Mining the Sky: Untold Riches From The Asteroids, Comets, And Planets

by John S. Lewis

While we worry over the depletion of the earth's natural resources, the pollution of our planet, and the challenges presented by the earth's growing population, billions of dollars worth of metals, fuels, and life-sustaining substances await us in nearby space. In this visionary book, noted planetary scientist John S. Lewis explains how we can mine these precious metals from the asteroids, comets, and planets in our own solar system for use in space construction projects. And this is just one of the possibilities. Join John S. Lewis as he contemplates milking the moons of Mars for water and hollowing out asteroids for space-bound homesteaders—all while demonstrating the economic and technical feasibility of plans that were once considered pure fiction.

Genres: Science, Space, Nonfiction, Astronomy, Economics, Technology, Geology

274 pages, Paperback

First published January 1, 1996

About the author

John S. Lewis (born June 27, 1941) is a Professor Emeritus of planetary science at the University of Arizona’s Lunar and Planetary Laboratory. His interests in the chemistry and formation of the solar system and the economic development of space have made him a leading proponent of turning potentially hazardous near-Earth objects into attractive space resources.

Reviews

[Peter Tillman · Rating 4 out of 5]

Rating: A+ (ideas); A- (writing). An entertaining and visionary look at the future of humanity in a space-based economy. 1997 book, so doubtless somewhat dated now.

The idea of moving mining to space dates back at least to Russian space visionary Konstantin Tsiolkovski (1903). Robert Goddard's pioneering rocketry experiments in the 1920's were paid for by the Guggenheim Foundation, with money from mining (ASARCO). Goddard himself envisioned the migration of industry and people to space (1918).

Mr. Lewis, (then) Codirector of the Space Engineering Research Center at the University of Arizona, brings these speculations up to date for the turn of the 21st century.

The resources available in the asteroid belt are truly staggering. Lewis estimates that there is enough iron there to cover the earth to a depth of one-half mile(!). At 1996 prices, this iron would be worth about $7 billion for each person now alive. Add in nickel, platinum, copper, gold, uranium and so on, and the total exceeds $100 billion per person (in 1996 dollars).

Of course, there are a *few* steps to be taken before these resources become economic, not the least mustering the courage and imagination to take them. Yogi Berra reminds us that "the trouble with predicting the future is that it is very hard", but from an engineering standpoint,
there's no reason why humanity can't become healthy, wealthy and *very* numerous. Just can't do it all *here*...

Review written in 1998, for the Arizona Geological Society newsletter, I think. Lightly edited in 2021.

[Sohaib Qureshi · Rating 4 out of 5]

John S. Lewis is a professor of planetary science at the University of Arizona. His expertise on the composition and chemistry of asteroids and comets really shines through in this book. The premise of the book is to explore the possibilities of a self sufficient space program. Lewis argues that with initial investment in some properly planned space missions, in contrast to the flags and footprints missions of the Apollo program, a reasonably profitable space economy can be set up. He explores the economic and technological possibilities of having a permanent base of operations on the moon beaming solar power in the form of microwaves back to the Earth. He proposes that for this to be economically feasible the majority of propellants and photovoltaic cells be manufactured using processed materials from the moons regolith. The major obstacle that this plan runs into is the lack of hydrogen on the moon; hydrogen is essential to the manufacture of water and propellants. If space missions are to be economically feasible, the book proposes that we mine near earth asteroids (NEO's). Over half the NEO's are dead comet nuclei, rich in water and other volatiles. The remaining half are rich in metals. With these resources solar cells can be manufactured and placed in geocentric earth orbit, beaming cheap solar power 24/7 to Terra. He then outlines several possibilities of how the space industry can export materials and power to the resource limited earth such as helium-3 from the moon and the atmospheres of giant planets. He argues that humanity's expansion into space, forced by overpopulation and dwindling resources, is inevitable. This book was a pure joy to read. It is well thought out and written, each chapter begins with a brief story like narrative taking place in the future, showing us various possibilities and exiting our imagination.

[Brahm · Rating 4 out of 5]

Really cool non-fiction book all about what it would take to become a spacefaring civilization. Each chapter starts off with a futuristic little story/vignette then Lewis dives into some topic like lunar geology, asteroid geology, or the logistics of moving around huge quantities of mass in the solar system.

Written in 1996 with a '97 afterword, it didn't seem terribly dated. Although being written before 2000, it predates the era of humanity's continuous presence in space (on the ISS).

