LIMB CAMERAS

Objective of the flight was to obtain photographs of the earth limb from a balloon gondola in the stratosphere during sunset or sunrise to reveal structures in the stratospheric aerosol through scattered sunlight. The observational program was carried out by the Institut d'Aeronomie Spatiale de Belgique (IASB) starting in late 1970's decade. For that purpose a sun azimuth oriented gondola was constructed and equipped with Hasselblad 500EL 70 mm cameras mounted with 80 mm focal length lenses, their parallel optical axis being horizontal. The gondola rotated about its vertical axis so that pictures can be taken at various azimuth angles, relative to the Sun's position.

A transparent shade with an optical density equal to 2.7 was attached in front of the cameras in order that the sun be photographed through the shade when at elevation angles larger than 3°, up to 20°. By taking successive snapshots at sunset or sunrise when the sun was in this range of elevation angles, an accurate angular scale could be determined on the pictures while the aerosol scattered radiation was simultaneously photographed below the shade.

Balloon launched on: 6/5/1980
Launch site: Aérodrome de Gap-Tallard, Haute Alpes, France  
Balloon launched by: Centre National d'Etudes Spatiales (CNES)
Balloon manufacturer/size/composition: Zero Pressure Balloon  
End of flight (L for landing time, W for last contact, otherwise termination time): 6/5/1980

• Volcanic material from Mount St Helens in the stratosphere over Europe Nature 287, 614 - 615 (16 October 1980)