John Hile, right, an Arnold Engineering Development Complex (AEDC) test engineer, speaks with Sen. Bill Hagerty of Tennessee about the arc heaters used for high-temperature materials characterization and evaluation during a visit by the senator to the headquarters of AEDC, Arnold Air Force Base, Tenn., Aug. 23, 2021. Arc heaters allow for the testing of thermal protection systems in simulated environments representative of hypersonic flight. (U.S. Air Force photo by Jill Pickett)