Description of the payload

The primary focus of the SPRITES'99 campaign was to support a series of stratospheric balloon missions over and near transients electromagnetic events generating storms in conjunction with coordinated ground-based measurements in several distant points.

The instrumentation package -designed and developed by the University of Houston- included a three axis broad band electric field and magnetic field detector with sufficient dynamic range and bandwidth to resolve the expected sprite excitation field and to distinguish between ac and dc excitation mechanisms.

A gamma ray spectrometer consisting of a scintillation counter and a pulse height analyzer was also flown.

On board memory was sufficient to record over a thousand bursts, with 160 ms sampling times and a 40 ms pre-trigger period.

Details of the balloon flight and scientific outcome

Launch site: Ottumwa Industrial Airport, Iowa, US  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon 1.500.000 cuft - SF3-1.507-.8/0-NHR
Balloon serial number: R 1.507-0-4-04
Flight identification number: 468N
Campaign: SPRITES 99  

The flight was launched at 23:57 UTC on August 14th, 1999 using dynamic method assited by a fixed crane as launch vehicle.

Float altitude of near 30 km was achieved at 2:36 UTC on August 15th.

After a flight of near 13 hours cutdown command was transmited at 12:35 UTC on the same day.

The balloon required just over one hour to reach its ceiling (around 33 km) after which it was expected to float generally westerly at 20-30 kts. In order to prepare for launch, a decision was required several hours before sprites were expected to begin. As a further complication, the balloon was expected only to fly near the target storm, but not over it. Such overflights are now disallowed given the 1989 uncommanded payload release over Dallas, Texas.

During much of the experimental period, adverse weather at the launch site (rain and/or high surface winds) severely limited the launch opportunities.

This was the first launch od the campaign and was only a partial success. Clouds at all ground stations obscured the views of any sprites. In addition, part of the telemetry system on board failed.

External references and bibliographical sources

Images of the mission

View of the launch pad before the start of the flight