Landsat 7

Landsat 7
NASA · Public domain · source
Name	Landsat 7
Mission type	Earth observation
Operator	National Aeronautics and Space Administration / United States Geological Survey
COSPAR ID	1999-046A
SATCAT	25994
Manufacturer	Lockheed Martin
Launch date	1999-04-15
Launch rocket	Delta II
Launch site	Vandenberg Air Force Base
Orbit type	Sun-synchronous
Mission duration	Ongoing (commissioned 1999)

Landsat 7 is an American Earth-observing satellite in the Landsat program constellation, launched in 1999 to continue the multi-decadal record of global surface observations begun by Landsat 1 and sustained through Landsat 5 and later complemented by Landsat 8 and Landsat 9. The spacecraft was developed by NASA in partnership with the United States Geological Survey to provide calibrated multispectral and panchromatic imagery for applications across science, resource management, and policy, supporting users from the European Space Agency and Japan Aerospace Exploration Agency to national agencies like USDA and international organizations such as the United Nations.

Overview

Landsat 7 continues the heritage initiated by Landsat 4 and Landsat 5 to deliver systematic global observations used by National Oceanic and Atmospheric Administration researchers, Environmental Protection Agency analysts, World Bank planners, NASA Goddard Space Flight Center scientists, and academia including Massachusetts Institute of Technology and Stanford University. The mission complements other programs like Sentinel-2 and MODIS on Terra (satellite) and Aqua (satellite), forming part of long-term Earth system records employed by Intergovernmental Panel on Climate Change assessments and initiatives led by National Science Foundation and European Commission projects.

Mission and Design

Designed by Lockheed Martin under prime contracts with NASA Jet Propulsion Laboratory and the USGS EROS Center, the spacecraft bus integrates systems influenced by missions such as EO-1 and Ikonos. The design objectives prioritized instrument stability for cross-calibration with Landsat 5, traceability to National Institute of Standards and Technology standards, and operational continuity for users including US Department of Agriculture and United States Forest Service. Engineering teams from Ball Aerospace, Raytheon, and Northrop Grumman contributed subsystems, while mission operations have been coordinated through NASA Headquarters and field centers like Vandenberg Space Force Base operations and USGS Center for Earth Resources Observation and Science.

Instruments and Payload

The primary payload is the Enhanced Thematic Mapper Plus (ETM+), developed drawing on heritage from Thematic Mapper instruments used on earlier Landsat satellites and calibrated with references from Lunar Reconnaissance Orbiter and SeaWiFS. ETM+ includes multispectral bands spanning visible to thermal infrared wavelengths, plus a high-resolution panchromatic sensor enabling fusion techniques employed by researchers at California Institute of Technology and University of Maryland. Calibration activities have involved collaborations with NOAA National Centers for Environmental Information, National Oceanic and Atmospheric Administration, and international calibration facilities such as those utilized by European Space Agency missions.

Launch and Orbit

Launched from Vandenberg Air Force Base aboard a Delta II rocket built by Boeing subcontractors, the satellite was injected into a sun-synchronous, near-polar orbit similar to predecessors including Landsat 5 and contemporary platforms like SPOT (satellite) and ERS-2. The orbit enables revisits coordinated with the Landsat data continuity mission cadence and harmonization with Sentinel-2 ground tracks for combined time-series analyses used by Food and Agriculture Organization programs and regional agencies such as US Fish and Wildlife Service.

Operations and Data Products

Operational control and data stewardship have been managed by USGS EROS Center with mission support from NASA Goddard Space Flight Center; the data policy evolved to support free and open access following precedents set by Landsat 4 and Landsat 5 that transformed usage by institutions like Google, Amazon Web Services, and universities including Harvard University. Product suites include Level-1 calibrated radiance and surface reflectance products used by National Aeronautics and Space Administration researchers, climate modelers at NOAA and European Centre for Medium-Range Weather Forecasts, and practitioners in Food and Agriculture Organization and World Resources Institute. Users apply products to map croplands for United States Department of Agriculture, monitor wetlands for Ramsar Convention participants, track deforestation cited by Intergovernmental Panel on Climate Change, and assess urban expansion analyzed by United Nations Human Settlements Programme.

Anomalies and Degradation

In 2003, the ETM+ Scan Line Corrector (SLC) failed, a hardware anomaly that introduced gaps addressed by gap-filling algorithms developed by teams at University of Arizona, University of Zurich, and NASA Ames Research Center. The anomaly spurred research collaborations with institutions such as Jet Propulsion Laboratory, Carnegie Mellon University, and University of California, Berkeley to generate compositing methods and data fusion techniques combining Landsat 7 with sensors like MODIS, ASTER, and Sentinel-2. Ongoing calibration and validation campaigns have involved National Institute of Standards and Technology, NOAA, and international partners including Canadian Space Agency and Australian Cooperative Research Centres.

Impact and Applications

Landsat 7 imagery has supported high-profile studies and operational programs conducted by NASA, USGS, European Space Agency, UN Environment Programme, and nongovernmental organizations such as Conservation International and World Wildlife Fund. Applications range from monitoring glacier retreat analyzed by teams at Columbia University and University of Colorado Boulder, mapping urban heat islands studied by Massachusetts Institute of Technology and University College London, to supporting disaster response coordinated by Federal Emergency Management Agency and International Red Cross and Red Crescent Movement. The mission has contributed critical data to initiatives like Global Forest Watch, Group on Earth Observations, and academic efforts published by journals such as Nature, Science (journal), and Remote Sensing of Environment.

Category:Earth observation satellites Category:NASA satellites Category:United States Geological Survey