Saturday Night Science: The Case for Space

“The Case for Space” by Robert ZubrinFifty years ago, with the successful landing of Apollo 11 on the Moon, it appeared that the road to the expansion of human activity from its cradle on Earth into the immensely larger arena of the solar system was open. The infrastructure built for Project Apollo, including that in the original 1963 development plan for the Merritt Island area could support Saturn V launches every two weeks. Equipped with nuclear-powered upper stages (under active development by Project NERVA, and accommodated in plans for a Nuclear Assembly Building near the Vehicle Assembly Building), the launchers and support facilities were more than adequate to support construction of a large space station in Earth orbit, a permanently-occupied base on the Moon, exploration of near-Earth asteroids, and manned landings on Mars in the 1980s.

But this was not to be. Those envisioning this optimistic future fundamentally misunderstood the motivation for Project Apollo. It was not about, and never was about, opening the space frontier. Instead, it was a battle for prestige in the Cold War and, once won (indeed, well before the Moon landing), the budget necessary to support such an extravagant program (which threw away skyscraper-sized rockets with every launch), began to evaporate. NASA was ready to do the Buck Rogers stuff, but Washington wasn’t about to come up with the bucks to pay for it. In 1965 and 1966, the NASA budget peaked at over 4% of all federal government spending. By calendar year 1969, when Apollo 11 landed on the Moon, it had already fallen to 2.31% of the federal budget, and with relatively small year to year variations, has settled at around one half of one percent of the federal budget in recent years. Apart from a small band of space enthusiasts, there is no public clamour for increasing NASA’s budget (which is consistently over-estimated by the public as a much larger fraction of federal spending than it actually receives), and there is no prospect for a political consensus emerging to fund an increase.

Further, there is no evidence that dramatically increasing NASA’s budget would actually accomplish anything toward the goal of expanding the human presence in space. While NASA has accomplished great things in its robotic exploration of the solar system and building space-based astronomical observatories, its human space flight operations have been sclerotic, risk-averse, loath to embrace new technologies, and seemingly more oriented toward spending vast sums of money in the districts and states of powerful representatives and senators than actually flying missions.

Fortunately, NASA is no longer the only game in town (if it can even be considered to still be in the human spaceflight game, having been unable to launch its own astronauts into space without buying seats from Russia since the retirement of the Space Shuttle in 2011). In 2009, the commission headed by Norman Augustine recommended cancellation of NASA’s Constellation Program, which aimed at a crewed Moon landing in 2020, because they estimated that the heavy-lift booster it envisioned (although based largely on decades-old Space Shuttle technology) would take twelve years and US$36 billion to develop under NASA’s business-as-usual policies; Constellation was cancelled in 2010 (although its heavy-lift booster, renamed. de-scoped, re-scoped, schedule-slipped, and cost-overrun, stumbles along, zombie-like, in the guise of the Space Launch System [SLS] which has, to date, consumed around US$14 billion in development costs without producing a single flight-ready rocket, and will probably cost between one and two billion dollars for each flight, every year or two—this farce will probably continue as long as Richard Shelby, the Alabama Senator who seems to believe NASA stands for “North Alabama Spending Agency”, remains in the World’s Greatest Deliberative Body).

In February 2018, SpaceX launched its Falcon Heavy booster, which has a payload capacity to low Earth orbit comparable to the initial version of the SLS, and was developed with private funds in half the time at one thirtieth the cost (so far) of NASA’s Big Rocket to Nowhere. Further, unlike the SLS, which on each flight will consign Space Shuttle Main Engines and Solid Rocket Boosters (which were designed to be reusable and re-flown many times on the Space Shuttle) to a watery grave in the Atlantic, three of the four components of the Falcon Heavy (excluding only its upper stage, with a single engine) are reusable and can be re-flown as many as ten times. Falcon Heavy customers will pay around US$90 million for a launch on the reusable version of the rocket, less than a tenth of what NASA estimates for an SLS flight, even after writing off its enormous development costs.

