A new higher-resolution infrared camera equipped with a variety of lightweight filters could examine sunlight reflected from Earth’s upper atmosphere and surface, improve forest fire warnings and reveal the molecular composition of other planets.
The cameras use sensitive, high-resolution superlattice sensors originally developed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, using IRAD, Internal Research and Development funding.
Their compact construction, low mass and adaptability allow engineers like Tilak Hewagama to adapt them to the needs of a variety of sciences.
“By attaching filters directly to the detector, the significant mass of traditional lens and filter systems is eliminated,” Hewagama said. “This enables a low-mass, compact focal plane instrument that can now be cooled for infrared detection using smaller, more efficient coolers. Smaller satellites and missions can benefit from their resolution and accuracy.”
Engineer Murzy Jhabvala led the initial sensor development at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and also led the current filter integration efforts.
Jhabvala also led the Compact Thermal Imager experiment on the International Space Station, which demonstrated how the new sensor technology could survive in space while proving to be a major success for Earth science. More than 15 million images captured in two infrared bands earned inventors, Jhabvala and NASA Goddard colleagues Don Jennings and Compton Tucker, a 2021 Invention of the Year award.
Data from the test provided detailed information about forest fires, a better understanding of the vertical structure of Earth’s clouds and atmosphere, and captured an updraft caused by winds rising from Earth’s land features, called a gravity wave.
The groundbreaking infrared sensors use layers of repeating molecular structures to interact with individual photons or units of light. The sensors resolve more wavelengths of infrared at higher resolution: 260 feet (80 meters) per pixel from Earth orbit compared to 1,000 to 3,000 feet (375 to 1,000 meters) possible with current thermal cameras.
The success of these thermal cameras has led to investments from NASA’s Earth Science Technology Office (ESTO), Small Business Innovation and Research, and other programs to further adapt their range and applications.
Jhabvala and NASA’s Advanced Land Imaging Thermal IR Sensor (ALTIRS) team are developing a six-band version for this year’s LiDAR, Hyperspectral and Thermal Imager (G-LiHT) airborne project. This camera, the first of its kind, will measure surface heat and enable pollution monitoring and fire observations at high frame rates, he said.
NASA Goddard Earth Scientist Doug Morton is leading an ESTO project developing a Compact Fire Imager for detecting and predicting wildfires.
“We’re not going to see fewer fires, so we’re trying to understand how fires release energy during their life cycle,” Morton said. “This will help us better understand the new nature of fires in an increasingly flammable world.”
CFI will monitor both the hottest fires, which release more greenhouse gases, and cooler, smoldering coals and ash, which produce more carbon monoxide and airborne particles such as smoke and ash.
“These are key ingredients when it comes to safety and understanding the greenhouse gases released during combustion,” Morton said.
After testing the fire imager during airborne campaigns, Morton’s team is considering equipping a fleet of ten small satellites to provide global fire information with more images per day.
Combined with next-generation computer modeling, he said, “this information can help the Forest Service and other fire agencies prevent fires, improve the safety of firefighters on the front lines and protect the lives and property of those living in the path of the fires.” to protect.”
Exploring clouds on Earth and beyond
Equipped with polarizing filters, the sensor could measure how ice particles in the clouds of Earth’s upper atmosphere scatter and polarize light, said NASA Goddard earth scientist Dong Wu.
These applications would complement NASA’s PACE — Plankton, Aerosol, Cloud, ocean Ecosystem — mission, said Wu, who unveiled the first light images earlier this month. Both measure the polarization of the light wave’s orientation in relation to the direction of motion from different parts of the infrared spectrum.
“The PACE polarimeters monitor visible and short-wave infrared light,” he explained. “The mission will focus on aerosol and ocean color sciences based on daytime observations. At mid- and long-infrared wavelengths, the new infrared polarimeter would capture cloud and surface properties from both day and night observations.”
In another effort, Hewagama is working with Jhabvala and Jennings to incorporate linear variable filters that provide even more detail within the infrared spectrum. The filters reveal the rotation and vibration of atmospheric molecules, as well as the composition of the Earth’s surface.
That technology could also benefit missions to rocky planets, comets and asteroids, said planetary scientist Carrie Anderson. She said they were able to identify ice and volatile compounds emitted in huge plumes from Saturn’s moon Enceladus.
“They are essentially geysers of ice,” she said, “which are of course cold, but emit light within the detection limits of the new infrared sensor. If we look at the plumes against the background of the sun, we can identify their composition and vertical distribution very clearly.”
By means of Karl B. Hille
NASA’s Goddard Space Flight Center, Greenbelt, Maryland.