Grant David Callin is part of the hard science fiction stream of authors. Callin graduated from the Air Force Academy in 1963, and retired from the service in 1984. He holds a bachelor's degree in basic sciences, and advanced degrees in space physics, physiology and biophysics. An amateur astronomer, he built his own 8-inch (200 mm) telescope and does some astrophotography. As of 1986, he worked for Boeing Aerospace Company as a research analyst, involved with the work on the NASA Space Station Program. He is currently in retirement in Sammamish, WA.