Ok, between the trip to DC for the awards ceremony on Thursday, and taking all of next week off for a long-needed vacation, I’m not quite out of the woods yet. But after that I want to get back into blogging. And I have a few topics I’d like to write about, but wanted to get reader input on which sounds most interesting (yes at some point I may actually use that Skribit tool I put up over a year ago):
- Parallel Ascent Air-Launch Glide-forward TSTO with Exo-Atmospheric Refueling. A crazy idea I’ve been stewing on involving the intersection between air-launched TSTOs, propellant transfer, FLOC, and Boom Rendezvous, and my attempt at making it seem a little less crazy than it sounds. If it can be made to work, it might allow for fully reusable manned orbital launch off of carrier planes as small as WK2.
- Boom Rendezvous. An introduction to a clever rendezvous and docking technique that I think deserves more investigation.
- Dual Fluid Propellant Depots. A little more in-depth discussion of my favorite depot concept from my prop depot paper.
- Refuelable Un-Crasher Stages for Early Lunar Lander Reuse. A discussion of a lunar lander architecture I came up with that leverages propellant depots to enable early reuse of a significant part of the lunar lander system, while still allowing impressive (ie >>ESAS) landing capabilities.
- The Slings and Arrows of Outrageous Lunar Transportation Schemes. A discussion of several of the non-rocket methods for getting payloads off of (and in some cases back onto) the Moon. Including pro’s, con’s, and technology hurdles.
Not too much yet on the why’s, but I’ve been keeping these how’s bottled up for too long. Which of these sounds most interesting to you guys? In the comments, pick your favorite one or two, and say why.
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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 the founder and CEO of Altius Space Machines, a space robotics startup that he sold to Voyager Space in 2019. Jonathan is currently the Product Strategy Lead for the space station startup Gravitics. 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.

Latest posts by Jonathan Goff (see all)
- NASA’s Selection of the Blue Moon Lander for Artemis V - May 25, 2023
- Fill ‘er Up: New AIAA Aerospace America Article on Propellant Depots - September 2, 2022
- Independent Perspectives on Cislunar Depotization - August 26, 2022
#4, #3, #5, #2, #1
Jon, #5….. I’d love to see a real comparison on some of those crazier schemes.
Since #1 involves #2, you really should do #2 before #1 😉
#5 seems quite interesting to me as well
#1 is my first choice and #5 is my second choice. You sound the most excited about these options – “crazy”, “outrageous”.
#1 because cheap access to orbit is the most needed of the 5 options.
#5 because I enjoy hard SF…
I’ll also throw my vote in for #5.
1 & 2, the others are kinda pointless without cheap launch.
Boom rendezvous is a bit like no-contact freefall relative work, or naval underway replenishment ops- a lot less vehicle dynamics hassle. Sounds promising…
Agreeing with Doug Jones, #1 and #2. I love depots, but mainly because they would help emergence of RLVs and thus hopefully commercial development of at least LEO. #1 sounds like a plausible near term thing and I like near term things. Plus I have some RLV ideas I’d like to bounce off you. #2 sounds cool.
1,2,5,3,4….6,7…….51,52………………
#2: Because exoatmospheric rendezvous is exactly the kind of GNC problem that will keep Ian awake at nights… er, motivated.
#1, #2 and #3, in that order are probably sufficient for CATS, everything else follows from there.
With regard to #1, I have started playing with the idea of electric VTVL air launch. Similar to lunar lander challenge vehicles but using lithium batteries and electric ducted fans.
Practical air launch altitude is about 10-15km, and increasing every year as batteries improve, one could go higher with staging. This is sufficient to design rocket vehicles without altitude compensating engines, significant aero drag losses (small scale limitations) or even cryogenic tank insulation (shroud the rocket vehicle until release).
Development costs (similar to an electric car), fuel costs, utilization rates and general operating costs appear to be orders of magnitude less than for traditional air launch – this has by far become my favored method of air launch and changes the design and economics significantly. This is far cheaper than any alternative for the atmospheric delta v section of launch, as far as I can see.
The glide forward trajectories are still possible, though range is limited. For fast pick up and return of stages landed down range is also possible – without the need for runways.
Such electric aircraft could also be used to test or replicate many of the challenges associated with #1, at much lower cost and far greater convenience. I suspect a fully reusable CATS vehicle as per #1 could thus be developed at the scales so far used for the lunar lander challenge. $10 million might go a long way, perhaps even all the way to orbit, definitely high enough to start testing reentry systems (I am ignoring regulatory costs here).
An electric aircraft capable of launching a one ton rocket vehicle at 10-15km might cost a few hundred thousand dollars to develeop, can be capable of many thousands of flights with little maintenance and cost perhaps $10 per flight to recharge. Turnaround time could be as little as ten minutes with some battery types. Interestingly, this is fairly scalable, up and down.
#5. I would like to know if you have given any thought to using a gun for launching bulk payloads off the moon. You were pretty skeptical last time I brought it up.
I vote for number 5 then number 1
How about, as a #6. low cost space stations/hangers? If anything is to get done in space then people need a low cost place to live and work (the ISS does not really provide either).
Only Bigelow seems to be working in this area, though they do not seem to be working on developing workshops and they also seem trapped somewhere between old and new space.
Not being able to develop stuff in space leads to the when failure is not an option success becomes very expensive paradigm, this is not the new space way. Space workshops must come before #4. and #5 at least. Developing space infrastructure without a usable workshop is really asking for trouble. It would be like developing a lunar lander challenge vehicle without a workshop…
I don’t know what you consider “boom rendezvous” in #2 but it always seemed that one could rendezvous with an object on a tether and be hauled in like a fish on a line. It would be interesting to see what you had in mind for #2.
As for #5 you could include an idea (from Alan Stern?) of firing chunks of ice to the moon (if no indigenous ice could be found) with astronauts excavating some fraction that would wind up embedded in the lunar regolith. Outrageous, but seems more reasonable than firing extracted oxygen at an approaching spacecraft to generate aerobraking in the lunar vacuum.
(15432)
I’m most interested in #1 and #2, if they can be developed fairly cheaply by the private sector. The public sector (NASA, etc.) seem to be permanently attached to ELVs. I have pretty much given up hope on them developing RLVs. I liked your previous series of posts on RLV types. It didn’t seem to be complete yet [he says while enjoying the free ice cream].
Pete’s #6 “low cost workshops” sounds worthwhile as well.
1
4,5
2 – booms first (and any other innovative approach concepts that reduce the required amount of delta-v
3 – depots next – what would be the next steps to make this a reality. especially if we wern’t willing to wait until Boeing to do something on their own.
I hope Masten’s success doesn’t keep you from exploring these options.
Getting to LEO would seem the first step and minimizing that delta v would seem a high priority.
I am not exactly sure what the delta v difference between the barest once around orbit and a depot might be, but I suspect it is significant. Perhaps a tug to make up the difference and do the docking. Maybe even often only bringing the payload to the depot and leaving the RLV to reenter – saving the RLV deorbiting delta v.