A5053664358- Planetary Science and Exploration
- Astro and Planetary Science
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Space Exploration and Technology
- Geomagnetism and Paleomagnetism Studies
- Space exploration and regulation
- Space Science and Extraterrestrial Life
- Earthquake Detection and Analysis
- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Spaceflight effects on biology
- Magnetic confinement fusion research
- Atmospheric Ozone and Climate
- Spacecraft Design and Technology
- Geology and Paleoclimatology Research
- Laser-induced spectroscopy and plasma
- Electronic Packaging and Soldering Technologies
- Nuclear physics research studies
- Atmospheric and Environmental Gas Dynamics
- Nuclear Materials and Properties
- Nuclear Physics and Applications
- Plasma Diagnostics and Applications
- Hydrogen embrittlement and corrosion behaviors in metals
- Particle accelerators and beam dynamics
The University of Tokyo
1997-2025
RIKEN Nishina Center
2013-2023
Institute of Space and Astronautical Science
2013-2022
Kobe University
2020-2021
Japan Aerospace Exploration Agency
2012-2021
Tokyo University of Science
1994-2020
University of Tokyo Health Sciences
2020
The Graduate University for Advanced Studies, SOKENDAI
2020
Meenakshi Mission Hospital and Research Centre
2019
Siriraj Hospital
2019
AKATSUKI is the Japanese Venus Climate Orbiter that was designed to investigate climate system of Venus. The orbiter launched on May 21, 2010, and it reached December 7, 2010. Thrust applied by orbital maneuver engine in an attempt put into a westward equatorial orbit around with 30-h period. However, this operation failed because malfunction propulsion system. After failure, spacecraft orbited Sun for 5 years. On 2015, once again approached insertion successful, whereby apoapsis ~440,000 km...
The electric field detector (EFD) on board GEOTAIL measures the by two different techniques, one probe technique and other electron beam technique. (EFD-P) gives in plane perpendicular to satellite spin axis measuring voltage difference between sphere probes; each deployed 50 meters from spacecraft opposite direction. (EFD-B), drift motion of gyration center artificially emitted electrons obtain field. is measured methods, itself time return flight spacecraft. To realize these measurements,...
After the arrival of Akatsuki spacecraft Japan Aerospace Exploration Agency at Venus in December 2015, radio occultation experiment, termed RS (Radio Science), obtained 19 vertical profiles Venusian atmosphere by April 2017. An onboard ultra-stable oscillator is used to generate stable X-band downlink signals needed for experiment. The quantities be retrieved are atmospheric pressure, temperature, sulfuric acid vapor mixing ratio, and electron density. Temperature were successfully down ~ 38...
Explaining super-rotation on Venus The solid surface of rotates very slowly, once every 243 days, but its thick atmosphere circles the planet in just 4 days. This phenomenon, known as super-rotation, requires a continuous input angular momentum, from an unknown source, to overcome friction with surface. Horinouchi et al. mapped planet's winds using ultraviolet observations Venus' clouds orbiting Akatsuki spacecraft (see Perspective by Lebonnois). They incorporated these data into global...
The Dst index has been conventionally used as a measure of the storm intensity, which ideally assumes that associated ground magnetic disturbance is caused by ring current. present study examines contribution tail current to , focusing on occurrence geosynchronous dipolarization close minimum, in other words, start recovery phase. Sym‐H (referred ( ) hereafter) rather than conventional because its higher time resolution (1 min). For June 1998 event, started at two GOES satellites and Geotail...
In this paper we present a survey of the three‐dimensional ion and electron distributions measured on AMPTE IRM near neutral sheet in near‐Earth magnetotail (R ≈ 10–19 R E ). The data are classified according to substorm phases. Individual case studies velocity reveal that ions consist single population. Fast slow flows both occurred during two extremes magnetospheric activity, expansion phase quiet times. Ion beams occasionally observed, their shapes space similar those observed plasma...
The Akatsuki spacecraft of Japan was launched on May 21, 2010. planned to enter a Venus-encircling near-equatorial orbit in December 7, 2010; however, the Venus insertion maneuver has failed, and at present is orbiting Sun. There possibility conducting an again several years later. main goal mission understand Venusian atmospheric dynamics cloud physics, with explorations ground surface interplanetary dust also being themes. angular motion roughly synchronized zonal flow near base for 20...
We present observational evidence of the variation cloud‐tracked zonal velocity by ~20 m s –1 with a timescale few hundred days in southern low latitude region based on an analysis cloud images taken Venus Monitoring Camera board Express. A spectral suggests that has periodicity period about 255 days. Although features are not always passive tracers, periodical dynamical state is robust feature. Superposed this long‐term velocity, Kelvin wave‐like disturbances tend to be observed periods...
