity and ephemeris of the asteroid, which are crucial to scientific investigations and the navigation of the spacecraft. In particular, mass informati...
Chapter
Hayabusa2, Japan's interplanetary probe, arrived at asteroid 162173 Ryugu on June 27, 2018 to perform a variety of complex critical operations to collect and return surface and subsurface samples from the asteroid. Because the operating environment and characteristics of the asteroid could be known only after the arrival, the Hayabusa2 operations t...
Article
Full-text available
In this study, we determined the alignment of the laser altimeter aboard Hayabusa2 with respect to the spacecraft using in-flight data. Since the laser altimeter data were used to estimate the trajectory of the Hayabusa2 spacecraft, the pointing direction of the altimeter needed to be accurately determined. The boresight direction of the receiving...
Article
The weather-forecast based Radio Meteorological Operation Planner (RMOP) model for the dynamical link-budget design in satellite communications at Ka-band is described and validated. For the first time, actual received Ka-band data from a deep-space satellite mission (Hayabusa2 mission from JAXA and supported by ESA) were available for operational...
Preprint
Full-text available
The near-Earth asteroid (162173) Ryugu displays a Cb-type average spectrum and a very low average normal albedo of 0.04. Although the majority of boulders on Ryugu have reflectance spectra and albedo similar to the Ryugu average, a small fraction of boulders exhibit anomalously high albedo and distinctively different spectra. A previous study (Tats...
Preprint
Full-text available
Many small boulders with reflectance values higher than 1.5 times the average reflectance have been found on the near-Earth asteroid 162173 Ryugu. Based on their visible wavelength spectral differences, Tatsumi et al. (2021) defined two bright boulder classes: C-type and S-type. These two classifications of bright boulders have different size distr...
Conference Paper
Full-text available
This work explores the possibility of performing in-orbit particle collection for sampling and exploration missions towards asteroids. Ejecta is generated via a small kinetic impactor and two possible collection strategies are investigated: collecting the particle at the L 2 Lagrangian point or collecting them while they orbit the asteroid and befo...
Article
Full-text available
Ryugu is a carbonaceous rubble-pile asteroid visited by the Hayabusa2 spacecraft. Small rubble pile asteroids record the thermal evolution of their much larger parent bodies. However, recent space weathering and/or solar heating create ambiguities between the uppermost layer observable by remote-sensing and the pristine material from the parent bod...
Article
Full-text available
The orbital motion of spacecraft around asteroids is strongly disturbed primarily because of solar radiation pressure (SRP) and higher-order gravitational forces. To achieve stable orbits in such an environment, the implementation of frozen orbits is a promising approach. This research derives semi-analytical solutions of frozen orbits subject to S...
Article
Full-text available
Planetesimals—the initial stage of the planetary formation process—are considered to be initially very porous aggregates of dusts1,2, and subsequent thermal and compaction processes reduce their porosity3. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30–50% (refs. 4–6), higher th...
Article
Full-text available
One of the major challenges in the Hayabusa2 sample-return mission was the second touchdown on the asteroid Ryugu, which was designed to collect subsurface materials near the artificial crater formed by a small carry-on impactor. Due to engineering and scientific requirements, a narrow area with a radius as small as 3.5 m was selected as the target...
Conference Paper
Full-text available
In the context of future asteroid exploration missions, within the MSCA CRADLE project in collaboration between Politecnico di Milano and JAXA, we envision the possibility to perform in-orbit collection. In this work, the dynamical behaviour of ejecta following the impact of a small kinetic impactor is analysed in the context of the circular restri...
Preprint
Full-text available
C-type asteroids are considered to be primitive small Solar-System bodies enriched in water and organics, providing clues for understanding the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing and on-asteroid measurements with Hayabusa2, but further studi...
