Landsat 5 Thermal Imager Kaput, But MSS Resurrected

Landsat 5 Thermal Imager Kaput, But MSS Resurrected

The U.S. Geological Survey (USGS) gave up on its attempts to restore daily image transmissions from Landsat 5’s Thematic Mapper (TM) thermal imaging instrument.  Launched by NASA in 1984, the satellite is decades past its design lifetime so an instrument failure is hardly unexpected.  Yet there also is good news.  Landsat 5’s other instrument, a Multi-Spectral Scanner (MSS), was brought back to life, so the spacecraft will continue to return data, albeit of less quality.

The Landsat program has experienced a tumultous programmatic history since the first satellite, then called ERTS-1, was launched in 1972.  The program celebrates its 40th anniversary on July 23.   NASA successfully launched Landsat 1-5.  An attempt to privatize the system failed in the early 1980s for many reasons including a launch vehicle malfunction that sent Landsat 6 to a watery grave in the Pacific Ocean.  The program was brought back into the government.  Landsat 7 was built and launched by NASA, but USGS took over operations of that satellite as well as Landsat 5.  NASA is building Landsat 8 (also called the Landsat Data Continuity Mission), with launch expected in January 2013.   The future of the program after that is up in the air.

USGS has been trying to restore the Landsat 5 TM since November when it suffered an electronics malfunction and daily image transmissions were suspended.  USGS said today that it will “attempt only a few additional image acquisitions over specific sensor-calibration sites as the TM transmitter nears complete failure.”

In the meantime, USGS reactivated Landsat 5’s MSS in a test mode after more than a decade of inactivity.  USGS Director Marcia McNutt said “the resurrection of the MSS a decade after it was last powered up and 25 years beyond its nominal lifespan is welcome news indeed.”  The MSS has fewer spectral bands (it does not acquire thermal data) and lower pixel resolution, but is an insurance policy in case Landsat 7 fails before the new Landsat 8 is launched in January.  Landsat 7 is also well past its design lifetime.  Launched in 1999, it has a scan line error problem meaning that each image has a 22 percent loss of data.

Unlike the high resolution imagery obtained from commercial remote sensing satellites operated by GeoEye and DigitalGlobe, medium resolution Landsat data have little commercial value, but are highly valued by the scientific community and specialized users such as the agriculture industry.

USGS is sponsoring a contest to celebrate the Landsat program’s 40th anniversary.  The deadline for submissions is Wednesday, June 6.

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