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Renamed Terra


Designation 25994 / 99068A
Launch date 18 Dec 1999
Country of origin United States
Mission Remote sensing
Perigee/Apogee 654/685 km, sun-synchronous (descending node: 10:30)
Inclination 98.2°
Period 98.1 min
Launch vehicle Atlas 2AS #123

Terra simultaneously will study clouds, water vapor, small particles in the atmosphere called "aerosol" particles, trace gases, land surface and oceanic properties, as well as the interaction between them and their effect on the Earth's energy budget and climate. Moreover, Terra will observe changes in the Earth's radiation energy budget, together with measurements of changes in land/ocean surface and interactions with the atmosphere through exchanges of energy, carbon and water.

Worth $1.3 billion

Right after launch the high-gain antenna had problems tracking the TDRS satellites. A few days later the main computer shut down. Both problems seem linked and new software is expected to fix them. On 26 Oct 2000 the satellite stopped providing high-rate data because an onboard monitor switched the service off. It could be resumed the next day.

External resources


sat-index articles

Technical data


Prime contractor Lockheed Martin
Mass at launch 4854 or 4725 kg
Mass in orbit  
Paylaod mass 1100 kg
Solar array  
Stabilization 3-axis
DC power 7500 W
Design lifetime 6 years

The 45 m² solar array will use 36,480 advanced gallium arsenide germanium (GaAs/Ge) and weigh 73 kg

MODIS (Moderate-resolution Imaging Spectroradiometer) collects the most detailed sea surface temperatures measurements.

Operates at 2, 13 and 15 GHz

Acquisition via TDRS
Telemetry: 2287.5 MHz
Command: 2106.4 MHz
Data: 15003.4 MHz (upto 150 Mbps)

ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer)

ASTER provides high-resolution images of the land surface, water, ice, and clouds using three separate sensor subsystems covering 14 multi-spectral bands from visible to thermal infrared. The significant resolution scales are 15m, 30m, and 90m in the visible, short-wave IR, and thermal fR, respectively.

CERES (Clouds and the Earths Radiant Energy System)

CERES measures Earth's radiation budget and atmospheric radiation from the top of the atmosphere using a broadband scanning radiometer with bolometers detectors.

MODIS (Moderate-Resolution Imaging Spectroradiometer)

MODIS measures biological and physical processes on land and the ocean using a cross-track scanning multi-spectral radiometer with 36 spectral bands from visible to thermal infrared. Detector cooling is through a passive radiant cooler, and filters are interference type.

MISR (Multi-Angle Imaging Spectroradiometer)

MISR measures top-of-atmosphere, cloud and surface angular reflectance functions, and measures surface BRDF, aerosol, and vegetation properties using four spectral bands in each of nine pushbroom imaging cameras oriented at different angles along-track. The detectors are CCDS, the filters are interference qw.

MOPITT (Measurements of Pollution In The Troposphere)

MOPITT measures carbon monoxide and methane in the troposphere using correlation spectroscopy with pressure modulated and length modulated gas cells. Detectors are cooled using a Stirling Cycle mechanical cooler.

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