In Four Minutes, Robert Zubrin Answers the Question "Why Mars?"
Originally, NASA had planned to extend the Apollo Program, so that after landing on the Moon in 1969, we could go on to land on Mars in the 1980s. Those plans were thrown out during the Nixon Administration.
But then, in 1996, Robert Zubrin published his book The Case for Mars. The book was so successful that it created a popular fascination with Zubrin's plans for travelling to and settling Mars. Zubrin founded The Mars Society in 1998 to promote his ideas.
Elon Musk read The Case for Mars, and he was persuaded by Zubrin's argument. As one of the cofounders of PayPal, Musk was on his way to becoming a multibillionaire; and he was looking for ambitious new projects. In 2001, he met Zubrin, and he began contributing to the Mars Society. Following Zubrin's advice, Musk set up SpaceX in 2002, which became the most amazing aerospace company, doing things that NASA thought impossible.
Today, SpaceX has over 6,000 Starlink satellites in low-Earth orbit, providing satellite internet service to over 70 countries. SpaceX launches hundreds of new satellites into orbit every year.
Tomorrow, SpaceX has scheduled the fourth test flight of Starship from Starbase in South Texas. Starship is the biggest and most powerful space rocket ever built. Musk predicts that an uncrewed Starship will test land on Mars in 3 to 4 years. Then, Starship will begin taking people to Mars and establishing permanent settlements on the planet within the next two decades.
Is this a good idea? Let's consider both the case for Mars and the case against Mars. And then let's consider Zubrin's response to the Weinersmiths' case against Mars.
THE CASE FOR MARS
Although the Moon is often considered the most suitable planetary body for human settlement, mostly because it is so close to the Earth, Mars seems to be the only planetary body in our solar system that has all the raw materials required for human life and for a technologically advanced civilization.
Unlike the Moon, Mars has carbon, nitrogen, hydrogen, oxygen, and water in readily accessible forms, which are the basic elements of life. Mars has huge stores of water in its ice and permafrost. The Moon is so dry that water is nowhere accessible, with the possible exception of the perpetually dark craters at the poles, which appear to have some water ice, but even there the amount of water is very small.
Like the Earth, Mars has a history of hydrologic and volcanic processes that probably have left large concentrations of high-grade mineral ore, which could be a source for the metals required for industrial production. Since the Moon has no geological history of water or volcanic action, it probably has no mineral ores.
The Sun can be a source of power on both the Moon and Mars, but since the Moon has a 28-day light/dark cycle--14 days of sunlight followed by 14 days of darkness--there would be large energy storage requirements. By contrast, Mars has an Earth-like 24.7-hour day. Mars also has the large supplies of carbon and hydrogen needed for producing the pure silicon for photovoltaic panels and other electronics. Mars also has geothermal power resources. But, eventually, the power-hungry civilization of a Mars settlement will require the power from exploiting the large stores of deuterium fuel for fusion reactors, although as of now no one knows how to build a fusion reactor.
The atmosphere of Mars is 95 percent carbon dioxide. That makes it toxic for humans. But, of course, carbon dioxide is crucial for photosynthesis: plants use photons of sunlight to power the process by which carbon is taken from the carbon dioxide in the atmosphere and "fixed" into living tissues, a process that requires water and chlorophyll, and which gives off oxygen that is then available for animal respiration.
Also, through the Sabatier process, carbon dioxide and hydrogen can be combined at elevated temperatures and pressures in the presence of a nickel catalyst to produce methane and water. The water is then available for humans and plants. The methane can be used to power rovers, habitats, and in liquid form, it's a rocket propellant. The first uncrewed landings on Mars will be directed to setting up the production and storage of methane, so that when the first astronauts land on Mars, they will have plenty of rocket propellant already on Mars for their return trip to Earth.
THE CASE AGAINST MARS
The biggest problem for a Mars settlement is distance. A trip from Earth to Mars will take at least six months. And since a Mars orbit around the Sun takes 687 Earth days, once you have landed on Mars, the Earth will have raced ahead of Mars, which is in a slower orbit around the Sun. Consequently, the first trips to Mars will require at least two to three years away from Earth.
No human being has been to space for longer than 437 days in a row. So, we don't know anything about the physiological and psychological dangers for people traveling in the vacuum of space for two or three years.