On the heels of SpaceX, Jeff Bezos’s Blue Origin is developing its New Glenn orbital launcher, which will have comparable payload capacity and a fully reusable first stage. With competition on the horizon, SpaceX is developing the Super Heavy/Starship completely-reusable launcher with a payload of around 150 tonnes to low Earth orbit: more than any past or present rocket. A fully-reusable launcher with this capacity would also be capable of delivering cargo or passengers between any two points on Earth in less than an hour at a price to passengers no more than a first class ticket on a present-day subsonic airliner. The emergence of such a market could increase the demand for rocket flights from its current hundred or so per year to hundreds or thousands a day, like airline operations, with consequent price reductions due to economies of scale and moving all components of the transportation system down the technological learning curve.

Competition-driven decreases in launch cost, compounded by partially- or fully-reusable launchers, is already dramatically decreasing the cost of getting to space. A common metric of launch cost is the price to launch one kilogram into low Earth orbit. This remained stubbornly close to US$10,000/kg from the 1960s until the entry of SpaceX’s Falcon 9 into the market in 2010. Purely by the more efficient design and operations of a profit-driven private firm as opposed to a cost-plus government contractor, the first version of the Falcon 9 cut launch costs to around US$6,000/kg. By reusing the first stage of the Falcon 9 (which costs around three times as much as the expendable second stage), this was cut by another factor of two, to US$3,000/kg. The much larger fully reusable Super Heavy/Starship is projected to reduce launch cost (if its entire payload capacity can be used on every flight, which probably isn’t the way to bet) to the vicinity of US$250/kg, and if the craft can be flown frequently, say once a day, as somebody or other envisioned more than a quarter century ago, amortising fixed costs over a much larger number of launches could reduce cost per kilogram by another factor of ten, to something like US$25/kg.

Such cost reductions are an epochal change in the space business. Ever since the first Earth satellites, launch costs have dominated the industry and driven all other aspects of spacecraft design. If you’re paying US$10,000 per kilogram to put your satellite in orbit, it makes sense to spend large sums of money not only on reducing its mass, but also making it extremely reliable, since launching a replacement would be so hideously expensive (and with flight rates so low, could result in a delay of a year or more before a launch opportunity became available). But with a hundred-fold or more reduction in launch cost and flights to orbit operating weekly or daily, satellites need no longer be built like precision watches, but rather industrial gear like that installed in telecom facilities on the ground. The entire cost structure is slashed across the board, and space becomes an arena accessible for a wide variety of commercial and industrial activities where its unique characteristics, such as access to free, uninterrupted solar power, high vacuum, and weightlessness are an advantage.

But if humanity is truly to expand beyond the Earth, launching satellites that go around and around the Earth providing services to those on its surface is just the start. People must begin to homestead in space: first hundreds, then thousands, and eventually millions and more living, working, building, raising families, with no more connection to the Earth than immigrants to the New World in the 1800s had to the old country in Europe or Asia. Where will they be living, and what will they be doing?

In order to think about the human future in the solar system, the first thing you need to do is recalibrate how you think about the Earth and its neighbours orbiting the Sun. Many people think of space as something like Antarctica: barren, difficult and expensive to reach, unforgiving, and while useful for some forms of scientific research, no place you’d want to set up industry or build communities where humans would spend their entire lives. But space is nothing like that. Ninety-nine percent or more of the matter and energy resources of the solar system—the raw material for human prosperity—are found not on the Earth, but rather elsewhere in the solar system, and they are free for the taking by whoever gets there first and figures out how to exploit them. Energy costs are a major input to most economic activity on the Earth, and wars are regularly fought over access to scarce energy resources on the home planet. But in space, at the distance Earth orbits the Sun, 1.36 kilowatts of free solar power are available for every square metre of collector you set up. And, unlike on the Earth’s surface, that power is available 24 hours a day, every day of the year, and will continue to flow for billions of years into the future.

Settling space will require using the resources available in space, not just energy but material. Trying to make a space-based economy work by launching everything from Earth is futile and foredoomed. Regardless of how much you reduce launch costs (even with exotic technologies which may not even be possible given the properties of materials, such as space elevators or launch loops), the vast majority of the mass needed by a space-based civilisation will be dumb bulk materials, not high-tech products such as microchips. Water; hydrogen and oxygen for rocket fuel (which are easily made from water using electricity from solar power); aluminium, titanium, and steel for structural components; glass and silicon; rocks and minerals for agriculture and bulk mass for radiation shielding; these will account for the overwhelming majority of the mass of any settlement in space, whether in Earth orbit, on the Moon or Mars, asteroid mining camps, or habitats in orbit around the Sun. People and low-mass, high-value added material such as electronics, scientific instruments, and the like will launch from the Earth, but their destinations will be built in space from materials found there.

