Granat

International Astrophysical Observatory "GRANAT"

picture credit: NASA
Mission type	Gamma-ray astronomy
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	Venera class
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 (1989-12-01T20:20:00)
Rocket	Proton-K Blok D-1
Launch site	Baikonur Cosmodrome 200/40
End of mission
Disposal	deorbited
Decay date	May 25, 1999 (1999-05-25)
Orbital parameters
Reference system	Geocentric
Regime	Highly elliptical
Eccentricity	0.92193
Perigee	1,760 kilometres (1,090 mi)
Apogee	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
SIGMA X-ray/gamma-ray telescope ART-P X-ray telescope ART-S X-ray spectrometer PHEBUS Gamma-burst detector WATCH All-sky monitor KONUS GRB experiment TOURNESOL GRB experiment

The International Astrophysical Observatory "GRANAT" (usually known as Granat; Russian: Гранат), 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.

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.

Granat was a three-axis-stabilized spacecraft and the last of the Venera-class spacecraft produced by the Lavochkin Scientific Production Association. It was similar to the Astron observatory which was functional from 1983 to 1989; for this reason, the spacecraft was originally known as the Astron 2. It weighed 4.4 metric tons and carried almost 2.3 metric tons of international scientific instrumentation. Granat stood 6.5 m tall and had a total span of 8.5 m across its solar arrays. The power made available to the scientific instruments was approximately 400 W.