Newest Landsat Readied for Launch as Oldest Nears End of Mission
WASHINGTON — A day after the eighth Landsat moderate-resolution land imaging satellite arrived at Vandenberg Air Force Base in California to be prepared for launch, the U.S. Geological Survey (USGS) announced it will begin procedures to decommission the 28-year-old Landsat 5 in January.
The USGS, which operates Landsat satellites and manages the data the spacecraft gather, said in a Dec. 21 press release that a gyroscope failure discovered in November spurred the decision to deorbit the venerable Landsat 5, which launched March 1, 1984. That satellite, one of only two Landsat craft on orbit, has long been operating on backup systems and in recent years has experienced a number of technical issues.
“Upon completion of the decommissioning process in the next several months, Landsat 5 will be left in a decaying orbit that will result in atmospheric reentry in approximately 33 years, based on NASA debris assessment software,” Tim Newman, a USGS spokesman, said in a Dec. 21 email.
In late 2011, problems with an amplifier began to severely degrade Landsat 5’s imaging capabilities. Its main Thematic Mapper instrument was subsequently switched off and a backup sensor, the Multi-Spectral Scanner, was activated for the first time in more than a decade. In 2009, Landsat 5 experienced a gyroscope anomaly that sent it temporarily tumbling out of control.
Meanwhile, the Landsat Data Continuity Mission (LDCM) spacecraft, the latest in the 40-year-old Landsat program, arrived Dec. 20 at Vandenberg for integration with the United Launch Alliance Atlas 5 scheduled to launch it Feb. 11. Landsat 5 will be well clear of LDCM’s intended polar low Earth orbit by the time the new spacecraft launches, Newman said.
Launch preparations are underway at Vandenberg, where pad technicians are scheduled to fuel LDCM the week of Jan. 7, said Omar Baez, NASA’s launch director for the mission. The fueled satellite is scheduled to be mated with its launch adapter Jan. 17, encapsulated into its fairing shortly thereafter, and brought out to the pad Jan. 25 for integration with Atlas 5, Baez said in a Jan. 3 phone interview.
The Atlas 5 rocket that will launch LDCM has been vertical at the pad at Vandenberg since late last year. NASA and United Launch Alliance (ULA) fueled the rocket in early December in a wet dress rehearsal, then performed a borescope inspection on the launcher.
The borescope inspection, which is not part of the standard Atlas 5 preflight pad routine, was intended to detect any trace of particulates in the rocket’s plumbing. The test was deemed necessary due to an ongoing anomaly investigation of an upper-stage engine anomaly during a ULA Delta 4 launch in October, Baez said.
Delta 4 and Atlas 5 upper stages use different variants of Pratt & Whitney Rocketdyne’s RL-10 engine. Delta 4 is grounded until ULA and the Air Force finish their anomaly investigations. On Dec. 11, Atlas 5 flew for the first time since the Delta 4 anomaly, launching the Boeing-built X-37B spaceplane on a classified mission for the U.S. Air Force.
LDCM has two main instruments: a $188 million medium-resolution Operational Land Imager, built by Ball Aerospace & Technologies Corp. of Boulder, Colo., and the $160 million Thermal Infrared Sensor, which was built at the NASA Goddard Space Flight Center in Greenbelt, Md. The satellite platform was built at the Gilbert, Ariz., facilities of Orbital Sciences Corp.
In March, the U.S. Government Accountability Office estimated that the LDCM would cost $930 million including spacecraft construction, launch and five years of operations.
Once in space, LDCM will be renamed Landsat 8. Orbital will not officially turn the spacecraft over to the USGS until after the craft completes on-orbit testing to verify that all of its systems are running smoothly.
Since the 1970s, Landsat-series satellites have been collecting low- to medium-resolution imagery of land masses in multiple spectral bands for applications including resource management, agriculture and land-use planning. NASA manages procurement and launch of the satellites on behalf of the USGS.
In addition to Landsat 5, the USGS operates Landsat 7, which was launched in 1999 on a mission intended to last at least five years. That satellite suffered a glitch on its main sensor in 2003 and has been returning degraded but usable data ever since.
The Landsat 6 satellite suffered an on-board propulsion failure after separating from its launch vehicle in 1993 and never reached orbit.