Close this search box.

Ten Years of TIRS: Data for a Thirsty World

Ten Years of TIRS: Data for a Thirsty World

By Laura E.P. Rocchio

Grounded sea ice in the Caspian Sea. A dot of purple in a patch of orange.
In the Caspian Sea, as sea ice begins to melt in February 2017, Landsat 8’s TIRS instrument captured this image of a lone chunk of grounded sea ice surrounded by thinner, warmer ice and open water (orange). In addition to water consumption estimates, Landsat 8’s TIRS instrument has been used to detect the birth of icebergs, monitor lava flows, and assess urban heat islands. Image credit: Joshua Stevens, NASA’s Earth Observatory

This past February we celebrated the 10-year launch anniversary of Landsat 8.  For a decade, Landsat 8 with its two scientific instruments—the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS)—has collected data about Earth’s surface. Providing information that is used routinely for environmental resource management around the world. The thermal information measured by TIRS has been particularly crucial for water management.

Yet, Landsat 8’s initial design, unlike that of preceding Landsats (4, 5 ,7), did not include a thermal instrument. Early return on investment sentiment was that the thermal data user group was small, and their applications didn’t warrant the additional cost of thermal data collection.

A faction of water managers in the U.S. West was determined to set the record straight, correct that misperception, and get a thermal sensor onto Landsat 8.

The Idaho Department of Water Resources had started using Landsat thermal data (together with its near infrared and shortwave infrared data) to map water consumption in 2000. Their water planners soon came to rely on Landsat-derived evapotranspiration (ET) data for long-term water supply estimates and water demand analysis. They increasingly found themselves turning to Landsat ET data to provide information for water rights legal proceedings. By 2007, twelve western states were actively using Landsat thermal data in their water management operations.

With the very real prospect of Landsat 8 launching without a thermal sensor and water managers losing their only data source for field-level water consumption measurements, western water managers began a sustained letter-writing campaign that changed the course of history. Governors, senators, state engineers, and natural resource department directors worked together to let Congressional decision-makers know that Landsat thermal data provided the “only efficient and accurate way to map how much and where water is being consumed.” Congress was made aware that continuing to have thermal sensors on Landsat satellites was fundamental for meeting the challenge of western water supply. The message had impact.

By 2009, funds were secured to add a thermal sensor to Landsat 8—the same year that Idaho won Harvard’s prestigious Ash Institute Innovations in American Government Award for its Landsat-based water management tool.

2022 ET estimate for fields around Corcoran, CA.
Information from OpenET showing ET estimates for fields near Corcoran, CA. OpenET provides estimates of the "total amount of water that is transferred from the land surface to the atmosphere through the process of evapotranspiration (ET)." Estimates are calculated by an ensemble of satellite-driven models. All models currently used by OpenET use Landsat data. As stated on the OpenET website, "Landsat is the only operational satellite that combines thermal and optical data at the spatial resolution needed to assess water use and water rights, which is often at the level of individual agricultural fields."

Challenge After Challenge: Getting TIRS Built

Mass model of TIRS wrapped in plastic.
A mass model of the TIRS instrument awaits in 2011, wrapped in plastic, to fly as “dead weight” on Landsat 8 if the TIRS instrument is not ready on time. Fortunately, the real TIRS was ready in time to fly on Landsat 8. Photo credit: Matt Montanaro

It was late in the game when funding for TIRS came through, and the thermal sensor had to be built quickly. Given the tight timeline, NASA decided to build TIRS as a “Class C” instrument, a system with less redundancy, required to satisfy only a three-year design life.

TIRS was built in-house at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. It was a fast build. The pressure was high. With an extremely demanding schedule to meet, the threat of cancelation was relentless.  NASA created a mass model—a piece of metal that weighed the same amount as the TIRS instrument—that would fly as “dead weight” if TIRS wasn’t ready in time.

But the design team came through; TIRS flew on Landsat 8.

TIRS—the sensor that very nearly wasn’t—has now been imaging Earth for a decade.

“I’m very glad that TIRS has lasted this long on-orbit,” says Landsat calibration scientist Matthew Montanaro. “That’s a testament to the hard work put in by the TIRS team during development, and the Cal/Val and Flight Operations teams that continue to monitor it on-orbit and step in to fix any issues that arise.”

Thanks to TIRS, satellite-based water management has continued, and projects like OpenET—“filling the biggest data gap in water management”—have been made possible.

The value of medium-resolution thermal data has been cemented.

“I highly doubt there will ever be a Landsat mission without a thermal band going forward,” Montanaro speculates.

Related Reading & References

Idaho Department of Water Resources, “Landsat Thermal Band: Importance of Landsat for Water Resources in Idaho.” Accessed May 30, 2023.

Goward, Samuel N., Darrel L. Williams, Terry Arvidson, Laura E.P. Rocchio, James R. Irons, Carol A. Russell, and Shaida S. Johnston. 2017. Landsat’s Enduring Legacy: Pioneering Global Land Observations from Space. Bethesda, MD: American Society for Photogrammetry and Remote Sensing; pp. 361-362.

Landsat 8 Thermal Data Ghost-Free After Stray Light Exorcism; Landsat Science

Banner Image Caption: A very early TIRS image of the Richat Structure in Mauritania taken on March 18, 2013, during Landsat 8's commissioning period. Image credit: Matt Montanaro

On Key

Recent Posts


STELLA Spring Webinar: April 15, 2024

STELLA users will talk about their experiences using the DIY spectrometer during this webinar. Panelists include Bianca Cilento (RIT), Karen Karker (SUNY), and Peder Nelson (OSU and NASA GLOBE Observer).

Read More »
On Key

Related Posts


STELLA Spring Webinar: April 15, 2024

STELLA users will talk about their experiences using the DIY spectrometer during this webinar. Panelists include Bianca Cilento (RIT), Karen Karker (SUNY), and Peder Nelson (OSU and NASA GLOBE Observer).

Read More »