NASA Orion's rocket ready for critical December test flight

The high fidelity rehearsal included fully powering up the booster and loading the tanks with cryogenic fuel and oxidizer, liquid oxygen and liquid hydrogen

The huge rocket that will blast NASA's first Orion spacecraft into orbit is ready to Rock 'n' Roll on a critical two orbit test flight scheduled for December.

In addition, Orion is so big and heavy that she's not launching on just any old standard rocket.

To blast the uncrewed Orion to orbit on its maiden mission requires the most powerful booster on Planet Earth, namely the United Launch Alliance Delta IV Heavy rocket.

Liftoff of the state-of-the-art Orion spacecraft on the unmanned Exploration Flight Test-1 (EFT-1) mission is slated for December 4, 2014 from Space Launch Complex 37 (SLC-37) at Cape Canaveral Air Force Station in Florida.

Just days ago, the launch team successfully completed a countdown and wet dress rehearsal fueling test on the rocket itself – minus Orion – at launch complex 37.

The high fidelity rehearsal included fully powering up the booster and loading the tanks with cryogenic fuel and oxidizer, liquid oxygen and liquid hydrogen.

ULA technicians and engineers practiced the countdown on Nov. 5 which included fueling the core stages of the Delta IV Heavy rocket.

"Working in control rooms at Cape Canaveral Air Force Station in Florida, countdown operators followed the same steps they will take on launch day. The simulation also allowed controllers to evaluate the fuel loading and draining systems on the complex rocket before the Orion spacecraft is placed atop the launcher," said NASA.

The next key mission milestone is attachment of the completed Orion vehicle stack on top of the rocket.

Today's scheduled rollout of Orion to the launch pad for hoisting atop the rocket was scrubbed due to poor weather.

The triple barreled Delta IV Heavy booster became the world's (US) most powerful rocket upon the retirement of NASA's Space Shuttle program in 2011 and is the only rocket sufficiently powerful to launch the Orion EFT-1 spacecraft.

The first stage of the mammoth Delta IV Heavy generates some 2 million pounds of liftoff thrust.

"The team has worked extremely hard to ensure this vehicle is processed with the utmost attention to detail and focus on mission success," according to Tony Taliancich, ULA's director of East Coast Launch Operations.