GSAT-6A

GSAT-6A was a communication satellite launched by the Indian Space Research Organisation (ISRO) It featured a 6-metre (20 ft) unfurlable S-band antenna similar to the one used on GSAT-6.^[1] Around 17 minutes after lift-off, the three stage GSLV Mk.II rocket flying on GSLV F08 mission successfully injected the satellite into a geosynchronous transfer orbit.^[3] Due to power failure during its orbit raising burns the communication was lost with GSAT-6A^[4][5] before it could reach its final circular geostationary orbit (GSO).

GSAT-6A

Mission type	Communications
Operator	ISRO
COSPAR ID	2018-027A
SATCAT no.	43241
Website	www.isro.gov.in/Spacecraft/gsat-6a
Mission duration	Planned: 10 years
Spacecraft properties
Bus	I-2K
Manufacturer	ISRO Satellite Centre Space Applications Centre
Launch mass	2,117 kilograms (4,667 lb)
Dimensions	1.53 × 1.65 × 2.4 m (5.0 × 5.4 × 7.9 ft)
Power	3,119 watts
Start of mission
Launch date	29 March 2018, 11:26 (2018-03-29UTC11:26) UTC[1]
Rocket	GSLV Mk.II F08
Launch site	Satish Dhawan SLP
Contractor	ISRO
Entered service	Failed before being operational
Orbital parameters
Reference system	Geocentric
Regime	Geostationary
Slot	83°E (Planned)
Semi-major axis	37,552 kilometers (20,276 nmi)[2]
Eccentricity	0.1383056[2]
Perigee altitude	29,580 kilometers (15,970 nmi)[2]
Apogee altitude	36,367 kilometers (19,637 nmi)[2]
Inclination	3.29 degrees[2]
Period	20.8 hours[2]
RAAN	158.9 degrees[2]
Argument of perigee	184.72 degrees[2]
Mean anomaly	125.81 degrees[2]
Mean motion	1.19302622[2]
Epoch	April 11, 2018[2]
Revolution no.	17[2]
Transponders
Coverage area	India
GSAT ← GSAT-17 GSAT-11 →

History

GSAT-6A was launched to complement GSAT-6 satellite which was launched in August 2015 by ISRO. The cost of building GSAT-6A was around ₹270 crore.^[6][7][8] GSAT-6A was to provide mobile communication services to the Indian Armed Forces.^[9]

Launch

GSLV F08 launch from SLP

GSLV-F08 carrying GSAT-6A spacecraft was launched from Second Launch Pad of Satish Dhawan Space Centre on 29 March 2018, 11:26 UTC and after flight of 17 minutes 45 seconds,^[10] placed GSAT-6A into its planned geostationary transfer orbit with 36,692.5 kilometres (22,799.7 mi) apogee, 169.4 kilometres (105.3 mi) perigee and orbital inclination of 20.64°. GSAT-6A spacecraft deployed its solar array after separation from CUS and established contact with ground station.^[11]

On GSLV-F08, a High Thrust Vikas engine (HTVE) was inducted on second stage (GS2) of GSLV with 6% higher thrust than before.^[12][13] The improved engine increased the payload capability of the vehicle.^[10] The electrohydraulic actuation system on second stage was also replaced with simpler and robust electromechanical system.^[13] The Cryogenic Upper Stage of GSLV F08 performed a burn to depletion for the first time. Officials said any improvement done to the vehicle would be incorporated into GSLV's future missions.^[10]

Loss of communication

The first orbit raising maneuver for GSAT-6A was carried out as planned on 30 March 2018 by firing the Liquid Apogee Motor (LAM) for 2188 seconds from 09:22 AM IST. The second orbit raising maneuver was carried out at 10:00 AM on 31 March 2018. As the satellite was on-course for its third and final orbit raising maneuver on 1 April 2018, communication with it was lost and the spacecraft was temporarily untraceable.^[14][15][5] After regaining its track,^[16] efforts to re-establish communication with the satellite could not succeed.^[17][18] Power system malfunction was suspected to be the reason behind loss of contact.^[19][20][21]

