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.

  • 8
    $\begingroup$ For manned mission - it depends on scenario. Is it one-way trip or with return? Is it flyby of Mars, orbit at Mars, landind on Phobos/Deimos or landing on Mars surface? These different scenarios have VERY different deltaVs. I think no-return missions could be technically possible with Apollo-era technologies, even landing on Mars. Flyby of Mars could be done too. But orbiting Mars with return requires very large mass so the spaceship should be assembled in-orbit. And Mars landing with return is even more hard, of course. And surely deltaV is not only problem $\endgroup$
    – Heopps
    Commented Jun 20, 2018 at 5:31
  • 1
    $\begingroup$ @Heopps If you have time, expanding your comment a bit and posting as an answer would be great! $\endgroup$
    – uhoh
    Commented Jun 20, 2018 at 5:35
  • 8
    $\begingroup$ This is covered quite well (for a slightly later time period) in "The Case for Mars" (note this idea was finished in/around 1990) by Dr. Robert Zubrin, head of the Mars Society. The Mars Direct proposal used technologies from that era to propose a manned Mars program. $\endgroup$
    – Edlothiad
    Commented Jun 20, 2018 at 5:47
  • 5
    $\begingroup$ I'd say the other answers cover this in some depth, but for a pretty hard-science novel depicting exactly this scenario you might enjoy reading Voyage - Stephen Baxter. The premise is that when President Nixon was presented with the choice to switch funds to the Shuttle program, he elected to continue apollo style missions and shoot for mars instead. Its depiction of NASA's culture and the technologies available at the time are particularly good. $\endgroup$ Commented Jun 20, 2018 at 15:03
  • $\begingroup$ @Ruadhan2300 it's quite noble to self-delete something with several upvotes! Thanks for your contribution. $\endgroup$
    – uhoh
    Commented Jun 20, 2018 at 15:08

5 Answers 5


If you want to get really bummed out for 'what could have been', check out the Wikipedia page for List of manned Mars mission plans.

The earliest plan to get to Mars was written by von Braun in 1948, with the idea that we would be landing in 1965. With our current knowledge of Mars, it reads like science fiction. Seven passenger ships and three cargo ships would be assembled in Earth orbit using reusable shuttles to launch the materials. They would fly to Mars in the same way we do currently, at the optimal transfer window. They would find a landing site from orbit. A manned glider would be used to make the first landing on Mars, using skis to land on the polar ice cap. The crew would then travel overland using rovers and then build a landing strip. Mars 1949http://www.astronautix.com/v/vonbraunmarpedition-1952.html

Obviously we now know much of this would be impossible. Mars doesn't have the thickness of atmosphere needed to support landing with gliders, and the radiation of interstellar space was completely unknown at the time. Additionally, the technology and engineering which would be needed to develop reusable shuttles were almost 30 years away, and even then NASA was unable to keep reuse tempos anywhere near what would be necessary for an extended space construction project.

Quick budgetary baseline here: Apollo cost about $107 billion in today's dollars. Here are the yearly figures in that-year-dollars from Wikipedia:

Apollo budget costs

The NASA estimates for the space shuttle (which was being costed and developed around the same time Von Braun and Boeing were putting together) was 43 billion in 2011 dollars. This was based on 50 launches per year, which was very unrealistic (lots more to be said here, effectively NASA planned for the Space Shuttle as being the sole launch vehicle for the entirety of the US including commercial and military launches). The actual final total for the space shuttle was 196 billion, so the estimates were way off.

Back to the plans. Von Braun updated his plan throughout the Apollo program, and at the very end of his career, proposed his 1969 plan. This plan was huge, and would likely have required an amount of investment in excess of what Apollo ran (his estimate was a peak of $8 billion per year, which is more than double what Apollo cost at its peak). The first step of the plan was the space shuttle, albeit a far different shuttle than the one you and I know, mainly because it would use a nuclear rocket for propulsion. This would be followed by an earth space station, and finally the creation of the spacecraft which would take us to Mars. The main lifting vehicle from Earth for this would be a future-state Saturn V, the Saturn V -25U. This rocket would be a longer version of the Saturn V which took us to the moon, with four solid rocket boosters attached to the bottom, and the upper stages replaced by NERVA, a nuclear rocket engine. This rocket was entirely technically possible at the time, and would have required significant but not impossible engineering and integration work.

Mars 1969 http://www.astronautix.com/v/vonbraunmarpedition-1969.html

The two Mars ships would be assembled in Earth orbit, fly to Mars using a standard trajectory, astronauts would descend using a to-be-designed descent module, stay for 90 days, then swing by Venus on their way back to Earth, docking with the space station and then returning in the reusable shuttle.

