For the first time since May 1999, the Landsat 7 satellite has left the Worldwide Reference System-2 (WRS-2) orbit. Following two maneuvers, the satellite was lowered last week to an altitude of 697 kilometers, placing it outside the official envelope of the Earth Observation Satellite (EOS) constellation.
Landsat 7 Lowered from Standard Landsat Orbit
The satellite's primary science mission has ended
The EOS constellation is made up of the AM satellites (Landsats 7, 8, 9, and Terra) and the PM satellites (Aqua, Aura, GCOM-W). These satellites all fly at 705 kilometers, but at differing equatorial crossing times.
Landsat 7 joined Landsats 4 and 5 (launched in 1982 and 1984, respectively) in the WRS-2 orbit about a month after its launch on April 15, 1999. Sporting the Enhanced Thematic Mapper Plus (ETM+) instrument, Landsat 7 heralded unmatched radiometric and geometric calibration and a 250-scene-per-day coverage.
Despite technical issues such as the scan line corrector failure in 2003, the mission collected a treasure trove of Earth observations adding up to more than 3.1 million scenes that are available in the USGS Landsat archive. On April 6, the ETM+ sensor was placed in “stand-by” mode and ended Landsat 7’s primary science mission.
Planning for the orbit lowering started a year ago and was executed flawlessly. Soon Landsat 7 will be in a new orbit, where it will provide new insights to help inform the design of future missions and prepare for a historic refueling operation with NASA’s On-Orbit Servicing, Assembly, and Manufacturing-1 (OSAM-1) spacecraft.