The United Launch Alliance Delta II rocket with the Aquarius/SAC-D spacecraft atop is prepared for launch.

At NASA's Launch Complex-2 at Vandenberg Air Force Base in California the United Launch Alliance Delta II rocket with the Aquarius/SAC-D spacecraft atop is prepared for launch.

Liftoff is slated for 7:20 PDT/10:20 EDT today. Aquarius, the NASA-built instrument on the SAC-D spacecraft will provide new insights into how variations in ocean surface salinity relate to fundamental climate processes on its three-year mission. For more information visit: www.nasa.gov/aquarius. Photo credit: NASA/VAFB