The Landsat program has revolutionised how we view the Earth during its 40 continuous years of operation. The reams of data generated by seven generations of satellites has helped govern both public and private policies from agriculture and forestry management to cartography, geology and urban planning. The eighth iteration of Landsat is slated for launch next week and is expected to deliver more detailed data than ever.
The Landsat program is a collaboration between NASA and the Geological Survey (USGS) and has been generating medium-resolution satellite imagery (15m to 60m resolution) non-stop since the first Landsat satellite launched in 1972. Over this time, the program has generated millions of images which provide a constant, near real-time record of the Earth's surface and humanity's interactions with it, not to mention providing invaluable data during natural disasters and subsequent relief efforts. Through publicly available records, researchers, educators, government agencies and private citizens can access torrents of scientific data relating to climate change, carbon and water cycles, ecosystems, and more.
"The Landsat program provides the nation with crucial, impartial data about its natural resources," said Matthew Larsen, USGS associate director for climate and land use change in Reston, Va said in a press statement. "Forest managers, for instance, use Landsat's recurring imagery to monitor the status of woodlands in near real-time. Landsat-based approaches also now are being used in most western states for cost-effective allocation of water for irrigation. This mission will continue that vital role."
This role began in 1965 when then-director of the USGS, William Pecora, proposed the program after being inspired by the orbital photography of the Mercury and Gemini projects. Until that point, weather satellites were the only orbiting devices that looked back at the Earth and they only stared at the clouds. That same year, NASA had begun taking land surveys with plane-mounted instruments, though the cost of continually operating these planes was unfeasible. Due to the budget constraints and the glacial pace of progress in Washington, the first Landsat satellite didn't launch for another seven years.
Landsat 1 launched on July 23, 1972, the first Earth-observing satellite launched specifically to monitor landmasses. To perform this task, the Landsat 1 carried a Return Beam Vidicon (RBV) camera system built by RCA and a Multispectral Scanner (MSS) built by Hughes Aircraft. Though the RBV was initially sent up as the primary data collection device, an electrical glitch that caused the satellite to lose altitude whenever the RBV switched on (as well as inferior data quality) forced mission control to demote it as the primary camera and use the four-band MSS instead. This is believed to be the first instance of the Kaepernick Effect observed outside of the Earth's atmosphere.
In the years since, an additional six Landsats have been launched. All but Landsat 6, which failed to reach orbit in 1993, have been operating for anywhere from 5 to 28 years. Landsats 5 and 7 are actually still functional to certain degrees (#7 has battled a faulty scan line corrector since 2003, #5 is practically dead) but continue to produce data. The Seventh iteration features eight spectral bands (double that of the original) and can achieve resolutions of 15m to 60m and completes a full sweep of the Earth every 16 days.
The newest iteration, dubbed the Landsat Data Continuity Mission (LDCM) until the satellite reaches orbit, will continue this critical data collection while improving the rate and quality of the information it captures. Circling the planet once every 99 minutes (14 times a day) at a height of 438 miles, the new satellite will cover more of the electromagnetic spectrum, generate more precise data while capturing 60 per cent more shots per orbit.
The Landsat 8 will use new imaging equipment with capabilites far superior to even what the last satellite carried. It will use an Operational Land Imager (OLI) from Ball Aerospace & Technologies, to observe landmasses, near infrared and shortwave infrared as well as two additional bands for observing high altitude cirrus clouds and water quality in shallow bodies like lakes and coastlines. It will also carry the NASA-built Thermal Infrared Sensor (TIRS) which records thermal fluctuations on the surface in two distinct bands -- vital for irrigation and agricultural management.
NASA intends to launch the LDCM on February 11th at 10:02AM PST from Vandenberg Air Force Base in California aboard the massive Atlas V-401 rocket. Once it enters a polar orbit and properly boots up, it will fall under the jurisdiction of the USGS and begin transmitting data to one of three ground stations in Alaska, South Dakota, and Norway for archival and posting.