1. A thing ppl may not realize about the canceled lunar mission: NASA probably cancelled it to save funds for the SLS rocket. But, SLS will end up being marginalized with only @elonmusk BFR doing Mars missions unless we can make Mars missions affordable w/in NASA's risk profile.
2. So NASA needs to change the game to make Mars more affordable, or SLS will ultimately be marginalized & never do Mars surface missions. There is only ONE serious idea to make Mars affordable for NASA, and that is to develop a vibrant cislunar economy involving space resources.
3. How can a vibrant cislunar economy make Mars more affordable for NASA? Multiple ways. Provide propellant made in-space to avoid launch costs. Cheaper in-space assembly of spacecraft. More space activity so economies of scale reduce overall cost of doing business in space. Etc.
4. If we do those things, then IMO (and in many people's opinions), the costs will steadily come down and Mars will soon be achievable. The quickest way for NASA to get to Mars is therefore to prime the cislunar economy.
5. NASA recognizes that it can't afford Mars so it has a new philosophy of "sustainable exploration". It describes how every mission must leave some infrastructure in place to build upon. The reason this can't work is that infrastructure must be maintained at a cost, and...
6. ...and the people who know how to fly the rockets and manage the infrastructure must be kept on those projects to avoid losing institutional knowledge. So building up infrastructure = building up an ever larger burden of cost. The cost still comes out to be too much for Mars.
7. And this is EXACTLY why we need to develop the cislunar economy. The idea is to offload the cost of maintaining all the infrastructure to the commercial sector, getting it off the NASA budget. But the commercial sector won't maintain infrastructure unless there's a cash flow.
8. So for NASA's "sustainable exploration" philosophy to work, we need to put more emphasis on finding ways for commercial companies to develop cash flows in space, offloading infrastructure and capabilities from the federal budget, saving the budget for the remaining Mars tasks.
9. If we do those things, and ONLY if we do them, then NASA will be able to use the SLS to land humans on Mars. Otherwise, the SLS ends up never doing the mission it was designed for.
10. And this is why it makes no sense to cancel the Resource Prospector mission in an effort to save SLS. Canceling RP actually dooms the SLS. It may give the appearance of a SLIGHTLY better SLS budget in the near term, but RP is the investment that can save the SLS/Mars budgets.