Lewis writes with humour and passion, but some of his ideas I think are overly optimistic or pretty far "out there". Example, problems of mineral/element separation in any non-Earth environment are portrayed as trivial. Context-free excerpt: "If we recover all the water and crack the carbon dioxide into carbon and oxygen..." - the two HUGE assumptions baked into that sentence are a 100% water recovery rate and a perfect carbon/oxygen separation. (with my work in mining/mineral processing I am skeptical but always happy to be wrong!)

Another idea I'm unsure about is that early colonized space will be a "haven for refugees". The way things spaceflight is going, costs are coming down but it seems more like the wealthy billionaire adventurer crowd will be the first long-term residents.

Would recommend to space geeks and fans of space science fiction (I was thinking about The Expanse a lot). I need to take a geology course to better appreciate some of the details. Lewis is a super-visionary long-term thinker who writes with a great mix of passion and technical detail on exactly what's required to make a viable permanent manufacturing presence in space.

Non-content-related note, this book appears to have been printed on demand. The back inside cover says "Manufactured by Amazon.ca" (which didn't exist in '97) which kind of blows my mind as it still arrived in just a few days.

[Hong · Rating 3 out of 5]

- Disorganized. Last two chapters are disconnected from the rest of the book.

- The depth disappoints me. Instead of discussing the barriers of Solar Power Satellites (SPS) and possible technological advancements that can possibly overcome them, the author focuses on how useful SPS can be to humankind. Issues of reducing space launching cost and possibility of near-future propelling systems, which are critical, are ignored. Power generations are assumed to be trivial without a detailed discussion. Economic calculations are annoyingly rough or sometimes left blank (e.g., in the discussion of producing CFCs in Mars terraforming). Development of self-replicating machines, another critical technology, is ignored. Estimations on economy and population are naïve or even ridiculous.

- History of lunar missions, ancient Chinese sea explorations and classification of asteroids are things that I don’t care.

- The good things: learn a number of things especially on the chemistry of space objects. It is entertaining to see how the author approach an unthinkable question of mining the sky based on his knowledge. The author knows his stuffs well. This book is written from a perspective based on his expertise.

- Over-optimistic. Whenever mining He3 for fusion is discussed, I want to skip.

[Clay Davis · Rating 5 out of 5]

I liked the idea of a gold rush to space.

[James · Rating 5 out of 5]

Very good. This book is a companion to the same author's book Rain of Iron and Ice, which is about the history and threat of comet and asteroid impacts on Earth, and both books were published in 1996. Although that would seem to make this dated, as with the other book it actually boosts Dr. Lewis' credibility, because events since then have pretty much borne out his expectations regarding the makeup of the rest of our solar system.

Mining the Sky is the positive or "heads" side of the same metaphorical coin for which Rain of Iron and Ice is the tails side. Both relate to the huge number and variety of kinds of other bodies orbiting the Sun in roughly our neighborhood - say from the orbit of Jupiter inward. But whereas Rain of Iron and Ice is about the threat some of them pose through the risk of their colliding with Earth, Mining the Sky is about how we can put them to good use instead - to move polluting industries into space; to replace resources we're running out of, especially sources of energy; and to provide enough other places to live that whenever the next dinosaur-killer-sized rock does wallop Earth, we as a species won't still have all our eggs in that one basket.

This book is a bit wonkier than the other one - more math and formulae - but to get the ideas, the reader can breeze through those parts and take in the possibilities they offer.

I want our grandchildren (now 8 and 10) to have careers in space as a realistic option if they want them fifteen years from now. Don't know whether it's going to happen, but if it does it will be thanks to thinks like this author.

[Steve Van Slyke · Rating 4 out of 5]

The most interesting thing for me was his compelling argument that NEO's (asteroids and expired comets in orbits that cross Earth's) are much more attractive for resource extraction than the moon. First, the valuable materials--metals and water--are more highly concentrated in the NEO's and second they are less expensive to travel to and from because of their significantly lower gravity than the moon. (Could it be that Obama's space advisers were influenced by Lewis in their decision to promote a human mission to a NEO over a return to the moon?)

I think he let his enthusiasm for space exploration and colonization get the better of him at times such as when he makes rather extreme estimates of population growth and the resulting inevitability of human missions to NEO's and Mars in the near term.

Still, I found it interesting to the point that I would definitely acquire a revised edition if he were to publish one, and I may re-read this edtion some day if he doesn't.

[Bernhard · Rating 3 out of 5]

A little bit dry but quite ahead of its time. Lacks the imagination-capturing prose of Zubrin's Mars direct. Also, mining is simply not sustainable, but the resources could be used to refuel ships exploring space beyond our solar system; we'll need any boost we can get for those long distance voyages...

