Flight controllers at the agency's Columbia Scientific Balloon Facility in Palestine, Texas, conducted a controlled flight termination of the balloon, which slowly descended back to Earth impacting in the Pacific Ocean about 813 miles east of New Zealand.

"After an especially rewarding mission and due to mission constraints, we conducted termination operations of the mission over open water to ensure no risk to public or environmental concerns," said Gabriel Garde, chief of NASA's Balloon Program Office at the agency's Wallops Flight Facility in Virginia.

NASA conducted a thorough environmental analysis of an open-ocean landing before beginning its mid-latitude super pressure balloon flight program in 2015. The open-ocean flight termination procedure makes use of the two-ton flight payload as an anchor to pull the entire balloon flight train to the bottom of the ocean as quickly as possible. In this way, the balloon does not remain in the primary water column zone where most marine species are known to live, minimizing environmental impacts.

While the mission successfully met its minimum requirements for qualification of the balloon, the team had been monitoring minor performance issues and suspected that the system had a small leak. The balloon was maintaining its predicted float altitude during daytime hours; however, it started to show considerable drops in altitude, especially as it passed through areas of colder temperatures like storm systems.

"We detected a performance issue with one of our hardware interfaces that contributed to altitude performance stability. While it would have been preferable to recover the hardware, we were able to ensure all our viable data both on the science and support sides were telemetered down," said Garde.

Teams continued to closely monitor the health and performance of the balloon as it continued flight, and its ability to safely make it to the next predicted land crossing in South America for recovery of the balloon and payload. However, at approximately four additional days until land, all ballast expended to manage altitude stability, and recent altitude excursions during night periods down to 60,000 feet, continued flight became unlikely. NASA ultimately decided to terminate the flight to ensure the greatest level of control and safety during descent.

"Due to the mission's trajectory coupled with system performance, termination and recovery at the next land over flight was not possible due to unacceptable public risk," said Garde.

While the primary goal of the flight was to further test and qualify the super pressure balloon technology, the balloon was also carrying the High-altitude Interferometer Wind Observation (HIWIND) mission of opportunity, led by High Altitude Observatory, National Center for Atmospheric Research in Boulder, Colorado. The HIWIND payload was measuring neutral wind in the part of Earth's atmosphere called the thermosphere to help scientists understand and predict changes in the ionosphere, which can affect communication and navigation systems. Minimum requirements for the science mission were met during the flight.

"Following engineering assessments of the likely hardware issue, we performed mitigations and planning to reduce the likelihood of a similar issue occurring on our second flight of the campaign," said Garde.

The second super pressure balloon of the campaign, carrying several smaller payloads, launched from Wanaka, New Zealand, at 7:38 p.m. Saturday, May 3 (U.S. Eastern Time). The follow-on mission is seeking to extend the mission duration and profile, as well as qualify the system for current and future science missions. To track the balloon's path in real-time, click here.

"I am very proud of our team's efforts and dedication throughout this first mission. We have confidence in the balloon structure, design, and system architecture to enable ultra long duration mid-latitude missions now and into the future," said Garde.

The campaign's first super pressure balloon test flight, along with the HIWIND payload, achieved a full circumnavigation of the Southern Hemisphere at 7:22 a.m. Saturday, May 3 (U.S. Eastern Time).

NASA will further investigate the cause of the anomaly.

Related Links
NASA's Balloon Program
Aerospace News at SpaceMart.com