NASA is now preparing and planning for the "Journey to Mars," in which it will send humans to Mars by the 2030s. It will absolutely cost a lot, and the space agency estimated it to be $450 billion over the next three decades. This could be the costliest space mission ever.
The updated cost of $450 billion accounts for a one-month Mars surface stay in 2037, crewed landing on the Mars' moon, Phobos, in 2033 and one-year surface stays in 2041 and 2046. The cost will also include a new International Space Station (ISS) or a docking station. This is because NASA will end support for the ISS in 2024, according to The Space Reporter.