[A · Rating 2 out of 5]

I really wanted to like this book, but the author’s writing style is unbearably dry and technical. Had to stop halfway because I just couldn’t stand it any more.

[Erik Heter · Rating 4 out of 5]

An interesting book, but a little bit scattered.

[Rebeckah Sypik · Rating 4 out of 5]

Learned a about the potential of mining in space.

[Josh · Rating 3 out of 5]

I picked up this classic of 1990s space optimism hoping for the strongest, most grounded case for asteroid mining and off-Earth resources delivering "untold riches." What I got was a book brimming with fascinating astrogeology, a compelling long-term vision for space industrialization, and plenty of '90s futurist flavor—but ultimately a failure to deliver a rigorous economic argument for near-term mining viability.

Lewis excels when surveying the raw material inventory of the solar system. Chapters on the Moon, near-Earth objects (NEOs), the asteroid belt, Mars, and even the outer planets offer solid, pre-1997 science: detailed compositions, histories, and potentials like insulated water ice in dead comets or speculative polar lunar ice (later confirmed). The discussions of in-situ resource utilization (ISRU)—turning regolith into shielding, extracting volatiles for propellant, or building with local metals—are thoughtful and still relevant today. Yet the book's central thesis falters repeatedly. Lewis promises a business case but relies on the same seductive trick: multiply enormous extraterrestrial masses by Earth market prices to yield quadrillions in "wealth." In practice, there is no discussion of how to get at it, and the value prop for 1e20kg of iron is pretty weak. He's closer to science fiction here than economics. Bulk commodities like iron or nickel aren't scarcity-limited on Earth; flooding markets would crash prices, turning imputed riches into something more like crypto (a speculative financial asset with an imputed market cap that's not actually achievable).

Flagship ideas fare no better. Space solar power beaming and lunar Helium-3 for fusion get optimistic treatment without confronting processing costs, low concentrations, or alternatives (e.g., Earth-side deuterium breeding). Lewis obsesses over launch costs—correctly predicting competition would help, though hindsight shows SpaceX's technical/process breakthroughs (aided by government) mattered more than pure market magic—while ignoring that launch has historically been only ~20% of mission budgets. Hardware development, refining in vacuum, and infrastructure dominate, but these get hand-waved.

The book drifts: Mars chapters are interesting (delta-v discussions, space elevator feasibility with composites in the ballpark) but irrelevant to the mining thesis. Late chapters venture into environmental benefits (space energy solving climate/pollution/peak oil—reasonable for 1996) and pure '90s futurism (VR, nanotech, satellite internet, humanoid robots, plus dubious predictions like "collapse to subsistence agriculture by 2030"—we have four years left!).

Chapters start with grating fictional vignettes, and tangents into reflexive centrism ("both sides bad, let's pursue common-sense Uranus mining") feel like time capsules.

Believe it or not, I enjoyed reading this book. There's a lot of interesting astrogeology in there, a strong vision, and a lot of interesting discussions about the material basis for an interplanetary economy. At the same time, this book set itself a clear mission: To develop a grounded argument for the way we can 'Mine the Sky' and generate 'untold riches' and it simply does not do that. On its own terms, the book is a failure.

Despite that, I share substantial overlap with Lewis's vision—my own "outside-in" industrialization ideas align closely with his long-term picture. Recommended for space enthusiasts interested in resource surveys and inspiration, but pair it with modern, skeptical analyses for a realistic view of when (or if) the sky's riches become accessible.

[Joseph Hirsch · Rating 4 out of 5]

As the population of Earth explodes, and affluence (generally) increases, the crunch on resources becomes greater and greater. Regardless of how one feels about Malthus, scarcity, and population booms, ten billion humans is a lot of mouths to feed and mucho houses to heat. Unless we want the rich and poor to diverge into something like subspecies, and suffer permanent alienation from their common humanity , we have to find new resources.

"Mining the Sky" builds on previous works, and lays groundwork for future efforts to get humanity closer to the mineral-rich asteroids and the energy-abundant stars of our solar system. It's written in clear, mostly straightforward language by a geophysicist whose credentials are unimpeachable, which makes it harder to shrug off his vision (and his warnings) as the ravings of a kook.

Each chapter explains in its way the limits of Earth and the infinite riches of the cosmos waiting for us. Short, science fiction style-excerpts leaven the work and humanize it, softening the parts where mathematical formulae cause the eyes of your typical lunkhead (like me) to glaze over.

