I should correct my moment of snide bitterness above. The Russians were not yet part of the space station program when AFE was cancelled in 1991. AFE went away (mothballed & shelved might be a better description) more properly on the tail end of the evaporation of the SEI. The agreement to have Russia come on board was signed during 1993, even as NASA was executing its orders from the White House to downsize Freedom into the less-expensive ‘Alpha’ configuration.

Cheerio.

I didn’t realize we were expressing our religious views here. : )

One of the original viewgraph selling points of placing the lunar outpost at a pole was “minimum delta V.” I am STILL waiting for someone to explain this, because it runs counter to every ounce of space mission design training I received. I think someone somewhere did some pretty fancy hand-waving to come up with that ‘advantage.’ All I see, coupled to the chosen EOR-LOR architecture, is another layer of lunar-focused constraints that inhibit flexibility and applicability to supporting other destinations, such as the E-M L4/L5 points, asteroids, and Mars. I personally think it’s a little presumptuous to plan on placing a base at a pole before we put anything down there to assess the ground truth.

As for aerobraking from 85-95 degree inclination lunar-return trajectories down to 51.6, I don’t recall ever seeing specific analyses indicating how many degrees might be accommodated with a given lunar-return trajectory pass. My gut tells me that it would require quite a few dips into the atmosphere to bend a full 45-55 degrees without vaporizing the vehicle. That was one of those things that the Aeroassist Flight Experiment might have taught us (you know, that relatively inexpensive forward-looking project that was cancelled during the 90s to help us afford the “much-less-expensive-now-that-the-Russians-are-onboard” ISS?). I suspect that such a multi-pass operation, necessary for every returning vehicle, would add significant complexity to the logistics train for minimum benefit. I still hold that building a new purpose-built servicing facility (if it is in fact required) at 28.5 makes more sense in terms of enabling trips to ALL possible destinations.

Charles, the Soyuz was initially designed for flights into lunar space, then adapted to LEO. Further adoption, with suitable upper stages, should recreate that capability. Near earth asteroids may involve slightly higher reentry speeds, and will certainly require better life support and / or supplies, and better radiation protection during long flight times, but I agree with Al that the requirements (with the possible exception of the last one) should be easily within reach.

Unfortunately, Paul is entirely correct about future budget difficulties, and this all may be academic.

Bob: I am agnostic on using the ISS itself for assembly — though I think assembly is an essential skill — however, it’s my understanding that vehicles returning from a lunar polar base will reenter over the terrestrial poles. If so, it should be possible to aerobrake into the ISS orbit, which might make it appropriate to support a reusable infrastructure optimized for the lunar poles. Any thoughts?

— Donald

ONLY a 6% payload hit? From where to where, exactly?

If Earth-based, each piece of hardware and each pound of propellant lofted into orbit from KSC will lose some delta V advantage by not launching directly east to 28.5 (which is only 5-degrees above the ecliptic). [And impose the ~5-minute planar constraint to the launch window, but I digress.] THEN all that same hardware, now assembled in the 51.6 degree inclination orbit, would ultimately have to get itself back down to 28.5-18.5 (the range of the Moon’s orbit plane) for lunar operations or 23.5 (i.e., the ecliptic) for interplanetary missions. [This of course assumes you don’t want to constrain your arrivals at your ultimate destination to the 51.6 deg departure plane.]

If we advance ourselves along to being able to bring material (propellant and/or h/w) from the Moon for incorporation in an interplanetary mission to be assembled at ISS (eventually we hope this level of technological maturity will come to pass even if the utility of doing so doesn’t become apparent), then we have to climb off the 5-deg inclination lunar orbit plane to reach ISS at 51.6, transfer/assemble the parts, and then climb back down into the ecliptic plane at 23.5.

For any long-term set of operations (meriting nonterrestrial COMSATS, ongoing deliveries of supplies & crew, etc), even if you break up and optimize the planar changes for all these transfers or fold in Libration Point rendezvous options, 6% (assuming this number does account for all the plane changes required or desired), stolen from EVERY payload pound destined for an outbound (or in-bound) trajectory, is going to add up.

And all this complexity (=operational cost) is just in the realm of the repeating underlying dynamics and consequent propellant consumption concerns. You also must factor in the cost of modifying the ISS to accommodate interplanetary vehicle assembly, checkout, and servicing. By the time we’re ready to develop such a capability, the current ISS hardware will be 20+ years old. How many SARJ-like breakdowns will have occurred by then across the entire structure/vehicle?

Yes, you CAN accommodate the ISS in a long-term architecture, but I doubt the benefits of doing so will outweigh the cost—both in dollars and operational complexity. For good or ill, this particular die was cast when we shifted from Freedom to ISS in the 90s.

