11 days ago, Landsat 9 launched on an Atlas 5 rocket. Landsat 9 is part of one NASA's oldest programs. It has provided high-quality images of the Earth in the visible and infrared portions of the electromagnetic spectrum. The images have been acquired on a constant basis since the 1970's. These images have been extremely useful to farmers, scientists, and urban planners, and probably benefit you in multiple ways. So what's the history of the Landsat program? And how does it help people throughout the world?
Program Beginnings
In 1966, the US Department of the Interior announced that they were going to work with NASA to develop a program to observe the Earth and gather "facts on the distribution of needed minerals, our water supplies and the extent of water pollution, agricultural crops and forests and human habitations.” (Department of the Interior, 1966). The program was originally called the Earth Resources Observation Satellites, but was later given a shorter name, Landsat.
The first 3
The first 3 Landsat missions used a spacecraft constructed by General Electric that was based on the Nimbus 4 weather satellite. The satellites were each powered by two large solar array panels that could rotate to face the sun. There were two science instruments, the RBV and MSS, which could both image the Earth in different ways. Once Landsat 1 reached its orbit, it was discovered that the MSS created better images, so it was used more.
Landsat 1 was launched from Vandenburg AFB on July 23rd, 1972 on a Delta 904 rocket. Three years later, Landsat 2 was also launched into orbit on a Delta 2910. NASA launched the third Landsat satellite in 1978, also on a Delta 2910. By the time that Landsat 3 had launched, Landsat 1 had been decommissioned because of difficulties with it's tape recorder. Landsat 1 operated 5 years longer that it was designed for.
A new generation
After Landsat 3 launched, NASA redesigned the Landsat spacecraft.
Landsat 4 and 5 were based on the MultiMission Modular Spacecraft, a spacecraft bus that was designed to be compatible with the space shuttle. Landsat 4 and 5 each had one large solar array, and an antenna attached to a retractable boom. NASA also replaced the RBV with a more advanced instrument, the Thematic Mapper (TM). TM was better than the MSS in multiple ways, it had 7 bandwidths instead of 4, and could now see further into the infrared and see blue. The TM also had much better resolution.
Landsat 4 and 5 were both launched on Delta 3920's into a lower orbit, which allowed them to map the entire Earth in 16 days, instead of 18. Landsat 4 launched in 1982, and for a short time 3 Landsat satellites were operating at the same time. In 1983, Landsat 2 and 3 stopped operating and were retired, they were replaced by Landsat 5, which launched in 1984. Landsat 5 operated until 2013, and was the longest operating Earth observing satellite .
Landsat 6 and 7
In order to make sure that NASA and the USGS continued to get high-quality pictures of Earth, Landsat 6 and 7 were built. These two satellites used Lockheed Martin's TIROS-N satellite bus. They also had upgraded versions of the Thermal Mapper, Landsat 6 had the Enhanced Thermal Mapper (ETM) and Landsat 7 had the ETM+. In 1993, Landsat 6 launched on a Titan II, but failed to reach orbit. For a time, the aging Landsat 5 was the only Landsat in orbit, and there were concerns that there would be a gap in data collection.
In 1999, Landsat 7 was completed and was launched on a Delta II rocket. It operated properly until 2003 when NASA discovered that Landsat 7 had a major issue. The Scan Line Corrector, a key component of the ETM+, failed. Without the Scan Line Corrector, images were made of zigzags, not straight lines. This compromised the quality of Landsat 7 images, but was not mission-ending.
Landsat 8 and 9
Landsat 8 and 9 were built by Orbital Sciences corporation (now Northrop Grumman). They each have two science instruments, the Operational Land Imager (OLI) and the Thermal InfraRed Sensor (TIRS). OLI can detect 9 different spectral bands in the visible and infrared. TIRS can detect infrared waves to determine the temperature of different areas of the Earth. Together, the two instruments are able to gather information about plants, water, and urban growth.
Landsat 8 was launched on an Atlas V rocket in 2013 to replace Landsat 5. Soon after it arrived in orbit, Landsat 5 was decommissioned because of numerous issues with the spacecraft.
And now we come to present. Landsat 9 launched on September 27th, 2021 on an Atlas V rocket. It has been undergoing testing to make sure that it's operating properly. Landsat 7 ran out of fuel in 2011 and it's orbit has been degraded low enough for Landsat 9 to move directly above it. NASA plans to decommission Landsat 7 once Landsat 9 comes into full operation.
Benefits to you
Landsat data is free to use and benefits you in countless ways. It helps farmers around the world know when to water and fertilize crops, scientists understand the impact of volcanic eruptions and forest fires, and helps the urban growth of cities be easily measured. Landsat provides data that is key to helping us understand the effects of climate change. This data also helps us understand our water resources, track algal blooms, learn about the affects of natural disasters, and assists scientists working to restore natural habitats. And all of this comes from Landsat, a project that simply images the Earth.
Some Images
This article wouldn't be compete without some amazing pictures of the Earth. See the gallery below, which is filled with Landsat images. They all come from NASA's Landsat Image Gallery.
Landsat imagery courtesy of USGS/NASA Landsat