Purpose of the flight and payload description

This flight was part of a balloon expedition to study cosmic rays in the vicinity of the equator during the International Quiet Sun Year (IQSY) organized and managed by the National Center for Atmospheric Research as a joint United States - India activity. The program was conducted in Hyderabad, India during the late winter and early spring of 1965.

The main objective of the flight was to expose a package of nuclear research emulsions with various sensitivities and having a large horizontal area provided by the U.S. Naval Research Laboratory, Washington, DC. The mission called for the detector to reach reach a pressure altitude of approximately 3 mb and stay there for 10 to 12 hr. That would make possible for the first time to obtain a charge spectrum for primary heavy nuclei with an almost negligible correction for fragmentation in the overlying atmosphere near the earth's magnetic equator. These data, in combination with data obtained from similar exposures during IQSY at Ft. Churchill and Minnesota, would make possible the comparison of spectra, fluxes and ratios of light to medium to heavy groupings for primary cosmic ray nuclei with Z > 3 over a wide range of energies. The combined data could then be used to study various mechanisms which may play a role in the propagation of the cosmic radiation through interstellar space.

Another set of emulsion stacks were provided by Tata Institute of Fundamental Research, Bombay, India for primary cosmic ray experiments.

Details of the balloon flight

Balloon launched on: 3/26/1965 at 6:43 ist
Launch site: Osmania University Campus, Hyderabad, India  
Balloon launched by: Raven Industries Inc.
Balloon manufacturer/size/composition: Zero Pressure Balloon Winzen 2.940.000 cuft (0.5 Mil. Stratofilm)
Balloon serial number: SF-199.78-050-NS-01 S/N 170
End of flight (L for landing time, W for last contact, otherwise termination time): 3/26/1965 at 8:10 ist
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 1 h 30 m
Landing site: 57 miles ENE of Hyderabad, India
Campaign: No Data IQSY-EQEX
Payload weight: 284 lbs
Overall weight: 644 lbs

Balloon was launched from Osmania Campus on March 26, 1965 and had an average ascent rate of 855 ft/min. At 51,600 ft the balloon burst. Impact was 57 miles ENE of Hyderabad. The aircraft was in the area but was unable to locate the parachute. The balloon was found on the ground so the recovery crew was directed to the small village in the area. A small boy had seen the parachute come down and directed the crew to the instrument load. The payload suffered severe damage and the orienter was demolished.

External references

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