Article
Many small boulders with reflectance values higher than 1.5 times the average reflectance have been found on the near-Earth asteroid 162,173 Ryugu. Based on their visible wavelength spectral differences, Tatsumi et al. (2021, Nature Astronomy, 5, doi:doi:10.1038/s41550-020-1179-z) defined two bright boulder classes: C-type and S-type. These two cla...
Article
The asteroid explorer Hayabusa2 was launched by Japan Aerospace Exploration Agency (JAXA) on December 3rd, 2014. The primary mission of the spacecraft is to sample pieces of the asteroid and return it to Earth for more advanced scientific analysis on the Earth. After three-year cruise phase, Hayabusa2 finally arrived at the asteroid Ryugu on June 2...
Article
The resurfacing process on Ryugu accompanying the artificial impact crater formation by Hayabusa2's Small Carry-on Impactor (SCI) was studied by comparing pre- and post-impact images of this region captured by an optical navigation camera. Three different aspects of the resurfacing process were examined: the crater rim profiles, the motion of bould...
Article
The near-Earth asteroid (162173) Ryugu displays a Cb-type average spectrum and a very low average normal albedo of 0.04. Although the majority of boulders on Ryugu have reflectance spectra and albedo similar to the Ryugu average, a small fraction of boulders exhibit anomalously high albedo and distinctively different spectra. A previous study (Tats...
Conference Paper
At 01:57:20 UTC on October 3rd, 2018, after 3½ years of cruise aboard the JAXA spacecraft HAYABUSA2 and about 3 months in the vicinity of its target, the MASCOT lander was separated successfully by from an altitude of 41 m. After a free-fall of only ~5m51s MASCOT made first contact with C-type near-Earth and potentially hazardous asteroid (162173)...
Preprint
Full-text available
Hayabusa2 is the Japanese Asteroid Return Mission and targeted the carbonaceous asteroid Ryugu, conducted by the Japan Aerospace Exploration Agency (JAXA). The goal of this mission was to conduct proximity operations including remote sensing observations, material sampling, and a Small Carry-On Impact experiment, as well as sample analyses. As of S...
Article
Hayabusa2 is the Japanese Asteroid Return Mission and targeted the carbonaceous asteroid Ryugu, conducted by the Japan Aerospace Exploration Agency (JAXA). The goal of this mission was to conduct proximity operations including remote sensing observations, material sampling, and a Small Carry-On Impact experiment, as well as sample analyses. As of S...
Article
Full-text available
Analyses of meteorites and theoretical models indicate that some carbonaceous near-Earth asteroids may have been thermally altered due to radiative heating during close approaches to the Sun1–3. However, the lack of direct measurements on the subsurface doesn’t allow us to distinguish thermal alteration due to radiative heating from parent-body pro...
Article
After 3.5 years of cruise, and about 3 months in the vicinity of its target, the MASCOT lander was deployed successfully on 3rd October 2018 by the Hayabusa2 spacecraft onto the C-type near-Earth asteroid (162173) Ryugu. After a free-fall of 5 min 51 sec from an altitude of 41 m MASCOT experienced its first contact with the asteroid hitting a big b...
Article
Visual images are effective tools for monitoring the condition of spacecraft. In this article, we developed a low-cost, low impact, compact visual monitoring system using commercial off-the-shelf (COTS) devices to perform critical situation monitoring of the Hayabusa2 touchdown mission. The in situ performance of all devices for the touchdown missi...
Article
Full-text available
The article “Orbit insertion strategy of Hayabusa2’s rover with large release uncertainty around the asteroid Ryugu” written by Yusuke Oki, Kent Yoshikawa, Hiroshi Takeuchi et al., was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 05 November 2020 without open access. After publication in Volume...
Article
Full-text available
Seismic shaking has been regarded as an essential source of resurfacing on asteroids. The Small Carry‐on Impactor (SCI) operation on Hayabusa2 has been expected to be a unique opportunity for testing in situ seismic shaking whose energy is sufficiently large to excite observable surface modification. However, no obvious regolith hopping was identif...
