GSAT-18

GSAT-18 is an Indian communications satellite. Built by ISRO and operated by INSAT, it carries 24 C-band, 12 extended C-band, and 12 K_u-band transponders.

GSAT-18

Mission type	Communications
Operator	INSAT
COSPAR ID	2016-060A
SATCAT no.	41793
Website	GSAT-18
Mission duration	Planned: 15 years Elapsed: 8 years, 1 month, 15 days
Spacecraft properties
Bus	I-3K[1]
Manufacturer	ISRO Satellite Centre Space Applications Centre
Launch mass	3,404 kg (7,505 lb)[2]
Dry mass	1,480 kg (3,263 lb)[2]
Power	6,474 watts[2]
Start of mission
Launch date	5 October 2016 (2016-10-05), ≈20:30 UTC[3]
Rocket	Ariane 5 ECA, VA-231[1]
Launch site	Guiana Space Centre ELA-3[1]
Contractor	Arianespace[1]
Orbital parameters
Reference system	Geocentric
Regime	Geostationary
Longitude	74° E
Perigee altitude	35,750 km (22,214 mi)
Apogee altitude	35,822 km (22,259 mi)
Inclination	0.0616°
Epoch	11 June 2017 01:46:00 UTC[4]
Transponders
Band	24 × C band 12 × extended C band 12 × Ku band 2 × Ku beacon
GSAT ← GSAT-15 GSAT-9 →

The satellite was launched on 5 October 2016 at approximately 20:30 UTC aboard an Ariane 5 ECA rocket from the Guiana Space Centre in Kourou, French Guiana.^[3][5] The launch vehicle inserted the satellite into a geosynchronous transfer orbit, and once in service it will occupy the orbital slot at 74° East longitude.^[1][6] The total cost of the satellite and launch services was about US$153 million.^[7]

GSAT-18 was originally scheduled to launch on 12 July 2016 alongside Japan's Superbird-8 satellite, but a shipping mishap which damaged Superbird-8 forced a delay in the launch schedule.^[8][9] Arianespace later paired GSAT-18 with Australia's Sky Muster II for a 4 October 2016 launch.^[10] The launch was delayed 24 hours to 5 October due to excessively high crosswinds at the launch site.^[11]

Orbit raising and station keeping

Orbit raising operations were made using an on-board LAM and chemical thrusters^[2] to place the satellite in the intended geostationary orbital slot.

Op #	Date/ Time (UTC)	LAM burn time	Height achieved		Inclination achieved	Orbital period	References
			Apogee	Perigee
1	6 October 2016 10:16	6040.6 sec	35,802 km (22,246 mi)	14,843 km (9,223 mi)	1.325°	15 hrs, 36 mins	[12]
2	8 October 2016 05:59	-	35,840 km (22,270 mi)	32,518 km (20,206 mi)	0.129°	22 hrs, 34 mins	[13]
3	9 October 2016 04:51	256.17 sec	35,802 km (22,246 mi)	35,294 km (21,931 mi)	0.136°	23 hrs, 44 mins	[14][15]

References

• Spaceflight portal

1. "Annual Report 2015-2016" (PDF). Indian Space Research Organisation. December 2015. p. 28. Archived from the original (PDF) on 2016-07-05.
2. "GSAT-18" (PDF). Indian Space Research Organisation. Archived from the original (PDF) on 2016-12-13. Retrieved 2017-06-12.
3. Bergin, Chris (5 October 2016). "Ariane 5 launches Sky Muster II and GSAT-18". NASA Spaceflight. Retrieved 6 October 2016.
4. "GSAT-18 - Orbit". Heavens-Above. 11 June 2017. Retrieved 12 June 2017.
5. "India's communication satellite GSAT-18 launched successfully". Business Standard. Press Trust of India. 6 October 2016. Retrieved 6 October 2016.
6. "Launch Schedule". Spaceflight Now. 4 October 2016. Archived from the original on 5 October 2016.
7. Clark, Stephen (5 October 2016). "Ariane 5 goes on test run after launching two satellites". Spaceflight Now. Retrieved 6 October 2016.
8. de Selding, Peter B. (20 June 2016). "Japan's DSN-1 military communications satellite damaged during transport to launch base". Space News. Retrieved 10 September 2016.
9. D. S., Madhumathi (10 July 2016). "Deferred GSAT-18 awaits October launch at Kourou". The Hindu. Retrieved 10 September 2016.
10. "Sky Muster II comes to French Guiana for launch on Ariane 5". Arianespace. 31 August 2016. Retrieved 10 September 2016.
11. "Bad weather delays Isro's launch of communications satellite GSAT-18". Hindustan Times. Press Trust of India. 5 October 2016. Retrieved 5 October 2016.
12. "The first orbit raising manoeuvre..." Indian Space Research Organisation. 7 October 2016. Retrieved 12 June 2017.
13. "The second orbit raising manoeuvre..." Indian Space Research Organisation. 8 October 2016. Retrieved 12 June 2017.
14. "Third LAM firing of GSAT-18..." Indian Space Research Organisation. 9 October 2016. Retrieved 12 June 2017.
15. "Orbit Determination results..." Indian Space Research Organisation. 9 October 2016. Retrieved 12 June 2017.