The space race between the world's two richest people is picking up steam after SpaceX chief Elon Musk stabbed Jeff Bezos to challenge a major NASA contract.

Two billionaires who tried to launch long-range orbital rockets were competing for a government contract to build a spacecraft that will take astronauts to the moon as early as 2024.

Musk won. Bezos is unhappy.

Bezos's company Blue Origin has filed a protest with the Audit Chamber, accusing NASA of changing the conditions for bidders at the last minute.

Blue Origin has lagged well behind SpaceX and the United Launch Alliance (ULA) in orbital transportation, having lost launch contracts that begin in 2022.

These rocket launches are mainly aimed at sending satellites into orbit at an affordable cost and reusing rocket parts to contain costs.

Earlier this month, Blue Origin was dealt another blow when NASA signed a lunar contract with SpaceX. The popular project aims to return people to the moon for the first time since 1972.