Jeff Bezos' ongoing rivalry with SpaceX is heating up. His aerospace company, Blue Origin, has filed a lawsuit against NASA after the agency awarded a highly coveted contract for a lunar lander to Elon Musk's SpaceX instead.Blue Origin's federal suit accuses NASA of having been "unlawful and improper" in its evaluation of proposals concerning its human landing system program, SpaceNews reported. In April, NASA awarded a nearly $2.9 billion contract to SpaceX to collaborate with the agency to design and develop a lunar lander to carry astronauts to the moon — ensuring that SpaceX will likely play a big role in the first lunar landing with humans since 1972.In July, Blue Origin argued in an open letter that NASA gave SpaceX an unfair advantage during the proposal process. Bezos' company also said by choosing only one company to receive a contract, the space agency made it possible for one firm possibly to "[have] insurmountable leverage over NASA." Without competition, Blue Origin said, "short-term and long-term lunar ambitions will be delayed, will ultimately cost more, and won't serve the national interest."In the letter, Blue Origin offered to sacrifice up to $2 billion in future payments should NASA amend its decision. Blue Origin and Dynetics, another private company, filed a formal complaint with the Government Accountability Office over NASA's decision to work solely with SpaceX. But the GAO concluded in July that NASA did nothing wrong. NASA said in its initial announcement that the agency had the option of issuing multiple awards, a single one or none at all, dependent on funding, GAO said. NASA in the end went with only one company because it didn't have enough funding for more than one award. The GAO also said that NASA evaluated all proposals fairly.NASA must respond to Blue Origin's suit by Oct. 12, according to BBC News. However, the details of the suit will likely remain a mystery; Blue Origin was granted a protective order, sealing details of the case, on Monday, according to Space.com.Representatives for NASA told The Verge that they are "currently reviewing" the case. Copyright 2021 NPR. To see more, visit https://www.npr.org.