The moon may soon be a tourist destination for millionaires with Excalibur Almaz, a British spaceflight firm, preparing to sell $150,000 tickets aboard a 1970s Soviet space station retrofitted with new thrusters

Space tourists may soon be able to pay their own way to the moon on board old Russian spacecraft retrofitted by a company based in the British Isles.

The spaceflight firm Excalibur Almaz estimates that it can sell about 30 seats between 2015 and 2025, for $150 million each, aboard moon-bound missions on a Salyut-class space station driven by electric hall-effect thrusters.

Excalibur Almaz founder and chief executive officer Art Dula estimates it will take 24 to 30 months to develop the remaining technology needed and to refurbish the ex-Soviet spacecraft and space stations the company already owns. It bought four 1970s-era Soviet Almaz program three-crew capsules and two Russian Salyut-class 63,800-pound (29,000 kilograms) space station pressure vessels.

Declaring that he is ready to sell tickets and that a 50 percent return on investment could be achieved in three years, Dula told the Royal Aeronautical Society's third European space tourism conference on June 19, "At $100 million to 150 million [per seat, we can sell] up to 29 seats in the next 10 years, and that is a conservative estimate. We [chose] not to use, for this presentation, the aggressive estimates." [Gallery: Private Space Stations of the Future]

Those conservative and aggressive estimates are from a market study entitled "Market analysis of commercial human orbital and circumlunar spaceflight" carried out for Excalibur Almaz by the management consultancy Futron. In 2009, Excalibur Almaz officials told SPACE.com the company's first flight would be in 2013.

The architecture for the lunar mission involves a Soviet Almaz Reusable Return Vehicle (RRV), which can carry three people, launched by a Soyuz-FG rocket. This rocket also launches Russia's Soyuz manned capsule. The RRV weighs 6,600 pounds (3,000 kg) and has a habitable volume of 159 cubic feet (4.5 cubic meters). The lunar flight also uses a Salyut-class 63,800-pound (29,000 kg) space station that is launched by a Proton rocket. While Excalibur Almaz intends to use the Soyuz-FG and Proton initially, Dula did not rule out using other rockets, including Space Exploration Technologies' (SpaceX) Falcon 9 in the future. Dula said Excalibur Almaz would wait for the Falcon 9 to accumulate enough flights that it became feasible to insure the space station module aboard the rocket.

"Our customers are private expedition members and I think it is fundamentally different to tourism," Dula said. "What we are offering [with the lunar flight] is more like expeditions."

Once in orbit, the station and RRV will dock and the station's propulsion system, which is a group of electric hall-effect thrusters, propels the stack out to the moon. Excalibur Almaz is in talks with Natick, Mass.-based Busek Space Propulsion to develop the hall-effect thrusters needed. Dula described an electric system for the station module that would use up to 100,000 watts of power for its thrusters. If a solar or cosmic radiation event threatened a flight's crew and passengers, the company could run power through "electrical lines around the station and keep most of the charged articles away protons you can keep out with an electrical field." He also said the station would have a refuge area crew and passengers could use to protect against radiation storms.

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Company promises flights to the moon aboard recycled Soviet space station