Depot-Centric Human Spaceflight

In light of how well today went at the Augustine Committee, I felt that it would be worthwhile to post the propellant depot white paper that a group of us submitted last week. I was originally planning a much longer paper, trying to make the case that depots were technologically mature enough to be worth pursuing, and that they work well with any architecture. But with the release of the Beyond LEO document last week on the Augustine Committee website, we realized that we didn’t need to convince them of the feasibility of depots, so we focused this white paper more on the benefits of going with a depot-centric model for human spaceflight.

Depot-Centric Human Spaceflight: Strengthening American Industry, Creating a Robust Beyond-LEO Exploration Program, and Enabling the Commercial Development of Space

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Jonathan Goff

Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
This entry was posted in Commercial Space, Launch Vehicles, Lunar Commerce, Lunar Exploration and Development, Propellant Depots, RLV Markets, Space Transportation. Bookmark the permalink.

17 Responses to Depot-Centric Human Spaceflight

  1. Thanks for sharing this. I’m glad these options are being presented to the HSF Committee, but I’m even happier to see them shared widely.

    If depots are feasible, then the barriers to Lunar, asteroid, and Mars trajectories are even lower than I hoped. We might not need Elon’s BFR to get us beyond LEO after all. 🙂

  2. MG says:

    While at the NewSpace conference, I had occasion to visit with a retired USAF space guy who is now a Lockheed guy. We talked about depots, and in particular my surprise that the USAF (as a potential customer) hadn’t been a topic of discussion at the conference.
    My friend observed that while on-orbit refueling *can* reduce system costs, the argument against it is that longer lifespan of spacecraft (like the KH series) means that the industrial base withers.
    I didn’t get into a long debate with him — the argument against on-orbit logistics depends on the mission requirements and available / prospective technologies and architectural concepts at that particular time. If you are in a rapid technological race, and need frequent updates to your capability, and can’t afford the time or money to develop on-orbit logistics, then you do small serial production efforts.
    Or, I suppose on-orbit logistics exists within the USAF assets, and it is highly classified. Though, if that *were* the case, the New York Times would have made it page 1 info by now.
    Suffice it to say, DARPA’s “fractionated satellite” efforts might offer one response to this industrial base concern.

  3. Rick Boozer says:

    Hi Jon,

    Great paper and I think the chart that you included helps a lot. If you don’t mind, I’ll post a link to it on relevant blogs that don’t already mention it. I’m also going to notify people that I know will be interested.

  4. Patrick says:

    Excellent paper. I hope the committee is paying attention.

  5. Jonathan Goff Jonathan Goff says:

    Patrick–Fortunately, it really looks like they are.

  6. Jonathan Goff Jonathan Goff says:

    Rick, go right ahead! The chart was Rand Simberg’s idea. I added the color-coding because I thought it made it even more obvious how much more responsive a depot-centric architecture using commercial launch vehicles was to what the committee was trying to do.

  7. Jonathan Goff Jonathan Goff says:

    Yeah, it’s a complicated subject with lots of tradeoffs. There are some that are interested in upgradeable, refuelable satellites. Launch the bus once, and then the workforce can be working on designing modular upgrades to send up to get swapped into the bus over time…but as I said devil’s in the details.


  8. Patrick says:

    Jon, after a bit more reading, I agree, they are listening. Wow! You guys stand a chance, collectively, of being the John Houbolt of the modern space age. That must be a nice feeling.

  9. Jonathan Goff Jonathan Goff says:

    It is exciting to see them taking it seriously. But we’ve still got a long way to go. I’ll start breathing easier again when I see Congress actually authorize and appropriate funds for depot tech maturation.


