POLDER

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This article is about the environmental satellite radiometer. For the terran type, see Polder.
POLDER
Polarization and Directionality of the Earth's Reflectances
Operator CNES
Mission type Earth observation
Launch date 17 August 1996 (6388 days ago)
14 December 2002 (4078 days ago)
18 December 2004 (3343 days ago)
Carrier rocket H-II (POLDER 1)[1]
H-IIA (POLDER 2)
Ariane 5 (POLDER 3)
Launch site Tanegashima Space Center (POLDER 1 and 2)
Guiana Space Centre (POLDER 3)
Current destination In orbit
Homepage http://smsc.cnes.fr/POLDER/
Mass ~30 kilograms (66 lb)
Power 70 W
Instruments
Data rate 880 kbit/s
Imaging resolution 242x548 pixels
Transponders
Transponders Formed broad beam pattern UHF antenna
Twta output > 5 W
EIRP 27.1 dBm

POLDER (POLarization and Directionality of the Earth's Reflectances) is a passive optical imaging radiometer[2] and polarimeter[3] developed by the French space agency CNES.

Description

The device was designed to observe solar radiation reflected by Earth's atmosphere, including studies of tropospheric aerosols, sea surface reflectance, bidirectional reflectance distribution function of land surfaces, and the Earth Radiation Budget.[4]

Specifications

POLDER has a mass of approximately 30 kilograms (66 lb), and has a power consumption of 77 W in imaging mode (with a mean consumption of 29 W).[5]

Imaging

POLDER utilizes a push broom scanner. The device's optical system uses a telecentric lens and a charged coupled device matrix with a resolution of 242x548 pixels.[3] The focal length is 3.57 millimetres (0.141 in) with a focal ratio of 4.6. The field of view ranges from ±43° to ±57°, depending on the tracking method.[3]

Spectral characteristics

The device scans between 443 and 910 nm FWHM, depending on the objective of the measurement. The shorter wavelengths (443–565 nm) typically measure ocean color, whereas the longer wavelengths (670–910 nm) are used to study vegetation and water vapor content.[3]

Data transfer

It transmits data on 465.9875 MHz at bit rate of 200 bit/s, and receives on 401.65 MHz at 400 bit/s.[2] The data rate is 880 kbit/s at a quantization level of 12 bits.

Missions

POLDER was first launched as a passenger instrument aboard ADEOS I[4] on 17 August 1996.[6] The mission ended on 30 June 1997 when communication from the host satellite failed.[7] POLDER 2 was launched in December 2002 aboard ADEOS II. The second mission ended prematurely after 10 months when the satellite's solar panel malfunctioned.[8] A third generation instrument was launched on board the French PARASOL microsatellite. Although the satellite has been manoeuvred out of the A-Train on 2 December 2009, data is still being acquired by the satellite.

Footnotes

  1. ↑ Krebs (2010)
  2. ↑ 2.0 2.1 Kramer (2002, p. 339)
  3. ↑ 3.0 3.1 3.2 3.3 Kramer (2002, p. 333)
  4. ↑ 4.0 4.1 Kramer (2002, p. 332)
  5. ↑ Kramer (2002, p. 1069)
  6. ↑ Kramer (2002, p. 52)
  7. ↑ Satellite News Digest (2006)
  8. ↑ Satellite News Digest (2003)

Sources

  • Kramer, Herbert J (2002), Observation of the Earth and Its Environment: Survey of Missions and Sensors, Berlin, Germany: Springer Science+Business Media, ISBN 3-540-42388-5 
  • Krebs, Gunter (2010), ADEOS 1 (Midori 1), Germany: Gunter's Space Page, retrieved 19 September 2010 
  • Satellite News Digest (2006), Midori I (ADEOS I), Luebeck, Germany: Sat-ND, retrieved 19 September 2010 
  • Satellite News Digest (2003), Midori II (ADEOS II), Luebeck, Germany: Sat-ND, retrieved 17 September 2010 

External links

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