Washington, Dec 3 (IANS): In its bid to send astronauts to asteroids and eventually Mars in the future, the US space agency is all set for the Thursday launch of its ambitious exploration spacecraft Orion from the Space Launch Complex 37 at Cape Canaveral air force station in Florida.

From the launch on a gigantic United Launch Alliance Delta IV Heavy from Florida to the expected splash-down under billowing parachutes, the mission will test many risky events, NASA reported.

"Orion is the exploration spacecraft for NASA, and paired with the Space Launch System (SLS) rocket, it will allow us to explore the solar system," said Mark Geyer, programme manager of Orion.

While the Delta IV Heavy will send Orion on its flight test, SLS will launch the spacecraft on future missions.

The flight test will also mark NASA's Kennedy Space Center's transformation into a multi-user spaceport.

"The team is enthused, it's good to go flying," said Bob Cabana, director of the Kennedy Space Center.

The two-hour, 39-minute launch window opens at 7.05 a.m. (EST) so the launch and recovery of the spacecraft after splash down can both take place in daylight.

Hitting the atmosphere at 20,000-mph four hours and 13 minutes after launch, Orion will encounter about 80 percent of the heat it would endure during a return from lunar orbit with astronauts aboard.

After about four hours and 23 minutes, Orion will be bobbing in the Pacific Ocean off the coast of Baja California as recovery forces move in.

The lessons NASA will learn from Orion's test flight would improve the spacecraft's design while building the first SLS rocket - a heavy booster with enough power to send the next Orion around the moon for Exploration Mission-1.