NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, and its rocket flew above the palm trees to arrive at their launch location at the U.S. Army's Reagan test site at Kwajalein Atoll.

Kwajalein, located midway between Hawaii and Australia, is one of the world's largest atolls - coral islands with lagoons in the middle.

The mission is scheduled to launch June 13 no earlier than 8:30 a.m. PDT (11:30 a.m. EDT).

Currently, NuSTAR is tucked into the top of the rocket, a Pegasus XL from Orbital Sciences Corporation, which is strapped to the bottom of a carrier plane, the L-1011 "Stargazer," also from Orbital.

About an hour before launch, NuSTAR and its rocket will be flown out over the Pacific Ocean and dropped. Five seconds later, the rocket will ignite and boost NuSTAR into its final orbit around Earth's equator.

A video showing a previous Pegasus launch is online here.

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va.

Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA's Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; and ATK Aerospace Systems, Goleta, Calif. NuSTAR will be operated by UC Berkeley, with the Italian Space Agency providing its equatorial ground station located at Malindi, Kenya.

The mission's outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

Launch management and government oversight for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida.

Live launch commentary and coverage will be broadcast online beginning at 7 a.m. PDT (10 a.m. EDT) June 13.