Jeff Bezos' space company Blue Origin filed a lawsuit Monday that aims to prevent a rival company, Elon Musk's SpaceX, from exclusive rights to land astronauts on the moon. 

The Verge reported that Blue Origin filed the suit against NASA because the American space agency rejected Blue Origin's lunar landing proposal and picked SpaceX instead.

Three companies made bids for the right to return NASA astronauts to the moon, almost 50 years since they last walked on the lunar surface.

NASA had signaled that it might choose two companies for the mission, but in April, it announced that it was awarding the contract solely to SpaceX's $2.9 billion Starship proposal.

NASA argued that it gets funding from Congress, and with funds limited, sided with less-expensive SpaceX over Blue Origin's $5.9 billion proposal.

But in Monday's lawsuit, Blue Origin argued that NASA carried out an "unlawful and improper evaluation of proposals submitted under the Moon competition." Blue Origin and Elon Musk have also been openly trolling each other, each claiming that they are better equipped to handle the NASA program, dubbed "Artemis.”

In July, the US Government Accountability Office (GAO) upheld the NASA decision to side with SpaceX, but the GAO's investigation created a three-month delay in starting the SpaceX contract, and the lawsuit filed Monday could further delay NASA's plans, regardless of which company ultimately wins.

The court battle among billionaires and their companies represents an entirely new shift in space travel, a domain that once belonged solely to governments.

Bezos launched his first Blue Origin manned spacecraft, New Shepard, with him on board, in July, which came several days after Virgin Galactic billionaire Richard Branson launched his own manned spacecraft. Each made just brief trips into space, with the goal of proving that space tourism is a viable enterprise.