A February 22, 2014 story in NASASpaceFlight.com reports that with the planned extension of the International Space Station to 2024, NASA is considering new options for cargo resupply. Currently the SpaceX Dragon and the Orbital Sciences Cygnus are in use as cargo carriers, with the Dragon able to take cargo back to Earth. Both companies are obviously the front runners for the cargo missions to take place between 2017 and 2024, but a couple of new options have arisen.
Sierra Nevada’s Dream Chaser, a lift body vehicle that takes off on top of a rocket but lands horizontally like the space shuttle used to do, could be used in a cargo capacity. Currently Dream Chaser is one of the competitors for NASA’s commercial crew program, which would take astronauts to and from the International Space Station. As a bonus, Dream Chaser could take cargo back to Earth, similar to the SpaceX Dragon.
The other possibility is a revival of the ATK Liberty rocket, based on the Constellation program’s Ares 1. The Liberty could be used to take a logistic module capable of delivering four full sized science racks to the ISS as well as a crew capsule. Liberty failed to make the cut for the commercial crew program, though the project seems to be very much still alive.