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Will We Stop at Mars?

In the heady days of Apollo, Mars by 2000 looked entirely feasible. Now we’re talking about the 2030s for manned exploration, and even that target seems to keep receding. In the review that follows, Michael Michaud looks at Louis Friedman’s new book on human spaceflight, which advocates Mars landings but cedes more distant targets to robotics. So how do we reconcile ambitions for human expansion beyond Mars with political and economic constraints? A career diplomat whose service included postings as Counselor for Science, Technology and Environment at U.S. embassies in Paris and Tokyo, and Director of the State Department’s Office of Advanced Technology, Michael is also the author of Contact with Alien Civilizations (Copernicus, 2007). Here he places the debate over manned missions vs. robotics in context, and suggests a remedy for pessimism about an expansive future for Humankind.

by Michael A.G. Michaud


Many people in the space and astronomy communities will know of Louis Friedman, a tireless campaigner for planetary exploration and solar sailing. He was one of the co-founders of the Planetary Society in 1980, with Carl Sagan and Bruce Murray.

In his new book, entitled Human Spaceflight: From Mars to the Stars, Friedman states his argument up front: Humans will become a multi-planet species by going to Mars, but will never travel beyond that planet. Future humans will explore the rest of the universe vicariously through machines and virtual reality.

Friedman acknowledges that public interest in space exploration is still dominated by “human interest.” No one, he writes, is going to discontinue human spaceflight. Yet there is a conundrum. While giving up on manned missions to Mars is politically unacceptable, getting such a program approved and funded is not an achievable political step at this time. If another decade goes by without humans going farther in space, Friedman writes, public interest will likely decline and robotic and virtual exploration technologies will pass us by.

Friedman claims that going beyond Mars with humans is impossible not just physically for the foreseeable future but culturally forever. The long-range future of humankind, he declares, is to extend its presence in the universe virtually with robotic emissaries and artificial intelligence. This argument puts a permanent cap on human expansion, as if travel beyond Mars never will be possible.

Friedman sees having another world as a prudent step to prevent humankind being wiped out by a catastrophe. He argues that the danger of not sending humans to Mars is that we will become complacent. If that complacency overcomes making humankind a multi-planet species, we are doomed.

Friedman dismisses big ideas about exploiting planetary resources throughout the solar system and living everywhere to build civilizations and colonies on other worlds. He can’t see why or how we would do this, nor can he see waiting to do so. This illustrates an old split in the space interest community between those advocating space exploration and those supporting space utilization and eventual human expansion.

In his chapter entitled Stepping Stones to Mars, Friedman lists potential human spaceflight achievements with dates. An appendix presents a plan for a manned Mars mission in the 2040s. That first landing is to be followed later by missions establishing an infrastructure for human habitation, an effort that will take many decades.

Interstellar flight


This book’s subtitle is From Mars to the Stars. Yet Friedman dismisses interstellar travel by human beings as a subject of science fiction. People are too impatient, he writes, to wait for the necessary life-support developments. This contrasts with Carl Sagan’s 1966 comment that efficient interstellar spaceflight to the farthest reaches of our galaxy is a feasible objective for humanity.

Friedman argues that we have only one technology that might someday take our machines to the stars – light sailing. It may be another century before we have large enough laser power sources to drive small unmanned spacecraft over interstellar distances. The barrier of bigness will be overcome by the enablement of smallness.

Friedman suggests three interstellar precursor missions: the first launched in 2018 to the Kuiper Belt and onward to the heliopause; the second launched in 2025 to the solar gravity lens focus and on to 1,000 astronomical units; the third launched in 2040 to the Oort Cloud.

Virtual Reality

Friedman oversells virtual reality just as some others have oversold manned spaceflight. He acknowledges that we have yet to reach full cultural acceptance and satisfaction with the virtual world. Yet he seems to assume that such acceptance by the general population is inevitable.

Calling virtual reality human exploration may confuse many readers. Will we be content to watch all future exploration through robotic eyes?

