An innovative study published in The Aeronautical Journal describes a low-cost and efficient way to lift space rockets to higher altitude for launch using balloons.
Launching satellites and rockets from high altitudes, instead of launching them from ground reduces air drag and thus improves efficiency. At higher altitudes as air is thin, it becomes considerably easier to launch a satellite.
This concept of launching small rockets from balloons is not new, however in the past scientists used balloons filled with hydrogen or helium. But both these gases have huge drawbacks as they are more expensive than steam and hydrogen in particular is flammable and is highly explosive.
Researchers at the Finnish Meteorological Institute proposed the use of hot steam balloons in the launch of rockets and satellites.
“The balloon is filled by hot steam on ground and released. As the balloon ascends, part of the water vapor condenses. The condensation releases a lot of latent heat, which slows down the cooling and helps maintain the remaining vapor in gaseous state,” says the lead author Pekka Janhunen. “After reaching sufficiently high altitude, the rocket is released; it ignites and flies into space. The balloon is emptied of vapor; it descends and may be collected for reuse.”