New X-ray Astronomy Satellite ASTRO-H Striving to Solve the Mysteries of the Universe History of Japanese X-ray Astronomy Satellites X-ray astronomy started when Riccardo Giacconi and his associates launched an observation rocket in 1962, and found a bright X-ray source other than the Sun. Full-scale X-ray observations from space began in the 1970s, with the launch of scientific satellites carrying X-ray detectors. Japan has launched five X-ray astronomy satellites to date, starting with HAKUCHO in 1979, and has achieved tremendous research results. Working in the field of X-ray astronomy since its early days, Japan has become the world leader in this sector.

HAKUCHO (CORSA-b)

HAKUCHO (CORSA-b)

Date of Launch: February 21, 1979

Dimensions: 0.75 m × 0.75 m × 0.65 m    Weight: 96 kg

HAKUCHO was the first Japanese X-ray astronomy satellite, named after the black hole Cygnus X-1. (Cygnus is Latin for swan. Hakucho is the Japanese word for swan.) It had an X-ray detector with a modulation collimator to give better positional accuracy, enabling several previously unknown X-ray sources to be identified with optical counterparts.
Major achievements include the discovery of many new sources of X-ray bursts, which are explosive thermonuclear fusion events on the surface of accreting neutron stars.

TENMA (ASTRO-B)

TENMA (ASTRO-B)

Date of Launch: February 20, 1983

Dimensions: 0.94 m x 0.94 m x 0.89 m    Weight: 216 kg

TENMA was equipped with a new device called a Scintillation Proportional Counter which gave better energy resolution than previous detectors. It observed X-rays from black holes and neutron star accreting systems in our Galaxy.
Major achievements include the discovery of plasma at temperatures of tens of millions of degrees Celsius along the galactic plane of our Galaxy.

GINGA (ASTRO-C)

GINGA (ASTRO-C)

Date of Launch: February 5, 1987

Dimensions: 1.0 m x 1.0 m x 1.5 m    Weight: 420 kg

The large area detector on GINGA was a breakthrough in sensitivity, allowing the first detailed observations of faint X-ray sources. It successfully detected X-ray emissions from Supernova 1987A, which occurred right after its launch. GINGA observed the full range of celestial X-ray sources, both galactic and extragalactic.
Major achievements include tracing the spectral evolution of black hole binary accretion flows as a function of mass accretion rate, and the discovery of reflection of X-rays from the accretion disc in Active Galactic Nuclei. Additionally, full-scale international cooperation began with GINGA as the instruments were co-developed with scientists from the United Kingdom and the United States.

ASCA (ASTRO-D)

ASCA (ASTRO-D)

Date of Launch: February 20, 1993

Weight: 420 kg

ASCA achieved a dramatic advance in energy resolution by flying the world’s first X-ray CCD at the focus of an imaging X-ray telescope as well as a Gas Imaging Spectrometer.
Its major achievements include: analysis of the chemical elements produced by supernovae, how these elements are dispersed into the hot gas in clusters of galaxies, the discovery of an iron line from the accretion disc around a black hole with the shape predicted Albert Einstein’s general theory of relativity; and the observation of particle acceleration in supernova remnants.

Suzaku (ASTRO-EII)

Suzaku (ASTRO-EII)

Date of Launch: July 10, 2005

Dimensions: 6.5 m x 2.0 m x 1.9 m    Weight: 1700 kg

Suzaku’s energy resolution and angular resolution were even more advanced than those of ASCA. It carries a soft-X-ray telescope and a highly sensitive hard-X-ray detector so it can observe spectra over a wide range in energy.
Its major achievements to date include the observation of the composition of carbon in normal stars and planetary nebula, and the discovery of rare metals in a galaxy cluster that told the history of element composition from a star to a supernova explosion. Suzaku also discovered a black hole covered by thick gas and dust in a galaxy cluster, and observed that explosive phenomena occur in the middle of the Milky Way galaxy. It has performed research on high-energy phenomena in the universe, and found evidence of particle acceleration in a supernova remnant. It is still performing observations, and more achievements are anticipated in the future.