Space Launch Initiative; 2000 – 2002; perhaps $100 million.
This was an ill-defined shuttle-replacement project pursuing a variety of new approaches, with vague hopes of major commercial participation. The effort included a small "Alternate Access" project studying commercial re-supply of the space station. The project was hampered by constant changes in NASA's requirements; further work was first deferred due to uncertainty about the project's requirements, and then quietly abandoned in the wake of the Columbia shuttle accident in 2003. Afterwards, NASA's efforts were redirected towards an EELV-launched manned spacecraft, the Orbital Space Plane (OSP), which eventually merged into the Constellation programme. (Illustration: NASA-MSFC)