Landsat infrared instrument ready after stringent testing

September 16th, 2019, Published in Articles: PositionIT

From orbit aboard the Landsat 9 satellite, the Thermal Infrared Sensor 2, or TIRS-2, will measure the temperature of Earth’s land surfaces, detecting everything from a smouldering wildfire, to the amount of irrigation used on crop fields, to wispy clouds that are all but invisible to other instruments. First, however, it had to survive tests that simulated the harsh environment of space.

This month, TIRS-2 successfully passed the stringent twelve-week testing process at NASA’s Goddard Space Flight Center in Maryland, US. It was shipped to Northrop Grumman’s facility in Arizona, where it and the Operational Land Imager 2 will be assembled onto the Landsat 9 spacecraft. Landsat 9 is a joint effort of NASA and the US Geological Survey (USGS).

Engineers at NASA’s Goddard Space Flight Center work on the TIRS 2 instrument, which will measure surface temperatures on earth from the Landsat 9 satellite. (Credit: NASA)

TIRS-2 is designed to work in the same way as the first TIRS instrument, which launched on Landsat 8 in 2013 and is still collecting important data on Earth’s surface temperature. But the latest version has a couple improvements. It incorporates a new optical component to shield the instrument’s sensor from stray light that had caused problems on the original instrument, requiring software fixes. The first TIRS was also designed, constructed, and integrated in less than three years – which is an incredibly quick turnaround for a satellite’s instrument – and so it was only required to last three years. TIRS-2, however, is designed with redundant electronics and other components in order to last at least five years.

TIRS-2 has about ten main components, and each one was built and tested individually before engineers brought everything together to ensure the instrument worked. The engineering team, which included as many as 250 people, then tested the whole instrument both in the clean room, as well as in environmental chambers that simulate the launch and space environments.

With round-the-clock shifts and successful tests, the team delivered the instrument more than two weeks ahead of its target date. TIRS-2 passed its pre-ship review on 12 August and was trucked to Gilbert, Arizona in two shipments. At the Northrop Grumman facility, the team will reassemble it, test it, and make sure everything is ready to integrate the instrument with the Landsat 9 spacecraft.

Landsat satellites have been observing Earth since 1972, building the longest continuous record from space of the planet’s forests, farms, cities, and other surfaces. Starting with Landsat 4 and continuing through the first TIRS instrument on Landsat 8, the satellites have carried instruments that can detect thermal energy as well as visible and infrared light.

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