If we need a LEO assembly base for interplanetary vehicles or lunar base OTV support (a very big if, but the radiation protection afforded by being below the VA belts is but one advantage), I believe it makes more sense to gracefully retire the ISS National Lab in two or so decades, from its current orbit, and put any lessons learned toward a 28.5-degree inclination facility. Unlike JSC in Houston, KSC was put where it was for legitimate technical reasons along with the political and economic ones: its latitude skirts the top of the Moon’s orbit plane and is only 5 degrees away from the ecliptic.

Regarding the Russians, they will be launching Soyuz vehicles from Guyana (at 4 degrees latitude) soon. If they so desire, they can build launch pads for other vehicles there as well. Imposing such a constraint (a 51.6 degree inclination) on an entire solar system exploration architecture merely to accommodate one partner’s geographic history is just the sort of short-sighted “engineering assumption” that we must avoid.

We’ve had too many of those imposed already.

Cheers.

They will when they start launching out of Kourou.

Common misconception. It is only a 6% payload hit

“to an inclination closer to the ecliptic”

makes it unusable for the Russians. Their vehicles can’t access it

Your clarifications were helpful but again I view them as too narrowly defined; they speak only of the mechanics of the linking of modules once delivered. This is a significant driver but not the only important one.

I must admit I had forgotten about the Pirs delivery.

I disagree that Agena/Gemini, with the propulsion module launched separately from the chaser, is fundamentally the same as Apollo. I consider it very important to include the launch architecture (among many other factors) as part of the overall picture because it is a fundamental driver of feasibility both technically and economically. (Just as important is the location of your rendezvous & docking/link-up.)

Continuing to fly Shuttle is likely not a viable option, primarily because of its operating cost. $3B+ per year just to get to and from LEO is a crippling expense. [Not that it’s looking like Ares I/V will be any cheaper…] The time to have evolved its design was post-Challenger; another lost opportunity born of shortsightedness. [But I’m still waiting for someone to explain why we can’t develop an ET insulation that doesn’t fall off; SO WHAT if we take a payload hit?]

This is why I believe the time for your suggestion to pursue a robust, reusable vehicle (or vehicles) for access to the Moon, asteroids, and Mars has come. This was the idea behind the CEV; let’s not confuse the current lunar-centric ESAS/Constellation implementation with the original VSE intent.

ISS’s current config & orbit make it a very expensive choice for use in interplanetary (or lunar) mission support. Even if we could move it gradually (perhaps with long-term electric ion thrusters and/or an electrodynamic tether) to an inclination closer to the ecliptic, it’s current design is that of an orbiting laboratory, not a vehicle assembly hanger. By the time it might be called on to support such operations, we’re going to be talking about the same lifetime and upgrade issues that are plaguing Shuttle today.

I heartily concur that development of commercial alternatives to replace the shuttle’s up & down capabilities is vital. If NASA were to get serious about this instead of building its own version to compete, it just might bring about a revolution that could change the entire picture.

Thanks for your thoughts.

Constellation/ESAS architecture is simply not sustainable for much the same reasons that the Apollo architecture was not sustainable.

I personally advocate that NASA maintain and utilize the current shuttle architecture, developing, if necessary, one or more robust new shuttles based on the current infrastructure. At the same time NASA should invest heavily in CRS and COTS D and expand that to include delivery of modules. NASA’s current CRS method of paying by the Kg. delivered could be an excellent way to motivate development of cost effective LEO access if stringently applied to the procurement criteria and should be carried over to COTS D and follow on programs. Once those assets come online the shuttle should be retired or redesigned as an experimental craft of exploring the RLV envelope. The ISS should be partially repurposed for interplanetary vehicle assembly, maintence, and refueling. And finally the development of a robust, long lifetime reusable vehicle for access to the moon, the asteroids, and Mars should be begun.

That’s what I would hope an independent review of the current NASA mission/architecture would select. Something sustainable, long term, and that would grow both our commercial capabilities and have space for our international partners.

WRT Agena/Gemini and Apollo I believe they use the same general assembly method in different locations. More or less the same method proposed for Constellation.

WRT Progress, I was referring specifically to the Progress M service module used in M-SO1 to deliver the Pirs module and that was launched with and used with several modules during MIR assembly.

I probably made an error when using program/ship names to classify the various assembly architectures used to date.

Perhaps this would be better.

1) Modules with integrated maneuver, rendezvous, and docking capabilities.
2) Modules using tugs with some portion of the maneuver, rendezvous, and docking capabilities disposed of after assembly.
3) Using a manned ship to assemble modules by stacking.
4) Using a manned ship with RMS and EVA capability to assemble modules.

In any case I have difficulty believing that the CEV would be capable of performing assembly of a multi-module Mars transport vehicle. This means that over and above all the issues that the Constellation program faces now they will still have to develop some form of module assembly for Mars and beyond.