Jeff Bezos’s Blue Origin has sued the US government over Nasa’s decision to award a $2.9bn lunar lander contract to Elon Musk’s SpaceX. Bezos, the founder of Amazon and one of the world’s richest people, founded Blue Origin to pursue the dream of commercial space flight, which saw him, his brother and two other crew members blast off from Texas last month. After that flight, Blue Origin offered Nasa $2bn if it would change its mind on the lunar lander contract. It did not, and the Blue Origin lawsuit was filed in the US court of federal claims on Friday. In a court filing, the company said it was challenging “Nasa’s unlawful and improper evaluation of proposals”. Last month, the federal Government Accountability Office (GAO) sided with Nasa over its decision to pick a single lunar lander provider, rejecting Blue Origin’s protest. Blue Origin’s lawsuit remains under seal. Nasa must file a response to the challenge by 12 October. Blue Origin and defense contractor Dynetics have argued that Nasa was required to make multiple awards. The GAO said it “denied the protest arguments that Nasa acted improperly in making a single award to SpaceX”. Blue Origin said earlier it remained convinced that there were “fundamental issues” with Nasa’s decision, and that GAO was not able to address them “due to their limited jurisdiction”. Blue Origin said it will continue to advocate for two immediate providers as it believes that to be the right solution.