Taking the long view: Alumna helps satellite “see” changing ice sheets

Monday, April 21, 2014 - 3:59pm

By David Zubenko

Sometimes the best way to solve a problem is to observe it from a distance. That is the approach  Kaitlin Walsh (B.S. ’09) has chosen to take when it comes to studying ice sheets. Walsh is currently working on the ICESat2 satellite at the NASA Goddard Space Flight Center in Greenbelt, Maryland. Upon its arrival in space in 2017 ICESat2 will use lidar technology to measure the height of the Earth’s surface and any variations that occur over time. Of particular interest to Walsh is the data that will be gathered on our planet’s melting ice sheets, which she will use in her quest to preserve this vital component of our environment.

Like many geographers before her, Walsh was drawn to the profession by its all-encompassing nature. While at Penn State, she took advantage of this diversity and completed courses in meteorology, climatology, geology, and glaciology. Walsh found glaciology particularly fascinating, and in 2008 dove deeper into the field by participating in the College of Earth and Mineral Science’s CAUSE (Center for the Advancement of Undergraduate Student Experiences) program. The class culminated in a 10-day trip to Iceland where Walsh, “had the opportunity to collect data on an outlet glacier of Vatnajökull, the largest ice cap in Europe.”  Upon completion of her undergraduate degree, Walsh continued her studies at Ohio State, where she got a M.S. in Earth Sciences with a focus in glaciology. While at OSU she participated in NASA’s Operation IceBridge, “a multi-instrument mission that flies over Greenland and Antarctica to study glacier and ice sheet change,” she explains. As a result of this experience, Walsh was able to develop relationships with NASA scientists that helped her get a job at the agency as a support scientist for the ICESat2 satellite.



Kaitlin Walsh

As a part of NASA's Operation IceBridge mission, Walsh had a chance

to study ice sheets in Chile in 2010.


How ICESat2 works

“ICESat2 is a micro-pulse, multi beam, photon-counting laser altimeter (lidar) that is planned for launch in the fall of 2017,” Walsh explains.
A lidar is an instrument that directs a laser shot at the ground and then detects the amount of time it takes for the return pulse to arrive back at the instrument (or sensor). A photon-counting lidar is a bit different – the instrument sends down a stream of photons, and the pulse that is returned to the sensor shows the stopping point of these photons on the Earth’s surface. 
“We’re looking for when a large agglomeration of continuous photons are returned to the instrument in order to determine the elevation of the ground (the signal) by calculating how long it takes the photons to return to the sensor,” Walsh says, adding, “Currently, we’re using MABEL (Multiple Altimeter Beam Experimental Lidar), which is a test photon-counting lidar that flies on a high-altitude aircraft (roughly 65,000 feet) to simulate the data that we’ll receive from space onboard ICESat2. The algorithms onboard the spacecraft will determine which photon information gets sent back to Earth for analysis and signal finding. The satellite will pass over the same locations on Earth every 91 days and take a measurement roughly every 70 cm along the track of the satellite, which will allow scientists to develop a picture of how certain ground surfaces are changing.”
 “My main task for the first year and a half was working with another scientist to develop an algorithm and computer software that would take data from MABEL and locate the ground from the photons that had been returned to the instrument,” Walsh says. “This ground-finding algorithm will eventually be incorporated into ATLAS (Advanced Topographic Laser Altimetry System), which is going to be the laser altimeter onboard ICESat2.”
“Right now, my software is being used to identify surface photons in MABEL data from ice sheets, vegetated surfaces, sea ice, and open water. These results give us an idea of what we can expect from ICESat2 once it’s launched. In addition to writing this ground-finding software, I’m also in charge of managing satellite orbit planning for the science team. This is not necessarily where the satellite will fly, but how the satellite will act when it is flying over certain land and water types,” she explains.

Walsh credits her success at NASA to her organizational and communication skills, which she developed as an undergrad through her involvement in a variety of clubs, including UnderDoGs. When asked for career planning advice, she provided the following recommendations:

“While you’re an undergraduate, challenge yourself. Take a difficult class that you might not need to take, but one that expands and deepens your knowledge on a subject that you’re passionate about. Make sure you are doing what you can to seek out professional development opportunities – your dream internship or summer job probably won’t get offered to you out of the blue. Connect with faculty members that are doing research in what you find interesting and find out if they have opportunities for undergraduate students to help out with that research.  Most importantly, be sure to speak up and take any opportunity that sounds of interest!”

It is safe to say that Walsh followed her own advice in her journey from Penn State to NASA. While no one knows what will happen next, the sky is the limit.