NASA's second-ever commercial launch in Australia has taken off from the Northern Territory, with the US aeronautical giant hailing the moment as a landmark for science in the southern hemisphere.

A week of drizzling rain, wind and a 52-hour delay failed to stop the suborbital sounding rocket launch, which fired from the Arnhem Space Centre near Nhulunbuy around 11:15pm ACST on Wednesday.

With a guttural boom and a flash of light, the rocket, named the Sistine III, tore through the outback night sky and into space, off to explore the mysteries of the distant Alpha Centauri star system.

One of those watching on was John Carsten, from space firm Equatorial Launch Australia, who said he believed the launch and its scientific discoveries "shows the future that's ahead of us".

"This is just remarkable … it's really progressing us as civilisation goes forward," Mr Carsten said.

Earlier in the day, NASA and Equatorial Launch Australia scientists and technicians were busily preparing for the launches, and allowed the ABC a rare behind-the-scenes look at the build-up.

NASA campaign scientist and principal investigator Kevin France said the spaceport "becomes frantic starting at T-minus two hours" prior to launch.

"Around T-minus two hours we prepare to arm the rocket motors, we prepare to take the experiment's vacuum pump off and raise the launcher vertical – and then things start to get really exciting," he said.

In a hangar at the spaceport, NASA technicians were also tinkering on the finer details for another sounding rocket, named Deuce, to ensure it was ready for take-off later in the month.

According to astrophysicist Dr Brad Tucker, two of the sounding rockets being used in north-east Arnhem Land stand about 12 metres tall and weigh 2,200kg, with nearly half of that weight in the fuel tanks.

Wednesday's rocket has the capacity to blast as high as 500 kilometres into space and generate about 7,700 kg of thrust, propelling it skyward in less than 27 seconds. 

Senior NASA scientist Michael Garcia, who is usually based in NASA's Washington DC headquarters, said it had so far been a "fabulous" experience at the newly built remote Northern Territory spaceport.

"NASA will certainly come back … you can't predict the future, but my fingers are crossed that it really does become a viable commercial thing for the Northern Territory, that'd be great."

NT launches a 'landmark for science'

Mr France has traded his usual home in Colorado, in the US, for the mission in the tropical NT township, about 700 kilometres south-east of Darwin.

"We just can't get to some extremely interesting astronomical targets from the north.

"We've been asking to come down here because it's a unique part of the astronomical sky."

Mr France, one of the campaign's chief architects, described the East Arnhem Land launch mission as a "landmark for science" for being NASA's first on a commercial rocket port outside of the US.

"I hope it's the harbinger for not just suborbital rockets, but even larger rockets, and joint science ventures going forward," he said.

Mission aiming to unlock star secrets

Mr France said the mission would seek to open up the secrets of Alpha Centauri A and B, "our nearest solar twins", and probe the possibility that planets around those stars could be habitable.

"The first key ingredient to that is, what is a star doing?" he said.

"All the things we sort of take for granted that happen here on Earth with our sun, we just don't know those things about planets around other stars.

"So that's what we're here to measure."

Wednesday night's launch had originally been scheduled for two days prior – on July 4, an auspicious day for the United States team – but a prolonged bout of poor weather triggered the delay.

The launch marked the second of three for NASA's current Arnhem Land launch mission, with the first rocket fired late in June, and the third currently scheduled to go ahead on July 12.