Landsat 4, 5

Landsat 5 [NASA]

The Landsat 4 system was an experimental earth resources monitoring system with the new powerful remote-sensing capabilities of the thematic mapper (TM), and it provided a transition for both foreign and domestic users from the multispectral scanner (MSS) data to the higher resolution and data rate of the TM. It had a complete end-to-end highly automated data system, which was designed to be a new generation system, and was a major step forward in global remote-sensing applications. The Landsat 4 mission consisted of an orbiting satellite (flight segment) with the necessary wideband data links and support systems, and a ground segment. The Landsat 4 flight segment consisted of two major systems: 

• the instrument module, containing the instruments together with the mission unique subsystems, such as the solar array and drive, the TDRS antenna, the wide-band module (WBM), and the global positioning system (GPS); and
• the multimission modular spacecraft (MMS) that contained the modularized and standardized power, propulsion, attitude control, and communications and data handling subsystems.

The flight segment was designed with 3 years nominal lifetime in orbit and could be extended through in-orbit replacement capability when the Space Shuttle became operational. The spacecraft was placed into an orbit having a descending node equatorial crossing between 9:30 and 10:00 a.m. local time. The spacecraft and attendant sensors were operated through the GSTDN stations before the Tracking And Data Relay Satellite System (TDRSS) was available. Landsat 4 was decommissioned on June 15, 2001.

An identical back-up spacecraft, Landsat-D Prime (NSSDC ID Landsat-E) was placed in storage and launched on March 1, 1984 as Landsat 5. Landsat 5 is still operational (as of January 2006) after 22 years in orbit, surpasing its 3 years design lifetime widely.