NASA's Orion space capsule is scheduled to blast off on its first test flight Thursday (Dec. 4).

The unmanned mission, called Exploration Flight Test-1 (EFT-1), will send Orion zooming about 3,600 miles (5,800 kilometers) from Earth, before rocketing back to the planet at high speeds to test out the capsule's heat shield, avionics and a variety of other systems.

No human-spaceflight vehicle has traveled so far since 1972, when the last of NASA's Apollo moon missions came back to Earth. Indeed, in all that time, no craft designed to carry crews has made it beyond low-Earth orbit (LEO), just a few hundred miles from the planet. [Photos: NASA's Orion Space Capsule EFT-1 Test Flight]

If all goes according to plan, Orion will eventually fly farther than any Apollo capsule ever did, taking astronauts to near-Earth asteroids and — by the mid-2030s — the ultimate destination, Mars.

"I gotta tell you, this is special," Bob Cabana, director of NASA's Kennedy Space Center in Florida, said about EFT-1 during a press briefing last month. "This is our first step on that journey to Mars."