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