Satellite replacement

ISRO will launch GSAT-32 satellite as replacement for GSAT-6A.^[22]

See also

• Indian military satellites

References

1. "GSAT-6A". Indian Space Research Organisation. Archived from the original on 30 March 2018. Retrieved 29 March 2018.
2. "GSAT-6A Satellite details 2018-027A NORAD 43241". N2YO. 11 April 2018. Retrieved 11 April 2018.
3. "GSLV Successfully Launches GSAT-6A Satellite". Archived from the original on 2018-11-14. Retrieved 2018-11-14.
4. "GSAT-6A: 30 years on, ISRO loses another satellite to power failure". 2018-04-03.
5. "We now know the exact location of GSAT-6A communication satellite, says Isro chief". The Times of India. April 10, 2018.
6. "ISRO Twin Satellites To Boost Communication For Security Establishment". 29 May 2018. Retrieved 1 November 2019.
7. "Report on hybrid satellite digital multimedia broadcasting service agreement with Devas" (PDF). Archived from the original (PDF) on 1 November 2019. Retrieved 1 November 2019.
8. "Report on hybrid satellite digital multimedia broadcasting service agreement with Devas" (PDF). Archived from the original (PDF) on 1 November 2019. Retrieved 1 November 2019.
9. "India's new satellite to boost armed forces". NDTV,edited by -Suraj Sarkar 1805. Retrieved 30 March 2018.
10. Clark, Stephen (29 March 2018). "India tests upgraded engine tech in successful communications satellite launch". Spaceflight Now. Retrieved 30 March 2018.
11. "GSLV Successfully Launches GSAT-6A Satellite - ISRO". www.isro.gov.in. Archived from the original on 2018-11-14. Retrieved 2019-11-01.
12. "GSLV F08/GSAT-6A Brochure" (PDF). ISRO. Retrieved 1 November 2019.
13. "With eye on lunar mission, ISRO to test high-thrust Vikas engine". The New Indian Express. Retrieved 2019-11-01.
14. "The first orbit raising operation of GSAT-6A Satellite has been successfully carried out by LAM Engine firing for 2188 sec from 09:22hr IST on March 30, 2018. - ISRO".
15. "The second orbit raising operation of GSAT-6A satellite has been successfully carried out by LAM Engine firing for about 53 minutes on March 31, 2018 in the morning. - ISRO". Archived from the original on April 1, 2018. Retrieved April 1, 2018.
16. "We now know the exact location of GSAT-6A communication satellite, says Isro chief". Retrieved 1 November 2019.
17. "Chandrayaan-2 to be launched in January-March window in 2019". 12 August 2018. Retrieved 1 November 2019. Asked about GSAT 6A, with which communication had been lost after its launch in March 31 this year, he said ISRO has not given up hope and was still trying to establish radar contact with the satellite. "We have not given up hope. We will wait till a year," he said when asked how much time ISRO would take to announce that the GSAT 6A was a failed mission.
18. "ISRO loses contact with GSAT-6A, trying to establish link". The Economic Times. April 1, 2018.
19. D.s, Madhumathi (2018-08-11). "We averted a possible debacle: ISRO chairman". The Hindu. ISSN 0971-751X. Retrieved 2022-02-03. GSAT-11 had the same set of power system configuration that two older satellites had. RISAT-1 died prematurely and GSAT-6A lost communication contact soon after launch on March 29 because of suspected power system failure, harnesses etc.
20. "Power failure haunts ISRO again as it loses contact with GSAT-6A satellite". ThePrint. 2018-04-01. Retrieved 2022-02-03.
21. "In Major Setback, Contact With Satellite GSAT-6A Lost, Confirms ISRO". NDTV.com. Retrieved 2022-02-03.
22. "ISRO to launch GSAT-32 satellite in October 2019 to replace the silent GSAT-6A". Tech2. 2018-08-13. Retrieved 2018-09-25.