WATCH: NASA Prepares to Launch Orion Spacecraft Into Space

Launch was delayed on Thursday due to poor weather conditions and sticky valves.

NASA is taking another shot at launching its new Orion spacecraft , a day after gusty wind and sticky valves held up the critical test flight.

The unmanned rocket holding Orion is poised to blast off at sunrise Florida time, although weather is again threatening to interfere.

Rain and clouds are forecast and the wind, while stiffer, is expected to blow in a more favorable direction. Forecasters put the odds of acceptable conditions at 50-50, as a nearly full moon glowed in the sky well before dawn.

Orion will orbit the world twice on this inaugural flight so NASA can wring out the riskiest systems before putting astronauts on board. Future missions will aim for asteroids and, ultimately, Mars. This time, the spacecraft will shoot for a high point of 3,600 miles (5,800 kilometers), farther than any spacecraft built for humans has gone since the Apollo moon program.

The entire mission will last less than five hours, culminating with an old-style splashdown in the Pacific. NASA needs that extra-high altitude to gain enough momentum to re-enter at a speed of 20,000 mph (32,000 kph) and submit the capsule's massive heat shield to 4,000-degree (2,000 Celsius) temperatures.