For the first time, NASA is planning to open the International Space Station to private citizens, allowing commercial companies to arrange tours that could cost as much as $58 million per person, officials said at a news conference Friday.

The first phase of the plan will allow up to two private astronauts to make short-term visits to the station as soon as 2020, before opening the station to other tourism opportunities.

NASA said the commercial activity is an effort to raise money for sending a new round of astronauts to the moon by 2024.

Hours after the announcement, President Donald Trump tweeted that he does not think NASA should focus on returning to the moon and should instead turn its attention toward Mars (while incorrectly stating “the Moon is a part” of Earth’s neighboring planet). Trump just last month said he was beefing up NASA’s budget “and we are going back to the Moon.”