Because billionaires like Elon Musk and Jeff Bezos have developed reusable, more fuel-efficient rockets, the cost of exploring space has lowered considerably. Many of the developments that were hypothetical when this book first came out are now a matter of fact. This makes "Mining the Sky" not just an important read, but perhaps an essential one. Many among us certainly cringe when we hear a phrase like "colonizing the stars," (imagining some kind of intergalactic Manifest Destiny) but the simple fact is that humanity either has to shrink down and scale back (not likely) or understand that we need space exploration, to save, house, and feed the people of Earth.

If we leave it to Musk and Bezos, our posterity may not go to the stars as colonists, but as assembly line workers and Fulfillment Center factotums. That's assuming we even escape the bonds of Earth before we commit collective suicide, which is at least as possible as a future in orbit, unfortunately. With photos. Recommended.

[Brendan Newport · Rating 3 out of 5]

Lewis' seminal volume on the subject of exploiting off-Earth resources, for raw materials and power.

Although published in 1996 (with an updated Afterword from 1997) quite a bit of Mining The Sky is still relevant. The expansion of rocket launches, contributed by SpaceX and other firms wasn't anticipated though, but the return of humans to the Moon still seems a long way off.

The book does address some fallacies that persist today. Such as helium3 from the Moon's regolith. Sounds great in theory, but the huge amount of regolith that needs to be dug-up, crushed and heated, just to get a useful amount of helium3. The alternative, mining helium3 from the outer gas giants, sunds much more attractive.

What though is really attractive, and has carried-over the near-30 years since the books publication, is the value in visiting (and mining) NEO (Near Earth Orbit) asteroids. Their value in ore, volatiles and other resources is fabulous, and best-of-all, the asteroids are easier to get to and return back from than the Moon. NASA and other agencies seem to be missing a trick not pursuing missions to exploit these vast resources.

Some graphs would have been nice. There's a brief illustration section at page 115, but I reckon some of the data could have been presented in such form and would have enhanced the arguments.

[Pete · Rating 4 out of 5]

Mining the Sky: Untold Riches from Asteroids, Comets and Planets (1996) by John S Lewis is an interesting but quite heavy going look at the resources available in the solar system that could be extraced. Lewis is Professor Emeritus at the University of Arizona's Lunar and Planetary Laboratory.

The book systematically looks at the resources available in the moon, asteroids and on other planets and points out that the potential is staggering, enough minerals, metals and energy to provide all the resources for a much larger population of humans and for exploration of other solar systems.

The book isn't an an easy read because it tends to barrage the reader with the details of the chemical composition of the planetary bodies but it is definitely a worthwhile read for anyone interested in how space exploration could be economically viable.

[Kara · Rating 4 out of 5]

The space mining is more of a hook then an overall theme as Lewis spends more than half of the book covering the history of space study, the development of the tech needed to study space, and the fall of NASA.

He is more or less begging people and politicians to get back to space exploration, dangling the idea of asteroids stuffed full of platinum as the carrot. Some good foundation and background work, but I wanted to see more speculation on the development of this possible future industry.

[Keith · Rating 3 out of 5]

dnf

I tried I really did. I love the ideas being discussed and the science ... but then I learned that the author is a climate-change denialist (as a result of his conversion to Mormonism), and while this shouldn't affect the physics of the science he's writing about ... it just caused me to fall out of interest in his writing and ideas.

edited to add ... I would love to be shown to be wrong about Dr. Lewis. And maybe denialist is not the right word .. skeptic may be better.

[Roshni · Rating 5 out of 5]

An awesome book....so glad I came across it!

[Thomas Myers · Rating 5 out of 5]

Optimistic, yet practical. Technical, but accessible. This is what a science book should be. Plus, I like the little chapter vignettes.

[Gf · Rating 4 out of 5]

What begins with an outdated feel (this book is already 20 years old) ends in an incredibly optimistic and logical vision for the future. I urge the reader to power through the technical jargon of the first few chapters, the reason behind the 4/5 star rating I am giving it, in order to access the vision of John S. Lewis, and challenge him or her not to be disturbed by the apparent facility of moving to outer space.

With the hindsight provided by 20 years of posterity, clearly some of John S. Lewis' ideas were pure speculation and futurist optimism, and yet in the final chapters one can see how clairvoyant he was about the state of our civilization in the early 21st century, accurately describing smartphones, the internet and other micro-computers. The disappointing realization that in these 20 years, our technology has greatly improved in the field of communication and not in the field of transportation builds up to the last chapter.

I am torn between outrage and dismissal. Outrage because if what Mr. Lewis says is true, we are kept from these adventures by partisan politics and risk-allergic businessmen. Dismissal because if what Mr. Lewis says is true, why wouldn't any clear thinking millionaire have started mining asteroids already ? Clearly technology has not accelerated as much as he foresaw, and the likes of Blue Origins and SpaceX are still focusing on the space tourism market.

