The US space agency's Orion capsule blasted off Friday on its first journey into orbit, in a key test flight before carrying people to deep space destinations like Mars in the coming years.

The unmanned spacecraft soared into space at 7:05 am (1205 GMT) atop a United Launch Alliance Delta IV Heavy rocket that rumbled and roared as it climbed into pastel skies over the Florida coast at sunrise, leaving a plume of smoke in its wake.

Cheers could be heard at Kennedy Space Center as the rocket took off, though the crowds were thinner than they were on Thursday, when 27,000 people showed up for a launch that was delayed by wind gusts and technical problems.

All those concerns vanished on Friday, however.

"It was just a blast to see how well the rocket did," said Orion program manager Mark Geyer.

"Being near a launch -- a rocket that big -- you can feel it," he said.

The launch is the first in more than 40 years of a US spacecraft intended to carry humans beyond the Moon. It has reinvigorated a US human exploration program that has been stagnant for more than three years since the last American space shuttle carried a crew of astronauts to the International Space Station.

The 30-year shuttle program ended in 2011, leaving the United States no option but to pay Russia to carry astronauts on its Soyuz capsules at a cost of $71 million per seat.

Two loops
The four-and-a-half hour flight aims to test crucial systems like the heat shield and parachute splashdown.

The spacecraft entered the first of two loops around the Earth smoothly, orbiting about as high as the International Space Station, which circles at an altitude of about 270 miles (430 kilometers).

Next is the second orbit, which will carry it 15 times higher, to an apogee of 3,600 miles above the Earth.

Then, the spacecraft is supposed to plunge into the waters off San Diego, California to be retrieved by the US Navy.

An analysis of sophisticated sensors on the capsule should let NASA know if the temperature inside remained survivable for a potential crew, even as the spacecraft's exterior heated to 4,000 degrees Fahrenheit (2,200 Celsius) during its re-entry to Earth's atmosphere at a velocity of 20,000 miles per hour.

Potential future missions for Orion, which can fit four people at a time, include a trip to lasso an asteroid and a journey to Mars by the 2030s.

"I think it's a big day for the world, for people who know and love space," said NASA administrator Charles Bolden ahead of Friday's launch.

NASA has already spent $9.1 billion on Orion and the powerful rocket meant to propel it with crew on board, the Space Launch System (SLS).

Another unmanned test flight is slated for 2018. The first Orion test flight with people on board is scheduled for 2021, when total costs are projected to reach $19-22 billion.

About $370 million dollars in equipment is at stake in Friday's launch.