NASA is scheduled to launch its super pressure balloon (SPB) from Wanaka, New Zealand, Friday, May 27 (Thursday, May 26 in the United States) after multiple failed attempts due to unacceptable wind conditions.
If weather and the predicted launch trajectory are conducive for launch, lift-off is scheduled between 8 and 11:30 a.m. locally (between 4 and 7:30 p.m. U.S. EDT Thursday, May 26). [20:00 to 23:30 UTC 2022-05-26]
After launch the 18.8-million-cubic-foot (532,000 cubic-meter) SPB will ascend to its float altitude where the stratospheric winds will propel it at speeds up to and exceeding 100 knots on a weeks-long journey around the southern hemisphere.
The primary goal of the flight is to validate and certify the SPB technology, and in particular, the balloon’s capability to pressurize at high altitudes. This ability to pressurize and maintain a consistent, pumpkin-like shape enables the balloon to float at a constant density altitude despite the heating and cooling of the day-night cycle. Without this pressurization, the helium gas inside the balloon would expand and contract through the day-night cycle, causing changes in buoyancy that ultimately lead to changes in altitude.
If NASA is unable to launch its super pressure balloon Friday, the team will close out its 2022 Wanaka Campaign in order to meet the mission needs of other planned campaigns in Sweden and the United States.
With just 20 minutes left in the launch window, they have started to inflate the balloon with helium. I have no idea why they don’t use hydrogen: it provides more lift for a given volume balloon, as a diatomic molecule doesn’t leak through envelopes as fast, and in the upper atmosphere with an unmanned payload poses no safety risks. It is also much less expensive.
Scrubbed! That’s it for the New Zealand launch season. They’re off to Sweden for northern hemisphere launches, then back to Antarctica and New Zealand in 2023.