Purpose of the flight and payload description
This was the first scientific campaign carried out using constant level balloons designed to fly in the boundary layer. The goal was to trace the low-level air flow circulation within the tropical boundary layer over the Arabian sea, during the summer monsoon.
Following lessons learned during tests flights performed in 1973 y 1974, LMD decided to change the classical line-disposition of the equipment under the balloon by a new completely enclosed distibution of the equipment inside the balloon.
The balloon envelopes were 2-meter diameter spheres made of bilaminated mylar film 80 microns thick. The electronic equipment, except for the antenna and the pressure transducer, was placed inside the spherical envelope. A white plastic container attached to both poles of the balloon housed the power supply (lithium cells) and the transmitter-oscillator. The antenna, the barometric capsule and associated electronics were fastened to the upper pole of the balloon with an appropriate protection against water for the pressure transducer. In the flights made at levels 1000 and 1500 meters, the balloon upper hemisphere was covered by a thin aluminized mylar cap for radiative control of the envelope temperature and to prevent loss of buoyancy due to dew condensation at night.
The balloons were located every 12 hours by the Random Access Measurement System (RAMS) of the Nimbus-6 satellite which also served as a data relay system collecting the pressure measurements performed by the balloons. In order to monitor the balloon flight level, the pressure values measured by the barometric altimeter were recorded every hour. Then, during the sequences of emission, the balloon telemetered the instantaneous value as well as the last 12 recordings of the ambient pressure.
45 balloons were launched during the campaign that lasted from June to August, 1975.
Details of the balloon flight
Balloon launched on: 7/12/1975
Launch site: Seychelles International Airport, Mahe
Balloon launched by:
Balloon manufacturer/size/composition: Super Pressure Balloon Zodiac - 2 m diameter
Flight identification number: 1405
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 5 d