Gamma-Ray Instruments on High Altitude Balloons
Many of the gamma-ray instruments that are flown in space are first
developed and tested as balloon-borne payloads. NASA has an active balloon
program, flying huge helium research balloons at altitudes of 40 km. The
balloons fly for 1 or more days, after which the payloads return
to the ground on a parachute. In addition to instrument development, many
of the scientific results in gamma-ray astronomy have come from ballooning.
Examples of gamma-ray balloon payloads are the Gamma Ray Imaging Spectrometer (GRIS) (http://lheawww.gsfc.nasa.gov/docs/balloon/New_GRIS_homepage/gris.html) and the International Focusing Optics Collaboration for microCrab Sensitivity (InFOCµS) (http://lheawww.gsfc.nasa.gov/docs/balloon/FOCUS.html).