GSAT-6A
{{Short description|Indian telecommunications satellite}}
{{Infobox spaceflight|auto=all
| name = GSAT-6A
| image = GSAT-6A_Undergoing_Acoustic_Test.jpg
| image_caption =
| mission_type = Communications
| operator = ISRO
| website = {{URL|https://www.isro.gov.in/Spacecraft/gsat-6a}}
| COSPAR_ID = 2018-027A
| SATCAT = 43241
| mission_duration = Planned: 10 years
| spacecraft_bus = I-2K
| manufacturer = ISRO Satellite Centre
Space Applications Centre
| dry_mass =
| launch_mass = {{convert|2117|kg}}
| power = 3,119 watts
| dimensions = {{convert|1.53|xx|1.65|xx|2.4|m|ft|1|abbr=on}}
| launch_date = {{start date text|29 March 2018, 11:26}} UTC
| launch_rocket = GSLV Mk.II F08
| launch_site = Satish Dhawan SLP
| launch_contractor = ISRO
| entered_service =Failed before being operational
| disposal_type =
| deactivated =
| orbit_epoch = April 11, 2018{{cite web|url=https://www.n2yo.com/satellite/?s=43241|title=GSAT-6A Satellite details 2018-027A NORAD 43241|publisher=N2YO|date=11 April 2018|access-date=11 April 2018}}
| orbit_reference = Geocentric
| orbit_regime = Geostationary
| orbit_slot = 83°E (Planned)
| orbit_periapsis = {{convert|29580|km|nmi|sp=us}}
| orbit_apoapsis = {{convert|36367|km|nmi|sp=us}}
| orbit_inclination = 3.29 degrees
| orbit_semimajor = {{convert|37552|km|nmi|sp=us}}
| orbit_eccentricity = 0.1383056
| orbit_arg_periapsis = 184.72 degrees
| orbit_mean_anomaly = 125.81 degrees
| orbit_mean_motion = 1.19302622
| apsis = gee
| trans_band =
| trans_frequency =
| trans_bandwidth =
| trans_capacity =
| trans_coverage = India
| trans_TWTA =
| trans_EIRP =
| trans_HPBW =
| programme = GSAT
| previous_mission = GSAT-17
| next_mission = GSAT-11
}}
GSAT-6A was a communication satellite launched by the Indian Space Research Organisation (ISRO). It featured a {{convert|6|m|ft|adj=on}} unfurlable S-band antenna similar to the one used on GSAT-6.{{cite web |url=https://www.isro.gov.in/Spacecraft/gsat-6a |title=GSAT-6A |publisher=Indian Space Research Organisation |access-date=29 March 2018 |archive-date=30 March 2018 |archive-url=https://web.archive.org/web/20180330013057/https://www.isro.gov.in/Spacecraft/gsat-6a |url-status=dead }} 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.{{cite web|url=https://www.isro.gov.in/update/29-mar-2018/gslv-successfully-launches-gsat-6a-satellite|title=GSLV Successfully Launches GSAT-6A Satellite|access-date=2018-11-14|archive-date=2018-11-14|archive-url=https://web.archive.org/web/20181114182227/https://www.isro.gov.in/update/29-mar-2018/gslv-successfully-launches-gsat-6a-satellite|url-status=dead}} Due to power failure during its orbit raising burns the communication was lost with GSAT-6A{{cite web|url=https://www.deccanchronicle.com/nation/current-affairs/030418/gsat-6a-is-not-traceable-sources.html|title=GSAT-6A: 30 years on, ISRO loses another satellite to power failure|date=2018-04-03}} before it could reach its final circular geostationary orbit (GSO).
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.{{cite news |title=ISRO Twin Satellites To Boost Communication For Security Establishment |url=https://www.ndtv.com/india-news/isro-twin-satellites-to-boost-communication-for-security-establishment-1829967 |access-date=1 November 2019 |date=29 May 2018}}{{cite web |title=Report on hybrid satellite digital multimedia broadcasting service agreement with Devas|url=https://cag.gov.in/sites/default/files/audit_report_files/Union_Compliance_Scientic_Department_Multimedia_Broadcasting_Service_4_2012_chap_5.pdf|archive-url=https://web.archive.org/web/20191101152329/https://cag.gov.in/sites/default/files/audit_report_files/Union_Compliance_Scientic_Department_Multimedia_Broadcasting_Service_4_2012_chap_5.pdf|url-status=dead|archive-date=1 November 2019|access-date=1 November 2019}}{{cite web |title=Report on hybrid satellite digital multimedia broadcasting service agreement with Devas|url=https://cag.gov.in/sites/default/files/audit_report_files/Union_Compliance_Scientic_Department_Multimedia_Broadcasting_Service_4_2012_chap_2.pdf|archive-url=https://web.archive.org/web/20191101152530/https://cag.gov.in/sites/default/files/audit_report_files/Union_Compliance_Scientic_Department_Multimedia_Broadcasting_Service_4_2012_chap_2.pdf|url-status=dead|archive-date=1 November 2019|access-date=1 November 2019}} GSAT-6A was to provide mobile communication services to the Indian Armed Forces.{{cite web|url=https://www.ndtv.com/india-news/indias-most-powerful-communications-satellite-gsat-6a-to-launch-soon-1830292 | title= India's new satellite to boost armed forces | publisher= NDTV, edited by -Suraj Sarkar 1805|access-date=30 March 2018}}
Launch