Why? As with most things in space, it comes down to delta-v (pronounced delta-vee), the change in velocity needed to get from one location to another. This, not distance, determines the cost of transportation in space. The Earth’s mass creates a deep gravity well which requires around 9.8 km/sec of delta-v to get from the surface to low Earth orbit. It is providing this boost which makes launching payloads from the Earth so expensive. If you want to get to geostationary Earth orbit, where most communication satellites operate, you need another 3.8 km/sec, for a total of 13.6 km/sec launching from the Earth. By comparison, delivering a payload from the surface of the Moon to geostationary Earth orbit requires only 4 km/sec, which can be provided by a simple single-stage rocket. Delivering material from lunar orbit (placed there, for example, by a solar powered electromagnetic mass driver on the lunar surface) to geostationary orbit needs just 2.4 km/sec. Given that just about all of the materials from which geostationary satellites are built are available on the Moon (if you exploit free solar power to extract and refine them), it’s clear a mature spacefaring economy will not be launching them from the Earth, and will create large numbers of jobs on the Moon, in lunar orbit, and in ferrying cargos among various destinations in Earth-Moon space.

The author surveys the resources available on the Moon, Mars, near-Earth and main belt asteroids, and, looking farther into the future, the outer solar system where, once humans have mastered controlled nuclear fusion, sufficient Helium-3 is available for the taking to power a solar system wide human civilisation of trillions of people for billions of years and, eventually, the interstellar ships they will use to expand out into the galaxy. Detailed plans are presented for near-term human missions to the Moon and Mars, both achievable within the decade of the 2020s, which will begin the process of surveying the resources available there and building the infrastructure for permanent settlement. These mission plans, unlike those of NASA, do not rely on paper rockets which have yet to fly, costly expendable boosters, or detours to “gateways” and other diversions which seem a prime example of (to paraphrase the author in chapter 14), “doing things in order to spend money as opposed to spending money in order to do things.”

This is an optimistic and hopeful view of the future, one in which the human adventure which began when our ancestors left Africa to explore and settle the far reaches of their home planet continues outward into its neighbourhood around the Sun and eventually to the stars. In contrast to the grim Malthusian vision of mountebanks selling nostrums like a “Green New Deal”, which would have humans huddled on an increasingly crowded planet, shivering in the cold and dark when the Sun and wind did not cooperate, docile and bowed to their enlightened betters who instruct them how to reduce their expectations and hopes for the future again and again as they wait for the asteroid impact to put an end to their misery, Zubrin sketches millions of diverse human (and eventually post-human, evolving in different directions) societies, exploring and filling niches on a grand scale that dwarfs that of the Earth, inventing, building, experimenting, stumbling, and then creating ever greater things just as humans have for millennia. This is a future not just worth dreaming of, but working to make a reality. We have the enormous privilege of living in the time when, with imagination, courage, the willingness to take risks and to discard the poisonous doctrines of those who preach “sustainability” but whose policies always end in resource wars and genocide, we can actually make it happen and see the first steps taken in our lifetimes.

Zubrin, Robert. The Case for Space. Amherst, NY: Prometheus Books, 2019. ISBN 978-1-63388-534-9.

Here is an interview with the author about the topics discussed in the book.

This is a one hour and forty-two minute interview (audio only) from “The Space Show” which explores the book in detail.  The audio gets much better after the pre-recorded introduction.


Author: John Walker

Founder of, Autodesk, Inc., and Marinchip Systems. Author of The Hacker's Diet. Creator of

6 thoughts on “Saturday Night Science: The Case for Space

  1. Thank you, John, for shepherding us to this new (at least to many of us, methinks) paradigm with your essays and book reviews. The High Frontier, Delta-V (though fiction, it relies upon and explains orbital mechanics), and now The Case for Space, have combined to cure me, at least, of the fetish belief that my descendants must by necessity inhabit planetary (or even lunar) surfaces in the depths of gravity wells. This possibility of comfortable, productive and meaningful life in very large, self-sustaining space habitats in the solar system – and eventually, perhaps, beyond – offers a much-needed dose of optimism. As you observe, the “Green new deal” pales as an alternative future. I think the color ‘green’ in that stifling and Lilliputian construct is borrowed from the complexion of one suffering from nausea. Its promotion by know-nothings presuming themselves prophets of the goddess Gaia, surely makes me sick.


