Space Programs | FORMOSAT-5


FORMOSAT-5 carries an optical payload and a science payload as shown to execute remote sensing mission and perform science research, respectively.

1. Optical Remote Sensing Payload

The Remote Sensing Instrument (RSI) is composed of Telescope and Electrical Unit (EU). The Telescope consists of Optics, Structure Module (SM) and CMOS typed Focal Plane Assembly (FPA). The specifications of RSI are listed as follows.

Items Specifications
Resolution 2m @ nadir (PAN), 4m @ nadir (Blue, Green, Red, Infrared)
Swath 24 km
Bands PAN, Blue, Green, Red, Infrared
Digitization 12 Bits
Storage ≧80 Gbits
Duty Cycle 8% per orbit
Orbit 720 km, Sun-synchronous
Contrast Transfer Function (CTF) ≧ 0.1(PAN)
≧ 0.2(Blue, Green, Red)
≧ 0.16 (Infrared)
Signal-to-Noise Ratio (SNR) ≧83 (Pan)
≧95 (Red); ≧95 (Green); ≧100 (Blue);
≧100 (Infrared)

Remote Sensing Instrument (RSI), has been jointly developed by NARL’s centers including NSPO), ITRC and CIC, as well domestic organizations of CSIST, AIDC, CMOS Sensor Inc., and Camels Vision Technologies. The Optics and Structure Model (including thermal control) have been integrated as Optical Structure Assembly (OSA) which has been validated under space environmental tests.

ITRC is responsible for designing and manufacturing the optical components which include primary mirror, secondary mirror, corrective lenses and band-pass filters shown as follows.

Primary mirror Corrective lenses

Secondary mirror Band-pass filters

Main structure is made of the advanced carbon fiber composites (CFRP) material which possesses characteristics including high strength, low moisture absorption and high stability during rocket launch and in space. The Optics is composed of primary and the secondary mirror assemblies as well as corrective lens. The primary mirror using Iso-Static Mounting (ISM) mechanism glues to the structure. The operating temperature is under control at (20 +/- 2°C) with thermal elements (e.g. multilayer thermal insulation material, temperature sensors and heat sink) and electronic circuits.

The two critical components of RSI, Electronic Unit (EU) and CMOS-type Focal Plane Assembly (FPA, were contracted to CSIST and CMOS Sensor Inc. respectively. For details, please refer to the section of Key Components.

2. Science payload

Advanced Ionospheric Probe (AIP) is provided by Institute of Space Science, National Central University (NCU) for the FORMOSAT-5 satellite as a science payload. The AIP is an all-in-one plasma sensor to measure ionospheric plasma concentrations, velocities, and temperatures over a wide range of spatial scales. The transient and long-term variations of ionospheric plasma can be monitored as seismic precursors associated with earthquakes.

The anticipated data specification of the geophysical parameters measured by the AIP is shown in the following table:

Geophysical parameters Range Sensitivity Accuracy
Ion composition 3 % ~ 100 % 1 % 10 %
Ion concentration 4×102 ~ 1.2×107 cm-3 1 % 10 %
Ion velocity ±3.2 km/s (cross-track)
±5.0 km/s (ram)
±10 m/s
±100 m/s
±50 m/s
±200 m/s
Ion temperature 500 ~ 10,000 K ±50 K ±200 K

The AIP consists of a sensor unit located on the top panel of the satellite and a Science Payload Electronics Unit (SPEU) housed inside the satellite shown as figures below. The test results show that functions of AIP flight model are better than other similar products.

The AIP uses the following three sampling rates to acquire ionospheric plasma parameters:

  1. NORMAL: 128 Samples/s.
  2. FAST: 1,024 Samples/s.
  3. BURST: 8,192 Samples/s.

More complex measurement modes can be realized via uploaded commands to meet the needs of science team.