EMULSION STACK

The objective of the flight was the exposure of large stacks of stripped emulsions at high geomagnetic latitudes, to investigate the proton energy spectrum at energies equal to or less than 700 Mev; to search for primary D, H3 and He3; to determine the low energy end of the heavy particle spectrum, to study interactions of heavy nuclei and to study very high energy interactions.

The emulsion stacks were planned to be flown in such a manner that they would be positioned in the proper geometry only after the balloon had reached flight altitude. For this purpose a mechanism called the stack flipper was constructed at Rochester and installed in a large 1/4" fibre glass gondola purchased from L.C. Renslow of St. Paul, Minnesota. Associated timing and pressure recording apparatus was purchased from Raven Industries, Sioux City, South Dakota. The entire assemblies when prepared for flight weighed approximately 70 Kg.

Balloon launched on: 7/30/1957 at 6:30 local
Launch site: University of Minnesota Airport, New Brighton, US  
Balloon launched by: General Mills Inc.
Balloon manufacturer/size/composition: Zero Pressure Balloon  
End of flight (L for landing time, W for last contact, otherwise termination time): 7/30/1957 at 17:55 local time
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 11 h 25 m
Payload weight: 70 kgs

The package launched in this, the first flight of the program, consisted of 150 - 25cm x 30cm x 400 micron and 125 - 25cm x 30cm x 600 micron Ilford G-5 stripped emulsions packed as a single unit. The 150 - 400 micron emulsions were the contributions of Rochester, 90 of the 600 micron emulsions were the contributions of Dr. M. Friedlander of Washington University, St. Louis, and 35 of the 600 micron emulsions were exposed for Dr. Charles Dahanayake of the University of Ceylon. The exposure was with the 25cm edge horizontal.

The balloon was launched from New Brighton, Minnesota, at 6:30 local on July 30, 1957 as part of the ONR skyhook program. The plane of the emulsions was held horizontal until after the balloon had reached ceiling at 8:27 when it was rotated 90°. The effective collection time at altitude for cosmic ray events was 8 hr. 31 min. with the average amount of residual atmosphere above the balloon being 8.5 gm/cm2. The payload was separated from the balloon at 17:55 local time.

• Isotopic Composition of the Low-Energy Helium Nuclei in the Primary Cosmic Radiation Phys. Rev. 123, 295, 1961
• Primary cosmic-ray a-particles - I Il Nuovo Cimento, vol. 19, issue 6, pp. 1090-1099
• Project 2.29 - Energy and Charge Spectrum of Primary Cosmic Radiation IGY General Report Nº 21, Nov. 1965 p.115-116