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Landsat 7 History
April 15, 1999 - present
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Figure 1. Landsat 7
Participants
- National Aeronautics and Space Administration (NASA)
- National Oceanic and Atmospheric Administration (NOAA) (Initial participant who pulled out of the Landsat Program)
- Department of Interior (DOI) (U.S. Geological Survey (USGS))
- Spacecraft bus: Lockheed Martin Missiles & Space
- Enhanced Thematic Mapper Plus (ETM+): Hughes Santa Barbara Remote Sensing
Launch
- Date: April 15, 1999
- Vehicle: Delta II
- Launched by: NASA
- Site: Western Test Range at Vandenberg Air Force Base, CA
Figure 2. Landsat 7
Spacecraft
- Power provided by a single Sun-tracking solar array and two 50 AHr, NiCd batteries
- Attitude control provided through four reaction wheels (pitch, yaw, roll, and skew), three 2-channel gyros with celestial drift updating, a static Earth sensor, a 1750 processor, and torque rods and magnetometers for momentum uploading
- Orbit control and backup momentum unloading provided through a blow-down monopropellant hydrazine system with a single tank containing 270 pounds of hydrazine, associated plumbing, and twelve 1-pound-thrust jets.
- Weight: approx. 4,800 lbs (2200 kg)
- Length: 14 ft (4.3 m)
- Diameter: 9 ft (2.8 m)
Communications
- Direct Downlink with Solid State Recorders (SSR)
- Date rate: 150 Mbps
Orbit
- WRS-2 path/row system
- Sun-synchronous orbit at an altitude of 705 km (438 mi)
- 233 orbit cycle every 16 days covers the complete globe (except for the highest polar latitudes)
- Inclined 98.2° (slightly retrograde)
- Circles the Earth every 98.9 minutes
- Equatorial crossing time: 10:00 a.m. +/- 15 minutes
- Each scene is 185 km wide × 170 km high (115 mi×105 mi)
Sensors
Enhanced Thematic Mapper Plus (ETM+)
- Eight spectral bands, including a pan and thermal band:
- Band 1 Visible (0.45 – 0.52µm) 30m
- Band 2 Visible (0.52 – 0.60µm) 30m
- Band 3 Visible (0.63 – 0.69µm) 30m
- Band 4 Near Infrared (NIR) (0.77 – 0.90µm) 30m
- Band 5 NIR (1.55 – 1.75µm) 30m
- Band 6 Thermal (10.40 – 12.50µm) 60 m Low Gain / High Gain
- Band 7 Mid IR (2.08 – 2.35µm) 30m
- Band 8 Panchromatic (PAN) (0.52 - 0.90µm (15m)
- Ground Sampling Interval (pixel size): 30m reflective 60m thermal
- Added the Band 6 Low and High gain 60 meter thermal bands
- On-board calibration was added to Landsat 7. Full Aperture Solar Calibrator (FASC) and a Partial Aperture Solar Calibrator (PASC), in addition to the 2 Calibration Lamps.
Figure 3. Landsat 7
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U.S. Department of the Interior |
U.S. Geological Survey
