For the first time in more than 40 years, NASA is launching a spaceship designed to carry astronauts far beyond Earth. The Orion space capsule is due to blast off for an unmanned, trial run on Thursday from Cape Canaveral Air Force Station in Florida.
Here is a look at the key milestones of the 4-1/2-hour flight:
To get as far away from Earth as possible, Orion is launching aboard a Delta 4 Heavy rocket, currently the biggest booster in the U.S. fleet. The 2-1/2-hour launch period opens at 7:05 a.m. EST (1205 GMT).
One minute, 25 seconds after liftoff, Orion goes supersonic.
Four minutes after liftoff, two of the Delta 4's three liquid-fueled boosters are jettisoned.
Five minutes, 30 seconds, the last booster burns out and separates from the upper-stage engine.
Six minutes, 15 seconds, with the second-stage burning, three protective panels separate from Orion's mock-up service module. Five seconds later, the launch escape system is jettisoned.
Seventeen minutes, the second-stage engine shuts down, leaving Orion in its initial orbit 115- by 552 miles (185- by 888 km) above Earth.
Three hours, after a second burn of the upper-stage engine, Orion passes through intense radiation in the Van Allen Belts and reaches its peak altitude of 3,600 miles (5,800 km).
Three hours, 23 minutes, Orion separates from its service module and the Delta upper stage and prepares to return to Earth.
Three hours, 57 minutes, Orion fires its steering thrusters to position itself for atmospheric re-entry.
Four hours, 13 minutes, Orion, traveling at 20,000 mph (32,000 km/h) reaches upper limits of Earth's atmosphere.
Four hours, 15 minutes, Orion experiences peak heating of about 4,000 degrees Fahrenheit (2,200 Celsius).
Four hours, 19 minutes, parachutes begin deploying to slow Orion's descent.
Four hours, 23 minutes, Orion lands in the Pacific Ocean, 600 miles (965 km) off the coast of Baja California. Recovery teams will retrieve the capsule and take it to San Diego, California.
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