Although the figure of 25% is hyperbole, it is certainly true that it would take a substantial portion of the gross domestic product of a major industrial power to accomplish even a marginal crewed mission to another planet, and again, at an opportunity cost that denies advances in other areas of both space and terrestrial technology, all for the sake of putting footprints on another world and doing some modest amount of science and exploration at a cost ratio of something on the order of 1000:1 in comparison to robotic missions, which also do not have the added complexity of having to maintain a habitable environment and return the crew.
Again, the assumption by enthusiasts of crewed space exploration is that if we send people there, some kind of magical innovation happens which suddenly makes access and habitation in space massively less costly and hazardous. Our lessons from the history of space exploration to date, however, show us exactly the opposite. Specifically, the Apollo program–a crash effort to develop the barely sufficient technology to put a crew of two people on the Moon–deliberately jumped past the more logical steps to space exploration such as developing and maturing a cost-effective heavy space launch vehicle, constructing an orbital habitat, developing an orbital transfer infrastructure, et cetera in favor of of the Lunar Orbit Rendezvous, specifically because it was cheaper and required less technology development. The result was six Lunar landing missions, only one of which actually had a scientist on crew (and he very notably complained about the lack of decent inspection and exploration he could do in the bulky suit and limited instruments), and a lack of follow-on because the system was not built to perform any other kinds of missions and even though the costs of adapting components to fill other roles (such as Grumman’s efforts to demonstrate that the LM could be used as the basis for a space tug or remotely piloted vehicle) the basic costs for launching any mission on the Saturn V–particularly one which required multiple launches and in-space assembly–were just too costly for the US to bear. The plan to replace the Apollo system with the STS which would support a space infrastructure were undermined both from the costs and limitations of the STS and the fact that without already having constructed an orbiting station or habitat, there was really no place for the Shuttle to go that was worst the costs of maintaining it. Meanwhile, the knowledge we gained about the hazards of both the space environment and the Lunar surface increased, rather than reduced, estimates of the cost and effort to develop crewed space missions.
Let’s turn the issue around and look at it from a practical context. Let’s say, for the sake of argument, that a crewed mission to the surface of Mars could be developed and accomplished at a budget of US$200B over a period of 20 years in today’s dollars (which, on the basis of studies that I have worked on, is probably a ridiculously low estimate). Even if you can leverage the technology development for follow-on missions of the same level of capability for, say, 30% of the cost, that would be a US$60B mission. How many and how often do you think the public is going to be willing to fund such missions, and to what end? What we saw from Apollo was that the public interested in space exploration is a big “meh”, especially when the result isn’t flashy space shits and alien princesses, but slow flying cans, grainy video, and a big bag of rocks. Space exploration which which costs massive budgets and returns little of value to justify those costs is not sustainable, except in the sense of providing subsidy to aerospace contractors as with STS and the ISS.
Being realistic about the costs, hazards, and fundamental limitations of space technology development is not being “…so scared about Human progress…” or unsupported “naysaying”, (and claiming that it is so is a strawman argument). Nor is recognizing that there is not a limitless budget for performing whatever kind of mission you see fit regardless of any material benefits to result from it. Recognizing that there are realistic capability and fiscal limits to what can be done with existing technology is a necessary first step in laying out a practicable space technology development architecture which is sustainable (e.g. doesn’t cost hundreds of billions of dollars per mission, provides evident scientific and economic value, is sufficiently flexible to support a wide array of mission objectives and further technology development) and reduces risk to a level that would be fiscally and ethically acceptable.
Putting a crew on Mars, while perhaps ephemerally thrilling to a minority of space enthusiasts, is not human progress in the sense of improving the lives of the Earth-bound population which is funding this, nor does it develop the type of architecture necessary to make routine human space habitation and crewed missions to achieve other objectives viable. We are not going to be mining the surface of Mars for precious metals to be returned at enormous cost to Earth, nor is there any practicable way to transform Mars into a terrestrial-like environment. Even the cost of establishing and supplying a permanent outpost on Mars would be enormous at a significant risk for very little practical return, the costs of which could fund thousands of robotic missions and orbiting probes which would give us a broader and more comprehensive knowledge of Martian conditions than any single crewed outpost.
If you have some point of substance regarding actual space technology capabilities or material benefits, please expound upon them. But if the argument is simply to continue with vaguely overarching prerogatives to provide a haven against catastrophic disaster to life on Earth, or send crew to inspire schoolchildren, or profit on some hypothetical resource unobtainable on Earth, understand that these are not valid considerations in planning a practicable space architecture for exploration and resource utilization.
Stranger