  2. civil westman:
    Delta-V (though fiction, it relies upon and explains orbital mechanics)

    I just finished Delta-V a couple of days ago, and will post a review here once I can squeeze some more words out of the reviewer toothpaste tube with the hydraulic press.  This is an interesting book.  Daniel Suarez uses essentially nothing which is not present-day technology, although not necessarily applied to or yet implemented in space.  Unlike many novels of opening the space frontier, he presents some of those who make it happen as ruthless robber barons as rough-edged and amoral as those who built the railroads in the 19th century.  This rings true—even somebody who doesn’t need the money but is motivated by realising a dream may cut corners and engage in deception in order to make it happen.

  3. Another fine book written by an awful, horrible man.  I’ll “go there” in another post — Zubrin is a first-rate thinker on space and space issues.

    I don’t know this for a fact and can’t be bothered to find out, but I would wager that a huge proportion of this new generation of space enthusiasts, engineers, craftsmen, leaders, visionaries, and wannabe tourists can cite Zubrin by name and his Case for Mars / Mars Direct writings.

  4. Haakon Dahl:
    … I would wager that a huge proportion of this new generation of space enthusiasts, engineers, craftsmen, leaders, visionaries, and wannabe tourists can cite Zubrin by name and his Case for Mars / Mars Direct writings.

    Yes, his 1996 book, The Case for Mars, which presented the Mars Direct mission plan detail, was a watershed in thinking about human missions to Mars.  Earlier mission plans, such as von Braun’s from the 1950s through the late 1960s, and the Space Exploration Initiative proposed in the George H. W. Bush administration, were “Battlestar”-type missions which would cost in the tens or hundreds of billions of dollars (including the infrastructure they required), and mostly accomplish little other than “flags and footprints” like Apollo.

    Zubrin forcefully made the case for a “live off the land” approach (which the aerospace types immediately dubbed “in-situ resource utilisation” [ISRU]), likening it to Amundsen’s successful polar expedition as opposed to Scott’s disastrous one, which brought almost everything it needed in ships.  In addition to the concept, he worked out how it would be possible to use the Sabatier reaction to produce the fuel needed for the return mission to Earth from CO₂ in the Martian atmosphere reacted with a modest mass of hydrogen brought from Earth.  The return vehicle would arrive on Mars two years before the astronauts, who would depart for Mars only after their return vehicle had produced all of the fuel they would need for the return.  Each vehicle landed on Mars would produce fuel for the return of the next crew, providing for a sustained presence on the Red Planet, and additional fuel powering suborbital hoppers would allow exploration of the entire planet.

    This was originally greeted with disdain by the cost-plus aerospace establishment, but it slowly gained acceptance, and by 1993, the NASA Mars Design Reference Mission was largely based upon Mars Direct, with NASA gold plating added to keep the contractors and congressbeings happy.

    David Portree’s Humans to Mars, a NASA public domain book available on-line as a PDF, is an excellent review of the first half century of Mars mission planning, including the impact of Mars Direct.

    An updated version of the 2007 documentary film, The Mars Underground, is available on YouTube.  It follows the development of Mars Direct and explains the concepts of the mission.

  5. Again, thanks for this linked film. Having watched it, several things are noteworthy. Zubrin’s enthusiasm and thoughtful advocacy are important components of making human exploration (and not necessarily permanent large-scale habitation) of Mars an explicit and short-term goal. In addition, he made clear to me, at least, the evanescence of the political will to fund this goal and to maintain the political follow through. Given the incoherence and dysfunction of our society and political system, I am not optimistic it will happen. Zubrin also makes a good case for the imperative of human exploration and expansion. Makes me say, “Man is not fed by dread alone” (as in the dread comprising the ‘green new deal’).


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