The biggest rocket in the U.S. fleet blasted off at dawn on Friday, launching NASA's Orion deep-space capsule into orbit for its debut test flight.
The spaceship blasted off at 7:05 a.m. EST. After two swings around Earth, including one that stretches more than 3,600 miles away, the heavily instrumented capsule is due to splash down in the Pacific Ocean off the coast of Baja, Calif.
Photos: Orion's Journey High Above Earth
With today's launch, NASA begins what is expected to be a 4.5-hour test flight that will put Orion more than 3,600 miles from Earth - farther than any U.S. spaceship designed for astronauts has been since the end of the Apollo program in 1972.
It will take a lot more than an Orion capsule to land crews on Mars, but today's debut test flight of its new human spaceship is a critical first step, says NASA.
Eventually, NASA plans to use the capsule to fly astronauts to and from Mars.
Photos: NASA's Asteroid Capture Mission
There is no crew aboard Orion for the first test flight. Life support systems, displays and other equipment needed for astronauts are still in development. NASA also wants to make sure the capsule's heat shield, parachutes, avionics equipment and computers work as expected before any crew flies aboard.
Another Orion capsule, also unmanned, is due to fly in 2018 on a second test flight that includes the debut of NASA's new heavy-lift Space Launch System rocket. Astronauts are expected to fly aboard the third Orion spaceship around 2021 on a mission that will make a high pass around the moon.
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"This first step is a huge one," space station commander Butch Wilmore said during an inflight interview on NASA Television before Thursday's launch attempt.
"It's a thrilling prospect when you think about actually exploring the solar system. Who knows where it will take us," he said.
Thursday's launch attempt was called off at the end of the rocket's 2 hour, 39 minute launch window because of a technical issue with two of the rocket's liquid oxygen propellant valves. High winds scuttled launch attempts earlier Thursday morning.