Learn MoreHistory of X-ray astronomy
spacecraft in Japan
With 40 years of launching X-ray astronomy spacecraft, Japan has been consistently contributing to the world of X-ray astronomy. Observatory instruments with the latest technology have been launched in the past 6 spacecraft, providing new and never before seen views of the universe.
Hakucho(swan in Japanese)
Japan’s first X-ray astronomy spacecraft, named after the black hole “Cygnus X-1”. A modulation collimator, invented by Dr. Minoru Oda (the author of the black hole thesis in 1971 and later, Director of ISAS), was loaded onto the satellite, allowing the location of X-ray sources to be determined with high accuracy. A number of new X-ray bursts were found by this spacecraft, and this mission moved Japanese X-ray astronomy to the forefront internationally.
Tenma (Pegasus in Japanese)
The newly developed gas scintillation proportional counter doubled the possible energy resolution, enabling more detailed spectroscopy of X-ray sources. One of the main outcomes of this was the discovery of X-ray emisson from hot plasma along the Galactic ridge. This emission has been observed by succeeding spacecraft to elucidate the origin and nature of this emission. It remains one of the most important research themes in X-ray astronomy to this day.
Ginga(Galaxy in Japanese)
New instrumentation included high sensitivity detectors. Major outcomes included the X-ray detection of supernova 1987A shortly after the commencement of observations, and the discovery of many candidate black holes. A full-scale international collaboration begun with this spacecraft to develop the instruments with researchers from all over the world. Dr. Masatoshi Koshiba detected neutrinos from supernova 1987A using Kamiokande in Gifu prefecture, and was later awarded the Nobel Prize in Physics for this discovery.
ASCA (Flying bird)
The first satellite to carry an X-ray telescope and X-ray CCD camera, dramatically improving sensitivity. Major contributions included the detection of general relativistic effects near black holes through observations of active galactic nuclei, providing direct evidence to support the existence of supermassive black holes at the centers of galaxies. International public observations were begun for the first time, and ASCA data has been opened to and used by scientists worldwide, with a number of thesis projects supported.
Suzaku
(Legendary bird, the guardian of the universe)
An X-ray telescope with higher sentivitity than ASCA and instruments to cover a wider bandpass. The major contributions of Suzaku were to detect non-equilibrium ionized plasma in supernova remnants, research into cosmic-ray acceleration mechanisms by shock waves, the detection of X-ray reflection nebulae, detection of active galactic nuclei, elucidating the evolution of galaxy clusters by observing the heavy element distribution in their outer regions, and the X-ray emission from magnetars (highly magnetized neutron stars)
Hitomi(Eye pupil in Japanese)
Four distinct instruments were included to explore the mysteries of dark matter and the co-evolution of galaxies and black holes, which controls the growth of structure in the universe. The wideband detectors had ten times more sensitivity than before. The mission was terminated only a month after launch due to a mishap; however, Hitomi achieved revolutionary measurements of the speed of plasma in galaxy clusters and the abundance of heavy elements.
XRISM
Equipped with an X-ray micro-calorimeter and X-ray CCD camera, identical to those on Hitomi, specializing in soft X-ray imaging spectroscopy. XRISM’s aim is to develop the world of high resolution X-ray spectroscopy, the door to which was opened by Hitomi.
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