KOMPSAT (Korea Multi-Purpose SATellite)-5 was launched into a sun-synchronous low-Earth orbit on 22 August 2013 with an orbit altitude of 550km. The Atmosphere Occultation and Precision Orbit Determination (AOPOD) system, which is the secondary payload of KOMPSAT-5, consists of a space-borne dual-frequency GPS receiver and a laser retro-reflector. The GPS receiver provides GPS data for precise orbit determination (POD) of a satellite and GPS radio occultation data for atmospheric and ionospheric research.

Integrated GPS Occultation Receiver (IGOR) was developed by Broad Reach Engineering (BRE) and has been successfully operating in orbit. Two pairs of POD and occultation antennas are installed on the satellite; the POD antenna points towards the zenith and occultation antennas, which are mounted on different sides of the satellite, point towards velocity and anti-velocity direction of the satellite to be enabled to get rising and setting occultation data.

The Laser retro-reflector array of the AOPOD system was designed and manufactured by GeoForschungsZentrumin Germany and has been used for CHAMP and GRACE satellites. Satellite Laser Ranging (SLR) is the most accurate technique to measure distances between SLR stations and on-orbit satellites equipped with retro-reflectors. KOMPSAT5 can be tracked by a global network of satellite laser ranging stations and SLR data is available at the International Laser Ranging Service homepage (http://ilrs.gsfc.nasa.gov/).

For more information about the AOPOD system and data, please contact gnss@kasi.re.kr