German space agency DLR and the European Space Agency (ESA) have launched a two-year test and validation phase of a solar sail capable of propelling satellites and other spacecraft through space at velocities of up to 360,000km/h (223,600mph) using sunlight as its propulsion system.

In development for the past eight years and unveiled at the Berlin air show, the 20 x 20m (66 x 66ft) solar sail technology demonstrator, which weighs only 35kg (77lb), will show that extended missions into the Earth's solar system are possible. Solar sailing (or photonic propulsion) will allow endless propulsion using light, with no engine or fuel required to move the payload through space. Spacecraft with solar sails would use the momentum of the transfer of photons on large reflecting sails to travel.

A new company, High Performance Space Structures (HPS), a venture between Kayser-Threde of Munich and INVENT of Braunschweig, has been established to attract investors. HPS needs around $45 million to produce a larger 40 x 40m module which, weighing under 100kg, could support missions to the moon. Ariane 5 could launch the demonstrator by year-end.

The sail comprises aluminium coated sail segments between 0.004 and 0.012 mm thick which are "frogleg" folded before launch and attached to four carbon fibre reinforced plastic booms which flatten into a strip before deployment in space. The whole module can be stowed in a small suitcase.

A potential first customer is the "Star of Tolerance" organisation which plans to use the solar sail as a publicity tool to promote global peace and raise funding for education projects and environmental causes. Under phase two, the world's first space regatta is planned with an Earth-moon race. Military applications are also being assessed as the sailing concept could be used to transport payloads for a space-based missile shield which would be difficult to detect due to the lack of propulsion signature.

Source: Flight International