From an anonymous poster at Space Politics, here's a budget plan to reduce the ISS gap. Space prizes are one (although not central) feature of the proposal. There's some pain in the plan (Hubble servicing, JEM EF), but it's interesting to consider. See the link for the full, considerably longer (but worth reading) post.
1) Shut down the Space Shuttle program after the last major foreign ISS component is up in early 2008. Although most of the remaining 2008 Shuttle budget would have to go towards shutdown and contract termination costs, we should be able to salvage most of the 2009 and 2010 budgets, something on the order of $7-8 billion (call it $7.5 billion). And we avoid the unnecessary risks involved in flying the Shuttle longer.
2) Terminate Ares I now. It’s an unnecessary duplication of existing military/commercial launchers and commercial launchers under development. Worse, the underperforming design is suffering from major technical issues that are putting it and Orion into a spiral of dangerous cuts to safety systems to save mass, possibly to the point where the system cannot fly at all. Out of $10 billion or so total development pricetag for Ares I, we should be able to save the vast majority of the funding, roughly accounting for what’s been expended to date and contract termination costs. Call it another $7.5 billion in savings through 2015. Combined with the Shuttle savings, that’s $15 billion from 2008-2015 that can go towards other activities.
3) Reallocate some of the savings, say $5 billion, to human-rate EELVs and to acclerate/diversify/ensure COTS. $2.5 billion should be adequate to human-rate both EELVs given a reasonable re-examination of NASA’s human-rating requirements. We have not touched Orion’s funding, so Orion could still be ready to fly on those EELVs when its ready. (Although I would probably shrink Orion’s requirements to ensure that its safety systems can be bought back.) Another $2.5 billion to COTS should also be adequate to bring at least a couple new, cost-shared commercial systems online before 2013, presumably Falcon 9/Dragon and something else.
4) Use the remaining $10 billion to get some actual exploration programs and hardware underway. Assuming the near-term target is still the Moon, I’d probably restore and competitively restructure (e.g., prizes, Discovery-type AOs, etc.) the RLEP program for rapid results to get some momentum going on the robotic side. If the target is no longer the Moon, there’s also great robotic missions to be restored to Mars, the outer moons, and for extrasolar planet-hunting telescopes. On the human side, I’ll leave it up to others whether a heavy lift or in-space propellant servicing architecture makes the most sense for whatever human target is chosen (Moon, deep space telescope support, asteroids, Mars/Phobos, etc.). But the point would be to get the NASA workforce going on that (instead of reinventing the ETO wheel) and offer the new President and Congress in 2009 options all on the wonderful things that NASA can get started in exploration without asking for another dime — instead of asking for billions more to fix the same old ETO access problem that we’ve been fumbling with since Apollo.