Description of the payload

Is a spectrometer with six tunable diode lasers dedicated to in situ measurements of trace compounds in the upper troposphere and the stratosphere up to 35 km altitude.

The 6 laser beams circulate in a multipass HERRIOTT cell located below the gondola. The lower mirror of the two-mirror cell is fixed at the top of a deployable mast. The distance between mirror is about 3.50 m. Given the curvature of the two identical mirrors, two stable optical configuration can be used : first 86 reflections and 300 m optical path, second 156 reflections and 554 m optical path, by moving the lower mirror 5 mm up.

The mast is deployed during the flight to have the first measurements at the tropopause. Around the instrument, a rigid metal frame encompasses it, in order to have a instrument-safe landing.

Inside the instrument, three liquid nitrogen cryostats, hold the six diode lasers and the 12 detectors.

Vertical profiles of concentrations of a great number of species like O3, CH4, CO, CO2, N2O, HNO3, NO2, NO, HCl, HOCl, H2O2, and COF2, are measured with a very high vertical resolution, a high sensitivity and a high precision.

Details of the balloon flight and scientific outcome

Launch site: Aérodrome de Gap-Tallard, Haute Alpes, France  
Balloon launched by: Centre National d'Etudes Spatiales (CNES)
Balloon manufacturer/size/composition: Open balloon model 150z Zodiac - 150.000 m3
Balloon serial number: 150Z Nº 24
Payload weight: 791 kgs
Gondola weight: 465 kgs

The balloon was launched on June 29th, 1999 by dynamic method with the help of an auxiliary balloon.

The flight endured near 7 hours.

No additional data is available.

This was the first flight of the instrument.

External references and bibliographical sources

Images of the mission

The SPIRALE instrument being readied for his first flight. The image show clearly the deployable mast located full extended bellow the gondola Main balloon inflation The payload parachuting back to earth