Virtues of the 90-Day Study

Overblown? The 90-Day study, in a nutshell.

Overblown? The 90-Day study, in a nutshell.

Broach the topic of the “90-Day Study” with almost any random person involved with space for more than 25 years and you’re likely to provoke a reaction akin to showing Dracula a crucifix. This document is now offered as a cautionary tale about what flows from a devastating report – a bloated, impenetrable disaster of transcendent magnitude that doomed President George H.W. Bush’s Space Exploration Initiative, the 1989 attempt to fashion a set of long-range strategic goals for America’s civil space program. Released to near universal disdain and condemnation, its dread name lives in infamy in space history circles.

To understand what is behind all this opprobrium, I’ll begin by describing the historical circumstances under which this report was written, followed by the reasons it took the form that it did and what truth, if any, lies in the rather overblown reaction to it described above.

Twenty years after our space program’s peak during the Apollo effort, and despite President Reagan’s initiation of the Space Station Freedom project in 1984, our space program was under fire. The tragic loss in January 1986 of the Space Shuttle Challenger with her crew of seven led to critical reappraisals of the nation’s human spaceflight program. The fact that the accident seemed to result from hubris and incompetence only increased the volume of criticism. In time-honored Washington fashion, it was thought that a committee of experts should examine our space program and recommend a long-range direction. As it turned out, such a group was finalizing its report and mere months from issuing their results. The National Commission on Space (a.k.a. the Paine Commission) report (May 1986) was a grand vision of orbiting space cities, lunar and martian bases, and human expansion into the Solar System. Its unfortunate timing – along with its marked science-fiction flavor – led it to be largely ignored by policy makers in government.

However, the Paine Commission was not the only group working to devise a new direction for space. Several parallel efforts to plot a future course for NASA were also underway, both within and outside the agency. Since the early 1980s, a movement to examine the potential benefits of a return to the Moon had been studied by a group at the NASA Johnson Space Center (JSC) in Houston. Simultaneously, another effort was studying human missions to Mars (there had been no missions of any kind to Mars since the Viking explorations of the mid-1970s). These two streams converged within the agency in the Office of Exploration, which conducted paper studies on how to advance human spaceflight beyond low Earth orbit. An internal NASA group chaired by astronaut Sally Ride released a report to the administrator in 1987 that outlined the possible benefits and approaches for a variety of these initiatives, including human missions to the Moon and Mars. This report and the variety of work being done by NASA and others outside the agency provided the backdrop for a Presidential decision.

On July 20, 1989, the occasion of the 20th anniversary of the first landing on the Moon by Apollo 11, President George H.W. Bush gave a speech at the National Air and Space Museum in Washington that called for a return of people to the Moon – “this time to stay” – to be followed by a human mission to Mars. This policy proposal was dubbed the Human Exploration Initiative (HEI, later changed to “Space Exploration Initiative,” or SEI). The SEI included both robotic and human missions designed to extend human reach beyond low Earth orbit (LEO). SEI was largely the brainchild of the revived National Space Council, a White House-level policy group reporting to Vice-President Dan Quayle. Both Quayle and the Council were strong advocates of revitalizing the space program with a challenging set of goals. NASA was directed to produce a report within 90 days – a report that was to outline possible mission architectures and identify the technologies needed to accomplish those goals. The report effort was centered at JSC largely because that center’s Exploration Program Office had done the most detailed initial analyses of the problem. JSC Center Director Aaron Cohen was in charge of the study, with day-to-day operations headed up by engineer Mark Craig.

This intensive study effort took place during the months of August-October 1989, with the report issued late in November of that year. Upon its briefing and release to the National Space Council, the brickbats and invective began: unimaginative, bloated and “Battlestar Galactica approach” were just some of the descriptors attached to the report. Historical legend holds that because the report was so awful, the Space Council immediately engaged with a group at the Department of Energy’s Lawrence Livermore National Laboratory to devise and offer a counter-strategy – the “Great Explorations” scheme of Lowell Wood that used inflatable spacecraft and was rumored to cost less than one-tenth the amount of money estimated for the heavily panned 90-Day Study approach.