There may be an unstated reason for preferring virtual reality over human presence. If future space exploration were entirely robotic, scientists would be in charge.

Cautions about Mars

Mars is far from ideal as a future home for humankind. The thin atmosphere is mostly carbon dioxide. Temperatures are low. The surface is more exposed to radiation and meteorites than Earth. Yet Mars remains the best candidate for a second planetary home within our own solar system.

Like other schedules proposed by some space advocates, Friedman’s plan for missions to Mars may be too optimistic. Yet such optimism keeps goals alive and encourages others to get involved.

What seems wildly optimistic now may be possible over the longer term. In the 1950s, some scientists thought that sending humans to the Moon was impossible.

The failure of grand visions

Friedman is correct in stating the biggest problem of space policy: the merging of grand visions with political constraints. In 1988, President Reagan’s statement on space policy included the idea of expanding human activity beyond Earth and into the solar system, an endorsement long sought by some elements of the space interest community. President George H.W. Bush fleshed out this idea in 1989 with his Space Exploration Initiative, urging that the U.S. develop a permanent presence on the Moon and the landing of a human crew on Mars by 2019. These visions failed to win the financing that would make them feasible.

Frustration and Patience

It is understandable that long-time campaigners for further exploration and use of space get frustrated, in some cases foreseeing the end of such endeavors. We all want to see major hopeful events occur in our own lifetimes. Yet we share some responsibility to look beyond.

Writing off human expansion beyond Mars for all the humans who follow us is, despite Friedman’s claim, pessimistic. The remedy is a younger generation of advocates.

A Little History

Friedman states that the settlement of Mars is the rationale for human spaceflight. The leaders of the Planetary Society did not initially support that goal. In the organization’s early years, its chief spokespersons criticized NASA’s emphasis on human missions (particularly the Space Station), which they saw as robbing funds that should have gone into further robotic exploration.

Sagan and others later realized that the planetary exploration budget rose and fell with the rise and fall of manned spaceflight programs. When NASA funding was rising, space science prospered; when NASA funding declined, space science funding declined with it. After the cancellation of further Apollo missions, planetary science was hit hardest by budget cuts . This revived a debate as old as the space program, between advocates of manned spaceflight and those who believe that priority should be given to exploration by unmanned spacecraft.

Friedman wrote in a 1984 article in Aerospace America about extending human civilization to space, suggesting a lunar base, a manned expedition to Mars, or a prospecting journey to some asteroids undertaken by an international team.

By the mid-1980s, the Planetary Society was advocating a joint U.S. Soviet manned mission to Mars. Senator Spark Matsunaga of Hawaii introduced legislation to support this idea and published a book in 1986 entitled The Mars Project: Journeys beyond the Cold War. Soviet leader Mikhail Gorbachev made overtures to the U.S. in 1987 and 1988 for a cooperative program eventually leading to a Mars landing.

Bruce Murray, reacting favorably to the 1989 Space Exploration Initiative, published an article in 1990 entitled Destination Mars—A Manifesto. Observing that the space frontier for the U.S. and the USSR had stagnated a few hundred miles up, Murray commented that neither the United States nor the Soviet Union is likely, by itself, to sustain the decades of effort necessary to reach Mars. Murray urged a joint U.S.-Soviet manned spaceflight program leading eventually to Mars.

This reviewer argued at the 1987 Case for Mars conference that relying on the Soviet Union during the Cold War made such a mission subject to political volatility. This turned out to be true. As Friedman reports, a brief flurry of interest by President Reagan and Gorbachev in a cooperative human mission to Mars disappeared quickly in the face of large global events such as the dissolution of the Soviet Union.

More recently, when the U.S. sought to punish Russia for invading Ukraine, Russian officials made public statements threatening the continuation of Russian transport of Americans to the International Space Station, even though the U.S. was paying for those flights.


Louis Friedman, Human Spaceflight: From Mars to the Stars, University of Arizona Press, 2015.

