KOMPSAT-1 was the first Earth observation satellite developed and launched by the Korea Aerospace Research Institute (KARI) of South Korea as part of the country’s newly fledged space program. The satellite was a significant milestone for the country, marking its entry into the field of satellite technology while serving as a testbed for further indigenous space development.

The satellite was designed and manufactured domestically, with contributions from domestic and international partners for certain subsystems and technologies. The development of KOMPSAT-1 allowed South Korea to gain expertise in satellite design, construction, and operation. The mission contributed to the advancement of the country's satellite technology capabilities and paved the way for subsequent satellite missions.

KOMPSAT-1 was a compact spacecraft measuring 1.33 m in diameter and 2.33 m in length. The platform used a three-axis stabilized bus with a reaction control subsystem module, providing a 2-sigma pointing accuracy of 0.01° (roll), 0.18° (pitch) and 0.50° (yaw), and a pointing knowledge of 0.08° (roll and pitch) and 0.10° (yaw). The mass of the spacecraft was 510 kg (including 73 kg hydrazine). The design life of the satellite was three years.

The spacecraft was based on a TRW-developed standardized bus (of TOMS-EP heritage, including a MIL-STD-1555B communications bus) that could be easily modified to support a variety of mission requirements. A core (or equipment) module housed the housekeeping functions - power, telemetry and data handling, and attitude control - needed on all space missions. A payload module hosted mission-unique equipment, KOMPSAT's imaging instruments and space physics experiments. A third module, housing a monopropellant hydrazine propulsion system, provided on-orbit thrust and station-keeping.

Key Payload Module Instruments:

1. EOC (Electro-Optical Camera)
   
   The objective of the EOC was to obtain cartographic imagery of Korea (which was then extended to other regions of the globe) at a 1/25.000 scale. EOC collected panchromatic imagery (spectral region of 510 - 730 nm) with a ground sample distance (GSD) at nadir of 6.6 m and a swath width of 17 km by pushbroom scanning. The spacecraft featured a cross-track pointing capability (body pointing) of up to ±45°, thereby extending the field of regard for imagery collection.


2. OSMI (Ocean Scanning Multispectral Imager)
   
   OSMI was a whiskbroom-type imager generating imagery in up to six spectral bands (in the region of 400 - 900 nm) with a capability for bandwidth and band centre selection on command. The centre of each band could be varied within steps of 2.6 nm, and bandwidth ranges from 5.2 nm (min) to 166.4 nm (max) could be assigned.
   
   The ground resolution was 1 km in a swath of 800 km (0.85 km at nadir and about 1 km at the edge of the swath). The scanner assembly featured a line array of 96 detectors (Si), positioned in the along-track direction, thus providing an instantaneous parallel ground coverage of 96 km in one cross-track scan with the whiskbroom configuration. This wide along-track coverage permitted sufficient integration time for all cells in each scan sweep of about 15 seconds. Naturally, there was some overlap for successive scans.
   
   The ensuing collecting optics performed the spectral separation of the radiation received. The bands B0 through B4 provided ocean colour data, and the other bands provided information for atmospheric (aerosol) corrections.


3. Space Physics Sensor (SPS)
   
   The SPS package consisted of two instruments:
    
   • HEPD (High Energy Particle Detector)
     • To characterise the low-altitude high-energy particle environment and to study the effects of the radiation environment on microelectronics.
   • IMS (Ionosphere Measurement Sensor)
     • To measure the in-situ densities and temperature of electrons in the ionosphere.

In a joint development between the Korean Aerospace Research Institute (KARI) and TRW Inc., KOMPSAT-1 satellite was launched on a Taurus booster from Vandenberg Air Force Base, USA on Dec. 20, 1999. The satellite was placed in a sun-synchronous circular polar orbit, at an altitude of 685 km with 98.13º inclination. The satellite had a period of 98.46 min and a local equatorial crossing on ascending node at 10:50 hours, completing 14 17/28 orbits per day with a revisit time of 28 days.

The acquired imagery was stored onboard the satellite and downlinked to ground stations in South Korea using X-band and S-band frequencies. The KGS (KOMPSAT Ground Segment) was located at Taejon, Korea, and contained both the KMCS (KOMPSAT Mission Control Center) and the KRPS (KOMPSAT Receiving and Processing System). From 2004, KOMPSAT-1 data were also being acquired in Europe at DLR Neustrelitz (test acquisitions in preparation for KOMPSAT-2 data).

KARI lost contact with its spacecraft on Dec. 30, 2007 – ending the operational life of the KOMPSAT-1 mission after 8 years. Initial reviews pointed toward a possible machinery malfunction or a misalignment that may have affected power generation. As of Jan. 31, 2008, the KOMPSAT-1 mission was officially retired.

Learn more about KOMPSAT-1 from these websites:

• KOMPSAT-1 on the KARI website*
• KOMPSAT-1 on eoPortal*

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