Commercial Orbital Transportation Services (2006-2013)
NASA offered fixed-price awards to companies willing to deliver cargo to the International Space Station, instead of buying the rockets and spacecraft itself. SpaceX and Orbital Sciences won the early agreements and flew demonstration missions.
SpaceX's Falcon 9 and Dragon reached the station, and Orbital's Antares and Cygnus followed.
Buying services rather than hardware became NASA's default approach for low Earth orbit, and later for lunar delivery.
The VADR task orders apply the same structure to moving cargo between Earth orbit and the Moon, with NASA as customer rather than operator.