Louis D. Friedman, “New Era of Global Security: Reach for the Stars,” Aerospace America, August 1984, 4.

Michael A.G. Michaud, “Choosing partners for a manned mission to Mars,” Space Policy, February 1988, 12-18.

Chapter entitled “Scientists, Citizens, and Space” in Michael A.G. Michaud, Reaching for the High Frontier: The American Pro-Space Movement, 1972-1984, Praeger, 1986, 187-213.

Bruce Murray, “Destination Mars: A Manifesto,” Nature 345 (17 May 1990), 199-200.

Iosif Shklovskii and Carl Sagan, Intelligent Life in the Universe, Dell, 1966, 449.


Comments on this entry are closed.

  • Al Jackson November 27, 2015, 10:21

    I personally like the idea of virtual reality. I don’t mean forever, but at the rate of change of solid state instrumentality I could see even a private venture in the next ten years sending a sophisticated rover to Mars with the capability of total telepresence.
    Right now one can drop their smart phone into a headset teleport up a storm!
    I don’t mean it’s an end all but I would go for it!

    Louis Friedman really does seem to be projecting impatience. Seems to me one is going to have to patient about world economics and a stable world wide society. I don’t know how long that will take but a world wide unified effort at major manned spaceflight will happen.

  • Larry Kennedy November 27, 2015, 11:06

    Sounds like the start of a good conversation.

  • Hop David November 27, 2015, 11:25

    Robots vs humans is a false dichotomy. It is robots that will enable a sustained human presence. Ability to remotely establish infrastructure and mine propellents and life support consumables will eliminate the necessity to haul massive habs and huge rockets from the bottom of an 11 km/s gravity well.

    Moreover, mostly robotic mines could provide an incentive for human presence. See http://hopsblog-hop.blogspot.com/2013/12/who-needs-humans.html

    The preoccupation with Mars is why I ended my membership in the Planetary Society. Deep gravity wells suck. If they ever get over their planetary chauvinism, I might send them money again. When it comes to potential real estate and resources, the small bodies beat Mars. See http://hopsblog-hop.blogspot.com/2014/02/terraforming-mars-vs-orbital-habs.html

  • Project Studio November 27, 2015, 12:45

    “… the biggest problem of space policy: the merging of grand visions with political constraints. In 1988, President Reagan’s statement on space policy included the idea of expanding human activity beyond Earth and into the solar system … President George H.W. Bush fleshed out this idea in 1989 with his Space Exploration Initiative, urging that the U.S. develop a permanent presence on the Moon and the landing of a human crew on Mars by 2019. These visions failed to win the financing that would make them feasible.”

    While I generally tend to avoid political comments, in response to the article I feel it is fair to respond in this case as it is germane to this particular discussion.
    We shouldn’t infer that misleading and uncommitted governments are typical, or that that an evolving society responsive to peoples desires and aspirations will always be limited by political cabals which squander trillions for the sake of unchallenged dominance and cheat their constituency of their cosmic heritage. If such were forever the case, better that we be quarantined at the bottom of our gravity well forever.
    It wasn’t so much that these governments failed to win the funds to make the vast orbital and lunar infrastructure for supporting the open-slather mars missions feasible. The missions themselves were openly wasteful and conceived primarily to benefit the industrial vendors for fairly little scientific or cultural return. A brief visit to the Martian surface (equivalent to a moon walk) in exchange for many hundreds of billions.
    Reading articles about the ‘Mars Direct’ program and its circumspect alternative to the bloated Nasa response to the Space Exploration Initiative reveals the degree of cronyism and dis-ingenuousness within the government of and aerospace industry ‘of the day’ in bold relief.
    Our technical challenges to reach the starts are vastly outstripped by our challenges to reform our culture and political system. So long as we feel it is inappropriate to discuss the political and cultural factors, our efforts to advance Ad Astra are hamstrung.

