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Campaign information PIROG

PIROG (Pointed InfraRed Observation Gondola) platform is a general purpose balloon platform capable of carrying a 200 kg payload for stratospheric flights lasting up to 12 hours. The platform concept has been used during the last ten years at SSC carrying payloads for astronomical studies of the interstellar media in the infrared spectral range.

Mission
The current platform design is adapted for a 60 cm telescope and a 500 GHz receiver.

Attitude
The attitude acquisition system is based on a gas jet system with the sun as reference and has an accuracy of 1 arcminute.

Power
Power is supplied by a number of lithium batteries.

Communication
Telemetry and tele-command links handle data downlinking and ground control of all on-board functions. The telemetry includes image data from two TV systems and position data from an onboard GPS system.

Launching
The 500 kg gondola is launched to typically 40 km altitude using a 400.000 m3 hydrogen filled balloon.

PIROG 1-5 were launched from Esrange and PIROG 6-7 from Air sur l'Adour, France and their mission was to look at objects located at more southern parts of the sky.

Recovery
The flight was terminated by cutting the balloon line via ground command and the gondola then descended to ground by parachutes. A helicopter brought it back to the launch base. The descendance lasted for approximately 45 minutes. Due to the thin air the parachute deployed immediately and the gondola fell with a speed which increased to 200 m/s. But as it reached thicker air it slowed down and the landing speed was only 8 m/s. Crash pads under the gondola protected it further and it landed undamaged.

Curiosities
PIROG-5 was lost due to a malfunction in the cutting system. At the gondola´s top altitude it drifted away to the north. It flew over Norway and Russia and it made a loop over the Arctic and a few days later it passed Russia again and then headed for Finland. As the hydrogen leaked out of the balloon its altitude was now 20 km. Before passing the Finish border it was actually shut down by Russian jetfighters. Remember, in 1990, the "cold war" had just ended. At the moment they blow up the balloon, the gondola fell normally to the ground in its parachute. The gondola survived and after a couple of years of constructive diplomacy, it was returned to SSC.

For more information concerning PIROG, please contact: Mr. Kjell Stegner.