Question: In an "alternate universe" where NASA continued to receive a mandate, funding and public support at say peak Apollo levels, could another ten or twenty years have gotten boots on Mars, with astronauts in those boots?

Or would there be some clear technical challenge that really needed several more decades of development before this would have been possible?

**Ideally:** a bit of math or some supporting links should be presented and not just an opinion or a list.

This question is motivated in part by [this thoughtful answer](https://space.stackexchange.com/a/27968/12102).

Answer: 
It seems strange to me that no one has mentioned Project Orion (1958-1965), a theoretical study of using atomic bombs to launch rockets and propel them in interplanetary space.

That would have been many times more efficient than chemical rockets and the members of project Orion hoped that it would enable manned lunar and interplanetary missions in the the 1960s and 1970s.

In regard specifically to Mars, in 2003 the BBC aired a documentary about Project Orion titled *To Mars by A Bomb: The Secret History of Project Orion*.

It seems quite possible that if Project Orion had been supported there could have been manned missions to Mars and other planets in the 1970s.
There's always the thought that if you put enough money/resources behind a project, you can do anything, and while this is true in many cases, the amount of resources needed without key innovations can be astronomical and ultimately prohibitive. An example I often cite is the Pyramids- they were built without the wheel, but the resources needed to do them without the wheel was an immense human-powered task!

Much in the same way, if we funneled a virtually limitless volume of resources into NASA, we could have any number of major advances using the technology we have available, and the funding to fuel new, incremental breakthroughs. Would these breakthroughs ultimately lead to an easier path to Mars is impossible to speculate, but consider this- if money were no object, a nation could incrementally build an immense space-faring habitat that could, in time, make it's way to Mars. Whether peak Apollo-era funding would have been sufficient to achieve something of that scale is hard to say- but consider this:

One Saturn V Rocket could move 310,000 pounds into orbit at the cost of roughly 190 million dollars. The modern International Space Station weighs 500 tons, or just about 1,000,000 pounds. Supposing the habitat that would travel to mars weighed a conservative double of that, or 2,000,000 pounds (1000 tons), you are looking at no less than 7 successful Saturn V rocket launches, totaling $1.3 Billion in launches alone, not counting the craft, support, development, labor, assembly, and other costs- all in 1970's dollars. At those dollar amounts, you're beginning to look at taking a huge slice out of the United States total budget pie-chart at the time.

So, in summation, while I think will and determination can overcome pretty much any technical hurdle, the economic factors make the possibility of this very, very slim, even with peak Apollo-level funding.