September 16, 2021
The second generation of NASA's Ice, Cloud and land Elevation Satellite (ICESat-2) is responsible for taking important measurements of our planet's key health indicators, including ice sheet mass balance, depth of bodies of water, cloud and aerosol heights, as well as land topography and vegetation characteristics.
And, it also, from time to time, turns up some fun and entertaining images from around the world — such as an old airplane hangar in Germany that has been converted into a water park (more on that later).
September 15 marks three years since ICESat-2 launched. It is the descendant of the original ICESat, and the satellite provides scientists with key information about how the planet is changing in response to a rapidly evolving climate. And leading scientific development of this important program is a fairly new Texas Engineering faculty member.
Lori Magruder joined the Cockrell School of Engineering in 2020 as an associate professor in the Department of Aerospace Engineering and Engineering Mechanics. Prior to that, she was at The University of Texas at Austin's Applied Research Laboratories for 14 years, where she still spends time as a senior research scientist. Magruder has been an integral part of the ICESat-2 team for the last seven years, leading the Science Definition Team to support mission development and early on-orbit satellite operations for ICESat-2.
Magruder is an expert in remote sensing. And one of her many important jobs with ICESat-2 is geolocation validation.
"That means that we make sure things actually are where ICESat-2 says they are," said Magruder.
To test this, Magruder travels to White Sands Missile Range in New Mexico frequently. There, she places a series of corner retroflectors, small cubes about 8 millimeters in diameter, around the site. She notes where they are and compares them to where ICESat-2 measures them to be.
These little sensors are a very important part of Magruder's work. So much so, that she had a pair of them made into earrings.
Magruder moved over to the Cockrell School because she wanted to teach and foster greater student involvement in her research. Magruder is teaching a 3D remote sensing course this semester that focuses on lidar and photogrammetry systems, data analysis and applications. As part of her research, students are working on developing new missions and techniques for ICESat-2 in bathymetry —measuring the depth of bodies of water — and monitoring sea floors.
In the last year, she has published nearly a half-dozen papers related to ICESat-2. They've covered a variety of aspects of the satellite, including geolocation and several other topics:
- A mission overview of ICESat-2 and an evaluation of its performance so far — the Advanced Topographic Laser Altimetry System (ATLAS) onboard has taken more than a trillion measurements and is able to repeat measurements to within 10 meters and pointing control within 45 meters.
- A description of the system that influences laser pointing direction for ATLAS — the accuracy of ICESat-2's measurements hinges on the ability to precisely determine the correct pointing angle of the laser beams from the satellite to the target area on the surface.
- In tandem with researchers from Oregon State University, Magruder and team published a paper focused on capturing data and imagery of the seafloor. They found that in clear conditions, ICESat-2, from 300 miles above the surface, can measure underwater to a depth of 50 meters.
"These measurements allow us to map places that have never before been mapped, filling in a big void in our knowledge of the world," Magruder said.
Like most everyone else, the ICESat-2 science team has been working remotely since the onset of the pandemic. To spice up the spring meeting this year, Magruder challenged team members to pick their favorite world landmark, or fun offbeat place, and see if it had been captured by ICESat-2.
The pool in Krausnick, Germany, the world's largest indoor waterpark, was the winner of the contest.
The team also presented snapshots of breathtaking features, including the collapse of the Pine Island Glacier, the fastest melting glacier in Antarctica; the first underwater post office off the coast of Australia; the pyramids in Egypt; Fenway Park in Boston; and Nikumaroro Island, the possible landing spot of aviation legend Amelia Earhart, who disappeared on a flight in 1937.
The competition was a morale booster and also an interesting demonstration of all that the satellite has, and has not, captured during its time in orbit.
"I can tell you that ICESat-2 has not measured the Eiffel Tower yet but has hit my parent's house in Kansas," Magruder said.
Magruder is also affiliated with UT's Center for Space Research. Learn more about Magruder's work on her website.
