- Video report by ITV News Washington Correspondent Robert Moore
Nasa is to allow tourists to visit the International Space Station from 2020 - but it could cost £27,500 per night ($35,000).
The US space agency announced its plans to open the orbiting station to tourism and other business ventures at a press conference today.
Robyn Gatens, the deputy director of the ISS, revealed there will be up to two short private astronaut missions per year and they will be available through privately funded, dedicated commercial spaceflights
Nasa said that tourists, referred to as private astronauts, would be permitted to travel to the ISS for up to 30 days.
It will allow commercial companies to arrange the trips which could leave passengers with a bill of £47 million or more.
The two businesses chosen by Nasa for the private flights are Elon Musk's SpaceX, which will use its Dragon capsule, and Boeing, which is building a spacecraft called the Starliner.
"Nasa is opening the International Space Station to commercial opportunities and marketing these opportunities as we've never done before," chief financial officer Jeff DeWit said in New York.
Nasa will continue to carry out its own research in low-Earth orbit, but wants to work with private companies on testing new technologies, training astronauts and “strengthening the burgeoning space economy”.
Nasa said that private companies would be responsible for determining the line up of the crew and ensuring that the tourists meet the medical and training requirements for spaceflight.
It is expected that SpaceX and Boeing are likely to charge any private astronaut a similar "taxi fare" to what they intend to charge Nasa for its astronauts - close to $60m per flight.
William Gerstenmaier, Nasa’s associate administrator for the human exploration and operations mission directorate, admitted that the decision was a huge shift for the agency, despite already allowing more than 50 companies to conduct some research and development on board.
“The private sector will have the opportunity to think creatively and create new markets,” he said.
“Nasa’s approach is designed to lower but not totally remove the risk for the private sector, entrepreneurs and companies.
“Nasa is allowing the private sector access to the ISS to enable the next-generation of lower-Earth orbit research facilities.
“Nasa realises that we need help, we can’t do this alone, we need everyone to help us moving forward.
“We’re reaching out to the US private sector to see if we can push the economic frontier into space.”
Last year, the ISS celebrated 20 years since being launched into orbit.
In November 1998 the first piece was sent into space but it remained unmanned until nearly two years later, when American astronaut William Shepherd along with Russian cosmonauts Sergei Krikalev and Yuri Gidzenko went on board on October 30 2000.
The ISS has been inhabited every day since and crew members carry out research they would not be able to do on Earth.
However, main construction was not completed until 2011, when the final module was installed, and it looks set to be decommissioned by 2028.