The US space agency NASA announced Friday that it is opening the International Space Station (ISS) for private citizens, with a hefty price tag.

NASA will provide two privately funded trips to the station per year, each lasting up to 30 days, and the first mission could be as early as 2020, according to NASA.

Those private travelers will firstly pay an estimated 58 million US dollars for a round-trip ticket for the 30-day trip. Then they have to spend about 35,000 dollars per night for accommodations, said Jeff Dewit, NASA's chief financial officer, at a press conference at Nasdaq in New York City.

They will use a US spacecraft developed under NASA's Commercial Crew Program, including the rocket-and-capsule systems being developed by Boeing and Elon Musk's SpaceX.

Previously, Russia's space agency has already brought a number of private travelers to the station.

NASA's ISS tour comes as the US space agency plans to end its support of the ISS by 2024, the same year when two US astronauts, including a woman, are slated to land on the south pole of the Moon.