Cryogenics make it easy to breathe
Senior Airman Seth Bruning, 86th Logistics Readiness Squadron hydrants technician, fills a liquid oxygen tank on Ramstein Air Base, Germany, Sept. 3, 2014. Cryogenics receive, store, maintain and issue liquid oxygen and liquid nitrogen to aircrafts so the aircrew can breathe while at higher altitudes. (U.S. Air Force photo/Airman 1st Class Michael Stuart)