The balloons are used primarily for environmental research, monitoring of the ozone layer and validation of satellites (which means making sure that the satellites provide accurate data). The balloons can also be used for testing of new aerospace vehicles.
Scientific balloons are made of thin polyethene plastic, usually between 10 and 20 μ thick. At Esrange Space Center we use balloons made by the French company Zodiac, and the American Aerostar. Manufacturers can also be found in China, Russia and India.
Better than a telescope
The dirt and the particles suspended in Earth's atmosphere prevents us from seeing very far into space by Earth-based telescopes. With the help of balloons, we can lift the telescope above the atmosphere and if you, for example, send up a telescope with a balloon above the atmosphere, you see everything much better and can study for example the life cycle of stars which helps us to understand the universe and how the earth was formed. The balloons fly with the wind at a height between 15 and 45 km.
Large, but cost effective
The balloons, which are launched from Esrange Space Center, are filled with helium. A balloon can be twice as large as the Globe Arena in Stockholm, lift a payload of two tonnes and fly from Esrange Space Center (Kiruna) to Alaska in just over four days. A major advantage of using balloons is that they are very cost effective.
Preparations before launch
It requires a lot of preparation before releasing a balloon. Both ground winds and the winds higher up are continuously checked. The wind speed should be between 1.5 - 5m/sek in order to be able to release the balloon. When one decides to take down the balloon there is accurate calculations made about where it might land, so it does not land in any settlement, over power lines or similar.
Separation of balloon and payload
There is a so called 'cutter' separating the balloon and its payload. Parachutes are winded so the payload can land safely. The payload is then brought back to Esrange Space Center either by helicopter or by snowmobile, depending on weather and season.
Winds make the difference
In the Arctic air mass it is always westerly winds in the summer and easterly winds during the winter. In that way you can figure out which way the balloon will fly. Between the periods when the wind turns, a so-called "turnaround" period occures, which means that winds above are standing still in the stratosphere. This allows the balloon to stay almost stationary over the place where it has been released and balloons can fly in two days and still land just a few miles from the launch site.