We do know that in space radiation is everywhere, and that radiation causes severe medical risks such as cancer. On Earth, we are surrounded by radiation. The Weinersmiths observe: "Some behaviors apt to increase your relative radiation dose include eating Brazil nuts, going to bed with a human next to you, or taking a trip to Denver, Colorado. Some daredevils may have done all three at once" (52). But we have evolved in the environment of the Earth so that our bodies can usually cope with certain types of radiation at the range typically found on Earth. The thin layer of dead skin on our bodies provides some shield from radiation. Also, our bodies are always working to repair or destroy radiation-damaged cells. Moreover, the Earth's atmosphere and magnetosphere (the magnetic field lines around the Earth) deflect much of the radiation from the Sun and from galactic cosmic sources (such as exploding stars). But once we leave that protective shell around the Earth, cosmic radiation will be striking every single cell nucleus in our body every few days. No one knows how harmful that will be.
We also don't know how harmful this is going to be for fetuses and growing children. The success of any permanent settlement in space, on Mars or elsewhere, will depend on the reproductive success of the settlers: to sustain their populations, they will need to produce healthy babies who grow into healthy adults who then can produce and rear their own babies. The Weinersmiths emphasize the point that there has been no experience or experiments in producing space babies. No pregnant women have gone into space. And we certainly have no experience with multiple generations of human beings in space. We can be sure that space radiation and microgravity will have some harmful effects on fetuses, children, and their parents (their sperm and eggs). But we don't know how severe that harm will be.
One first step in investigating this would be to send some monkeys or apes into space--perhaps even to Mars--for prolonged periods to see if they can successfully reproduce and rear healthy offspring. The need to do this is one of the best arguments for the "wait-and-go-big" approach of the Weinersmiths: we would need decades of research to determine whether and how human beings can reproduce in space. The fact that neither NASA nor SpaceX is sponsoring such experiments is clear evidence that they are not really serious about successful human settlement in space.
We do know that on Mars there are many toxic threats to the health of both children and adults. One of them is the Martian soil, which is poisonous, because it contains perchlorates, and perchlorates are known to harm human health, particularly by causing thyroid problems. Perchlorates can be taken up by edible plants. Furthermore, Mars is often covered in massive dust storms, and the sky is blotted out by toxic dirt.
Cleaning this toxic soil for use will require a lot of power. Indeed, Martians will have massive power needs not only to electrify their cities but also for farming and manufacturing, generating air, and extracting fuel from the atmosphere. Just to electrify a Martian city of 1 million people would require about 100 square miles of solar panels. Solar power is unlikely to be enough. They will need nuclear power as well. But while some nuclear fission reactors have been launched aboard some satellites, they have never been sent into deep space. A simpler use of nuclear power is the radioisotope thermoelectric generator, which has been put into deep-space probes (like Voyager 1 and Voyager 2). But these devices don't produce enough energy per unit of mass to provide for the power needs of a Martian settlement.
NASA has been experimenting with building a compact nuclear reactor--called "Kilopower"--for space projects. But even the biggest of these units now under way would only provide enough power to run thirty households.
Once again, the Weinersmiths argue, we see here that the technology for supporting a safe and flourishing human settlement on Mars will likely require many decades, or even a century, of research and development.
And so, to propose large human settlements on Mars in ten to twenty years, as Musk and Zubrin have done, is foolish.
ZUBRIN'S RESPONSE TO THE WEINERSMITHS
Zubrin has written a critique of the Weinershmiths' book for Quillette. Zubrin makes a least six main arguments, of which some seem persuasive to me and some not.
Here's the first argument: "The Weinersmiths' central thesis is inherently contradictory. Human settlement of space is pointless and impossible, they argue, but we also need laws to stop it, lest humanity destroy itself fighting over the unprecedented bonanza that space has to offer."
The Weinersmiths don't say this. What they do say is that it's pointless and impossible to attempt human settlement in space in the very near future, and that we need laws and policies that enforce their "wait-and-then-go-big approach." Against this, Zubrin needs to defend his approach: "Don't wait. Go big now!"
Zubrin complains that while the Weinersmiths play up the many risks in space travel and settlement, "they generally downplay or neglect to mention the fact that there are ways of overcoming these challenges--preferring instead to depict would-be space travelers in a variety of comically helpless predicaments." This is a fair criticism insofar as the Weinersmiths don't say enough about the "ways of overcoming these challenges" suggested by Zubrin and others.
But still Zubrin evades the critical issue here--are the "ways of overcoming these challenges" achievable in the very near future? So, for example, while the Weinersmiths agree with Zubrin that the development of thermonuclear fusion power for use in space would satisfy the energy needs of space settlements, they think this is unlikely to happen in the near future, and so, again, we should "wait and then go big" once we have control of nuclear fusion power.
Zubrin's second argument against the Weinersmiths is that while they "ridicule a number of silly and/or morally repugnant arguments" for space exploration, they "simply ignore or dismiss all the more important arguments in support of human space settlement."
