totm may 2024 Mars Sample Return discussion thread

[SunlitZelkova]

On 2/10/2025 at 12:55 AM, DAL59 said:

WT F this is the dumbest concept I've ever seen and made me lose all remaining respect for Boeing. 

How could any aerospace engineer endorse this? Three SLS launches (two of which must be within a month of each other) for 1 day of human proximity to Mars and a few grams returned from the surface. Note that physics wise, for the Mars Ascent Vehicle with the samples to intercept the Orion on a flyby trajectory, it would need to put itself on the same course as the Orion- so the Orion serves no purpose. I guess it means the sample capsule no longer needs a parachute or heatshield and those two systems can no longer fail... but the ones on Orion can! Its risking astronaut lives for literally no reason!

Human-assisted MSR has been floated since the mid 1960s when contractors and think tanks were pumping out mission concepts to try and figure out what the next best steps for NASA would be after Apollo. At the time it was not at all clear that NASA would fall into such a seemingly disgraceful state. Although it was realized budgets would be smaller than Apollo, because the infrastructure for Apollo already existed, most assumed the equipment would be adapted and continue to be used. It wasn't until after the Apollo I fire that the process of throwing out a perfectly good industrial base began to crystalize.

Mars flybys and human-assisted MSR were products of pragmatic views about expected funding. Mars flybys were examined in both the USA and USSR as cheaper alternatives to full-scale landing missions that would provide an opportunity to gain data about human health in space with the added "cool" factor of them journeying beyond the Earth-Moon system (essentially like a space station but for deep space, as it more or less orbits the Sun). Human-assisted MSR was examined as a possibility due to the low reliability of computers of the day. Although by the 1970s, the USA and USSR had overcome the huge amount of robotic spacecraft failures they experienced in the late 50s and early 60s (albeit with the USSR trading it for a still large number of only partial successes) the institutional memory of those failures loomed large. Having humans do it was seen as a way to avoid those risks while also having those "solar space station" benefits of a flyby.

Curiously, Soviet confidence in their robotic spacecraft, which was elevated by the successes of their lunar sample return missions and lunar rovers, was high enough that they continued to develop an MSR plan as late as 1979. In the end it was Soviet docking technology that was deemed to be the biggest risk: the final MSR plan required three near-simultaneous Proton launches and all three spacecraft docking together, and at the time the Soviets had a similar institutional memory of the numerous failed dockings during the uncrewed development phase of Soyuz. So it was cancelled.

I would argue both piloted flybys and human-assisted MSR still make sense in the present day, but only in an environment of the traditional government contract system. Notably, NASA was actually considering both piloted Mars flybys and orbital missions as late as 2019 with their concepts for the Deep Space Transport.

However, now that it is becoming more and more clear that Starship/Super Heavy is going to become a mature launch system, it doesn't make sense anymore. The rocket is no longer a "colonization fantasy" or "a grain silo hovering for 5 seconds" (two opinions I myself held of the rocket, more out of pure disbelief it could work than derision at the idea). Starship more or less does away with the need for "austerity" in space mission architecture. Even if Starship itself proves to have insurmountable challenges in being a self-contained Mars Transfer Vehicle and lander, the launch vehicle alone will likely be cheap enough and have a high enough cadence that it could easily allow for the accomplishment of a 4-5 launch surface expedition architecture, as proposed in 1969 as part of the Integrated Program Plan and later envisioned in 2005 for the Constellation Program (I love DRM 5.0 and Constellation btw, it was the last American traditional human spaceflight program that made reasonable sense before NASA delved into the SLS abyss that gave us Asteroid Redirection Mission, etc.).

It is important to note that Mars flyby missions were never considered ideal and were always a product of finding opportunistic ways to do exciting things with extra money on hand. The proposals always came from lower level institutions, and the big visionaries like Sergey Korolyov and Werner von Braun never had much interest in them, considering only a landing worthwhile.

In a sense, Boeing's proposal does make sense: do a (seemingly) exciting thing for as little money as possible. But SLS is inherently too costly to ever do anything for as little money as possible. The only other alternative SHLV at the moment is Starship, and its characteristics make it so that flybys can be forgoed and a surface expedition is feasible, not unlike how the Integrated Program Plan dropped the flyby concept because it intended to restart Saturn V production (whereas 1960s flyby proposals assumed that the number of available Saturn Vs would be finite).