So just what did the 90-Day Study advocate? In brief, it described the vehicles and technologies needed to undertake human lunar and martian missions. It assumed the continued operation of the Space Shuttle, with new missions beyond LEO staged from Space Station Freedom (currently, the International Space Station). The new vehicles necessary for trans-LEO missions were outlined and described, including a Shuttle-derived heavy lift vehicle and a reusable cislunar transfer stage to send payloads to the Moon (using an aerobrake for Earth return). It also called for research on a nuclear powered Mars transfer stage and nuclear reactors for surface power systems on both the Moon and Mars. Extensive robotic precursor missions were outlined, including global surveys from orbit for the Moon and Mars, geophysical networks for the martian surface, a robotic sample return from Mars to certify the planet safe for human landings, and deployment of an infrastructure of communications satellites in martian orbit.

This list of assets was comprehensive, and yes, expensive. However, what was being described was nothing less than a permanent human foothold off-Earth. Moreover, this system of space assets and transportation infrastructure would be acquired and placed into operation over the coming three decades. The Space Council was disappointed that cheaper options were not presented, but it isn’t clear that had been part of the mandate for the study that the Council ordered from NASA. In contrast to claims that no architectural options were presented, five “Reference Approaches” were described that varied the phasing and dates of initial operational capability for the lunar base and Mars mission. In this regard, the biggest criticism of the report is that it took President Bush’s SEI speech as its policy guidance – “back to the Moon to stay and then to Mars.” This seems a strange criticism of a report – that it followed a directive given by the President.

Knowing how the 90-Day Report came about and how it was received, what is so objectionable about the report? As I read it, it outlined a step-wise, incremental approach to conducting lunar and martian missions, whereby existing assets are incorporated – employing continuity of purpose to build sustainability – and not discarded. Shuttle and Station would both support the missions beyond LEO and become integral parts of the spaceflight system. I contend that the architectural framework laid out in the 90-Day Study is exactly how we should approach going to the Moon and conducting missions to Mars. The report was criticized on the one hand for being “old school” and unimaginative in its use of proven technology, but then simultaneously criticized as taking too much risk in its advocacy of some advanced technologies, such as nuclear thermal propulsion and aerobraking into martian orbit.

So which is it – too Buck Rogers or too stodgy?

I can agree with the criticism that the architectural details of the report contained a lot of featherbedding by various widget-makers throughout the agency, but there was nothing in it that a good scrub by some hard-nosed systems engineers could not have fixed. Yes, it was Christmas-treed, but by looking past those superfluous (and expected) tinsel-hanging efforts, one sees good roots and branches beneath. The basic approach harkened back to the original von Braun architecture – shuttle, station, Moon tug, Mars spacecraft, a stepwise, incremental, cumulative progression to ever-farther regions of the Solar System. In contrast to some opinions, the technical approach laid out in the 90-Day Study was the very antithesis of the Apollo approach – the “all-up”, single-shot, self-contained missions to dash somewhere, plant a flag, and return, only to learn that your program’s been cancelled the day after your ticker-tape parade.

The cost numbers associated with the plan outlined by the 90-Day Study are subject to much confusion. The report itself contains no cost numbers whatsoever, the decision having been to include the estimates in a separate document, presumably on the fear that they would be misinterpreted (which happened). The numbers came from two different cost estimation models (then in use by JSC and NASA Marshall Spaceflight Center in Huntsville) and ran to about $470 to $540 billion (FY1990 dollars), over a 30-year period of execution. These numbers included a 55% reserve for unexpected difficulties or accidents. While such budget numbers are substantial (the agency budget in those years was about $15 billion/year), spending such sums on NASA would still not have exceeded about 1.5% of the federal budget – this at a time when massive cuts in defense spending associated with the alleged “peace dividend” produced by the end of the Cold War were looming. Such a sum of money would have been about the same amount spent by the Department of Energy during this 30-year period. The idea that we “could not afford it” is simply ludicrous, especially as one motivation for devising the SEI in the first place was to partly maintain the industrial-technical infrastructure used to defeat the Soviet Union.

