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| Tenma (satellite) | |
|---|---|
| Name | Tenma |
| Names list | ASTRO-B |
| Mission type | X-ray astronomy |
| Operator | Institute of Space and Astronautical Science |
| Cospar id | 1983-058A |
| Satcat | 14047 |
| Mission duration | 1 year 3 months (operational) |
| Launch date | 1983-02-20 |
| Launch rocket | M-3SII |
| Launch site | Kagoshima Space Center |
| Manufacturer | Institute of Space and Astronautical Science |
| Decay date | 1984-05-25 (communication lost) |
| Orbit reference | Geocentric |
| Orbit regime | Low Earth |
| Apsis | gee |
Tenma (satellite)
Tenma, also designated ASTRO-B, was a Japanese X-ray astronomy satellite developed and operated by the Institute of Space and Astronautical Science. Launched in 1983, Tenma carried instruments to study cosmic X-ray sources including binaries, supernova remnants, and active galactic nuclei. The mission contributed to international X-ray astronomy efforts alongside observatories such as and programs.
Tenma arose from a collaboration among Japanese institutions including the Institute of Space and Astronautical Science, the University of Tokyo, and national agencies influenced by predecessors like the Hakucho and Ginga missions. Designed to follow up on discoveries by Uhuru, HEAO-1, and Einstein Observatory (HEAO-2), Tenma sought to extend surveys begun by SAS-3 and Ariel 5 while complementing contemporaneous efforts by EXOSAT, GINGA, and the European Space Agency. The satellite embodied Japanese advances in detector development and mission operations, reflecting ties to the Japan Aerospace Exploration Agency's predecessors and to university-led X-ray programs in Asia and North America.
Primary objectives included precise spectroscopy and timing of X-ray sources identified by missions such as Uhuru, HEAO-1, and Ariel 5, and refinement of source positions initially reported by SAS-3 and Einstein Observatory (HEAO-2). Tenma aimed to characterize X-ray spectra of accreting neutron stars and black hole candidates like those observed in Cygnus X-1 and GX 1+4, to study supernova remnants exemplified by Cassiopeia A and Crab Nebula, and to probe active galactic nuclei including Centaurus A and NGC 4151. Additional goals encompassed temporal studies of X-ray pulsars discovered by HEAO-1 and follow-up on transient events monitored by satellites such as Vela 5B and ground networks coordinated with observatories like Arecibo Observatory and Nobeyama Radio Observatory.
Tenma's spacecraft bus and payload were built by teams at the Institute of Space and Astronautical Science with contributions from universities and laboratories experienced with Hakucho (satellite) and Ginga. The primary instruments included gas-scintillation proportional counters and solid-state detectors optimized for 0.5–20 keV X-ray spectroscopy, modeled after detectors used on Einstein Observatory (HEAO-2) and EXOSAT. Onboard systems supported timing analyses crucial for studies of pulsars like Her X-1 and Vela X-1 and spectral resolution comparisons with instruments on ASCA and future missions such as ROSAT and Chandra X-ray Observatory. The payload suite enabled simultaneous broad-band coverage to cross-calibrate with experiments on HEAO-1 and GINGA.
Tenma was launched on 20 February 1983 from the Kagoshima Space Center aboard a Japanese M-3SII launch vehicle. The launch placed Tenma into a low Earth orbit optimized for X-ray observations, facilitating coordinated observing windows with ground stations and space observatories including Kashima Space Research Center and international partners. Orbit parameters allowed repeated visibility to facilities involved in multiwavelength campaigns, including radio arrays like Very Large Array and optical telescopes such as Subaru Telescope's predecessors, enabling follow-up observations of transients cross-checked against archives from Uhuru and HEAO series.
During its operational phase, Tenma performed spectral and timing observations of X-ray binaries, pulsars, supernova remnants, and active galactic nuclei, producing data sets compared with results from HEAO-1, Einstein Observatory (HEAO-2), and EXOSAT. Tenma provided improved spectral measurements for sources including Crab Nebula, Cygnus X-1, and Sco X-1, and contributed to studies of emission mechanisms in accretion-powered systems like those investigated in the literature associated with Shakura–Sunyaev models and pulsar torque investigations related to Ghosh–Lamb model. Its timing results refined pulse period histories for pulsars such as Her X-1 and GX 1+4, informing theoretical work linked to researchers from institutions such as the University of Tokyo and Kyoto University. Tenma's data complemented contemporaneous surveys by GINGA and served as calibration references for future observatories including ASCA and Chandra X-ray Observatory.
Communications with Tenma ceased in 1984 after about a year of scientific operations. Despite the relatively short lifetime, Tenma's spectroscopy and timing contributions enriched catalogs maintained by teams working with HEASARC and influenced instrument design and science planning for subsequent Japanese missions like Ginga and ASTRO-E (and later Suzaku). Tenma's legacy persists in archival data sets used in comparative analyses with later missions such as ROSAT, ASCA, BeppoSAX, and Chandra X-ray Observatory, and in the continued development of X-ray astronomy programs at institutions including the Institute of Space and Astronautical Science and Japanese universities.
Category:Japanese satellites Category:X-ray telescopes Category:1983 in spaceflight