After a successful launch from the Wanaka Airport last week, Nasa's stadium-sized super pressure balloon will be brought back down to earth well short of its planned 100-day journey.
Three days after the launch from Wanaka Airport, the 532,000cu m helium-filled balloon lost altitude after travelling through a cold storm.
Since then, the balloon has continued to lose altitude at night and has then repressurised during the day and returned to an altitude of 33.2km.
The balloon is designed to maintain a stable altitude during the heating and cooling of the day-night cycle.
It is suspected a leak has occurred, meaning the balloon and its payload will have to be brought back to earth once it has crossed the Pacific Ocean.
The balloon is now floating above the ocean close to Pitcairn Islands.
Nasa communications chief Jeremy Eggers said that the mission to keep a stadium-sized balloon afloat with a 2400kg payload attached through the harshness of the day-night cycle at a near-space environment was not easy.
''That's what Nasa does - we take on the toughest challenges head on. It's part of our DNA.
''We didn't lick it this time, but we won't give up.''
Wanaka and the airport would continue to be key to Nasa's ongoing work, Mr Eggers said.
Nasa balloon programme office chief Debbie Fairbrother said it was clear the balloon was no longer operating as designed and the data pointed to a leak in it.
''This is an unfortunate development in our test flight, but we're gaining some important data from this mission that will apply to future flights.''
Once the balloon crosses the Pacific Ocean, Nasa will seek a safe area to terminate the flight and recover the balloon and payload.
Until then data would continue to be collected which would be key to improving the balloon's design to support future missions, Ms Fairbrother said.
Nasa's past two balloon missions from Wanaka Airport have also been shortened by leaks.
A 2015 mission was cut short and the balloon brought down over Australia after 35 days after it developed a leak.
Another leak meant 2016's mission was also cut short, ending in Peru after 46 days.
The space agency has made a commitment to use Wanaka Airport as a launch site for at least the next 10 years.
A decision on whether a mission will be based at the airport next year is expected to be made in the next two months.
