A large part of the energy it takes to put an object into space is needed to lift it through the thick lower atmosphere.

That is why an innovative Spanish company is developing a satellite launch system called Bloostar. It uses balloons, rather than rockets, for the first launch stage.

"75% of the cost of a rocket launch happens in the first 75 seconds as its going up,” says Jose Mariano Lopez-Urdiales, Founder of Zero2infinity, the company behind the technology.

“If you replace that altitude of the first 75 seconds with something else cheap and simple like a balloon, you suddenly reduce dramatically your cost and also your environmental impact.”

Bloostar uses high-altitude helium balloons.

These can carry a payload of up to 75kg to an altitude of 20 kilometers.

The balloon then drops a cluster of three reusable ring-rockets, which fire in sequence to carry the satellite into orbit.

Zero2infinity says it has designed an engine for the rockets that is much simpler and cheaper than conventional rockets.

The engines use the near-vacuum conditions found at high altitudes to create pressure. This then feeds liquid natural gas to the engines.

“If you compare it with the engine of an airplane it is way simpler,” says Lluc Palerm, and Aerospace Engineer with Zero2infinity.

“You don’t have any moving parts… and [using] new technologies like 3D printing we can do it in two or three pieces. Its very simple to integrate and very simple to operate.”

Zero2infinity says the combination of using the balloons and the simple gas engines will cut the cost of launching a small satellite to just a few million dollars, around ten times cheaper than a traditional rocket launch.

Bloostar is likely to be of greatest interest to companies, universities and even small countries that are increasing putting tiny 'cubesats' into orbit.

These typically weigh around 1 kg, making it possible for Bloostar to launch a number of them at the same time.

Zero2infinity are also looking at using the balloons to take tourists to the edge of space.

It has already tested an experimental pod at high altitudes. It is in the process of developing an insulated and pressurized carbon fiber capsule capable of carrying two passengers up to an altitude of 40km.

Zero2infinity is hoping successful trials of both systems over the next two years will help demonstrate the role balloons can play in opening access to space for all.