# KOMPSAT-3

KOMPSAT-3 (Korean Multi-purpose Satellite-3), also known as Arirang-3, is a South Korean multipurpose Earth observation satellite. It was launched from Tanegashima Space Center, Japan at 16:39 UTC on 17 May 2012. Like the earlier KOMPSAT-1 and KOMPSAT-2 satellites, it takes its name from the popular Korean folk song Arirang. Its launch was the culmination of a project begun in 1995.
KOMPSAT-3 orbits at a height of 685.1 km (425.7 mi), circling the Earth 14 times per day, and is expected to maintain that orbit for 4 years. It weighs 980 kg (2,160 lb). The satellite carries an Advanced Earth Imaging Sensor System (AEISS), which can distinguish to a 70-cm resolution, allowing the identification of individual vehicles on the ground.
The satellite was succeeded by KOMPSAT-5 and KOMPSAT-3A, which were launched on 2013 and 2015 respectively.

## History

South Korea started the KOMPSAT programme in 1995 to nurture its national Earth-imaging industry and supply services for remote-sensing applications. The South Korean KOMPSAT-3 Earth-imaging satellite was developed by Korea Aerospace Industries (KAI) and Korea Aerospace Research Institute (KARI), in partnership with EADS Astrium, to assure continuity with the KOMPSAT-2 satellite launched in 2006. KOMPSAT-3 was orbited on 17 May 2012 by a launch vehicle from Tanegashima Space Center, Japan. SI Imaging Services is the worldwide exclusive distributor of KOMPSAT imagery since November 2012.

## Technologies
### Orbit

KOMPSAT-3 operates in a near-polar, circular Sun-synchronous orbit. The orbital parameters are:
* Mean altitude: 685.1 km
* Mass: 980 kg
* Inclination: 98.13° (Sun-synchronous orbit)
* Orbital period: 98.5 minutes
* Orbital cycle: 28 days

### Instruments

KOMPSAT-3's instruments are designed to acquire high- and very-high-resolution imagery with a footprint of 16.8 km. The satellite has the capacity to acquire 20 minutes of imagery on each orbit and it can steer its sensors both ways out to 30° off track. Panchromatic and multispectral images can be acquired at the same time.
KOMPSAT-3 radiometer features:
Kompsat-3 radiometric parameters :
| mode | Channel | Spectral band | Spatial resolution | Footprint |
| Multispectral | 1 | 0.45 - 0.52 μm (blue) | 2.8 m | 16.8 km |
| | 2 | 0.52 - 0.60 μm (green) | 2.8 m | 16.8 km |
| | 3 | 0.63 - 0.69μm (rouge) | 2.8 m | 16.8 km |
| | 4 | 0.76 - 0.90 μm (near-infrared) | 2.8 m | 16.8 km |
| Panchromatic | P | 0.50 - 0.90 μm (black and white) | 70 cm | 16.8 km |

### Ground receiving stations

Two receiving stations deliver KOMPSAT-3 imagery 1 to 3 days after acquisition. The Deajeon station in South Korea is responsible for tasking the satellite.

## Advantages and applications of KOMPSAT-3 imagery

KOMPSAT-3 is designed for very-high-resolution (VHR) remote-sensing applications, such as:
* Land planning: to detect and identify features smaller than 1 square meter, e.g. vehicles, street furnishings, roads and bushes
* Agriculture: to pinpoint crop or tree diseases
* Urban planning and demographics: to locate detached houses
* Civil engineering: to plan road, railroad and oil pipeline corridors
* Defence: to describe high-value assets or military sites

## South Korea

It serves along with the existing Kompsat-2 to provide continuous satellite observation of the Korean Peninsula, sending images twice a day at 01:30 and 13:30.