From left, Dr. Phil Kreth and Haley Goldston, with the University of Tennessee Space Institute, set up equipment in SL-2, a sea level turbine engine test cell at Arnold Air Force Base, Tenn., April 27, 2022, to observe and record shadowgraph data of the air flow from various nozzles. (U.S. Air Force photo by Jill Pickett) (This image has been altered by obscuring a badge for security purposes.)