Abstract The existence of large stationary gravity waves was discovered during Akatsuki's first observation sequence in 2015. In this study, the further detection brightness temperature images over a 1.5 year period is reported. periodically appeared mostly above four specific highland regions low latitudes when these were local afternoon. wave amplitudes attenuated after locations passed beyond evening terminator, and tended to slowly drift eastward their lifetimes. appearances depend not...
The ultraviolet imager (UVI) has been developed for the Akatsuki spacecraft (Venus Climate Orbiter mission). UVI takes (UV) images of solar radiation reflected by Venusian clouds with narrow bandpass filters centered at 283 and 365 nm wavelengths. There are absorption bands SO2 unknown absorbers in these wavelength regions. UV provide spatial distribution absorber around cloud top altitudes. also allow us to understand morphologies haze properties. Nominal sequential 2-h intervals used...
On April 26, 1995, while Geotail was in the near‐equatorial magnetotail at 13 R E and 2300 LT, a substorm onset occurred that documented by ground magnetograms, auroral kilometric radiation, magnetic field particle data from four spacecraft near geosynchronous orbit. Although initially outside greatly thinned current sheet, plasma sheet thickening associated with dipolarization quickly caused to move into where it observed field‐aligned earthward moving ions velocities of 400 km/s. During...
Ion-acoustic solutions in a plasma traversed by weak ion beam are studied experimentally double device. Large amplitude compressive pulses amplified and steepened to become solitons of which the n/n0 is comparable or less than 40%. The soliton maximum at velocity Vb/Cs=1.7 while linear growth rates Vb/Cs=1.3. Theoretical explanations presented with use fluid model.
The Longwave Infrared Camera (LIR) is one of a suite cameras onboard the Venus orbiter Akatsuki. It will take images thermal radiation in wavelength range 8–12 µm emitted by cloud tops. use an uncooled micro-bolometer array as infrared image sensor makes LIR lightweight, small and low-power consumption instrument with required noise equivalent temperature difference 0.3 K. Temperature horizontal wind fields at cloud-top be retrieved for both dayside nightside equal quality. This provide key...
Radial variations of the amplitude and energy flux compressive waves in solar corona were explored for first time using a spacecraft radio occultation technique. By applying wavelet analysis to frequency series taken at heliocentric distances 1.5–20.5 RS (solar radii), quasi-periodic density disturbances detected almost all distances. The period ranges from 100 2000 s. fractional fluctuation increases with distance reaches ∼30% around 5 RS, implying that nonlinearity wave field is...
Abstract Global Lightning and Sprite Measurements on Japanese Experiment Module (JEM‐GLIMS) is a space mission to conduct the nadir observations of lightning discharges transient luminous events (TLEs). The main objectives this are identify horizontal distribution TLEs solve occurrence conditions determining spatial distribution. JEM‐GLIMS was successfully launched started continuous in 2012. global detected shows that most occurred over continental regions local summer hemisphere. In some...
Despite the tremendous progress that has been made since publication of Venus II book in 1997, many fundamental questions remain concerning Venus' history, evolution and current geologic atmospheric processes. The international science community taken several approaches to prioritizing these questions, either through formal processes like Planetary Decadal Survey United States Cosmic Vision Europe, or informally definition teams utilized by Japan, Russia, India. These are left future...
Radio scintillation observations have been unable to probe flow speeds in the low corona where scattering of radio waves is exceedingly strong. Here we estimate outflow continuously from vicinity Sun outer (heliocentric distances 1.5–20.5 solar radii) by applying strong theory scintillations for first time, using Akatsuki spacecraft as source. Small, nonzero were observed over a wide latitudinal range quiet-Sun corona, suggesting that supply plasma closed loops wind occurs an extended area....
The objective of the present study is to examine timing various onset‐associated signatures and address cause‐and‐effect relationship between formation a near‐Earth neutral line (NENL) trigger tail current disruption. An event selected for this took place on December 31, 1995. In Geotail satellite was located at X = −30.3 R E in midnight sector local time GOES 8 9 geosynchronous satellites. observation fast (950‐km/s) tailward convection flow accompanied with southward B z (< −10 nT)...
Abstract MAP-PACE (MAgnetic field and Plasma experiment-Plasma energy Angle Composition Experiment) is one of the scientific instruments onboard SELENE (SELenological ENgineering Explorer) satellite. PACE consists four sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), IEA Energy Analyzer). ESA-S1 S2 measure distribution function low-energy electrons below 15 keV, while low ions 28 keV/q. Each sensor has a hemispherical view. Since three-axis stabilized...
Since insertion into orbit on December 7, 2015, the Akatsuki orbiter has returned global images of Venus from its four imaging cameras at eleven discrete wavelengths ultraviolet (283 and 365 nm) near infrared (0.9–2.3 µm), to thermal (8–12 µm) a near-equatorial orbit. The Express Pioneer Orbiter missions have also monitored planet for long periods but polar or near-polar orbits. wavelength coverage views differ all three missions. In reflected light, reveal features seen cloud tops (~ 70 km...