Landsat 7, launched in 1999, is the most recent addition to the Landsat program.

The Landsat program is the longest running enterprise for acquisition of satellite imagery of Earth. On July 26, 1972 the Earth Resources Technology Satellite was launched. This was eventually renamed to Landsat.^[1] The most recent, Landsat 7, was launched on April 15, 1999. The instruments on the Landsat satellites have acquired millions of images. The images, archived in the United States and at Landsat receiving stations around the world, are a unique resource for global change research and applications in agriculture, cartography, geology, forestry, regional planning, surveillance, education and national security. Landsat 7 data has eight spectral bands with spatial resolutions ranging from 15 to 60 meters; the temporal resolution is 16 days.^[2]

History[link]

Hughes Santa Barbara Research Center initiated design and fabrication of the first three MSS Multispectral Scanners in the same year man landed on the moon, 1969. The first prototype MSS was completed within nine months by fall of 1970 when it was tested by scanning Half Dome at Yosemite National Park.

The program was called the Earth Resources Technology Satellites Program when it was initiated in 1966, but the name was changed to Landsat in 1975. In 1979, Presidential Directive 54 under President of the United States Jimmy Carter transferred Landsat operations from NASA to NOAA, recommended development of long term operational system with four additional satellites beyond Landsat 3, and recommended transition to private sector operation of Landsat. This occurred in 1985 when the Earth Observation Satellite Company (EOSAT), a partnership of Hughes Aircraft and RCA, was selected by NOAA to operate the Landsat system under a ten year contract. EOSAT operated Landsats 4 and 5, had exclusive rights to market Landsat data, and was to build Landsats 6 and 7.

A simulated-color satellite image of Kolkata taken on NASA's Landsat 7 satellite.

In 1989, this transition had not been fully completed when NOAA's funding for the Landsat program was due to run out (NOAA had not requested any funding, and Congress had appropriated only six months of funding for the fiscal year)^[3] and NOAA directed that Landsats 4 and 5 be shut down.^[4] The head of the newly formed National Space Council, Vice President Dan Quayle, noted the situation and arranged emergency funding that allowed the program to continue with the data archives intact. ^[3][4][5][6]

Again in 1990 and 1991, Congress provided only half of the year's funding to NOAA, requesting that agencies that used Landsat data provide the funding for the other six months of the upcoming year.^[3] In 1992, various efforts were made to procure funding for follow on Landsats and continued operations, but by the end of the year EOSAT ceased processing Landsat data. Landsat 6 was finally launched on October 5, 1993, but was lost in a launch failure. Processing of Landsat 4 and 5 data was resumed by EOSAT in 1994. NASA finally launched Landsat 7 on April 15, 1999.

The value of the Landsat program was recognized by Congress in October 1992 when it passed the Land Remote Sensing Policy Act (Public Law 102-555) authorizing the procurement of Landsat 7 and assuring the continued availability of Landsat digital data and images, at the lowest possible cost, to traditional and new users of the data.

Satellite chronology[link]

• Landsat 1 (originally named Earth Resources Technology Satellite 1): launched July 23, 1972, terminated operations January 6, 1978
• Landsat 2: launched January 22, 1975, terminated January 22, 1981
• Landsat 3: launched March 5, 1978, terminated March 31, 1983
• Landsat 4: launched July 16, 1982, terminated 1993
• Landsat 5: launched March 1, 1984, still functioning.^[7][8] but severe problems since Nov. 2011^[9]
• Landsat 6: launched October 5, 1993, failed to reach orbit
• Landsat 7: launched April 15, 1999, still functioning, but with faulty scan line corrector (May 2003) ^[10]

Technical details[link]

False-color composite (processed to simulate true color) image of the island of Hawaii was constructed from data gathered between 1999 and 2001 by the Enhanced Thematic Mapper plus (ETM+) instrument, flying aboard the Landsat 7 satellite. The Landsat data were processed by the National Oceanographic and Atmospheric Administration (NOAA) to develop a landcover map. The black areas on the island (in this scene) that resemble a pair of sun-baked palm fronds are hardened lava flows formed by the active Mauna Loa Volcano. Just to the north of Mauna Loa is the dormant grayish Mauna Kea Volcano, which hasn’t erupted in an estimated 3,500 years. A thin greyish plume of smoke is visible near the island’s southeastern shore, rising from Kilauea—the most active volcano on Earth. Heavy rainfall and fertile volcanic soil have given rise to Hawaii’s lush tropical forests, which appear as solid dark green areas in the image. The light green, patchy areas near the coasts are likely sugar cane plantations, pineapple farms, and human settlements.

The Multispectral Scanner had a 9" fused silica dinner-plate mirror epoxy bonded to three invar tangent bars mounted to base of a Ni/Au brazed Invar frame in a serreuire truss that was arranged with four "Hobbs-Links" (conceived by Dr. Gregg Hobbs) crossing at mid truss. This construct ensured the secondary mirror would simply oscillate about the primary optic axis to maintain focus despite vibration inherent from the 14-inch (360 mm) Be scan mirror. This engineering solution allowed the US to develop LANDSAT at least five years ahead of French SPOT which first used CCD arrays to stare without need for a scanner.

