After nearly a decade of design and planning, NASA is preparing to test the ship that could take astronauts to Mars and beyond. Thursday at 7:05 EST, Orion will launch for a trip that is scheduled to take 4.5 hours and hit speeds of 20,000 miles per hour before returning to Earth.

For this test flight, the craft will be loaded with sensors rather than people. In addition to the overall stability and reliability of the Orion, researchers need to test how it responds to heat and radiation. The capsule will travel 3,600 miles from Earth which is 15 times further out than the International Space Station.

Once outside the protective Van Allen belts, the craft will be exposed to intense levels of radiation. It is essential that this radiation be accurately measured. On future manned missions astronauts could be aboard the craft for months or even years. Prolonged exposure to high levels of radiation could be lethal, even if the spacecraft remains sound and free of mechanical problems.

For those who want to watch this potentially historic event, with commentary, NASA will be live streaming the event online. There is a good deal of conversation about it at NASA TV now, but coverage of Exploration Flight Test-1 will continue to intensify during the lead up to the liftoff from Kennedy Space Center in Florida.

Visit nasa.gov/multimedia/nasatv to watch.

NASATV also features archived footage, press conferences, educational material and streaming video from the International Space Station.

The ultimate goal of the Orion capsule is to carry astronauts to Mars. If the test flights are successful, however, the first few missions will carry human crews to asteroids.