CHAPTER 3 SECTIONS > Sensor Overview | ETM+ Design | ETM+ Subsystems

3.1 Sensor Overview

Figure 3.1 - Enhanced Thematic Mapper Plus

Landsat 7's sensor - the Enhanced Thematic Mapper Plus (ETM+) - was built by SBRS. The sensor is a derivative of the Thematic Mapper (TM) engineered for Landsats 4 and 5, but is more closely related to the Enhanced Thematic Mapper (ETM) lost during the Landsat 6 failure. The primary performance related changes of the ETM+ over the TM's are the addtion of the panchromatic band and two gain ranges (added for Landsat 6), the improved spatial resolution for the thermal band, and the addition of two solar calibrators.

The ETM+ design provides for a nadir-viewing, eight-band multispectral scanning radiometer capable of providing high-resolution image information of the Earth's surface when operated from Landsat 7, a 3 axis stabilized spacecraft located in a near polar, sun-synchronous and circular orbit at a 705 km nominal altitude, with an orbit inclination of 98.2 degrees. The ETM+ is designed to collect, filter and detect radiation from the Earth in a swath 185 km wide as it passes overhead and provides the necessary cross-track scanning motion while the spacecraft orbital motion provides an along-track scan.