A Trip Through Time With Landsat 9
August 31, 2021 • For half a century, the Landsat mission has shown us Earth from space. Now, come along with us on a "roadtrip" through the decades to see how the technology on this NASA and U.S. Geological Survey partnership has evolved with the times to provide an unbroken data record.
Our roadtrip begins with the idea for an Earth-observing sensor in the 1960s and then cruises through the first game-changing launches in the 1970s, the advent of natural color composite images in the 1980s, the increased global coverage in the 1990s, the move to free and open data archives in the 2000s, the modern era of Landsat observations in the 2010s, and now the launch of Landsat 9 in 2021.
Landsat satellites have allowed us to better manage our natural resources, and will continue to help people track the effects of climate change into the future. The Landsat Program is a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey (USGS). Landsat satellites have been consistently gathering data about our planet since 1972. They continue to improve and expand this unparalleled record of Earth's changing landscapes for the benefit of all.
From 438 miles above Earth's surface, the newest Landsat satellite will collect data so detailed, it can detect both natural and human-caused changes to the landscape.
But what really makes Landsat unique is the half-century of data, an unbroken chain of observations over five decades. Let's take a look at how we got here.
1966: The US Geological Survey proposed a satellite to study Earth's land masses. But what would that look like? Over the next few years, USGS and NASA research their options.
1970: NASA gets the green light to build an Earth Resources Technology Satellite, an experiment to study and monitor our planet's land surface from space. Launched in 1972, this was the first digital data of Earth, repeated at regular intervals, with geometric fidelity to allow comparison between observations. This changed how we drew maps, tabulated agricultural production, and assessed damage after disasters.
In 1975, NASA launched a second satellite, similar to the first. Now they were collecting twice as much data. With Landsat 3 replacing the aging original in 1978, focus shifted to the advanced technology planned for the 80s.
The Thematic Mapper instrument, launched on Landsat 4 in 1982 and on its twin Landsat 5 in 1984, was a major step forward. Collecting seven different wavelengths, at better ground resolution, and with higher precision, this was the beating heart of the satellite and became the work horse for a generation of scientists. For the first time, Landsat data had three visible bands—red, green, and blue—allowing natural-color composite images. And with the addition of short-wave infrared wavelengths, the data could better highlight flooded areas, mineral deposits, and burn scars from wildfires. The thermal bands were also upgraded allowing individual farm fields to be tracked.
The sixth Landsat was intended to be another big step forward, but it never reached orbit after launch in 1993. Plans immediately began for Landsat 7, which would carry an even more improved sensor.
At the time, the Enhanced Thematic Mapper Plus was the most stable Earth observation instrument ever sent into orbit, and the calibration could be updated while in space. For the first time, we had an instrument robust enough to collect lots of data, and we had a plan to thoroughly record the entire globe. Landsat 7 was put to work mapping coral reefs, and even produced the first high-resolution natural-color map of remote Antarctica.
Improvements to the thermal bands on Landsat 7 allowed states and counties to gauge how much water was used by crops. This helps manage water resources efficiently.
An important milestone occurred in 2008, when the USGS made the data available to download for free. Users were able to get the data they needed, and not just what they could afford. It really unlocked a ton of innovation and created about 2 billion dollars a year in economic benefits.
The modern era of Landsat observations began with the launch of Landsat 8 in 2013. Having a push-broom style sensor on Landsat 8 was a big improvement over the older scanning sensor.
The Landsat 8 ground system that USGS runs is capable of receiving a lot more data than before. We're downloading over 725 scenes each day. That just wasn't remotely possible until Landsat 8.
The two European Sentinel-2 satellites were designed to mesh with Landsat so that users can treat data from all the satellites as if it came from one single source. Now we get observations every 2 or 3 days, instead of every 2 weeks.
2021 is the launch of Landsat 9, the next step forward. It will collect the best data ever recorded by a Landsat satellite, while still integrating seamlessly with the extensive archive.
Since the early 1970s, Landsat satellites have allowed us to better manage our resources.
Landsat data has enabled countless innovations and will let us track the effects of climate change into the future.