In the historical telling, the story goes that upon receipt of the 90-Day Study, the Space Council was so aghast that it sent the report to the National Research Council (NRC) for evaluation (and presumably, dissection). If the thought was that the NRC would trash it, such hope was misplaced. The NRC evaluation, while not uncritical of some details, largely acknowledges that the 90-Day Study offered a reasonable, relatively low risk approach to carry out the Presidential mandate. The White House then set up an “outreach” program, asking for the best technological ideas from many sources in order to show just how off-base the 90-Day Study was. A special group was gathered to evaluate these ideas – the “Synthesis Group” led by astronaut Tom Stafford (of which I was a member). After a year of synthesis and analysis, the group issued its findings: there are no “magic beans” technologies. To carry out the President’s Moon-Mars initiative, heavy lift vehicles, nuclear propulsion, extensive robotic precursor missions and many other items found on the checklist of the “overblown” 90-Day Study, were needed.

What about Livermore’s “Great Explorations” idea? The use of inflatable vehicles for human spaceflight doesn’t actually solve the fundamental problem of trans-LEO missions: most of the mass of the vehicle on departure consists of propellant, not habitats or transit vehicles. Moreover, inflatables have their own technical issues. Interior supporting structures are complex mechanisms and potential fail-points during deployment in space. The real problem solved by inflatable spacecraft is not mass, but payload volume – in the 1990s, large diameter modules could not fit on existing expendable launch vehicles or inside the payload bay of the Shuttle. Supposedly, by using inflatables, we would avoid the huge expense of developing a new heavy lift vehicle. But even this criticism is not valid, in that development of the unmanned Shuttle side mount launch vehicle would have solved this problem at relatively low cost (most of the then-existing infrastructure could be used), as well as providing a way to get massive pieces into orbit in single chunks.

So now, 25 years after the release of the “disastrous” 90-Day Study, and in light of current events, this study deserves another look. It is not a perfect document, containing some superfluous elements and questionable cost estimates, but its basic architecture uses exactly the type of incremental, stepwise, cumulative approach we need (and more and more are calling for) if we are ever to build a sustainable deep space transportation system. One final aspect of the report is notable: the 90-Day Study was the first agency architecture to incorporate resource utilization (ISRU) – specifically, the production of oxygen from lunar regolith (oxygen is 4/5 of the mass of the total propellant load in a LOX-hydrogen system). This resource utilization aspect of the 90-Day plan was incorporated prior to any knowledge of the existence of lunar polar ice (a game changer that would have been soon discovered anyway from the robotic precursor missions planned as part of the SEI). So once again, the 90-Day Study is, in many ways, well in advance of current plans.

I urge you to read the 90-Day Report and judge its merits and faults for yourself. It’s tragic that so much written about it inaccurately describes its content, or at a minimum, fails to provide any historical context for why the report advocated certain approaches. It is remembered as a despised, failed report, rejected by those who requested it and to this day, misunderstood through ignorance of the facts. It contained the bad news (and nobody likes to receive that) that there are no magic beans to climb to the stars – it will require a variety of complex, difficult and (yes) expensive pieces to establish the spacefaring system that we need. Inflatable spacecraft were the magic beans of the 1990’s space program – today’s space program has its own version of them. The cold hard realities of human spaceflight cannot be denied and the truth of that always comes out in the end.

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32 Responses to Virtues of the 90-Day Study

  1. Joe says:

    Thanks for the link to the Study. Look forward to reading it.

    As a preliminary point part of the problem with the Studies reception may have been caused by it’s comprehensive nature.

    A key point is in your article:

    “The numbers came from two different cost estimation models (then in use by JSC and NASA Marshall Spaceflight Center in Huntsville) and ran to about $470 to $540 billion (FY1990 dollars), over a 30-year period of execution.”

    The sticker shock at the “$470 to $540 billion” figure ignored the “over a 30-year period” context.

    Wonder what would have happened if the cost of establishing the Lunar part of the architecture only over a shorter period of time had been estimated? Number would, undoubtedly, still have been large enough to subject it to demagogic attack; but it might have been easier to defend.

    • Paul Spudis says:

      Those numbers are actually broken down on page 92 of Thor Hogan’s history of the SEI, Mars Wars: The Rise and Fall of the Space Exploration Initiative, NASA SP-4410, 2007.

      For Reference Approach A, the total lunar outpost costs (FY1991-FY2025) was $308 billion. For Reference Approach E, it was $235 billion. This includes all aspects of outpost emplacement, including precursors, surveying, infrastructure and operations.

