KENNEDY SPACE CENTER, Fla. — One day after winds and technical problems scrubbed its first launch attempt, a Delta 4 Heavy rocket successfully placed NASA’s Orion spacecraft into orbit Dec. 5 on a brief but critical early test flight of the spacecraft.

The United Launch Alliance Delta 4 Heavy lifted off at 7:05 am EST Dec. 5, at the beginning of a 2-hour, 39-minute launch window. The rocket placed the Orion spacecraft into its planned transfer orbit of 185 by 888 kilometers 17.5 minutes after liftoff.

At approximately 9:00 am EST, after completing one orbit, the Delta 4’s upper stage will fire its engine again, sending Orion on a trajectory that goes to an altitude of 5,800 kilometers before reentering the Earth’s atmosphere. Splashdown in the Pacific Ocean off the coast of Baja California, Mexico, is scheduled for 11:28 am EST.

Mark Geyer, NASA’s Orion program manager, said on NASA TV shortly after Orion entered orbit that several key events early in the mission for the spacecraft, such as the separation of its launch abort system and panels protecting its service module, took place as planned.

NASA originally planned to launch Orion on Dec. 4, but that attempt suffered both weather and technical problems. The countdown was stopped twice with less than four minutes before liftoff when winds exceeded preset limits.

A third launch attempt, about halfway into the 2-hour, 39-minute launch window, was also halted with just over three minutes before launch. Liquid hydrogen valves on two of the three booster cores that comprise the Delta 4 Heavy’s first stage failed to close, and the problem could not be resolved before the launch window closed.

This mission, designated Exploration Flight Test 1 (EFT-1), is the first flight test of the Orion spacecraft. It is intended to test several key systems on Orion, including its heat shield and parachutes. Engineers will also measure the susceptibility of the spacecraft’s electronics to radiation as Orion passed through the lower portions of the Van Allen belts.

“It’s a test flight,” said Mark Geyer, NASA Orion program manager, during a pre-launch briefing here Dec. 3. “We are pushing the systems to make sure they work as we expect.”

Those tests will support further development of Orion, which is now expected to fly again in 2018 on the first launch of the Space Launch System heavy-lift rocket. That will be followed by first crewed Orion launch, also on the SLS, in 2021.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...