POLDER

This article is about the environmental satellite radiometer. For the terrain type, see Polder.

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

POLDER 1

Mission type	Earth observation
Operator	CNES
Website	CNES Page
Spacecraft properties
Launch mass	~30 kg (66 lb)
Power	30W
Start of mission
Launch date	07:00, August 17, 1996 (1996-08-17T07:00:00)
Rocket	H-II (POLDER 1)[1]
Launch site	Tanegashima Space Center
Main push broom scanner
Type	Telecentric lens
Focal length	3.57 mm (0.141 in)
Wavelengths	443 and 910 nm FWHM
Resolution	242x548 pixels
Transponders
Band	Formed broad beam pattern UHF antenna
TWTA power	>5W
EIRP	27.1 dBm
POLDER 2 →

POLDER 2

Mission type	Earth observation
Operator	CNES
Website	CNES Page
Spacecraft properties
Launch mass	~30 kg (66 lb)
Power	30W
Start of mission
Launch date	07:00, December 14, 2002 (2002-12-14T07:00:00)
Rocket	H-IIA (POLDER 1)[1]
Launch site	Tanegashima Space Center
Main push broom scanner
Type	Telecentric lens
Focal length	3.57 mm (0.141 in)
Wavelengths	443 and 910 nm FWHM
Resolution	242x548 pixels
Transponders
Band	Formed broad beam pattern UHF antenna
TWTA power	>5W
EIRP	27.1 dBm
← POLDER 1 POLDER 3 →

POLDER 3

Mission type	Earth observation
Operator	CNES
Website	CNES Page
Spacecraft properties
Launch mass	~30 kg (66 lb)
Power	30W
Start of mission
Launch date	07:00, December 18, 2004 (2004-12-18T07:00:00)
Rocket	Ariane 5G
Launch site	Guiana Space Centre
Main push broom scanner
Type	Telecentric lens
Focal length	3.57 mm (0.141 in)
Wavelengths	443 and 910 nm FWHM
Resolution	242x548 pixels
Transponders
Band	Formed broad beam pattern UHF antenna
TWTA power	>5W
EIRP	27.1 dBm
← POLDER 2 PARASOL →

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 charge-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. The satellite was maneuvered out of the A-train on 2 December 2009 and permanently shut down on 18 December 2013.^[9]