This is not true. The Weinersmiths begin their book by summarizing and then denying eight "bad arguments" for space settlement, which includes Zubrin's favorite argument--his version of the Frontier Thesis: "Creating Nations in Space Will Reinvigorate Our Homogenized Bureaucratic, and Generally Wussified, Earth Culture" (22-35). Much of their book attempts to refute that claim. Zubrin needs to show that their refutation fails.
Zubrin's third argument is a reduction ad absurdum: if you agree with the Weinersmiths that we should not attempt to settle on any planet in space where there are severe risks to human life, then we would have to conclude that the settlement of Earth is impossible, because there are many risks to human life on Earth, but such an argument against settling Earth is absurd.
This argument fails because the Weinersmiths do not say that a planet suitable for human settlement must be free of any serious risks to human life. What they do say is that "Earth isn't perfect, but as planets go it's a pretty good one" (383). So, for them, a good planet for human settlement would not have to be perfect for human life, but at least as good as the Earth.
Zubrin's fourth argument rejects the "crazy ideas" that the Weinersmiths have taken from David Deudney (in his book Dark Skies), "including the notion that, should they become spacefaring, the great powers of the Earth would divert asteroids for use as weapons of mass destruction against one another."
Zubrin explains:
"In the course of my 35 years in aerospace, I have had a fair amount of contact with the military, and I know what they look for in a weapons system. The key desirable include precision, readiness, security, and stealth. Firepower is also important--but only when the weapon's effects can be solely directed against the enemy. That is one reason why nuclear and biological weapons are unpopular among military men. Furthermore, the last thing you could possibly want would be a weapon of mass destruction that could easily be taken over and controlled by the enemy."
"A diverted asteroid would take decades to strike its target and could be detected years in advance of impact, which would give the target country plenty of time to wipe out the aggressor nation using intercontinental ballistic missiles, hypersonics, or other Earth-based weapons that take only minute to launch. It is thus an option completely lacking in both readiness and stealth. Furthermore, it is doubtful that an asteroid could be directed with sufficient precision to be guaranteed to hit a target country, rather than your own. And if that were possible, the enemy would have plenty of time to launch an expedition to nudge its trajectory enough to hit you instead."
"The idea that the major powers would find asteroids attractive weapons is completely off the wall. . . ."
I agree--for the reasons he has indicated. And I don't see that the Weinersmiths have responded to these objections.
Zubrin's fifth argument is against the Weinersmiths when they say: "If you believe, as we do, that there's no obvious economic case for Moon mining . . . then this new Moon Race is just a pointless escalation towards a crisis, possibly even a conflict" (270). Zubrin observes: "Why there should be a 'Moon Race' when there is 'no obvious case for Moon mining' is left unexplained."
But, in fact, they do explain this as "costly signaling" (225-28). The United States, Russia, China, and India could engage in a new Moon Race even though Moon mining has little or no economic utility, because space programs are so costly that nations can show off their power by engaging in a space race that demonstrates their wealth, organization, and technical competence, even though there is no economic benefit to them in doing this.
Rubin's sixth main argument is that the Weinersmiths have ignored the power of his Space as the New Frontier vision:
"This is the true value of space. It is not a question of obtaining raw materials. We will probably not get oil from Mars. We will get inventions that will benefit humanity greatly. For just as the joyously innovative frontier society that was early America showered the world with inventions from the steamboat and the telegraph to the lightbulb, centrally-generated electric power, recorded sound, motion pictures, airplanes, and much more, so explorers and settlers on Mars will be forced to innovate dramatically in many vital areas, including biotech (to deal with the critical shortage of arable land), robotics and artificial intelligence (to overcome the severe labor shortage), and advanced forms of nuclear power (to provide for the needs of an energy-intensive society completely lacking in fossil fuels).
This fails to answer the claim of the Weinersmiths that this analogy between America and Mars is false because while the American frontier was located in the biosphere of the Earth, Mars is located in what they call the "Necrosphere."
". . . The Necrosphere is a built structure on Earth. Inside it, the ground is poison, there is no air, and cascades of radiation are fired at the inhabitants on a perpetual basis."
"Why did we build it? In the sure knowledge that we can stick engineers inside who, due to the harsh environment combined with their need not to die, will spew forth valuable ideas like a spigot spews forth pressurized water. If this sort of thing seems implausible to you, you should ask yourself why anyone would expect a Mars base to generate all these supposed benefits" (34-35).
Zubrin's analogy between America and Mars could become a true analogy once we learn how to artificially recreate the Earth's biosphere on Mars--perhaps by terraforming Mars. The Weinersmiths think that's a possibility that we should strive for, but it will require a century or more of research and development: it would be wise to wait and then go big.
People like Musk and Zubrin will have to persuade us that waiting is foolish and that it would be wise for us to go now.
No comments:
Post a Comment