Article
Full-text available
The asteroid (162173) Ryugu and other rubble-pile asteroids are likely re-accumulated fragments of much larger parent bodies that were disrupted by impacts. However, the collisional and orbital pathways from the original parent bodies to subkilometre rubble-pile asteroids are not yet well understood1–3. Here we use Hayabusa2 observations to show th...
Article
Hayabusa-2, a JAXA mission, reached C-type asteroid (162173) Ryugu in June 2018. Hayabusa2 carried MASCOT (Ho et al., 2016), a small lander developed by DLR and CNES. The goal of MASCOT was to perform in situ measurements on the surface of the asteroid by means of its four scientific instruments, substantially contributing in this way to the overal...
Article
Hayabusa2 is a Japanese asteroid explorer launched by the H-IIA rocket on Dec. 3, 2014. After the long cruising with the ion engine system, the spacecraft approached its target body, Ryugu, using optical navigation. It arrived at Home Position (HP), 20 km above the sub-Earth point, on Jun. 27, 2018. The spacecraft is now on its way back to Earth. I...
Article
This paper describes a modeling technique of the solar radiation pressure (SRP) exerted on spacecraft which can incorporate general surface with anisotropic reflectance property. The SRP torque is a major disturbance for the attitude of spacecraft especially in deep space missions. It depends not only on the shape and attitude of spacecraft, but al...
Article
This paper presents an overview of a guidance, navigation and control method used in descent operations of Hayabusa2. The method consists of on-board and on-ground guidance systems to control the spacecraft, and an image-based navigation technique using a shape model and ground control points of the asteroid. Hayabusa2 has performed descent operati...
Article
Asteroid Explorer Hayabusa2 arrived at asteroid Ryugu in June of 2018. During its stay around Ryugu, Hayabusa2 will undertake several challenging missions such as collecting soil samples and deploying rovers, a lander, and an impactor. Before the spacecraft attempts these missions, our initial and most important work is to reveal the asteroid’s cha...
Article
Full-text available
Thermophysical properties of the surface of asteroid 162173 Ryugu have been investigated through global, local and close-up thermal imaging from the Hayabusa2 spacecraft using the thermal infrared imager TIR, a two-dimensional thermographic camera. The set of thermal images during one rotation of asteroid allowed to map thermal inertia of the aster...
Article
Full-text available
Abstract The precise orbit of the Hayabusa2 spacecraft with respect to asteroid Ryugu is dynamically determined using the data sets collected by the spacecraft’s onboard laser altimeter (LIght Detection And Ranging, LIDAR) and automated image tracking (AIT). The LIDAR range data and the AIT angular data play complementary roles because LIDAR is sen...
Article
The Japanese interplanetary probe Hayabusa2 was launched on December 3, 2014 and the probe arrived at the vicinity of asteroid 162173 Ryugu on June 27, 2018. During its 1.4 years of asteroid proximity phase, the probe successfully accomplished numbers of record-breaking achievements including two touchdowns and one artificial cratering experiment,...
Article
The asteroid explorer Hayabusa2 carries multiple rovers and separates them to land on an asteroid surface. One of these rovers, called MASCOT, was developed under the international cooperation between the Deutsches Zentrum für Luft- und Raumfahrt and the Centre National d’Etudes Spatiales. This rover was designed to be separated to land and perform...
Article
Hayabusa2 is a Japanese sample return mission from the asteroid Ryugu. The Hayabusa2 spacecraft was launched on 3 December 2014 and arrived at Ryugu on 27 June 2018. It stayed there until December 2019 for in situ observation and soil sample collection, and will return to the Earth in November or December 2020. During the stay, the spacecraft perfo...
Article
Full-text available
This paper describes the orbit design of the deployable payload Rover 2 of MINERVA-II, installed on the Hayabusa2 spacecraft. Because Rover 2 did not have surface exploration capabilities, the operation team decided to experiment with a new strategy for its deployment to the surface. The rover was ejected at a high altitude and made a semi-hard lan...