MULTI-INSTRUMENTED GONDOLA

Objective of the flight was to perform balloon-borne measurements of atmospheric constituents using a multi-instrumented gondola. Two of the four instruments flown in this mission were the following:

A modified spacecraft scanning radiometer, provided by the National Oceanic and Atmospheric Administration (NOAA) originally part of the Earth Radiation Budget Experiment (ERB) known as the Modified ERB Polarimeter (MEP) constructed from spare optics and electronics provided by Gulton Industries, the ERB contractor. The MEP measured the linear polarization of reflected sunlight across visible and near-infrared spectral intervals. Radiation passed through a Glan-Taylor polarizing prism and a telescope with a paraboloid primary mirror before being split and directed into two optical paths, each equipped with its own filters and detectors. The instrument operated by rotating the polarizer to three distinct angles, collecting data on the Stokes parameters (I, Q, and U) every three seconds. A digital logic system and a motorized turntable maintained the alignment of the scan plane with the principal plane of the sun, while a camera aligned with the telescope recorded time-lapse photographs of the observed area.

A Pressure Modulator Radiometer (PMR) was used to measure the vertical profile of gaseous HCl in the stratosphere, focusing on altitudes from 16 to 39 km. The PMR operated by modulating the pressure of a gas cell filled with HCl at about 19 Hz, selectively filtering incoming solar infrared radiation at the narrow spectral lines where HCl absorbs. This high-resolution filtering allowed detection of trace concentrations of HCl. The radiometer included a servo-controlled solar tracking system, a 400 Hz rotating chopper, and a broad optical filter centered around 2850 cm?�, covering the fundamental band of HCl. A lead selenide detector measured the radiation, capturing both wide-band and side-band signals, the latter being used for analysis due to convenience. The ratio of side-band to wide-band signal intensity was related to the HCl concentration along the line of sight.

Balloon launched on: 3/17/1976
Launch site: Holloman Air Force Base, Alamogordo, New Mexico, US  
Balloon launched by: Air Force Cambridge Research Laboratories (AFCRL)
Balloon manufacturer/size/composition: Zero Pressure Balloon  
End of flight (L for landing time, W for last contact, otherwise termination time): 3/17/1976
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 6 h 30 m
Landing site: 30 miles SSW of Deming, New Mexico, US

• Polarization of reflected sunlight as measured from a high-altitude balloon Proceedings Volume 112, Optical Polarimetry: Instrumentation and Applications; (1977)
• Radiometric measurement of stratospheric HCl Nature, 266 (5599), 243-244
• Summary of Balloon Flights launched from H.A.F.B. NM (1962 thru 1987) U.S. Gov. National Archives