In previous years, the hydrogen to fill the met. balloons came from a hydrogen generator. However that had been lost in a fire the previous year, so during 1982 and 1983 we used cylinders of hydrogen to fill the balloons. This limited us to 3 or 4 launches per week, instead of the normal 7. A hydrogen generator did arrive at Halley in January 1984 as part of the equipment for the new Halley 4 base.
The AIS was a computer-controlled radio transmitter and receivers, which sent radio signals into the ionosphere and listened for the echoes. The masts for the transmitter aerial were over 100 feet high.
We would make these observations whenever we had clear sunshine at local apparent noon. One of us would keep the instrument pointed at the sun and operate the filters, while the other inside the hut would note the time and the readings from the instrument.
When there was not enough room for everyone inside the Snocat, the rest of us rode on this sledge which was just an upturned wooden box mounted on sledge runners. For the building of Halley 4 in the summer 1982-3, when large numbers of people had to be ferried between the Bransfield and the building site, more luxurious sledges were provided which had roofs and padded benches inside. We could not understand the complaints of some builders about their discomfort.
We launched the balloons around 9:30am in the mornings, so that they would cross the tropopause at 10:00am (12 noon GMT). In the winter we used rubber balloons dipped in oil to soften the fabric, in the hope of achieving greater altitude. The radiosonde attached to the balloon would radio back atmospheric data for up to 90 minutes before the balloon burst, at maybe 15km altitude, and crashed back to Earth.
I took this photo using a flash to capture the balloon, combined with a time exposure of several seconds to register the sky, which explains the ghostly appearance of the balloon and the people.
Normally we would have used a radar to track the balloon's ascent. However vital parts of the radar had been destroyed in a fire the previous year, so if the sky was clear we could track the balloon's progress with a theodolite instead. Since a typical balloon flight lasted 90 minutes, this was a perishing cold job. Colleagues in the nice warm met room down in the base are calling out each minute over the headset, and Dave is reading back the balloon's elevation and azimuth.