      I hesitate to recommend this book as it contains several errors and misinterpretations, but it is the only complete history of the SEI story yet done.

      • Joe says:

        So, assuming the accuracy of the document, for a Moon Base only (using the higher figure) that would be an average of $9 B/year ($308 B spent over 34 years).

        Given that some of the year to year expense (Shuttle, ISS etc.) were already in the existing NASA Budget, that does not seem like it would be all that hard to justify if it were honestly evaluated. The problem would be in the demagoguery that would have surrounded the $308 B figure (or sadly, in all likelihood, any figure greater than zero).

        • Paul Spudis says:

          I no longer know what the term “honestly evaluated” means — I don’t think that such a thing is possible any more. Anything you suggest is immediately attacked by somebody with an ax to grind.

  2. guest666666 says:

    I participated in the study and SEI. It was well organized, well managed, and I felt it offered the roadmap to the future. Later I participated in the ‘vision’ study, prior to Griffin’s Constellation. The difference seemed to be that during SEI small teams with appropriate experience were chartered to develop concepts. During the vision they had large working groups with a lot of people of at best marginal knowledge and we were not really developing the ideas of where we might be going.

    • Joe says:

      “Later I participated in the ‘vision’ study, prior to Griffin’s Constellation.”

      If by the ‘vision’ study you mean the period under Admiral Stiedle’s direction, there were teams with appropriate experience making recommendations, but the Admiral would not listen to them.

      Later, neither would Griffin.

  3. John Strickland says:

    Yes, the 90 day study did get a lot of things right but it also got a lot of things wrong. It did mention aero-braking, lunar propellants and hydrogen engines. it did provide a range of options. But the main failure was political. Based on charges made to me by a person within the Administration at the time, (at an ISDC in Washington in the mid-1990’s), I was told that the White House had begged and begged to see the plan before it was released, and NASA refused. Then the half-Trillion dollar bombshell hit the media and the Congress. The staffer told me that the whole manner of releasing the cost figure was to scuttle any Mars program to protect the Shuttle program. (This may or may not be true, but at that moment, since the price as given separately from the report had a snowball’s chance in hell of being approved in any form, the whole thing was a disaster.

    Even if the plan had given the Annual cost instead of the Total cost over 30 years, this would have required more than doubling the NASA budget so as not to cut all the other NASA programs. (A 600 billion dollar program divided by 30 years is $20 billion a year, JUST for the Mars program alone.) This was totally unrealistic in 1990 and it is still unrealistic in 2016.

    In addition, while mention is made of some reusable components, the main propulsion systems are “jettisoned” left and right, almost in a ceremonious manner, as if it is a spaceflight obligation to throw away priceless hardware in space.

    I also notice that my 1990 discussion of this report included drilling for water. Now that we know that ice is available right on the surface of both Mars and the lunar poles, designing a propellant production plant which can be used in both locations is much easier. Base First and Ice deposit verification first policies are now major landing site imperatives for both Lunar and Mars mission concepts. We now know so much more about Mars and the Moon. In 1990, the EDL problem would not even be discovered for another 14 years, and now the same problem is part of the solution.

    • Paul Spudis says:

      Even if the plan had given the Annual cost instead of the Total cost over 30 years, this would have required more than doubling the NASA budget so as not to cut all the other NASA programs. (A 600 billion dollar program divided by 30 years is $20 billion a year, JUST for the Mars program alone.) This was totally unrealistic in 1990 and it is still unrealistic in 2016.

      First, these roll-up numbers are correct only if you accept their costing models, which I think was always questionable. Second, as I point out in the piece, in the context of what else we were spending billions on in the 1990s, it was NOT “unrealistic” — the proper case simply was not made for it. A key reason for SEI was to help maintain the technical industrial base/infrastructure/human capital that allowed us to win the Cold War. A fraction of the Reagan defense build-up money would have completely funded SEI. Instead, that money was rolled into new entitlements, a black hole from which none ever emerge..

      Things are worse now (2016) than they were then (1990) — much of the space infrastructure has been destroyed and the human expertise has been dispersed or lost, so now, you are correct: it IS unrealistic now.