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,{{cite news|url=https://spaceflightnow.com/2018/03/29/india-tests-upgraded-engine-tech-in-successful-communications-satellite-launch/|title=India tests upgraded engine tech in successful communications satellite launch|last=Clark|first=Stephen|date=29 March 2018|access-date=30 March 2018|publisher=Spaceflight Now}} placed GSAT-6A into its planned geostationary transfer orbit with {{Convert|36692.5|km||abbr=}} apogee, {{Convert|169.4|km||abbr=}} perigee and orbital inclination of 20.64°. GSAT-6A spacecraft deployed its solar array after separation from CUS and established contact with ground station.{{Cite web|url=https://www.isro.gov.in/update/29-mar-2018/gslv-successfully-launches-gsat-6a-satellite|title=GSLV Successfully Launches GSAT-6A Satellite - ISRO|website=www.isro.gov.in|access-date=2019-11-01|archive-date=2018-11-14|archive-url=https://web.archive.org/web/20181114182227/https://www.isro.gov.in/update/29-mar-2018/gslv-successfully-launches-gsat-6a-satellite|url-status=dead}}
On GSLV-F08, a High Thrust Vikas engine (HTVE) was inducted on second stage (GS2) of GSLV with 6% higher thrust than before.{{cite web|url=https://www.isro.gov.in/sites/default/files/flipping_book/GSLV-F08_GSAT6A/files/assets/common/downloads/GSLV%20F08GSAT6A.pdf|title=GSLV F08/GSAT-6A Brochure|publisher=ISRO|access-date=1 November 2019}}{{Cite web|url=https://www.newindianexpress.com/states/tamil-nadu/2018/mar/28/with-eye-on-lunar-mission-isro-to-test-high-thrust-vikas-engine-1793608.html|title=With eye on lunar mission, ISRO to test high-thrust Vikas engine|website=The New Indian Express|access-date=2019-11-01}} The improved engine increased the payload capability of the vehicle. The electrohydraulic actuation system on second stage was also replaced with simpler and robust electromechanical system. 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.
=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.{{Cite web|url=https://www.isro.gov.in/update/30-mar-2018/first-orbit-raising-operation-of-gsat-6a-satellite-has-been-successfully-carried|title=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}}{{Cite web|url=https://www.isro.gov.in/update/01-apr-2018/status-update-of-gsat-6a|title=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|access-date=April 1, 2018|archive-date=April 1, 2018|archive-url=https://web.archive.org/web/20180401065043/https://www.isro.gov.in/update/01-apr-2018/status-update-of-gsat-6a|url-status=dead}}{{cite news|url=https://timesofindia.indiatimes.com/india/we-now-knows-exact-location-of-gsat-6a-communication-satellite-says-isro-chief/articleshow/63701803.cms|title=We now know the exact location of GSAT-6A communication satellite, says Isro chief|newspaper=The Times of India |date=April 10, 2018}} After regaining its track,{{cite news |title=We now know the exact location of GSAT-6A communication satellite, says Isro chief|url=https://timesofindia.indiatimes.com/india/we-now-knows-exact-location-of-gsat-6a-communication-satellite-says-isro-chief/articleshow/63701803.cms |access-date=1 November 2019}} efforts to re-establish communication with the satellite could not succeed.{{cite news |title=Chandrayaan-2 to be launched in January-March window in 2019 |url=https://economictimes.indiatimes.com/news/science/indias-2nd-lunar-mission-on-january-3-with-lander-rover/articleshow/65376670.cms |access-date=1 November 2019 |date=12 August 2018 |quote=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.}}{{Cite news|url=https://economictimes.indiatimes.com/news/science/isro-says-contact-with-gsat-6a-lost-second-setback-in-seven-months/articleshow/63565348.cms|title=ISRO loses contact with GSAT-6A, trying to establish link |newspaper=The Economic Times |date=April 1, 2018}} Power system malfunction was suspected to be the reason behind loss of contact.{{Cite news|last=D.s|first=Madhumathi|date=2018-08-11|title=We averted a possible debacle: ISRO chairman|language=en-IN|work=The Hindu|url=https://www.thehindu.com/news/national/we-averted-a-possible-debacle-isro-chairman/article24660014.ece|access-date=2022-02-03|issn=0971-751X|quote=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.}}{{Cite web|date=2018-04-01|title=Power failure haunts ISRO again as it loses contact with GSAT-6A satellite|url=https://theprint.in/defence/power-failure-haunts-isro-again-as-it-loses-contact-with-gsat-6a-satellite/46282/|access-date=2022-02-03|website=ThePrint|language=en-US}}{{Cite web|title=In Major Setback, Contact With Satellite GSAT-6A Lost, Confirms ISRO|url=https://www.ndtv.com/india-news/isro-s-communications-satellite-gsat-6a-suffers-setback-in-space-sources-1831250|access-date=2022-02-03|website=NDTV.com}}
= Satellite replacement =
ISRO will launch GSAT-32 satellite as replacement for GSAT-6A.{{Cite web|url=https://www.firstpost.com/tech/science/isro-to-launch-gsat-32-satellite-in-october-2019-to-replace-the-silent-gsat-6a-4951441.html|title=ISRO to launch GSAT-32 satellite in October 2019 to replace the silent GSAT-6A|website=Tech2|language=en-US|access-date=2018-09-25|date=2018-08-13}}
See also
References
{{Reflist}}
{{GSAT satellites}}
{{Indian spacecraft}}
{{Orbital launches in 2018}}
{{Commons category|GSAT-6A}}