TWIRLING TELESCOPES by Benjamin Skuse ough Space had a "sail" section that always pointed toward the Sun and a "wheel" part that swiveled full circle every 2-10 seconds, like an Oreo twirling on a flag skewer. Both sections carried instruments, but the larger, more complex ones were housed in the stationary sail part of the telescope - after all, the main goal was to stare at a fi xed target, the Sun. AGILE's Happy Accident But spinning can provide much more than stability, as the experience of the Italian AGILE satellite team so vividly shows. Launched in 2007, Astrorivelatore Gamma a Immagini Leggero (AGILE) is a wide-field gamma-ray instrument that explores cosmic high-energy physics. The initial aim was for the telescope to point in one direction for a couple of weeks and then move on to another area until it covered a large swath of sky. This worked well until the end of 2009, when the team hit a snag: The telescope's inertia wheel keeping the platform stable malfunctioned. Automatically AGILE switched into a safe mode: The spacecraft swiveled so that its solar panels constantly faced sk yandtele scope.com * M A RCH 2 019 21http://www.skyandtelescope.com