The big driver for the 1969 plan, as well as for a competing plan from Boeing, was the NERVA rocket. Nuclear Engine for Rocket Vehicle Application (NERVA) was a nuclear-based rocket engine.

NERVA https://en.wikipedia.org/wiki/NERVA#/media/File:NERVA.jpg

This rocket engine was (and may still eventually be) the key to interplanetary travel. In a nuclear rocket, you don't need a chemical fuel. Liquid hydrogen is used, and is heated to a very high temperature in a nuclear reactor. As in a conventional rocket engine, the gas then expands and is propelled out the back of the ship. NERVA would have provided basically twice the fuel efficiency of a chemical rocket. I keep saying 'would have', but NERVA was an extensively developed project. Research on nuclear thermal rockets began in 1952, and continued for two decades. Two engines were built and tested. The second, NERVA XE, was basically a complete flight system and tested in a near-vacuum environment. It ran for a total of 115 minutes and was started 28 separate times.


In my opinion (and the opinion of 1960s engineers far far smarter than I), the answer to whether we could have done it technically is yes. The budget would have needed to exceed that of peak apollo, but that would have included far more than just the Mars mission, but also an earth-orbit space station, a reusable shuttle, and a nuclear rocket engine. Whether those estimates were reasonable, given the massive expansion of the space shuttle compared to initial estimates, is debatable. Whether it would have survived the political pressures not only to cut spending in the 70s and 80s, but also the environmental movement which was (and is) diametrically opposed to nuclear rockets is another. But if we'd been willing to double the investment we were making in Apollo, and public support had existed, I absolutely think we could have gotten not only there but to even more distant parts of our solar system.

  • 5
    $\begingroup$ $3B in 1966 is $23B today. NASA is already getting almost $20B a year now. So I agree that NASA would have needed much more money per year than the peak Apollo level to get to Mars in the 80's. Double seems plausible, but it's impossible to know without access to the parallel universe. There has never been a technical blocker. NERVA would have been nice, but not necessary. $\endgroup$
    – Mark Adler
    Commented Jun 20, 2018 at 16:04
  • 12
    $\begingroup$ @MarkAdler However, NASA's mission has been greatly expanded since Apollo, thanks in part to its innovations. Now NASA is paying for a fleet of space telescopes, Mars landers, tests of general relativity, asteroid sample return, earth science satellites, etc. The manned portion direct costs are about 1/4 of the total budget today. $\endgroup$
    – user71659
    Commented Jun 20, 2018 at 18:07
  • 4
    $\begingroup$ Apollo 1 took ~7y and over 10B. Apollo 17 cost under 1.5B (the budget for '71-'72) which is about 8.5B today. Given the US military budget of $610B, we could be launching ~71 Apollos a year. My point is that space travel is much less expensive if you don't have to invent space travel. However, spending the entire military budget on space is naive to say the least. 20B gets you 2... or we could be doing all that other stuff ^^ $\endgroup$
    – Mazura
    Commented Jun 21, 2018 at 2:11
  • 1
    $\begingroup$ All of this, even with adjustments, would have been a terrible mistake. Government exploration is not sustainable. The motivation must be profit -- it is almost a physical law -- you must get more out than you put in. $\endgroup$
    – Erik
    Commented Jun 21, 2018 at 14:50

I second what Edlothiad suggested, Mars Direct would have been perfectly feasible. Mars Direct was created and proposed mainly by Dr. Robert Zubrin. His approach to a human Mars mission was precisely to find a way to do it using the available technology and not using technologies that are still in development or experimental, such as Nuclear Thermal Rockets, advanced propulsion, on orbit assembly, which would all drive up the costs. His research was initiated due to the 90-day report* and the very high costs associated with a more extensive and elaborate plan for going to Mars. He also suggested a mission that is as lean as possible, requiring the least amount of mass to be launched to make this possible with the class of launch vehicle technology available.

Some of the key points to his approach:

  • Use available Saturn V/Shuttle class launch vehicle
  • Launch, transfer, land and verify an unfueled return vehicle prior to crewed transfer
  • Create propellant for return voyage on Mars with the Sabatier reaction using small amount of hydrogen and a small nuclear reactor brought from earth(ISRU).
  • Transfer crew on direct orbit to Mars, no on orbit rendezvous, use a slower orbit that is safer due to it having a free return in case of emergency
  • Land all crew on mars(no astronaut stays on orbit)
  • Stay on mars for an extended time (due to conjunction orbit)

Zubrin has been pushing this approach for decades without any real movement from NASA. The main reason for this is that, due to multiple reasons, NASA is no longer driven to a singular goal, such as mars, and has many technology driven goals instead. To do humans to mars with the available budget even in this cost effective way would mean giving up on other programs such as ISS.

