Landsat 6 [NASA]
The Landsat 6 satellite was a commercial program jointly with the Department of Commerce (NOAA) and EOSAT Company that provided data for a wide range of Earth resources applications including environmental monitoring, natural resource exploration, urban planning, and cartography. The Landsat 6 satellite continued the series of operational Earth resource monitoring spacecraft begun with Landsat 1 in 1972. Landsat 6 differed from previous Landsat missions in that it carried only one remote sensing instrument - The Enhanced Thematic Mapper (ETM). The Landsat 6 spacecraft, built by GE Astro Space, was based on RCA's Advanced TIROS-N spacecraft design used for the operational NOAA and DMSP polar orbiting meteorological spacecraft. The Landsat 6 sensors were mounted on the forward module of the central spacecraft bus which also housed three multichannel steerable X-band antennas. Power was generated by a 16.74 sq. meter 4-panel single solar array backed up by two 50 Ahr NiCd batteries. Attitude and control was maintained by hydrazine and nitrogen thrusters. The spacecraft was 3-axis, zero momentum stabilized to an accuracy of 0.015 degrees. Two redundant on-board tape Odetics tape recorders were able to store about 15 minutes (75 Gbits) of image data. Five transmitters permitted three simultaneous downlinks to three ground stations, two stations receiving different data sets. The X-band subsystem provided simultaneous panchromatic downlink and playback to the central EOSAT ground station in Oklahoma. The ETM sensor continued the high-resolution Landsat imagery begun with the Thematic Mapper (TM) on Landsats 4 and 5. The ETM consisted of 7 spectral channels (6 with a ground resolution of 30 meters and one (thermal IR) with a ground resolution of 120 meters) plus a panchromatic channel providing a ground resolution of 15 meters. The spacecraft lost contact with ground stations shortly after launch and before achieving orbit. The spacecraft failed to insert itself into orbit after launch.
Landsat 7 continued the long-term Earth observation Landsat program begun in 1972. Landsat 7 was a joint project between NASA, NOAA, and the US Geological Survey to obtain continuous high-resolution imagary of the earth's surface for environmental monitoring, disaster assessment, land use and regional planning, cartography, range management, oil and mineral exploration. Under the Land Remote Sensing Act of 1992 (PL 102-555), the Landsat program returned to the US Government and responsibilities assigned to NASA, NOAA, and the USGS. The Landsat 7 carried one instrument: (the Enhanced Thematic Mapper Plus (ETM+) The ETM+ was an improved version of the ETM on Landsat 6. The instrument provided improved spatial resolution. The Landsat 7 spacecraft provided improved ephemeris and attitude determination. The Landsat 7 spacecraft was built by Lockheed Martin Missiles and Space.
Landsat 7 is currently planned to be the target of the robotic OSAM 1 (Restore-L) servicing mission in 2025.
|Type / Application:||Earth observation|
|Equipment:||ETM (#6), ETM+ (#7)|
|Propulsion:||Star-37XFP / ISS (#6); ISS (#7)|
|Power:||Deployable solar array, batteries|
|Lifetime:||5 years (planned)|
|Mass:||2200 kg (#7)|
|Orbit:||669 km × 698 km, 98.2°|
|Landsat 6||1993-F04||05.10.1993||Va SLC-4W||F||Titan-2(23)G Star-37XFP-ISS|
|Landsat 7||1999-020A||15.04.1999||Va SLC-2W||Delta-7920-10C|