Characteristics - Landsat 4/5

Summary of Landsat Missions and Sensors

Landsat 4/5

Two types of image data from the satellite are available: MultiSpectral Scanner (MSS) and Thematic Mapper (TM). Landsat 4 and 5 carry both the MSS and the TM sensors; however, routine collection of MSS data was terminated in late 1992. The MSS and TM sensors primarily detect reflected radiation from the Earth's surface in the visible and near-infrared (IR) wavelengths, but the TM sensor with its seven spectral bands provides more radiometric information than the MSS sensor.

The wavelength range for the TM sensor is from the visible, through the Mid-IR, into the Thermal-IR portion of the electromagnetic spectrum. Sixteen detectors for the visible and Mid-IR wavelength bands in the TM sensor provide 16 scan lines on each active scan. Four detectors for the Thermal-IR band provide four scan lines on each active scan. The TM sensor has a spatial resolution of 30 meters for bands 1 - 5, and band 7, and a spatial resolution of 120 meters for band 6.

The satellites orbit at an altitude of 705 km and provide a 16-day, 233-orbit cycle with a swath overlap that varies from 7 percent at the Equator to nearly 84 percent at 81 degrees north or south latitude. These satellites also were designed and operated to collect data over a 185-km swath.

All five of the Landsat satellites have been in sun-synchronous orbits with equatorial crossing times ranging from 8:30am for Landsat 1 to approximately 9:45am for Landsat 5.

Spatial Resolution

The TM sensor is an advanced, multispectral scanning, Earth resources instrument designed to achieve higher image resolution, sharper spectral separation, improved geometric fidelity, and greater radiometric accuracy and resolution than the MSS sensor. The TM data are scanned simultaneously in seven spectral bands. Band 6 scans thermal (heat) infrared radiation. A Landsat 4 or 5 TM scene has an instantaneous field of view (IFOV) of 30 meters by 30 meters (900 square meters) in bands 1 through 5 and band 7, and an IFOV of 120 meters by 120 meters (14,400 square meters) on the ground in band 6. All TM bands are quantized as 8 bit data.

Sensitivity and Resolution Applied to Landsat 4/5 TM Missions