VANDENBERG AIR FORCE BASE, Calif. - Operations are in work to transfer an Orbital Sciences Pegasus XL rocket onto the transporter in Orbitals hangar at Vandenberg Air Force Base in California. The rocket has been mated to NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, encapsulated in the Pegasus payload fairing. Cool, dry air is being pumped into the fairing through a purge line to maintain the proper environment for the spacecraft in the confined space.The transporter will move them to the runway ramp where they will be attached to the underside of Orbitals L-1011 carrier aircraft. The aircraft will fly the pair from Vandenberg to the Ronald Reagan Ballistic Missile Defense Test Site on the Pacific Oceans Kwajalein Atoll for launch. A revised launch date will be set at the Flight Readiness Review, planned for later this week. The high-energy X-ray telescope will conduct a census of black holes, map radioactive material in young supernovae remnants, and study the origi