CAS500 (Compact Advanced Satellite 500)
Fire fractional cover
Multi-purpose imagery (land)
The Compact Advance Satellite 500 (CAS500) mission is a research and development mission of the Korean Aerospace Research Institute (KARI), with the aim of expanding Korea’s private space industry. There are a total of five satellites that have a range of Earth observation goals including crop observation, water management, marine environment monitoring, disaster/emergency monitoring, cartography and land use and planning. The first of five satellites launched in the series, CAS500-1, was launched on 22 March 2021.
|Mission status||Operational (nominal)|
|Launch date||22 March, 2021|
|End of life date||2029|
|Measurement category||Multi-purpose imagery (land), Vegetation|
|Measurement detailed||Fire fractional cover, Land cover|
|Instruments||Compact Advanced Payload Wide Swath, High Resolution Optical Sensor, CSAR|
|Instrument type||High resolution optical imagers|
|CEOS EO Handbook||See CAS500 (Compact Advanced Satellite 500) summary|
The CAS500 missions carry different optical payloads onboard for different Earth observation goals. CAS500-1 and CAS500-2 will carry the High Resolution Optical Sensor for land surface imagery, land topography imagery and vegetation type imagery. Meanwhile, CAS500-4 will carry the Compact Advanced Payload Wide Swath for the observation of crops, agricultural water and forest resources and CAS500-5 will carry a C-band Synthetic Aperture Radar for water resource surveying, river management, marine environment monitoring and disaster/emergency monitoring. CAS500-3 is not an Earth observation mission, with its primary use being for the Ministry of Science and ICT for space technology verification and space science research.
The High Resolution Optical Sensor is able to measure in the Visible (VIS) range from 0.4 μm to 0.75 μm and in the Near Infrared (NIR) range from 0.75 μm to 1.3 μm. This instrument can measure at a resolution of 50 cm in panchromatic mode and two metres in multispectral mode at a minimum swath width of 12 km. The Compact Advanced Payload Wide Swath can measure in five channels in the Visible (VIS) and Near Infrared (NIR) ranges at wavebands between 0.4 μm - 0.88 μm. It will have a swath width much larger than the High Resolution Optical Sensor at 120 km and will be able to measure at a resolution of 5m. The C-band Synthetic Aperture Radar will measure in the C-band frequency from 4-8 GHz with a resolution of 10 m and a swath width of 120 km.
Space and Hardware Components
The CAS500 satellites share a common satellite platform, each weighing around 500 kg. This platform includes the satellite bus and spacecraft system. The CAS500 satellites will differ by only their optical payloads of which KARI is proud to have been able to localise 98.6% of the components and technologies associated with these optical payloads that they have been dependent on overseas technology until now.
The Compact Advanced Satellite 500 (CAS500) is a research and development program of the Korean Aerospace Research Institute (KARI) with the aims of reducing the satellite development period and cost by using a common platform that can easily accommodate various payloads such as optical cameras, synthetic aperture radar, microwave sounder, and hyper-spectrometers. The program also plans to develop CAS500 series satellites in a short period of time and operate them simultaneously to satisfy the demands of various Earth observations in the domestic public sector. The CAS500 program aims to deliver five satellites with various objectives by the end of 2023.
The CAS500 satellites share a common satellite platform, each weighing around 500 kg. This platform includes the satellite bus and spacecraft system. The CAS500 satellites have different optical payloads ranging from the High Resolution Optical Sensor, onboard CAS500-1 and CAS500-2, to the Compact Advanced Payload Wide Swath, on CAS500-4, and the Synthetic Aperture Radar, on CAS500-5.
KARI is proud to have achieved a Koreanization rate of 98.6% by localising optical payload components and technologies that have been dependent on overseas technology until now. By localising these components, KARI aims to be able to produce these satellites using solely Korean industries in the future.
Onboard CAS500-1 and -2, there are many Korean companies that have contributed to the optical payload, including:
- The Korean Institute of Science and Standards (KRISS), who localised the mirror onboard the optical payload that collects the light entering the camera into the focal plane.
- DACC Aerospace, who localised the High Stability Telescopic Structure that supports the mirrors to prevent deformation.
- Hanwha Systems, who localised the Camera Electronic Unit that processes panchromatic and multi-spectral image systems.
- Lumir, who localised the Image Data and Handling Unit that stores, compresses, and encrypts image signals.
- Genoco, who localised the X-band Transmitter that converts image signals into X-band frequency to transmit them to the ground.
