Hinotori
Hinotori (ASTRO-A)
Mission Descriptions
Overview
"Hinotori (ASTRO-A)" is an X-ray solar observation satellite developed primarily by the Institute of Space and Astronautical Science (ISAS) of the University of Tokyo. Its mission was to observe two-dimensional images of solar hard X-ray flares, solar particle radiation, and X-ray bursts. Hinotori was launched on February 21, 1981, from the Kagoshima Space Center (now Uchinoura Space Center) by an M-3S-2 rocket and concluded operations on July 11, 1991.
The satellite weighs 188 kg and has an octagonal prism shape with a face-to-face distance of 92.8 cm and a height of 81.5 cm, equipped with four solar panels. It orbited in a near-circular orbit with a periapsis altitude of 576 km, an apoapsis altitude of 644 km, and an inclination of 31 degrees, completing one orbit every 97 minutes.
Observation Instruments
Solar Flare X-ray Imager (SXT)
The SXT is an instrument designed to capture X-ray images of solar flares. It primarily observes hard X-rays and aims to capture high-resolution images of high-temperature flare regions. The SXT detects high-energy X-rays and visualizes the distribution of high-temperature plasma as it changes during flare events.
Solar Soft X-ray Bright Line Spectrum Analyzer (SOX)
The SOX analyzes the soft X-ray bright line spectrum of the Sun. This analysis investigates the ionization state and elemental abundance in the solar corona. The instrument detects specific wavelengths of X-rays, gathering information about various elements from the soft X-ray spectrum's bright lines.
Solar Soft X-ray Monitor (HXM)
The HXM continuously observes soft X-rays from the Sun. It is used to monitor solar activity in real-time, providing crucial data during sudden flare occurrences. The HXM has high sensitivity to soft X-rays, tracking the occurrence and development of flares in detail.
Solar Flare Monitor (FLM)
The FLM is an instrument for real-time monitoring of solar flares. It detects the timing and intensity of flare occurrences immediately, providing critical information for the operation of other observation instruments.
Solar Gamma Ray Monitor (SGR)
The SGR monitors gamma rays emitted from the Sun. This instrument detects high-energy gamma rays and studies high-energy phenomena associated with solar flares. The SGR's data contribute to understanding the mechanisms of high-energy particle production during flares.
Particle Ray Monitor (PXM)
The PXM observes particle radiation emitted from the Sun. It monitors the flow of particles from solar wind and solar flares, analyzing their energy spectra. The PXM's data provide important information for understanding solar activity and its effects on the Earth's magnetosphere.
Plasma Electron Density Measurement Instrument (IMP)
The IMP measures electron density in the plasma. It observes the density distribution in the plasma, analyzing plasma variations during flare occurrences. The IMP's data track the temporal changes in electron density within the plasma in detail.
Plasma Electron Temperature Measurement Instrument (TEL)
The TEL measures the electron temperature in the plasma. It observes the temperature distribution in the plasma, analyzing high-temperature phenomena during flare occurrences. The TEL's data track the temporal changes in electron temperature within the plasma in detail.
Achievements
On the first day of its regular observation period, Hinotori observed a major solar flare, followed by the successful observation of 41 flares of various sizes over the next month. These observations led to the discovery of new phenomena, such as high-temperature events in the solar corona reaching 50 million degrees and clouds of electrons traveling at the speed of light. The data collected by Hinotori were also provided to international solar activity maximum observation projects, significantly contributing to the understanding of solar activity.