Innovative infrared sensors developed by NASA promise advances in environmental monitoring and planetary science by increasing the resolution of Earth and space images. The newly developed high-resolution infrared camera with an array of lightweight filters has the potential to analyze sunlight reflected from Earth’s upper atmosphere and surface, improve wildfire warnings and detect the molecular structure of other planets.

These cameras are equipped with sensitive, high-resolution strained superlattice sensors originally developed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and funded through the Internal Research and Development (IRAD) program.

Thanks to their compact design, light weight and versatility, engineers like Tilak Hewagama can customize them for a variety of scientific applications.

Advanced capabilities of the sensor

“Attaching filters directly to the detector eliminates most of the traditional lens and filter systems,” Hewagama said. “This enables a low-mass device with a compact focal plane that can now be cooled for infrared sensing with smaller, more efficient coolers. Smaller satellites and missions can benefit from their resolution and accuracy.”

Engineer Murzi Jhabwala led the initial development of the sensors at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and leads today’s filter integration efforts.

Jhabwala also led the Compact Thermal Imaging experiment on the International Space Station, which demonstrated how a new sensor technology could survive in space and was also a major breakthrough for Earth science. More than 15 million images captured in two infrared bands earned Jhabwali inventors and Goddard’s NASA colleagues Don Jennings and Compton Tucker the agency’s 2021 Invention of the Year award.

Groundbreaking discovery in Earth and space observation

The tests provided detailed information about wildfires, provided a better understanding of the vertical structure of Earth’s clouds and atmosphere, and recorded an upward pull caused by wind rising above the Earth’s surface, called a gravitational wave.

Innovative infrared sensors use repeating layers of molecular structure to interact with individual photons or units of light. The sensors detect more infrared wavelengths from orbit with a higher resolution of 260 feet (80 meters) per pixel, compared to the 1,000-3,000 feet (375-1,000 meters) possible with current thermal imaging cameras.

The success of these thermal imaging cameras prompted NASA’s Earth Science Technology Office (ESTO), Small Business Innovation and Research, and other programs to invest in further refining their coverage and applications.

Jhabwala and NASA’s Advanced Ground Imaging Thermal IR Sensor (ALTIRS) team are developing a six-band version for this year’s airborne LiDAR, Hyperspectral and Thermal Imager (G-LiHT) project. He said this first-of-its-kind camera will measure surface temperature and perform pollution monitoring and fire surveillance at high frame rates.

Image from new generation fires

NASA Goddard Earth scientist Doug Morton leads the ESTO project developing a compact device to detect and predict wildfires.

“We’re not going to see fewer fires, so we’re trying to understand how fires release energy throughout their life cycle,” Morton said. “This will help us better understand the new nature of fires in an increasingly flammable world.”

The CFI will monitor both the hottest fires, which release more greenhouse gases, and the cooler, smoldering embers and ashes, which produce more carbon monoxide and airborne particles such as smoke and ash.

“These are important components for safety and understanding the greenhouse gases released during combustion,” Morton said.

After testing the fire camera in air raids, Morton’s team plans to equip a fleet of 10 small satellites to provide global fire information with more images per day.

When combined with next-generation computer models, “this information can help the Forest Service and other fire agencies prevent wildfires, improve the safety of front-line firefighters, and protect the lives and property of those living in the fire’s path,” he said.

The sound of the clouds on Earth and beyond

NASA Goddard Earth scientist Dong Wu said the sensor, equipped with polarizing filters, can measure how ice particles in Earth’s upper atmosphere scatter and polarize light.

These programs will complement NASA’s PACE – Plankton, Aerosol, Cloud, Ocean Ecosystem – mission, which showed first light images early last month, Wu said. Both measure the polarization of the direction of the light wave relative to the direction of propagation from different parts of the infrared spectrum.

“PACE polarimeters monitor visible and shortwave infrared light,” he explained. “The mission will focus on studying aerosols and ocean color using daytime observations. At mid- and long-infrared wavelengths, the new infrared polarimeter will capture cloud and surface features both day and night.”

In another effort, Hewagama is working with Jhabvala and Jennings to incorporate linear variable filters that provide even greater detail in the infrared spectrum. The filters detect the rotation and vibration of atmospheric molecules as well as the composition of the Earth’s surface.

The technology could also benefit missions to rocky planets, comets and asteroids, according to planetary scientist Kerry Anderson. He said that they could detect ice and volatile compounds coming out in large clouds from Saturn’s moon Enceladus.

“These are basically ice geysers,” he said, “they are cold, of course, but they emit light within the detection range of the new infrared sensor. Looking at the clouds against the background of the Sun will allow us to determine their composition and vertical distribution very clearly.”