      In addition, while mention is made of some reusable components, the main propulsion systems are “jettisoned” left and right, almost in a ceremonious manner, as if it is a spaceflight obligation to throw away priceless hardware in space.

      True enough, but because of the modular nature of the architecture, it was possible to transition from disposable to reusable after the off-world foothold was established. In fact, that option was clearly thought about, given certain technical features of the architecture (e.g., aerobrake for the cislunar transfer stage).

      • I agree with several others that it was good to look back on the 90 day plan. I can still remember the bitter disappointment of those days.

        However, from the current pace of events, as will become even clearer after September 2016, what we have now and will have shortly is vastly superior and more affordable than any of the Apollo hardware. This is in spite of the Saturn V’s still amazing payload ratio of 0.04 or 4%. Other private companies are even talking about building their own space tugs, something that NASA has talked about for 40 years and done nothing.
        If it is that easy to redesign an expendable booster AFTER it is partly built, lets see them even make the NEXT SLS reusable. Good Luck!

        The current “cold war with Putin has very different characteristics from the old one, and it is still possible to cooperate with them on some common interests. A joint US-Russian lunar mining base is being discussed, partly supported by private lunar landers! Mine that ice! Right now I am much more optimistic about space than about global politics.


        • Joe says:

          “If it is that easy to redesign an expendable booster AFTER it is partly built, lets see them even make the NEXT SLS reusable. Good Luck!”

          On Orbit vehicles answer to a very different set of requirements than Earth surface to orbit vehicles, so comparing the two is a bait and switch.

          Since what SpaceX is supposedly trying to do is redesign an expendable surface to orbit booster (the much smaller Falcon 9) to make it reusable, why don’t we wait and see how that works out?

          Good Luck to you as well.

          • tomdperkins says:

            The Falcon 9 is already designed to be man-rated and reusable.

          • Joe says:


            “The Falcon 9 is already designed to be man-rated and reusable.”

            (1) The Merlin Engines had their beginning in the government developed Fastrac Rocket, intended to be expendable.


            (2) As a result their throttling range is limited and that causes the requirement for the Falcon 9 first stage hard landing.

            (3) I attended an early SpaceX briefing on what eventually became the Falcon 9 and at that time SpaceX described it as an expendable vehicle. They talked of the possibility of using parachutes to recover the first stage for examination (not reuse).

            (4) Somewhere along the way that morphed into recovering the stage using parachutes.

            (5) That then changed (again) into the current scheme.

            I have great admiration for the line engineers working for SpaceX in that they have accomplished the landings at all. However they are in the process of trying to back drive reusability requirements onto an expendable vehicle (as I stated) in answer to Musk’s edict to “Make it so.”

            They still have long way to go to make an economically viable reusable first stage, if they can manage it at all.

            Therefore, your statement is factually inaccurate.

          • tomdperkins says:

            If there were a “reply” associated with Joe’s comment, I would have hit it. I have a screenshot showing the lack of it, if anyone involved is interested in debugging the blog GUI. I hate finding typos after I hit send.

            1) No, the Merlin is not and has never been the Fastrac rocket. They did their own design and cut all their own metal. Both being crewed and being reusable was on the drawing broad from the start. This is not the same thing as saying the first flight article was such.

            2) The pintle concept has a great deal of potential throttleability and the hover slam landings are dictated by available fuel, not throttling. The current Falcon has a dry weight of about 56,000lb and the Merlin can throttle to produce less thrust than this. When they have landed or attempted to land with more than one burning, this is because they had so little fuel they could spend no time hovering and needed minimize fighting gravity while reducing descent rate.

            3) And the first launches were expendable, and developmentally paved the way for full re-usability. The first Saturns were not able to get to the moon, nor even conceived of being able to do so–but that was always the plan for the family (at least once the Nova was cancelled).

            4) & 5) Parachutes were considered and discarded. It is not clear how that detracts from the notion reusability was not always a consideration. The more mass efficient use of engines and fuel already provided for won out.

            It is as if you think the fact history is not planned out in perfect detail before hand means its an accident.

            “They still have long way to go to make an economically viable reusable first stage, if they can manage it at all.”

            The booster which will re-fly has already landed and I believe it was made years ago

            “Therefore, your statement is factually inaccurate.”

