GLAST will be launched into a circular orbit around the Earth at an altitude of about 560 km (350 miles). At that altitude, the observatory will circle Earth every 90 minutes. In sky-survey mode, GLAST will be able to view the entire sky in just two orbits, or about 3 hours. Because gamma rays in the GLAST's energy band are unable to penetrate the Earth's atmostphere, it is essential that GLAST perform its observations from space. Note: This beauty shot begins with the earth in full view and pans to reveal the spacecraft in orbit. Animator: Chris Meaney (HTSI). Scientist: Steven Ritz (NASA/GSFC). Platforms/Sensors/Data Sets: Fermi/LAT.