The MSS FPA, or Focal Plane Array consisted of 24 square optical fibers extruded down to .0002"square fiber tips in a 4x6 array to be scanned across the Nimbus spacecraft path in a +/-6 degree scan as the satellite was in a 10:30 polar orbit, hence it had to be launched from Vandenberg AFB. The fiber optic bundle was embedded in a fiber optic plate to be terminated at a relay optic device that transmitted fiber end signal on into six photodiodes and 18 photomultiplier tubes that were arrayed across a 0.30-inch (7.6 mm) thick aluminum tool plate, with sensor weight balanced vs the 9-inch (230 mm) telescope on opposite side. This main plate was assembled on a frame, then attached to the silver-loaded magnesium housing with helicoil fasteners.

Key to MSS success was the scan monitor mounted on the underbelly of the Mg housing. It consisted of a diode source and sensor mounted at ends of four flat mirrors that were tilted so that it took 14 bounces for a beam to reflect length of the three mirrors from source to sender striking Be scan mirror seven times as it reflected seven times off the flat mirrors. It only sensed three positions, both ends of scan and the mid scan, but that was all that was required to determine where MSS was pointed and electronics scanning could be calibrated to display a map.

Future[link]

The Landsat Data Continuity Mission (LDCM),^[11] scheduled to be launched January 2013, will be the next satellite in the Landsat series. It is being launched on an Atlas V 401 from Vandenberg Air Force Base by the Launch Services Program. It will continue to obtain valuable data and imagery to be used in agriculture, education, business, science, and government. The new satellite is being assembled in Arizona by Orbital Sciences Corporation.^[12]

Overview of the Thermal Infrared Sensor (TIRS), one of the instruments on the Landsat Data Continuity Mission (LDCM).

A timelapse of the Thermal Infrared Sensor (TIRS) instrument for the Landsat Data Continuity Mission (LDCM) being cleaned, bagged, and packed to ship to Orbital Sciences Corp, where TIRS will be integrated with the spacecraft.

See also[link]

• Remote sensing

References[link]

External links[link]

Wikimedia Commons has media related to: Landsat or Landsat images

• Landsat homepage
• Landsat NASA homepage
• Landsat.org Home Page
• Works by Landsat at Project Gutenberg
  • Landsat picture of Washington, D. C.
• (Free) Landsat imagery from GLOVIS and Global Land Cover Facility
• Atlogis Maps and Atlogis Meta-Maps: Online-Viewer for Landsat 5 and Landsat 7 Natural Color Mosaic from Atlogis. Meta-Maps includes Google, MSN and Yahoo Maps.
• (Free) Landsat mosaic imagery from the WELD project.
• Landsat imagery for circa 1975, 1990 and 2000 visualised in Google Earth (required GE installed)

v t e Landsat program Landsat 1 · 2 · 3 · 4 · 5 · 6 · 7 Landsat Data Continuity Mission (LDCM)

v t e World Reconnaissance Satellites, excluding Russia and the United States Commercial Electro-optical Quickbird · WorldView-1 · WorldView-2 · Ikonos · GeoEye-1 · GeoEye-2 · SPOT · EO1-ALI · ASTER · LANDSAT · ALOS Synthetic Aperture Radar RADARSAT-1 · RADARSAT-2 · PALSAR International Electro-Optical Disaster Monitoring Constellation  Brazil IMINT SCD-1 · SCD-2 · CBERS-1 · CBERS-2 · SSR  China IMINT JSSW · FSW-0 · FSW-1 · FSW-2 · FSW-3 · JianBing · CBERS-2 (joint Brazil) · Yaogan SIGINT JSSW-3  · SJ-2 · DQ-1 COMM Feng Huo-1 · ShenTong-1  France IMINT Hélios 1B · Helios 2A SIGINT Cerise · Clementine  Germany IMINT SAR-Lupe COMM TerraSAR-X · TanDEM-X  India IMINT Cartosat-1  · Cartosat-2  · Cartosat-2A Other RISAT-2  · RISAT-1  Israel IMINT Ofeq -> Ofeq 5 · Ofeq 7  · Ofeq 9 COMM AMOS 1 · AMOS 2 · AMOS 3 · AMOS 4 Other Eros · TecSAR  Italy IMINT COSMO-SkyMed  Japan IMINT IGS 1A/B · IGS 2A/B · IGS 3A · IGS 4A/B · IGS 5A · IGS 6A · IGS 7A  Turkey IMINT Göktürk I · Göktürk II COMM Turksat 1A  · Turksat 1B · Turksat 1C · Turksat 2A · Turksat 3A  Taiwan IMINT - COMM Formosat-1 · Formosat-2