ULDB (Ultra Long Duration Balloon)

A project to develope a balloon system capable of providing scientific measurements for 100-day missions with floating altitude close to 35km transporting payloads of near 1.5 tons.

It is a super-pressure balloon made of a composite fabric (polyester + polyethylene film and fabric) that is filled with Helium and hermetically sealed. Meridional tendons provide additional rigidity to the envelope. The pressure inside the envelop is maintained above the ambient pressure at all times to keep the balloon afloat at a constant altitude. During daytime the internal pressure increases due to solar heating but the volume remains constant due to the rigidity of the envelope. At night the pressure drops due to infrared radiative cooling to space, but as long as the internal pressure remains above the ambient pressure, the balloon stays at the same altitude.

On the future, transported by stratospheric winds around the globe at 30m/s the ULDB would be make a full circunnavegation to Earth in about 2 weeks.

Balloon launched on: 1/9/2011 at 22:46 utc
Launch site: Williams Field, McMurdo Station, Antarctica  
Balloon launched by: Columbia Scientific Balloon Facility (CSBF)
Balloon manufacturer/size/composition: Ultra Long Duration Balloon Raven Aerostar - 14.915.000 cuft
Balloon serial number: Aerostar 14.39-1.5U1-01
Flight identification number: 616NT
End of flight (L for landing time, W for last contact, otherwise termination time): 2/2/2011 at 0:52 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 22 d 2 h
Landing site: 483 miles NNW of McMurdo Station, Antarctica
Overall weight: 1818 kgs

After ten launch attempts due to uncooperative weather, the balloon was launched by dynamic method at 22:46 UTC, on January 9, 2011. After reaching float altitude of 110.000 ft, it started a counter-clockwise turn to the pole.

After 23 days aloft, the mission was terminated at 00:52 utc on Febraury 1st. The landing occured at 1:38 utc in a point located 483 nautic miles NNW of McMurdo Station. Once in the ground the parachute was separated of the gondola by remote command sent via satellite by the Columbia Scientific Balloon Facility (CSBF) control center in Palestine, Texas to prevent the wind would drag the gondola over the antarctic plateau. Although a longer flight for the balloon was expected, the decision to bring it down was not related to any kind of failure but to an easy recovery of the payload remains. The only notably issue during the flight was a slightly loss of altitude in the last days of the trip by unknown reasons. A few days later a CSBF recovery party was sent to the impact site in a Basler aircraft to recover the CSBF gondola, electronics, and flight train components and to obtain several samples of the SPB balloon envelope for further analysis.

• ULDB website - Balloon Programe Office NASA Wallops flight facility
• Pictures of the launch taken by Matthew Truch from the BLAST-pol team at Flickr
• Press release on the launch at Wallops flight facility website
• Raven Industries' Aerostar Flies a New Revolutionary Design for a Stratospheric High Altitude Balloon Mission for NASA press release from Raven Ind.