Granat
The International Astrophysical Observatory "GRANAT" (usually known as Granat; Russian: Гранат, lit. pomegranate), was a Soviet (later Russian) space observatory developed in collaboration with France, Denmark and Bulgaria. It was launched on 1 December 1989 aboard a Proton rocket and placed in a highly eccentric four-day orbit, of which three were devoted to observations. It operated for almost nine years.
picture credit: NASA | |||||||||||||||
| Mission type | Gamma-ray astronomy | ||||||||||||||
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| Operator | Soviet space program | ||||||||||||||
| COSPAR ID | 1989-096A | ||||||||||||||
| SATCAT no. | 20352 | ||||||||||||||
| Website | hea.iki.rssi.ru/GRANAT/granat.html | ||||||||||||||
| Mission duration | 9 years | ||||||||||||||
| Spacecraft properties | |||||||||||||||
| Bus | 4MV | ||||||||||||||
| Manufacturer | NPO Lavochkin | ||||||||||||||
| Launch mass | ~ 4,400 kg (9,700 lb) | ||||||||||||||
| Payload mass | ~ 2,300 kg (5,100 lb) | ||||||||||||||
| Dimensions | 4 m × 2.5 m (13.1 ft × 8.2 ft) | ||||||||||||||
| Power | 400 W | ||||||||||||||
| Start of mission | |||||||||||||||
| Launch date | 20:20:00, December 1, 1989 (UTC) | ||||||||||||||
| Rocket | Proton-K Blok D-1 | ||||||||||||||
| Launch site | Baikonur Cosmodrome 200/40 | ||||||||||||||
| End of mission | |||||||||||||||
| Disposal | deorbited | ||||||||||||||
| Last contact | 27 November 1998 | ||||||||||||||
| Decay date | May 25, 1999 | ||||||||||||||
| Orbital parameters | |||||||||||||||
| Reference system | Geocentric | ||||||||||||||
| Regime | Highly elliptical | ||||||||||||||
| Eccentricity | 0.92193 | ||||||||||||||
| Perigee altitude | 1,760 kilometres (1,090 mi) | ||||||||||||||
| Apogee altitude | 202,480 kilometres (125,820 mi) | ||||||||||||||
| Inclination | 51.9 degrees | ||||||||||||||
| Period | 5,880 minutes | ||||||||||||||
| Epoch | 01 December 1989 | ||||||||||||||
| Main telescope | |||||||||||||||
| Name | SIGMA | ||||||||||||||
| Type | Coded mask | ||||||||||||||
| Diameter | 1.2 metres (3.9 ft) | ||||||||||||||
| Focal length | 2.5 metres (8.2 ft) | ||||||||||||||
| Collecting area | 800 cm2 (120 sq in) | ||||||||||||||
| Wavelengths | X-ray to γ-ray, 1–620 pm (2 keV – 1.3 MeV) | ||||||||||||||
| Instruments | |||||||||||||||
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In September 1994, after nearly five years of directed observations, the gas supply for its attitude control was exhausted and the observatory was placed in a non-directed survey mode. Transmissions finally ceased on 27 November 1998.
With seven different instruments on board, Granat was designed to observe the universe at energies ranging from X-ray to gamma ray. Its main instrument, SIGMA, was capable of imaging both hard X-ray and soft gamma-ray sources. The PHEBUS instrument was meant to study gamma-ray bursts and other transient X-Ray sources. Other experiments such as ART-P were intended to image X-Ray sources in the 35 to 100 keV range. One instrument, WATCH, was designed to monitor the sky continuously and alert the other instruments to new or interesting X-Ray sources. The ART-S spectrometer covered the X-ray energy range while the KONUS-B and TOURNESOL experiments covered both the X-ray and gamma ray spectrum.