NASA has delayed awarding the next round of International Space Station resupply contracts until January 30th, 2016. In addition, the space agency has denied the submission from Boeing, one of five companies originally in the running for the billion-dollar contracts. This is the third time that NASA has pushed back awarding these contracts, having already delayed the decision in June and September of this year.

Boeing was planning to use a modified cargo-only version of its CST-100 Starliner spacecraft, the same one that — along with SpaceX's Dragon — will eventually shuttle NASA astronauts to and from the ISS as part of NASA's Commercial Crew program. Lockheed Martin's submission has widely been rumored to be out of the running as well, leaving SpaceX, Orbital ATK, and Sierra Nevada Corporation as the companies vying for the two contracts.

Just three companies are vying for the two contracts now

The contracts are for NASA's Commercial Resupply Services 2 (CRS2) program, which covers the space station cargo runs scheduled to take place between 2018 and 2024. (NASA is committed to operating the ISS until at least 2024, but other countries have yet to sign off on this date and any extension beyond that is still up in the air.) SpaceX and Orbital won the original CRS contracts back in 2008, which jump-started the first private space missions to ever dock with and deliver cargo to the ISS.

NASA has not disclosed the reason for the delays, but it's possible they have to do with the fact that three different cargo missions have failed in the last 13 months — two of which belonged to SpaceX and Orbital. That doesn't necessarily mean the agency has lost faith in these companies. Not only are they still in the running for the new contracts, but earlier this year NASA extended the CRS1 contracts with both companies, ordering more flights on the back end of the original schedule.

The other issue could be NASA's budget. Administrator Charles Bolden has been very vocal about how underfunding NASA would not only affect the agency's work, but the work of its private contractors, too. While the Senate recently passed a resolution that should help NASA stay near the budget it requested for 2016, a Congressional vote in December could still result in a government shutdown. It's possible that NASA delayed the CRS2 announcement while it waits for the results of that vote.

SpaceX and Orbital are likely the frontrunners for the CRS2 contracts since both companies' spacecraft have made repeated, reliable deliveries before the respective launch failures. Sierra Nevada’s offering, by contrast, is the Dream Chaser spaceplane. Though the shuttle-like design would make it easier to reuse after each flight, the Dream Chaser has only performed one partial test flight in 2013, and it botched the landing. The company originally designed the Dream Chaser spaceplane in hopes of being chosen by NASA for the Commercial Crew program, but the agency chose SpaceX and Boeing instead.