Some of the excuses given by opponents for why it would not work (or any other plan using available technology) are:

  • We do not know how to deal with radiation, so more radiation research needed
  • We want to go to Mars faster, so advanced propulsion needed
  • ISRU has never been done so we cannot rely on it, so we need to bring fuel, so we need a huge ship and advanced propulsion
  • The mass margins are too slim

Which can all be disproved, and have been, by Zubrin.

You can find multiple publications of this plan and the details such as:


*Report of the 90 Day Study on Human Exploration of the Moon and Mars, 1989

  • 1
    $\begingroup$ Which can all be disproved, and have been, by Zubrin. From a web search, it looks like Zubrin claims that the radiation problem is a total non-issue marssociety.org/r-zubrin-radiation-hucksters-strike-again , but this seems controversial. It would be nice to see a review of the literature written by someone who is not a dedicated enthusiast. $\endgroup$
    – user687
    Commented Jun 23, 2018 at 16:29
  • $\begingroup$ Yeah I respect a guy like Zubrin for his enthusiasm and dedication, but the dismissal of the radiation issue makes him seem fanatical. Instead of pretending it's not an issue he should probably just admit that it doesn't matter to him and likely won't matter to the first Martian explorers whether they might have an increased cancer risk. $\endgroup$
    – ben
    Commented Mar 12, 2019 at 20:33

Probably yes. To add to the other already excellent answers: There is the very relevant blog Spaceflight History which focusses on "space exploration history told through missions & programs that didn't happen".

It has many postings regarding Mars.

Some examples:

  • $\begingroup$ Thanks, if you re-read the question carefully, I think you'll see that you haven't addressed it at all. This is just a list of things that didn't happen. Can you try to focus more on answering the question as asked? $\endgroup$
    – uhoh
    Commented Jun 20, 2018 at 14:05
  • 1
    $\begingroup$ @uhoh: These are all proposals that could have happened, especially the first four. And "peak Apollo" applies to at least to the first three. $\endgroup$ Commented Jun 20, 2018 at 14:09
  • 1
    $\begingroup$ I understand, but a list of proposals is just a list, not really a proper Stack Exchange answer. Do you think it is possible to add something that answers the question to your post? Perhaps you can choose one and explain in words why you feel it supports a yes or no answer? I don't even see any indication of a "yes" or "no" here. What I'm "looking for" is an answer to the question as asked. Thanks! $\endgroup$
    – uhoh
    Commented Jun 20, 2018 at 14:15
  • 1
    $\begingroup$ @uhoh: Understood. Better? $\endgroup$ Commented Jun 20, 2018 at 15:52
  • 1
    $\begingroup$ @MartinSchröder It should be. Even in its first form, saying the question wasn't addressed "at all" is too much. What better answer can there be than "Here is what the experts said at the time. Here are the actual plans by the experts in these fields who say yes. Here are the ways it would have happened, had someone merely provided the funding rather than cancelled it." The only thing you were lacking before was explicitly stating "Yes" $\endgroup$
    – Aaron
    Commented Jun 22, 2018 at 16:59

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.

  • 1
    $\begingroup$ I am not an expert in wheels, but I think this answer is influenced by the deceptive articles that can be found online about how late the wheel was supposedly invented. Articles can be found stating the wheel post-dates many other inventions, including cast metal, and deceptively claim that the wheel was a complicated invention. The pyramid builders likely did use simple machines. What may not have come until later was specifically the wheel and axle. Primitive wheels can be made by simply lying a few logs down and rolling objects on top of them. No other ingenuity necessary. $\endgroup$
    – Aaron
    Commented Jun 22, 2018 at 18:03
  • 3
    $\begingroup$ ... As a case in point, I once challenged my son, when he was about 7 or 8, to move a heavy load. With no input from myself, he thought about it for a few minutes, vainly tugged and lifted at the load, thought some more, went through testing several ideas, eventually settling on using logs to roll the object on. He was set back when he realized that unattached wheels will make their way back and "fall off" the back of the load, until he said "let's just keep bringing the ones from the back back to the front." Bingo! He re-invented a form of wheel. And I have seen this happen with others. $\endgroup$
    – Aaron
    Commented Jun 22, 2018 at 18:09
  • $\begingroup$ In context though, I support the point of this answer. It is correct. Even a baby can finish a marathon if it makes enough tiny steps in the correct direction. $\endgroup$
    – Aaron
    Commented Jun 22, 2018 at 18:12
  • $\begingroup$ And on second thought, it appears the pyramids were also built even after the invention of the wheel and axle itself! So "built before/without wheels" I think is false in every sense. You should probably remove the wheel bit entirely from your answer. $\endgroup$
    – Aaron
    Commented Jun 22, 2018 at 18:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.