NASA's super pressure balloon has launched from Wānaka Airport.
NASA plan to launch two scientific payloads from the airport this year after five failed attempts last year.
Wanaka Airport duty manager Rushlee Smith said a tow lift balloon began to inflate just after 10am and the main balloon fully inflated within the hour.
She said a rise in wind speed earlier in the morning had caused a slight delay but things stayed on track for a successful launch.
Such balloons have been making headlines, after the US shot down a suspected Chinese spy balloon in its airspace earlier this year.
The balloon will carry a Super Pressure Balloon Imaging Telescope, from Princeton University.
NASA said the purpose of the launch is to further test and qualify the technology, which can offer cost savings compared to space missions.
Balloon programme office chief Debbie Fairbrother said a lot of different weather factors needed to line up, and so far, the forecast was favourable.
"We are excited to be back in Wānaka for two planned balloon missions set to qualify this game-changing technology that enables long-duration flight in a near-space environment for the science community," she said.
Wānaka Airport and the park alongside the airport will be closed to the public so anyone wanting to see the super pressure balloon is advised to head for higher ground.
The best viewing points will be on the hill on the Hāwea side of the Red Bridge by Kane Road or on the Hāwea Flat side of the Clutha River.
There will also be a live feed of the launch here.