            Less so than your is. Your memory seems to be selective.

            I remember hearing about the Falcons being intended to be re-usable 5 years ago and used for human access to space. This is not contradicted by the first several vehicles not meeting that goal.

            I believe you are discounting the word, “iterative”.

          • Joe says:


            It is pointless to have these back/forth statements where you simply assert what I said is untrue, often misrepresenting what I said (one example – I did not say the Merlin’s were the Fastrac I said their design began with the Fastrac and it did).

            Everything I said was factually accurate and anyone who wants to research the subject can confirm that fact.

            Have a nice day.

  4. Andrew Swallow says:

    A 30 year plan within NASA is interesting but an annual 5 year plan can be built, using 2 year action plans. The shorter term plans need writing.

    • Paul Spudis says:

      The “30 year plan” contained in the 90-Day Study had several milestones and intermediate goals contained within (e.g., spacecraft assembly keel on SSF, deployment and demonstration of a reusable cislunar transfer stage, lunar outpost, propellant production, Mars orbital mission, etc.).

      It does not make much sense to plan only 5 years ahead if you don’t have a clear vision of where you are going. Better to have that distant, strategic goal understood, then craft the architecture to yield intermediate results as appropriate.

  5. Thank you for giving us access to the old 90 day study. Very interesting!

    The primary purpose of sending humans to the Moon and Mars, IMO, is to find out if humans can actually live and reproduce on the lunar and martian surfaces while mostly living off lunar and martian resources.

    The exploitation of lunar resources to reduce the cost of satellite deployment and maintenance should also be a priority, but may not necessarily require a human presence.

    Any Mars architecture that doesn’t seriously address the significant deleterious effects of microgravity and cosmic radiation and major solar events should be ignored, IMO.

    NASA’s is already well on its way towards having an operational heavy lift vehicle. So the focus now needs to be on developing a reusable extraterrestrial landing vehicle that could be used on the Moon and on the moons of Mars– and the propellant producing water depots needed to refuel such reusable vehicles.

    And if all it takes is a magnetron to extract water or oxygen from lunar or martian regolith, then exploiting these precious extraterrestrial resources is going to be a lot cheaper than anyone ever imagined.


    • Joe says:

      “The exploitation of lunar resources to reduce the cost of satellite deployment and maintenance should also be a priority, …”

      Agreed on that point.

      “…but may not necessarily require a human presence.”

      Disagree on this one. If all the tasks required to support satellite deployment and maintenance (and eventual manufacture of components) – even with maximum use of automation/robotics – are considered there will be a sizable human population required in cis-lunar space.

      I will spare everyone the “war stories” of all the times the EVA Assembly/Maintenance teams for ISS were told that Assembly/Maintenance could be performed without crew involvement only to have EVA relied upon when it came time to actually perform the specifically defined tasks.

      That is however good news. Once the required in orbit population grows past a certain level, the primary limiting factor in system growth is likely to be transport of crew to/from Earth. That will need to be solved by extending “tours of duty” to minimize required transport and that will involve making the habitats safer and more comfortable.

      I have suspected for some time that if any of this ever really comes to pass, the first “space settlers” will likely not be part of an intentional settlement program, but workers who finally become so acclimatized to the habitats they just decide to stay.

  6. Grand Lunar says:

    This is probably the best showing of what the 90 Day Study had presented.

    Perhaps it could be said that the study was ahead of its time.

    NASA would do well to dust off these plans and get to work.

  7. gbaikie says:

    I don’t see the merit to go the the Moon and stay.
    If one were to build a lunar base, it could not help but stay on the Moon, forever.
    But generally, past exploration is not go there and stay.
    It seems the idea of staying on the Moon is as though the problem with Apollo was
    we didn’t stay. Which was not the problem of Apollo.
    The idea of refueling at the LEO space station, was a good idea.
    But ISS is now in the wrong orbit.
    NASA should establish a depot at 28 degrees inclination. It should be a robotic
    space station, which is capable of refueling LOX.

