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ISRO: GSAT 32 as a replacement for silent GSAT 6A

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August 15, 2018, 11:19 a.m.

On August 12, 2018, it was announced that the Indian Space Research Organization (ISRO) plans to launch GSAT 32 as a replacement for its failed communications satellite GSAT 6A.

GSAT 6A illustration
(Image: ISRO)
GSAT 6A was transported into space on March 29, 2018 on the Indian GSLV-MkII launcher with flight number F08. After separating from the launcher, the satellite with a launch mass of around 2,140 kilograms was initially able to establish a connection to the ground and any orbit lifting maneuvers were initiated. After completing the second of three major orbit raising maneuvers, however, contact with GSAT 6A was broken off. Since then this satellite has been silent.

Actually, ISRO wanted to use GSAT 6A at a position at 83 degrees East in geostationary orbit (GEO), in particular to provide communication services for the military and government agencies of India and to reinforce GSAT 6 alias INSAT 4E, launched on August 27, 2015. GSAT 6 and GSAT 6A are referred to as "Multi-media Mobile communication satellites for strategic applications". Like GSAT 6, GSAT 6A is based on the Indian I-2K satellite bus and should withstand a design period of ten years.

GSAT 6 illustration
(Image: ISRO)
The director of the Vikram Sarabhai Space Center (VSSC) S. Somanath had reported that they had analyzed and understood what might have happened on board GSAT 6A. Somanath described the difficulties as a problem in the power system consisting of accumulators, solar cell booms and electronic circuits. A short circuit is assumed which, in conjunction with possibly failing protective circuits, destroyed lines. Such a short circuit can occur, for example, after components of the satellite have become electrically charged and the possibility of such a charge has not been taken into account in the construction or has been prevented.

With regard to the additional reviews of the larger communications satellite GSAT 11 carried out because of the failure of GSAT 6A, ISRO chairman Dr. Sivan reported that GSAT 11's power system was configured like that of two older satellites. RISAT 1 failed prematurely and GSAT 6A stopped communicating soon after its start on March 29 because of assumed problems with the power supply system, cable harnesses, etc.

All efforts by ISRO to get in contact with GSAT 6A have so far failed. ISRO claims to continue tracking and monitoring GSAT 6A from the ground and will not declare him dead until 2019. Scenarios in which such a satellite reports back automatically after a long break or reacts to a signal from the ground are actually not completely absurd, but very unlikely - also according to ISRO officials.

In the event that it cannot use GSAT 6A, ISRO wants to start GSAT 32 in October 2019. GSAT 32 will likely have a GSAT 6A very similar to communications payload and, given the intended launch on a GSLV rocket, will have a launch mass in the range of just over 2,000 kilograms.

GSAT 6A is cataloged with the NORAD no. 43.241 and as Cospar object 2018-027A. After the last completed orbit lifting maneuver, the satellite was observed on an orbit inclined around 3.3 degrees to the earth's equator with an orbit point closest to the earth 25,979 kilometers above the earth and an orbit furthest away 36,368 kilometers above the earth. GSAT 6A is currently on an orbit inclined around 3.1 degrees to the earth's equator with an orbit point closest to the earth 25,990 kilometers above the earth and an orbit furthest away from the earth 36,372 kilometers above the earth.

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Source: Firstpost, Hindustan Times, Indian Express, India Finance News, ISRO,, The Hindu, VA Online News