Österreichisches Weltraum Forum Austrian Space Forum
The voice in the aviation radio belonged to the air traffic controller on the control tower of the airport in Graz. OE-ZCC was the registration of our hot air balloon, 12,000 feet was the altitude we wanted to reach. At that moment the balloon was floating over Stubenberg in Styria. The basket was full of scientific instruments.
How did this come about?
The Austrian Space Forum (OEWF) is a collaborator in the TRIPOLAR research project. The goal of the project is to determine the boundaries of the sustained existence of life. Up to which altitude can microorganisms like bacteria be found in the atmosphere? “Knowing the limits of life on our own planet will enable us to better design the search for life on other planets” explains Gernot Grömer. This first test flight was a pilot experiment designed to obtain basic experience with the sterile collection of samples in the Earth’s atmosphere. After all, the OEWF is planning to fly an (uncrewed) balloon into the stratosphere in the summer of 2012. The hardware for the collection of samples was developed by HTL Eisenstadt, the Project is being led by Birgit Sattler from Innsbruck University.
In the mornig of September 27 a team consisting of staff from the Institute for Ecology of the University of Innsbruck and members of the OEWF met at Stubenberg, one of the major ballooning centers in Austria. Weather conditions were ideal, a stable high pressure area assured low wind velocities even at high altitudes. Launch site was the field in front of Schielleiten Palace, a magnificent backdrop. A small camp was quickly set up and preparations started. It was important to make sure that the science requirements and the flight safety requirements were properly taken into account. A particular problem was the creation of a sterile working environment in the basket of the balloon. During launch and landing balloon baskets get dragged across the ground, so they are far from sterile. We also had to take safety considerations into account. A first aid kit including emergency oxygen was taken along.
A student and a scientist are the payload specialists during the balloon flight.
The samples are taken with special pumps which work like a vacuum cleaner. The air is passed through a collecting device. About 9000 liters of air were sampled in this manner during the first flight. Fortunately the temperature was high enough so the equipment did not freeze up.
Rudi Albrecht, member of the OEWF and an experienced balloon pilot coordinated the aviation aspects of the ascent. “Normal” ballooning happens at altitudes of 100 to 1000 meters. Taking a hot air balloon to higher altitudes, like to our target altitude of 4000 meters is, in principle, not difficult, but it requires a fair amount of preparation. Calculation of load limits at different altitudes, determination of the required amount of fuel including reserve, for good measure a phone call to the Austrian representative of the balloon manufacturer to make sure there are no hidden problems. Coordination with air traffic control is required- after all, our slowly floating balloon constitutes quite an obstacle for the air traffic at altitude. And the approach route to Graz airport goes right through the airspace over Stubenberg. In short, the controllers want to know everthing which happens above 6000 feet. Because the thing which they absolutely don’t want is surprises. This also meant that we had to file a flight plan.
The balloon rises with 3,5 meter per second.
The first launch happened on 26 September at 1700 local time. Several other balloons launched at the same time, this is always a magnificent sight. Swiftly we left them below and behind as we set up our initial climb rate of about 3.5 meters per second. Arriving at 5,000 feet we contacted Graz Tower. We continued to climb, slowing to 2 m/sec at 9000 feet. The sampling started at 11,000 feet. The balloon showed no signs of running into load limits even at our peak altitude of 12,000 feet, a fact much appreciated by the pilot. After about 10 minutes at altitude we slowly started our descend. At 8,000 feet the series of measurements was repeated, after which the equipment was stowed for landing.
After 1:25 hours of flight the onset of dusk had filled the valleys below with shadows. The GPS had us at a position about 6 km north of Gleisdorf. There are several requirements for landing a balloon. The first requirement is that it be gentle enough so nothing and nobody gets hurt or damaged. But it also should happen in a location which is free of obstacles, at which the balloon can be packed up, and which is located such that the chase crew first finds it and then can get to it with the chase vehicle. Which ideally means a meadow near a small road which is not too far from a major road. Sometimes this is wishful thinking considering the fact that the balloon is not steerable.
Impressive, beautiful view from 4,000 m height.
We did find a nice spot, and half an hour later the chase vehicle caught up with us. The day ended with dinner and with discussions about the flight and the experiments.
One of the lessons learned was that working in the confined environment of the basket took longer than we had expected. So during the second flight the next morning we started the preparations soon after we launched. There were, unfortunately, several small problems, like one of the pumps acting up erratically and one of the motors interfering with the aviation radio. But after the experience of the first flight this second ascent was almost routine. It was surprising to find that the Sun at altitude heated the (black) ballon so well that on the way down the descend rate never exceeded 3,5 m/sec. After 1:40 hours we landed smoothly on a small back road near Pischelsdorf.
The scientific evaluation of the data will take some time. In the meantime all first-flight crew members were properly elevated to the status of nobility in the traditional manner.
Thanks are due to Peter Flaggl, the Head of Flaggl Ballooning, who helped us with the preparations and supplied equipment. Markus Freiberger and two students joined the team on short notice.
The TRIPOLAR program is part of the “Sparkling Science” project, which is supported by the Austrian Ministry for Science and Research.
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