Chollian

Chollian, also known as Communication, Ocean and Meteorological Satellite 1 (COMS-1), was a South Korean satellite which was launched on 26 June 2010 and began operations on 1 April 2011. It was operated by the Korea Aerospace Research Institute, who used it for communication, oceanography, and meteorological observation.

COMS-1 was constructed by EADS Astrium, and was based on the Eurostar-3000S satellite bus, bringing together lessons learned from Eurostar satellites and NASA-made GOES satellites respectively. It had a mass of 2460 kg, and carried transponders broadcasting in the D/E and K bands of the NATO-defined spectrum, or the L/S and Ka bands of the IEEE-defined spectrum respectively. Its single solar array generated a minimum of 2.5 kilowatts of power.

COMS-1 was launched by Arianespace using an Ariane 5 ECA carrier rocket lifting off from ELA-3 at the Guiana Space Centre in Kourou, French Guiana. The first launch attempt occurred on 23 June 2010; the launch was scrubbed due to a problem with one of the rocket's subsystems. A subsequent attempt on 24 June was also scrubbed, due to a problem with the pressurisation of the rocket's fuel tanks. The launch occurred at 21:41 UTC on 26 June 2010. The Saudi Arabian Arabsat-5A satellite was launched by the same rocket, with a SYLDA adaptor being used to separate the spacecraft. Arabsat-5A was mounted atop the SYLDA, with COMS-1 underneath it.

Following launch, COMS-1 separated into a geosynchronous transfer orbit. It used an apogee motor to raise itself into geosynchronous orbit. It then underwent testing before beginning operations at a longitude of 128.2 degrees East on 1 April 2011. Its mission was scheduled to last seven years, though the satellite had a design life of ten years.

COMS-1 was deactivated on 31 March 2020, following a two-year extension of its seven-year primary mission.

As follow-up satellites to Chollian-1, Chollian-2A and Chollian-2B were launched in December 2018 and in February 2020 respectively.