I think we'll get there. I hope we'll get there.

[Jonathan Jeckell · Rating 4 out of 5]

This should have been an easy five stars for me, as enthusiastic as I am about the topic and how well he made the argument throughout most of the book (which troubles me about the objectiveness of my other reviews). 90+% of the book is fantastic, clear, and insightful. But the first sign of trouble was the vignette at the beginning of Chapter 14 where he portrayed average people in a harsh, unnecessary, and harmful way to his argument. Then he does it again a few chapters later strongly implying that just about everyone else are willfully ignorant and illiterate morons. Chapter 14 launched into a series of strawman arguments against broad swaths of the political spectrum giving them the same treatment. This is not how you persuade taxpayers to support your ideas. I would love to give this book to other people, but I would use a razor blade to extract chapter 14 if I did. Without that, it paints a vivid picture and a coherent, feasible plan of how and WHY we can sustainably and profitably expand into space and make Earth a better, more livable place at the same time. This book ought to be inspecting space entrepreneurs, politicians, scientists, engineers, and yes, environmentalists everywhere.

[Charlie George · Rating 5 out of 5]

Very engaging summary of asteroids and their extraordinary utility to any space endeavour. Not to mention some motivating factors to get us to that point, such as the threat of annihiliation by a Near Earth Asteroid or comet and large-scale solar power satellites as a future energy source. Lewis does come across as a dyed-in-the-wool, market-will-solve-everything capitalist, but I'm willing to forgive him that in light of his singularly insightful and well-presented argument for "mining the sky".

One of many interesting gems: the asteroid belt alone contains raw metals worth at current market value 500 billion-billion dollars, i.e. $100 billion for each person on earth when the book was written.

[Audun Forgard · Rating 3 out of 5]

Mining th Sky is a fascinating geological survey of outer space. How much gold nd diamonds can we expect to dig out of the asteriod belt, how could we most efficiently build moon settlements, or wether it is neccesary. The book thinks asteroids are more viable economically than the planets. ts a decent enough read if you are interested in outer space buisness for sure, and the world could need more like this. What drags it down a little is that the author interjects the chapters with his own parallel sci fi story which just disturbs the flow of the book. Also some factual errors on electricity and comets . But that is to be expected for a book written in the nineties

[Bradley Mazurek · Rating 5 out of 5]

As someone that is both an optimist and ponders potential futures of humanity, this book provides great insight into the the potential right in our backyard (cosmically speaking). I loved the way it unleashed my imagination into what is possible for our species if we can get our act together.

[Samuel · Rating 5 out of 5]

I loved this book, it offers an optimistic future that I hope humanity can one day achieve. If we can keep from destroying ourselves I think it is inevitable that we will explore the universe.

[David Seymour · Rating 5 out of 5]

I found this book very enjoyable to read and opened up many new possible ideas for space that I hadn't thought about before.

[Robert Garcia · Rating 2 out of 5]

A very odd mix of science, fiction, and political discussion that is difficult at times to complete. The author should have stuck with the science where he seems more comfortable.

[John]

excelent book

[Nicolas · Rating 4 out of 5]

This was a much more thorough and rigorous book than I was expecting! No "pie-in-the-sky" dreaming and futurist rainbow fluff here. John is a geologist who has turned his focus to the geology of NEOs, asteroids, and comets. It gets a bit information-dense after the second chapter, but that's exactly what I was looking for: *facts* and the most up-to-date scientific analysis of the rocks and minerals with solar orbits in the general neighborhood of Earth's, and what we can expect when we visit or capture some of them. John will definitely give you that, without any fluff and bombast!

There is so much information jammed in here I found myself studying it like a beloved textbook: looking up key terms, making my own mineralogical tables, using free online Eulerian calculators to figure out Hohmann transfer orbits from Earth and from Mars to various parts of the asteroid belt... but without John's excellent book, I could not even have begun all that work. With John's book, I was inspired to do so!

The only reason I didn't give it five stars is because eventually the readability suffers from the information density. Despite its exciting title, it borders on being a reference work: now that I've read it through once, that's how I'm going to shelve it, in fact.

If you work for Planetary Resources or Deep Space Industries, or you are considering investing heavily in space development, or are simply curious about what the "Asteroid Belt" really is—in detail— then this is a must-read. But if you're looking for a fun narrative that will teach you lots about the asteroid belt in the process, read Ben Bova's The Rock Rats instead.