The U.S. Geological Survey (USGS) has stopped acquiring images from the 27-year-old Landsat 5 Earth observation satellite due to a rapidly degrading electronic component.
Landsat 5 was launched in 1984 and designed to last 3 years. The USGS assumed operation of Landsat 5 in 2001 and managed to bring the aging satellite back from the brink of total failure on several occasions following the malfunction of key subsystems. There is now an increasing likelihood that the Landsat 5 mission is nearing its end.
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“This anticipated decline of Landsat 5 provides confirmation of the importance of the timely launch of the next Landsat mission and the need for an operational and reliable National Land Imaging System,” stated Anne Castle, Assistant Secretary for Water and Science at the U.S. Department of the Interior. “The USGS is committed to maintaining the unique long term imaging database that the Landsat program provides.”
For several months, the Landsat flight operations team has been closely tracking the fluctuating performance of an amplifier essential for transmitting land-surface images from the Landsat 5 satellite to ground receiving stations in the U.S. and around the world. Over the past 10 days, problems with the amplifier have led to drastically reduced image download capabilities, a sign of impending failure.
Numerous engineering and technical adjustments have been made to Landsat 5 in the past several days to sustain at least a limited imaging capability, but performance has continued to decline. Instead of continuing to operate until the amplifier fails completely, which could bring the mission to an end, USGS engineers have suspended imaging activities for an initial period of 90 days in order to explore every possible option for restoring satellite-to-ground image transmissions.
The USGS-operated Landsat 7 remains in orbit collecting global imagery. Since its launch in 1999 with a 5-year design life, Landsat 7 has experienced an instrument anomaly which reduces the amount of data collected per image. Landsat 8, currently called the Landsat Data Continuity Mission, is now scheduled to be launched in January 2013.
The era of privatization
The year Landsat 5 was launched Congress decided that land satellites could be privatized (1984 Land Remote Sensing Commercialization Act). NOAA, the agency in charge of all Landsat operations, was instructed to find a commercial vendor for Landsat data. NOAA selected Earth Observation Satellite Company (EOSAT).
The contract gave EOSAT the responsibility for archiving, collecting and distributing current Landsat data as well as the responsibility for building, launching and operating the following two Landsat satellites (with government subsidies).
Commercialization proved troublesome, EOSAT had limited commercial freedom due to provisions of the 1984 law. Given these constraints, NOAA and then EOSAT raised image prices from $650 to $3700 to $4400 and restricted redistribution. While the U.S. monopoly of Landsat-like data made this 600% increase feasible, the practice priced out many data users. (As a result, many data users migrated to the free low-resolution land data being captured by meteorological satellites.) In 1986, a French Landsat-like satellite launch broke the U.S. monopoly.
During the EOSAT commercialization era, Landsat coverage standards languished. Many observations from 1984 to 1999 were missed because there was no obvious and immediate buyer. With commercial data marketing, it makes sense to only collect data for which there is an established customer, whereas a true scientific mission collects as much global data as possible for future scientific study. Landsat 4 and 5 system calibration and characterization lapsed during this period as well.
By 1989, with two aging satellites and no operatonal budget, NOAA directed EOSAT to turn off the satellites (no government agency was willing to commit augmentation funding for continued satellite operations and data users were unwilling to make the hefty investments in computer processing hardware if future data collection was uncertain). The program was only saved by a strong protest from Congress and foreign and domestic data users, and an intervention by the Vice President.
Given this outcry and the unexpected outcome of privatization, Congress facilitated the Land Remote Sensing Policy Act of 1992, which instructed Landsat Program Management to build a government-owned Landsat 7.
Two years after the launch of Landsat 7, Space Imaging (formerly EOSAT) returned operational responsibility for Landsat 4 and Landsat 5 back to the U.S. Government.
On July 1, 200l when operational control was officially returned to the federal government, Space Imaging also relinquished their commercial right to Landsat data, enabling the USGS to sell all Landsat 4 and Landsat 5 data in accordance with the USGS pricing policy.
Timeline
- On March 1, 1984, NASA launched Landsat 5, the agency’s last originally mandated Landsat satellite. Landsat 5 was designed and built at the same time as Landsat 4 and carried the same payload: the Multispectral Scanner System (MSS) and the Thematic Mapper (TM) instruments.
- In 1987, the Landsat 5 TDRSS transmitter (Ku-band) failed. This failure made downlinking data acquired outside of the U.S. data acquisition circle (i.e., range of U.S. ground receiving antennas) impossible; Landsat 5 has no on-board data recorder to record acquired data for later downlink.
- The MSS instrument was turned off in August of 1995.
- The TM instrument is still in operation, some 27 years after its planned design life. Data is regularly acquired at stations in the U.S. and Australia for entry into the U.S. archive. A number of International Ground Stations download data for their local acquisition area.
- In November 2005, Landsat 5 TM operations were suspended after problems with the solar array left the satellite unable to properly charge its on-board batteries. Working together, USGS and NASA engineers were able to devise a new method of solar array operations. And, on January 30, 2006 Landsat 5 resumed normal operations.
- In November 2011, The U.S. Geological Survey (USGS) has stopped acquiring images from the 27-year-old Landsat 5 Earth observation satellite due to a rapidly degrading electronic component.
For further details and the latest information about the status of Landsat 5, visit the USGS Landsat Missions website.