    I don’t think the Moon is worth going to, unless there is a way to make rocket fuel at
    a low cost. Lunar water at the poles is way to make rocket fuel a low cost, and I think NASA
    should explore the lunar poles to determine if there is commercially minable lunar water.
    I don’t believe a government can mine lunar water.
    The idea of going to the Moon and staying is essentially the US government colonizing the
    Moon. I don’t know if I want US govt colonizing anything, but were the government to make this
    decision they probably should first explore the Moon to determine if there is minable water.

    Now if NASA were to stay a long time on the Moon, there are many things it could do- I think studying the subsurface might be important in terms of long term lunar habitation.
    In terms of lunar base, designing a base so it has long operational lifetime, could useful. And one
    do this without continuous habitation.
    But as said it seems what is important regarding the moon is exploration to find minable lunar water, and to be minable is must be commercially viable- not a government mining water.

    Now, I can see a reason to stay on Mars. Mars takes a long time to get to, any sortie type exploration would be waste of time and resources. And you basically want humans on Mars in order to accelerate the exploration of Mars.
    On the Moon I think the only place in near term to explore is lunar poles. With Mars the poles don’t
    seem to priority in terms of exploration. One spot on Mars is Hellas Basin, but it’s huge area, and so Hellas basin isn’t really narrowing down the exploration area. But anyhow there probably dozens smaller regions within Hellas Basin which should be investigated. Anyhow with Mars there is vast amount area to explore and it with some exploration of Mars, we might be able to narrow
    the focus of what seems like more favorable areas to explore.
    Or basically though they would be much planning of where to put a Mars base, I don’t think it matters much because we don’t know much about Mars. Or Mars needs to be explore to find places to explore.
    Now with the Moon, there some favored locations, but I don’t think there enough information to decide which pole- north or south would be a better place for a lunar base, were we going to
    land a lunar base. It seems what is desirable is at or near the peaks of eternal light. And other aspect would be being near minable lunar water. Of course minable water may be related to being
    near one of the peaks of eternal light.
    I think lunar exploration of finding a location which lunar base might be located and therefore near
    regions of minable water could be what NASA explores in terms of lunar program.
    But it possible the lunar base could some place other than near minable water. The lunar base could related to studying lunar subsurface- so near some volcanic area [or large and fresh impactor site]. But it seems what NASA should focus on is related to whether going to the Moon is
    viable, and that generally means being able to make low cost rocket fuel.
    So would explore the Moon mainly as a step to accelerate the exploration of Mars. And it seems
    if going to explore Mars +30 year in the future, you probably should not talk of exploring Mars.
    I think even +20 years is mostly waste of time.
    So I would start by making depot in LEO, and spend less than 10 years exploring the moon, and
    then explore Mars. With idea that after 10 years of exploring Mars, one would reassess, but also
    assume that since there is a lot to explore, that it will take longer than 10 years.
    So give congress a +20 year program, starting with Moon, and Mars.
    I think NASA should want the Moon to be mined and Mars to have settlements- but it’s not NASA
    job to mine or settle. Rather NASA job is to explore to help determine if and when these things
    could be done.

    • Andrew Swallow says:

      For the next 10 years the only things that need refuelling at the ISS are cubesats and its own robots.

      A LEO depot at 28 degrees could have cubesats as customers within 4-5 years. Unmanned probes to the Moon and beyond would start appearing a few years later. Manned trips to the Moon are 10-15 years away, since it will take that long to develop a lander. (Less time if a cargo lander can be matched with an existing ECLSS.)

      • gbaikie says:

        I would have NASA have depot in LEO as part of lunar exploration program and use it for lunar robotic missions. So have lunar robotic missions planned to use the LOX from depot. And as policy have all future NASA missions going beyond LEO using depot.
        I would not attempt to have NASA sell LOX to commercial customers.
        In terms of policy the LOX would be provided “free” to NASA missions-
        so mission with cost cap, would not include any cost for using LOX from
        the depot. So in terms of 200 million cap, maybe even “paying” to use
        depot as part of the Mission [increasing the cap]. Or if mission doesn’t need the “incentive” then they don’t “have to” plan to use depot.

