A5063739007- Astro and Planetary Science
- Planetary Science and Exploration
- Geology and Paleoclimatology Research
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- High-pressure geophysics and materials
- Space Exploration and Technology
- Space Science and Extraterrestrial Life
- Scientific Research and Discoveries
- Fluid Dynamics Simulations and Interactions
- Geotechnical and Geomechanical Engineering
- earthquake and tectonic studies
- Geological and Geochemical Analysis
- Spaceflight effects on biology
- High-Velocity Impact and Material Behavior
- Marine and environmental studies
- Paleontology and Stratigraphy of Fossils
- Isotope Analysis in Ecology
- Gamma-ray bursts and supernovae
- Methane Hydrates and Related Phenomena
- Hydrocarbon exploration and reservoir analysis
- Geomagnetism and Paleomagnetism Studies
- Mineral Processing and Grinding
- Tunneling and Rock Mechanics
- Rock Mechanics and Modeling
Tokyo Institute of Technology
2015-2024
Life Science Institute
2015-2024
Institute of Science Tokyo
2024
Earth-Life Science Institute
2015-2020
The University of Tokyo
2002-2017
Tokyo University of Science
2011
National Astronomical Observatory of Japan
2009
Samples of the carbonaceous asteroid Ryugu were brought to Earth by Hayabusa2 spacecraft. We analyzed 17 samples measuring 1 8 millimeters. Carbon dioxide-bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu's parent formed in outer Solar System. The contain low abundances materials at high temperatures, such as chondrules and calcium- aluminum-rich inclusions. rich phyllosilicates carbonates, which through aqueous alteration reactions temperature, pH,...
Abstract Martian moons exploration, MMX, is the new sample return mission planned by Japan Aerospace Exploration Agency (JAXA) targeting two with scheduled launch in 2024 and to Earth 2029. The major scientific objectives of this are determine origin Phobos Deimos, elucidate early Solar System evolution terms volatile delivery across snow line terrestrial planets having habitable surface environments, explore evolutionary processes both Mars environment. To achieve these objectives, during a...
From an astrobiological point of view, special attention has been paid to the probability habitable planets in extrasolar systems. The purpose this study is constrain a possible range mass terrestrial planet that can get water. We focus on process water production through oxidation atmospheric hydrogen--the nebular gas having attracted gravitationally--by oxide available at planetary surface. For work well planet, sufficient amount hydrogen and enough high temperature melt surface are...
The final stage of terrestrial planet formation is known as the giant impact where protoplanets collide with one another to form planets. So far this has been mainly investigated by N-body simulations an assumption perfect accretion in which all collisions lead accretion. However, breaks for high velocity and/or a large parameter. We derive condition protoplanet terms and angle masses colliding bodies, from results numerical collision experiments. For first time, we adopt realistic...
Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth planet. Here we speculate processes that led early on and its aftermath, finally leading evolution metazoans. We evaluate: (1) source nutrients, (2) chemistry primordial ocean, (3) initial mass (4) size Among life-building phosphorus potassium play a key role. Only three types rocks can serve as an adequate nutrients: (a) continent-forming TTG (granite), enabling primitive metazoans; (b)...
At the final stage of terrestrial planet formation, known as giant impact stage, a few tens Mars-sized protoplanets collide with one another to form planets. Almost all previous studies on orbital and accretional evolution in this have been based assumption perfect accretion, where two colliding always merge. However, recent simulations shown that collisions among are not merging events, is, sometimes move apart after collision (hit-and-run collision). As first step towards studying effects...
In our solar system, Mars-sized protoplanets frequently collided with each other during the last stage of terrestrial planet formation called giant impact stage. Giant impacts eject a large amount material from colliding into region, which may form debris disks observable infrared excesses. Indeed, tens warm around young solar-type stars have been observed. Here, we quantitatively estimate total mass ejected materials stages. We found that $\sim$0.4 times Earth's is in throughout Ejected are...
IRD is the near-infrared high-precision radial velocity instrument for Subaru 8.2-m telescope. It a relatively compact (~1m size) spectrometer with new echelle-grating and Volume-Phase Holographic gratings covering 1-2 micron wavelengths combined an original frequency comb using optical pulse synthesizer. The will employ 4096x4096-pixel HgCdTe array under testing at IfA, University of Hawaii. Both telescope/Adaptive Optics beams are fed to via fibers, while placed Nasmyth platform Expected...
The Infrared Doppler (IRD) instrument is a fiber-fed high-resolution NIR spectrometer for the Subaru telescope covering Y,J,H-bands simultaneously with maximum spectral resolution of 70,000. main purpose IRD search Earth-mass planets around nearby M-dwarfs by precise radial velocity measurements, as well spectroscopic characterization exoplanet atmospheres. We report current status instrument, which undergoing commissioning at Telescope, and first light observation successfully done in...
The presence of water on Earth has played important roles in shaping the solid regions planet as well origin and evolution life. This paper addresses three fundamental aspects Earth's water; (1) quantity surface interior that possesses, (2) length time oceans have been present, (3) mechanism(s) by which this was supplied or generated. From geochemical geophysical analysis, high-pressure experimental works, content mantle can be estimated to from one ten times present ocean mass. Although it...
Abstract Melting experiments were performed on the Fe‐C‐H system to 127 GPa in a laser‐heated diamond anvil cell. On basis of situ and ex sample characterizations, we found that solubility carbon liquid Fe correlates inversely with hydrogen concentration at ~60 ~3500 K, indicating preferentially incorporates rather than under conditions abundant C H. While large amounts both H may have been delivered growing Earth, C‐poor/H‐rich metals likely added protocore late stages core formation. We...
The high density of the close-in extrasolar planet HD149026b suggests presence a huge core in planet, which challenges formation theory. We first derive constraints on amount heavy elements and hydrogen/helium present planet: find that preferred values mass are between 50 80 M_E. then investigate possibility subcritical accretion as envisioned for Uranus Neptune scenario is unlikely case at least two reasons: (i) Subcritical planets such ratio their to total above ~0.7, contradiction with...
Hypervelocity impacts cause significant heating of planetary bodies. Such events are recorded by a reset 40Ar-36Ar ages and/or impact melts. Here, we investigate the influence friction and plastic deformation in shock-generated comminuted rocks on degree using iSALE shock-physics code. We demonstrate that conversion from kinetic to internal energy targets with strength occurs during pressure release, additional becomes for low-velocity (<10 km/s). This heat reduces impact-velocity thresholds...
Phobos and Deimos are the two small Martian moons, orbiting almost on equatorial plane of Mars. Recent works have shown that they can accrete within an impact-generated inner dense outer light disk, same impact potentially forms Borealis basin, a large northern hemisphere basin current However, there is no priori reason for to take place close north pole (Borealis present location) nor generate debris disk in Mars (in which orbit). In this paper, we investigate these remaining issues giant...