An Architecture for Direct Lunar Return Using SLS and Orion

I have been asked recently by several people to lay out an architecture for direct lunar return.  This includes what is required (e.g. LOP-G or no LOP-G?), how the pieces fit together and the likely outcome of such a program.  I find that almost all of these issues are addressed in a paper that Tony Lavoie and I wrote two years ago:

The Purpose of Human Spaceflight and a Lunar Architecture to Explore the Potential of Resource Utilization

This 2016 paper (updating an architecture written 6 years ago ) details how to fulfill the 2018 Presidential Directive to return to the Moon.  It also addresses how to use the existing SLS and Orion programs to enhance the plan.

As you read it, please note how this paper addresses many questions and talking points being bounced back and forth in the current national debate about the U.S. space program.

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11 Responses to An Architecture for Direct Lunar Return Using SLS and Orion

  1. Andrew_Swallow says:

    Great as a science papers but for a general (or political) audience it needs a picture showing the Earth, Moon, Mars plus proposed spacestations, spacecraft and bases.

  2. Gary Church says:

    When considering the most efficient way to build a cislunar infrastructure I keep coming back to the problem of fuel depots. I foresee the storing and transfer of cryogenic propellants as the most formidable obstacle in effecting such a program. It is not going to be as easy as NewSpace propaganda has made it out to be. Not even close.

    The Blue Moon Lander concept fascinates me and I wonder if the solution might be found in this vehicle by making it the “universal space tug” by having it dock with whatever needs to be boosted somewhere. Along with this tug would be hydrogen (or possibly methane) and oxygen cells that could be added and removed as needed.

    • Joe says:

      An interesting comment.

      Unlike science, in engineering there is not one correct answer but a continuum of possible answers with advantages/disadvantages to each. The trick is to pick the “best one” (always continuous) then stick with it.

      My reservations about various other orbital propellant depot proposals has always been that they assumed the depots to be free, while assuming large costs for developments of HLV’s.

      The Spudis/Lavoie proposal is the first and only study (with which I am familiar) to make a good faith effort to cost the orbital propellant depot system it proposes.

  3. Gary Church says:

    “It is the mindset of the space program that needs rethinking– not the next destination, not the next launch vehicle, and not the next spacecraft. How do we exit this endless discussion loop?”

    I strongly believe Gerard K. O’Neill stepped outside the discussion loop and did the major “rethink” by going after colonization as the ultimate aim of all space activities. One reason I so strongly dislike NewSpace is the complete reverse of O’Neill’s concepts by proposing Mars as a second home for humankind. This was one of the first problems addressed by O’Neill when his group ruled out any natural bodies on the basis of human biology (the requirement for 1G).

    “First, we need to understand and articulate true choices so people can understand and evaluate the different approaches and requirements.”

    A couple years ago I wrote about “The Parker-Dyson-Spudis continuum” which starts with radiation, continues with the only system capable of pushing a massive cosmic-ray-water-shield around the solar system, and finishes with the only place to acquire that water. The public does not understand dosing and debilitation, the rocket equation, or how absolutely necessary the Moon is if we are to expand off-world. One way to articulate this is the infographic I frequently refer to which shows the energy required to escape the lunar gravity well as 23 times less than Earth.

    “Second, we need to develop architectural approaches that fit the requirements for fiscal and political “sustainability.”

    The only architecture that mattes is a state sponsored program of Super Heavy Lift Vehicle launches with the goal of creating a cislunar infrastructure. LEO and Mars are dead ends.

    And third, in terms of leadership, we have Bridenstine. Which is the only good thing that has happened for a very long time.

  4. Gary Church says:

    “This decision was made to rendezvous in LEO for crew exchange to take advantage of the cost, flexibility, and redundant crew launch backup capability to utilize the Commercial Capability Crew concept (abbreviated in this report as CCCrew) as part of the crew rotation transportation concept at the LEO handoff point.”

    What about Lunar Cyclers? Using Cyclers a small capsule can intercept near Earth and a week later the crew can transfer to a Lander that intercepts near the Moon. Only a small capsule is needed and a small lander for the intercepts and return to Earth and the Moon.

    The Cyclers can also be heavily shielded against radiation while capsules and Landers cannot. The week long transit would thus entail far less dosing.

    • Paul Spudis says:

      I am more interested in a reusable, cislunar transfer stage, which can carry crew and cargo. Cyclers are more applicable to Mars.

      • Gary Church says:

        We are never going to Mars so the only Cycler of interest would be going around the Earth and Moon. The most recent paper I have seen talks about a Cycler “that has encounters with the Moon twice per month every
        other month.”

        “- the Cycler concept will gain great advantage over direct round-trip transfer from Earth-to-Moon because of the ability of the Cycler to be made very large, in affordable increments, and thereby provide radiation protection for astronauts in transit, propellant depot capability (ultimately cryogenics), and reusable life-support facilities. It was pointed out that
        the two-Cycler system recommended here is particularly amenable to incremental growth and efficiency because of the ability of the two Cyclers to rendezvous with each other and join, if desired, into a larger station while a third Cycler takes the now empty place of one of the first

        I am completely lost in terms of understanding the math in this paper and for all I know it is some clever April fools joke. Or….Dr. Rendezvous may have actually had a hand in it and it is in fact a way to build a semi-permanent superhighway-in-cislunar-space between the Earth and the Moon.

        With this kind of Cycler a small capsule can be used and the personnel make the two week journey (sorry I thought it was only a week) in a large cislunar transfer vehicle that need not expend large amounts of propellants or aero-brake.
        You and Mr. Lavoie might want to review the paper.

  5. Ben says:

    The first step to building the cis-lunar industry required to build orbital habitats is setting up a base on the moon.

    If manned, this base will provide the currently unavailable data on what the actual effects of prolonged exposure to 1/6g gravity is. Until we have this data we do not know how much gravity is required for humans to thrive. We know ~0g is too low and 1g is sufficient. What about 0.95g? 0.5g? 0.1g?

    It is premature to exclude all natural bodies. Especially since we likely will need to setup a base on one (the moon) to get the resources to build the orbital structures.

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