The planned first launch of NASA's new Orion MPCV spacecraft was scrubbed this morning after a string of delays kept the vehicle on the pad through the end of its 159-minute launch window. The mission, referred to as Orion EFT-1 (for "Exploration Flight Test 1"), would have sent the unmanned Orion spacecraft into an elliptical orbit with a 5,790 kilometer (about 3,600 miles) apogee, allowing it to reenter the atmosphere at very high speeds in excess of 32,000 km/h (about 20,000 miles per hour), simulating the type of reentry the spacecraft would experience when returning from a lunar mission.
The window for EFT-1 opened at 7:05am EST this morning, and NASA was compelled to hold the launch for weather-related conditions and also because a cruise ship wandered too near the launch area. However, the deciding factor behind NASA's decision to scrub the launch for today was an apparent malfunction with a fill and drain valve in the Delta IV Heavy launch vehicle's first stage. The small valve failed to properly close when commanded, and launch controllers were unable to remotely address the problem in the launch window time available.
The Delta IV Heavy on which the Orion capsule is perched is the largest active rocket in the United States' launch inventory. Built by the United Launch Alliance—a joint venture between Boeing and Lockheed Martin that provides rocket services to United States government entities—the Delta IV Heavy is a cryogenically fueled launch vehicle that can put about 28 metric tons into low Earth orbit. Usually employed to launch large reconnaissance satellites into high orbits that require extra oomph, this is the first time a Delta IV Heavy has been used to launch a payload for NASA instead of for the Air Force or the National Reconnaissance Office.
The reason for using the big Delta IV Heavy for the EFT-1 flight is that it's the only launch vehicle that can impart the delta-v necessary to push the big Orion capsule into the desired elliptical orbit. Once launched, the Orion crew module would go through a series of checks to verify both its on-board systems and the systems of its attached Service Module. The spacecraft would then reenter the atmosphere and splash down in the Pacific Ocean for recovery.
Though unmanned, CNN explains that the Orion spacecraft carries a small collection of mementos, including a Tyrannosaurus Rex fossil, a few props from the Sesame Street TV show, and a sample of lunar soil. If all goes well, this will be just the first of many Orion launches, with the Apollo-like spacecraft carrying an actual crew some time after 2020.
With today's launch scrub, NASA will have about 22 hours to address any problems with the launch vehicle before trying again at the same time tomorrow morning.