  10. Charles Grimm says:

    I understand explaining the cost avoidance of skipping the HLV, but isn’t it true that there’s a third stage cost avoidance as well? Whatever 2nd stage got itself into orbit, could be refueled and flown as is as a “third” stage. This seems like a major cost reduction which should be added to the benefits of propellant depots.
    As far as cryogenic boiloff is concerned, oxygen/hydrogen outgassing sounds like a delightful input for fuel cells, with the result being a very valuable orbital commodity, water. I thought fuel cells were efficient enough to allow reconversion of water to oxygen/hydrogen during a long duration spaceflight, and a water tank would be handy as a radiation shield. Thinking long term, a depot would have some fuel in liquid form, and some combined as water, ready for future use as needed.

  11. Dave Huntsman says:

    My friend observed that while on-orbit refueling *can* reduce system costs, the argument against it is that longer lifespan of spacecraft (like the KH series) means that the industrial base withers.

    That’s only if you accept his premises: that only large, once-in-a-while platforms are the one and only way to go; and that the current American ‘industrial base’ is somehow right-sized already. I disagree with both premises.

    Our actions on the government side need to be changed so that every major action is also judged in light of: how will this help in the long-term to create new, and sustainable, space industries? Industries that end up not solely dependent on going bust if one large government program goes away? Your friend’s (unfortunate) attitude would ensure those things never happen; and continue our aerospace industry on its current decline, in many ways following the path of America’s auto industry, which failed en-masse. Over-consolidation, fewer competitors, fewer new innovations created, fewer people employed – and then losing out to oversees competitors in the process – is something we really are repeating across many segments of aerospace, right now. But it can be avoided.

    Things like in-space propellant servicing go in the ‘right’ direction, and end up generating much more than they initially cost to set up (or, more realistically, ‘to enable’).

    And the benefits can end up being very subtle, but very important. Extrapolate to space what recently happened in Antarctica, where a team was crossing the most unexplored part of an entire continent – and met three different groups of people in one day!

    “…………….They didn’t expect to come across other travelers in the relatively unexplored area known as Queen Maud Land. But they did — three times in one day.

    “We were astonished because we were supposed to be all alone,” said Ted Scambos, a member of the Norwegian-U.S. science team that crossed a large slice of the Antarctic continent using tracked vehicles pulling sleds. “I don’t know where you can go in order to be on the edge of the Earth anymore.”

    The encounters, all involving people taking part in a commercial race to the South Pole, occurred near a fuel depot in an area where the ice sheet was more than 3,000 meters thick, hiding at least four distinct subglacial bodies of water called the Recovery Lakes.

    “Fuel depots in Antarctica are kind of the equivalent of watering holes in Africa,” mused Scambos, lead scientist at the Boulder, Colo.-based National Snow and Ice Data Center. “Everybody has to come to the fuel depot, and you see all kinds of people, all kinds of groups, gathered at the fuel depot.” ……………………..

  12. MG says:


    My only nit wrt your reply is that my friend was describing the USAF’s position — he didn’t comment on his own opinion about it.

  13. Jim says:

    Excellent work, Jonathan. Not only have you done good work and forward thinking, you really have gotten it to those in a position to act and make use of it. Well done.

    Nits: The mention of the Mormon migration was amusing, at least.

    The inclusion of Venus surface missions caused me to raise my
    eyebrows. Surely you were not speaking of manned systems?

    While you said that Mars and Venus missions “may require more EDL work or larger fairings” I am sure you are aware of the Russian inflatable reentry shields. Perhaps we can do without the larger fairings, in the same way inflatable structures decouple the volume of a habitat from the size of the fairing or payload bay. All the more reason to stick with an architecture that avoids Super-HLV.

    Again, these are nits on an excellent piece.

  14. Jonathan Goff Jonathan Goff says:

    Thanks for the kind words!

    I must not have been clear about manned Venus expeditions. I wasn’t talking about visits to the surface, but more referring to cloud-top expeditions like I’ve talked about here on the blog in the past.

    As for the may require more EDL work comment, I was trying not to oversell the concept. While I agree with you that the problems are probably solvable, I wanted to be conservative so they couldn’t just ignore the concept out of the box.


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