(01/10/2002) --- VANDENBERG AFB, CALIF. - A worker prepares the High Energy Solar Spectroscopic Imager (HESSI) for encapsulation atop the Pegasus XL rocket before its transport to Florida. The Pegasus is the vehicle that will launch HESSI on its primary mission to explore the basic physics of particle acceleration and energy release in solar flares. The launch of PegasusXL/HESSI is scheduled for Feb. 5, 2002, from beneath an Orbital Sciences Corp. L-1011 aircraft over the Atlantic Ocean