Tenma
Tenma (ASTRO-B)
Mission Descriptions
Overview
The X-ray astronomy satellite "Tenma" (ASTRO-B) was designed for precise observation of the energy spectra of X-ray celestial objects and the detection of gamma-ray bursts. It weighed 218 kg, with a square pillar of 94cm x 89.5cm, and had a maximum solar power generation capacity of 150 watts. Launched in February 20, 1983, Tenma was placed in a near circular orbit with an altitude of 497 km at perigee and 503 km at apogee, an inclination of 32 degrees, and an orbital period of 94 minutes. Tenma successfully deployed its solar paddles, tested various instruments, and performed attitude control and spin control using magnetic torque. Regular observations began in March 1983, focusing primarily on X-ray celestial bodies and performing detailed energy spectrum measurements.
Despite a power system malfunction in July 1984, the main instruments remained intact and the observations continued. Tenma conducted X-ray spectroscopy of many galactic and extragalactic celestial bodies until its re-entry into the atmosphere on January 19, 1989. DARTS archives Tenma's raw telemetry data and observation logs. However, data processing and analysis software are not archived, which may limit the ability to support scientific data analysis.
Observation Instruments
Scintillation Proportional Counter (SPC)
The SPC is Tenma's primary detector, covering the X-ray range from 2 to 60 keV. It consists of ten gas scintillation proportional counters, offering high energy resolution for detailed spectral analysis of X-ray celestial bodies.
X-ray Focusing Collector (XFC)
The XFC covers the low-energy range of 0.1-2 keV and is designed for the study of soft X-ray celestial bodies. It consists of two subsystems combining a one-dimensional focusing mirror and a thin-film multi-wire proportional counter.
Transient Source Monitor (TSM)
The TSM is a wide-range monitor detector comprising a Hadamard Transform Telescope (HXT) and a slat collimator (ZY Telescope; ZYT). With an angular resolution of approximately 1 degree, it can continuously monitor the intensity variations of known celestial bodies and discover new sources.
Radiation Belt Monitor/Gamma-Ray Burst Detector (RBM/GBD)
The RBM/GBD is a NaI scintillator detector operating in the 10-100 keV energy range, designed to detect transient celestial bodies such as gamma-ray bursts. It also monitors the high-radiation region known as the South Atlantic Anomaly, providing alerts to other instruments.
Achievements
Tenma utilized the high energy resolution of its scintillation proportional counters to perform precise measurements of the energy spectra of various X-ray celestial objects. It made significant contributions to the development of X-ray astronomy, including the discovery of high-temperature plasma along the galactic plane, the discovery of absorption lines of iron in X-ray bursts, and observations of rapid bursts.