Landsat 4

Landsat 4 was launched on July 16, 1982. The Landsat 4 spacecraft was significantly different than that of the previous Landsats, and Landsat 4 did not carry the RBV instrument.
In addition to the Multispectral Scanner System (MSS) instrument, Landsat 4 (and Landsat 5) carried a sensor with improved spectral and spatial resolution, i.e., the new satellites could see a wider (and more scientifically-tailored) portion of the electromagnetic spectrum and could see the ground in greater detail. This new instrument was known as the Thematic Mapper (TM).
Landsat 4 was kept in orbit for housekeeping telemetry command and tracking data (which it downlinked via a separate data path, the S-band) until it was decommissioned in 2001.
While Landsat 4 was built and launched by NASA, NOAA initially oversaw the operations of the satellite. Landsat 4 operations were contracted out to the Earth Observation Satellite Company (EOSAT) corporation in 1984.
By 1998, the management of the Landsat 4 (and Landsat 5) operations contract was transferred from NOAA to the USGS; operations were continued by the private sector until mid-2001 when Space Imaging (formerly EOSAT) returned the operations contract to the U.S. Government.
Despite the numerous transfers of satellite operation, the USGS has remained responsible for long-term preservation of Landsat data in its National Satellite Land Remote Sensing Data Archive (NSLRSDA) in Sioux Falls, South Dakota.

Multispectral Scanner (MSS)
Thematic Mapper (TM)

Sun synchronous
99 minutes
Earth observation; housekeeping telemetry command and tracking data