        Or purpose of depot is to demonstrate that any depot can be operated- or it’s experimental evolving into an operational status. Once it’s operational not sure NASA should continue operating it- privatize it, maybe.
        In terms of it’s experimental status, NASA could allow any US company to use it, but doing this would be encouraging US companies in the general technological capacity to use depots. So free LOX but a limited amount of free LOX in terms of trial/experimental basis.
        NASA doesn’t need to get into the depot business, rather it needs to start the depot business.
        NASA goal would be to be able to buy rocket fuel where ever NASA needs rocket fuel. So for instance, If NASA needs rocket fuel in Mars orbit, it would be a customer for that rocket fuel which would delivered [however it’s done] in quantities NASA wants and delivered on time for X amounts of dollar per lb of it.
        The reason NASA needs to make a depot in LEO, is that part of commercial lunar water mining- “probably” or near certain that lunar rocket business, needs a depot in Low lunar orbit- and that depot in low lunar orbit won’t be a NASA owned and operated depot.
        So LEO depot is part of the answer of is lunar water minable.
        How much is the expected cost vs profit from such a business.
        Or a key aspect of whether lunar water mining is minable is the market size of lunar water- 100 tons per year? 1000 tons per year?, or whatever. And exporting lunar rocket fuel to Lunar orbit at competitive cost of shipping rocket fuel from Earth is way to increase demand for
        lunar water.
        Or roughly first year of commercial lunar water miningis working thru problems and maybe making 50 tons of lunar rocket fuel [40 tons of LOX, less than 10 tons of H2]. Next year 100 tons, Next year 200 tons. By point in time of 200 tons, probably need to be exporting Lunar LOX to low lunar orbit.
        By time of making +500 tons, probably exporting lunar rocket fuel to low lunar and High earth orbits and Mars orbits. And eventually to LEO.
        Lunar water mining will not make NASA exploration costs much cheaper- though it would make Mars settlements, MUCH cheaper.
        What make NASA Mars exploration cheaper is having market for rocket
        fuel in Space- Maybe 1/2 of the rocket fuel will be delivered from Earth- all or most in beginning of Mars program- “perhaps” more from the Moon
        in later part of Mars exploration program.
        So NASA LEO depot is about future Mars exploration- in terms of lowering Mars exploration costs. Or part of both Lunar exploration and the Mars exploration which follows. Or it’s a lunar program cost/expense which a future Mars program “profits” from this “investment”.

        • Andrew Swallow says:

          Do not over engineer the future operations of the depot. It will be a rare operational mission that can be planned more than 5 years ahead. Just ensure propellant can be brought from both Earth and the Moon.

      • During the Apollo program, NASA invited private companies to submit proposals for the Lunar Module in July of 1962. And the Lunar Module took astronauts to the lunar surface in July of 1969. So it is possible to develop and deploy a manned lunar lander within 7 years.


        • Andrew Swallow says:

          Apollo used half a million people and 5% of the Federal Budget. If modern NASA could spend on that scale I am sure that a manned lander could be developed within 7 years. Where as the return to the Moon program may not even be NASA’s main program.

          However, having written that LunarCATALYST and NextSTEP-2 (or -4) may do it.

        • Andrew Swallow says:

          A cubesat will use 1-2 litres of monopropellant, where as a LEO to lunar orbit vehicle may need thousands of litres of bipropellant. Consequently they are unlikely to be the same depot, although they may be co-located.

          NASA does not have to own the depot just control its development and interfaces. A COTS like scheme where it pays milestones during development and contracts to pay ‘x’ litres of fuel may work.

        • DougSpace says:

          ULA and Masten have the concept of modifying a Centsur upper stage to become the Xeus lander which would land belly down on the lunar surface. Given that most of the descent velocity would be nullified by the already-developed, well-experienced RL-10 then it is conceivable that such a lander could be developed at less (adjusted) cost than the Apollo lander.

          • Joe says:

            The venerable RL-10 (with a heritage dating back to the 1960’s) is indeed well suited for use on a reusable lunar lander and a cis-lunar space orbit to orbit transport as well.

            Additionally Blue Origin says the BE-3 engine currently in use on their New Shepard sub-orbital vehicle (and intended as an upper stage engine for their proposed orbital launcher) has been designed with such uses in mind as well.

            So there are several efficient paths forward for developing a reusable transportation architecture for cis-lunar space, extending from LEO to the Lunar Surface.

            Now all that is required is the will to use them.

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