- Kukdong Telecommunication, who localised the X-band Antenna that transmits image singlas to the ground receiving antennas.
- Doowon, who localised the Heat control device that maintains a constant operating temperature of the focal plane unit.
CAS500-1 was launched on 22 March, 2021, aboard a Russian Soyuz-2.1a rocket from Baikonur Cosmodrome in Moscow. It was launched alongside 38 other satellite missions into a Sun-synchronous orbit at an altitude of 529 km, an orbital inclination of 98.1° and an orbital period of 98.5 days. CAS500-1 made its first communication with a ground station 102 minutes after liftoff as it entered its target orbit.
CAS500-2 is due to be launched in late 2022 with CAS500-3 and CAS500-4 both expected to be launched towards the end of 2023 with CAS500-3 to be launched onboard the Nuri (KSLV-2) Korean orbital launch vehicle which is currently undergoing testing. The development of this rocket is a major step in advancing Korea’s future in the Space and Earth Observation industry. CAS500-4 will be launched onboard a SpaceX Falcon-9 v1.2 rocket. CAS500-5 is planned to launch in December 2025.
The first stage of the CAS500 mission was to create a standard platform for the 500 kg class CAS500 satellites and to launch two satellites, CAS500-1 and CAS500-2.
For CAS500-1, KARI developed the satellite design and then transferred the accumulated satellite development technologies of the spacecraft system, bus and payload to the Korean Aerospace industries.
Korean Aerospace industries are leading the development of the CAS500-2 satellite, which has expanded the domestic satellite industry base and fostered the industry.
The second stage of the CAS500 mission consists of CAS500-3, CAS500-4, and CAS500-5. Development is underway by the Korean industry. KARI plays the role of technical audit and supervision in the second stage.
Upon the launch of CAS500-1, the chief of KARI’s Satellite Research Directorate, Lee Seung-Hoon, stated “the way we developed CAS500-1 provided a watershed moment opening up a new chapter for the domestic satellite industry.” He believes “the industry will evolve in a way that the private sector leads the development [of satellites], which used to be done by the government, with Indigenous or localised items.” This highlights the importance of the CAS500 missions in the advancement of the Korean space and satellite industry which could soon be a major player in Earth observation.
The CAS500 missions carry different optical payloads onboard for Earth observation. CAS500-1 and CAS500-2 will carry the High Resolution Optical Sensor while CAS500-4 will carry the Compact Advanced Payload Wide Swath and CAS500-5 will carry a C-band Synthetic Aperture Radar.
CAS500-3 is not an Earth observation mission, with its primary use being for the Ministry of Science and ICT for space technology verification and space science research.
High Resolution Optical Sensor
CAS500-1 and CAS500-2 have identical optical payloads, the High Resolution Optical Sensor, which has been developed by KARI with the help of a variety of Korean companies. 98.6% of the payload was developed in Korea.
The instrument is an optical sensor that carries out land surface topography, land surface imagery and vegetation type imagery. The performance details of the High Resolution Optical Sensor are shown in Tables 1 & 2.
Visible range (VIS)
0.4 - 0.75
Near Infrared (NIR)
0.75 - 1.3
Swath width (km)
Compact Advanced Payload Wide Swath
The Compact Advanced Payload Wide Swath is a wide-area-electro-optical camera that is able to measure in five channels in the Visible (VIS) and Near Infrared (IR) ranges at wavebands between 0.4 - 0.88 μm. It will have a swath width of 120km, much larger than the High Resolution Optical Sensor, and will be able to measure at a resolution of 5m.
5 channels between 0.4μm - 0.88μm (VIS and NIR)
CAS500-4 will be used mainly by the Rural Development Administration and the Korea Forest Service for observing crops, agricultural water resources, and forest resources.
C-band Synthetic Aperture Radar
The C-band Synthetic Aperture (SAR) is an imaging microwave radar that will measure radio frequencies in the C-band onboard CAS500-5. The details for the instrument are listed in Table 4.
C-band: 4-8 GHz
CAS500-5 will be mainly used by the Ministry of Environment for water resource survey, river management, marine environment monitoring, and disaster/emergency monitoring.
1) “Compact Advanced Satellite 500.” 한국항공우주연구원, https://www.kari.re.kr/eng/sub03_03_03.
2) “With CAS500, South Korea launches a journey toward private-led satellite development.” SpaceNews, 23 March 2021, https://spacenews.com/with-cas500-south-korea-launches-journey-toward-private-led-satellite-development/
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