Liftoff was slated for early Wednesday morning from Kennedy Space Center in Florida. The test flight aims to send an empty crew capsule into a far-flung lunar orbit, 50 years after NASA's famed Apollo moonshots.

The project is years late and billions over budget. The price tag for the test flight: more than $4 billion.

A rundown of the new rocket and capsule, part of NASA's Artemis program, named after Apollo's mythological twin sister:

ROCKET POWER

At 322 feet (98 meters), the new rocket is shorter and slimmer than the Saturn V rockets that hurled 24 Apollo astronauts to the moon a half-century ago. But it's mightier, packing 8.8 million pounds (4 million kilograms) of thrust. It's called the Space Launch System rocket, SLS for short, although a less clunky name is under discussion. Unlike the streamlined Saturn V, the new rocket has a pair of side boosters refashioned from NASA's space shuttles. The boosters peel away after two minutes, just like the shuttle boosters. The core stage keeps firing before crashing into the Pacific. Less than two hours after liftoff, an upper stage sends the capsule, Orion, racing toward the moon.

MOONSHIP

NASA's high-tech, automated Orion capsule is named after the constellation, among the night sky's brightest. At 11 feet (3 meters) tall, it's roomier than Apollo's capsule, seating four astronauts instead of three. For the test flight, a full-size dummy in an orange flight suit occupies the commander's seat, rigged with vibration and acceleration sensors. Two other mannequins made of material simulating human tissue—heads and female torsos, but no limbs—measure cosmic radiation, one of the biggest risks of spaceflight. Unlike the rocket, Orion has launched before, making two laps around Earth in 2014. For the test flight, the European Space Agency's service module was attached for propulsion and solar power via four wings.