The Super Pressure Balloon (SPB) is a balloon that always maintains a positive internal pressure in relationship to the environment it is floating in. The NASA Super Pressure Balloon is a sealed structure that is filled with a measured and specific amount of helium lifting gas. The balloon rises after launch, and the helium expands as the ambient atmospheric pressure goes down.
The balloon is designed to fly at a specific pressure altitude with a known mass of payload hanging from the balloon. When the balloon reaches the desired float altitude, the extra helium is not vented off, but fills out the shape and pressurizes the balloon. The amount of helium in the balloon is determined by how much is needed to lift the entire flight system plus some extra to provide an upward force. This extra helium is enough to pressurize the balloon when it reaches the float altitude and also to over pressurize the balloon to the design limits. The Super Pressure Balloon is designed to fly with a positive internal pressure at all times. As the sun heats up the balloon during the day, the internal pressure (differential pressure) increases, and at night when the balloon cools down, the differential pressure significantly decreases, but still above ambient, hence maintaining super pressure condition at all times. The differential pressure range is up to 180 Pa (0.0261 psi). This is a very small internal pressure, but it is enough to keep this balloon flying through the night!
As a result of maintaining near constant volume, the SPB will offer greater stability at float altitude with minimal altitude excursion during the day/night cycles when compared to that experienced on conventional or so called Zero-Pressure (ZP) balloons. This added stability and extended durations at mid-latitudes will enable new science missions that currently are not feasible with ZP balloons.
Balloon launched on: 8/14/2012 at 3:47 utc
Launch site: European Space Range, Kiruna, Sweden
Balloon launched by: Columbia Scientific Balloon Facility (CSBF)
Balloon manufacturer/size/composition: Super Pressure Balloon Raven Aerostar - Superpressure - 18.000.000 cuft
Flight identification number: 613NT
End of flight (L for landing time, W for last contact, otherwise termination time): 8/14/2012 at 9:00 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): ~ 5 h
Landing site: 15 kms NE of ESRANGE, Sweden
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