James Dean

Florida Today

CAPE CANAVERAL, Fla. — A wayward boat, weather and technical problems scrubbed NASA's first attempt to launch a new exploration capsule Thursday.

Teams plan to try again Friday to launch a United Launch Alliance Delta IV Heavy rocket carrying an unmanned Orion capsule on its first test flight from Cape Canaveral Air Force Station.

Friday's targeted launch time is again 7:05 a.m., but the weather forecast is worse, with only a 40 percent chance of acceptable conditions during the roughly two-and-a-half hour window.

Orion is the Apollo-like capsule NASA is developing to fly astronauts to an asteroid by the 2020s, and potentially Mars by the 2030s.

Crews won't climb on board before 2021.

The $375 million mission at hand is an early test intended to fly Orion's crew module for two orbits, primarily testing the crew module's computers, heat shield and parachutes.

Exploration Flight Test-1 hopes to culminate with a splashdown in the Pacific Ocean four-and-a-half hours after the launch from Florida.

Thursday's planned 7:05 a.m. liftoff was delayed when a boat strayed into the launch zone. Strong winds then twice halted countdowns within a few minutes of liftoffs planned at 7:17 a.m. and 7:55 a.m.

Finally, sensors showed liquid oxygen valves had not closed properly in two Delta IV rocket boosters, stopping another try at 8:26 a.m.

The launch time was reset once more for the end of the window at 9:44 a.m., but the valve trouble couldn't be resolved in time.

Engineers expect to solve the problem and be ready to try again Friday.

The mission aimed to loft the test version of the Orion capsule 3,600 miles up during two orbits, setting up a 20,000-mph re-entry through the atmosphere and splashdown in the Pacific four-and-a-half hours after liftoff.

NASA is developing Orion to fly astronauts to deep space destinations including an asteroid and eventually Mars. The first flight with astronauts will happen no sooner than 2021.

NASA anticipated 26,000 guests for the historic send-off — the roads leading into Kennedy Space Center were packed well before dawn — and the atmosphere was reminiscent of the shuttle-flying days. "Go Orion!!" urged a hotel billboard in nearby Cocoa Beach.

Launch commentator Mike Curie noted Thursday was the 16th anniversary of the launch of the first U.S. piece of the International Space Station, by shuttle Endeavour. "That was the beginning of the space station, and today is the dawn of Orion," he said.

Orion is aiming for two orbits on this inaugural run. On the second lap around the home planet, the spacecraft should reach a peak altitude of 3,600 miles, high enough to ensure a re-entry speed of 20,000 mph and an environment of 4,000 degrees. Splashdown will be in the Pacific off the Mexican Baja coast, where Navy ships already are waiting.

NASA's Mission Control in Houston was all set to oversee the entire 4½-hour operation. The flight program was loaded into Orion's computers well in advance, allowing the spacecraft to fly essentially on autopilot. Flight controllers could intervene in the event of an emergency breakdown.

The spacecraft is rigged with 1,200 sensors to gauge everything from heat to vibration to radiation. At 11 feet tall with a 16.5-foot base, Orion is bigger than the old-time Apollo capsules and, obviously, more advanced. As NASA's program manager Mark Geyer noted, "The inside of the capsule is totally different."

NASA deliberately kept astronauts off this first Orion.

Managers want to test the riskiest parts of the spacecraft — the heat shield, parachutes, various jettisoning components — before committing to a crew. The earliest Orion might carry passengers is 2021; asteroids are on the space agency's radar sometime in the 2020s and Mars, the grand prize, in the 2030s.

Lockheed Martin Corp., which is handling the $370 million test flight for NASA, opted for the powerful Delta IV rocket this time around. Future Orion missions will rely on NASA's still-in-development megarocket known as SLS, or Space Launch System. The first Orion-SLS combo launch is targeted for 2018.

NASA's last trip beyond low-Earth orbit in a vessel built for people was Apollo 17 in December 1972.

Contributing: The Associated Press