​Washington, April 7 (IANS) NASA is preparing to launch on Saturday a super-pressure balloon about the size of a football stadium to carry a pioneering telescope designed to detect ultra-high-energy cosmic rays from near space.

The super pressure balloon (SPB) test flight is set to be launched from Wanaka Airport in New Zealand, on a potential 100-day journey.

If weather is conducive for launch, lift-off is scheduled between 8 and 11.30 a.m. locally, NASA said in a statement on Friday.

"At this time, the weather at the ground and lower levels looks very good for a Saturday launch attempt," said Gabe Garde, mission manager for the 2017 Wanaka Balloon Campaign.

"However, we continue to evaluate the forecast stratospheric winds and predicted flight trajectory to ensure conditions are acceptable before launch," Garde added.

The purpose of the flight is to test and validate the SPB technology with the goal of long-duration flight at mid-latitudes. 

In addition, the University of Chicago's Extreme Universe Space Observatory on a Super Pressure Balloon (EUSO-SPB) is a mission of opportunity flying on the 2017 SPB test flight.

EUSO-SPB is designed to detect high-energy cosmic rays originating from outside our galaxy as they penetrate the Earth's atmosphere. 

As these high-energy particles enter the atmosphere, they interact with nitrogen molecules in the air and create a UV fluorescence light. 

EUSO-SPB will be looking downward at a broad swathe of the Earth's atmosphere to detect the UV fluorescence from these deep space cosmic rays coming in from above.

Once launched, the 532,000-cubic-metre balloon will ascend to an operational float altitude of 33.5 kilometres. 

NASA estimates the balloon will circumnavigate the globe about the southern hemisphere's mid-latitudes once every one to three weeks, depending on wind speeds in the stratosphere.