Nasa chief financial officer Jeff DeWit, speaking in NY during the announcement, said: 'Nasa is opening the International Space Station to commercial opportunities and marketing these opportunities as we've never done before'.
The new directive will allow private astronauts to spend up to 30 days in low-Earth orbit aboard the ISS through trips planned by private companies.
It said that a private commercial entity would be charged with determining crew composition and ensuring that the private astronauts meet the medical and training requirements for spaceflight. Those astronauts will be able to launch on commercial crew vehicles like SpaceX's Crew Dragon and Boeing's CST-100 Starliner.
NASA is now planning to end its support of the ISS by 2024, the same year that NASA astronauts are slated to return to the surface of the moon.
"If you look at the pricing and you add it up, back of a napkin, it would be roughly $35,000 a night, per astronaut", NASA's Chief Financial Officer Jeff DeWit told a news conference in NY.
Eventually, Nasa hopes the space station will be just one of several "commercial and free-flying habitable destinations in low-Earth orbit".
"Enabling a vibrant economy in low-Earth orbit has always been a driving element of the space station program, and will make space more accessible to all Americans", Koch said.
More than 50 companies are already using the ISS for research and development. Private astronauts can use the ISS for "missions of up to 30 days", NASA said in its announcement in NY on Friday.
NASA has published detailed guidelines for private companies wishing to apply for use of the ISS, which you can read here.
Parts of the ISS will be opened for space tourism and commercial filming, according to The Washington Post. The agency will also begin fielding ideas for a commercial module to the station soon.
'Commercial companies will play an important role both here in low-Earth orbit an around the moon, working with NASA to test technologies, train astronauts, and develop a sustainable human presence'.