  • Andrew_W November 27, 2015, 12:50

    So Friedman envisions settlement of Mars, with no one turning some of those manned ships towards other targets, several of which would be easier to reach than Mars. To me that sounds as logical as European settlement of North America but nowhere else.

  • Alex Tolley November 27, 2015, 12:57

    I’ve not read the book, so I apologize if I make any straw man arguments.

    If Friedman is right that humans will never go to the stars, then a lot of effort dreaming of starships and exploring/colonizing the galaxy is largely futile. I hope he is wrong there.

    Regarding telepresence, how is Friedman suggesting overcoming the latency due to c? I can believe we might make virtual worlds to explore using data from robotic craft, but I don’t see how we can explore a physical world other than by just going along for the ride. To me that isn’t virtual reality, as the individual cannot interact with the environment.

    I agree with Hop David that grand designs are ultimately doomed to fail as their is no driving reason for the exploration. Harnessing greed through economic profits is a better way to go, and if there are economic resources to acquire, then this will make a better, sustainable course for expansion into the solar system, even if it is primarily by smart machine.

    I also don’t see the logic of colonizing Mars. Large space colonies are both better suited to human presence, more adaptable and mobile, allowing humans to live wherever they want. This solves the existential threat from space, as well as allowing a broader range of Earth biota to accompany us. O’Neill’s logic still holds over planetary bases and terraforming.

    As for humans never reaching the stars, that seems overly pessimistic to me. I do think worldships and crewed starships will prove too expensive without a much larger solar system based economy, but there are options to send humans to the stars using small, light propelled vehicles, whether as DNA, embryos or just minds (human or human analogs) that our species of our descendants could make our mark on the galaxy in the next million years. I just think we need to be more open to ideas beyond most book and video Scifi, following technology drivers that make most economic sense.

  • Marcel Williams November 27, 2015, 13:15

    Even at cost between $25 to $50 million per passenger, there are at least 50,000 people currently living on Earth who could afford to travel to Earth orbit. Future spacecraft like the Skylon concept could make it affordable for at least tens of millions of people to travel to orbit.

    But there’s no doubt in my mind that, before the end of this century, a significant number of humans are going to be born and raised– off the surface of the Earth.

    I suspect that initially there will be human colonies on the Moon and Mars and later on the surfaces of Mercury and the Jupiter moon, Callisto– if it turns out that levels of gravity as low as 0.1g is not significantly deleterious to human health and reproduction.

    But in the long run, I think most humans will probably live inside of some sort of manufactured O’Neill type of rotating space island which could be located practically anywhere in the solar system where asteroid materials are located.

    I don’t think humans will ever colonize other star systems until humanity has developed interstellar vehicles capable of achieving light approximating velocities.


  • MBadgero November 27, 2015, 13:29

    I agree with Hop David. Friedman’s argument is too short sighted, based only on what we can do today.

    “A rocket will never be able to leave the Earth’s atmosphere.” said ‘The New York Times’. Sure, they retracted it after we landed on the moon; not because they believe it is possible, but only because the retraction helped sell papers.

    There will always be naysayers.

  • Sean M. Brooks November 27, 2015, 13:40

    I absolutely disagree with Mr. Friedman’s argument about it being impossible for mankind to either travel beyond Mars or to reach the stars. I also disagree with his views on NOT using the resources of the Solar System to enable colonies to be founded off Earth in other parts of the Solar System than Mars. Why on Terra should people care about space if other human beings are not also there?

    I am a zealous fan of the works of the late Poul Anderson, one of the greatest writers of hard science fiction in the 20th century. And he most certainly would not agree with Mr. Friedman’s argument. Two paragraphs quoted from the “Commentary” Poul Anderson included in his collection of stories called SPACE FOLK (Baen Books: 1989) would be appropriate here:

    Look up. Space begins about fifty miles above your head.
    Yonder are all the material, energy, elbow room and
    wonderful discoveries to make that our species can ever
    require. Whether or not we reach the stars (and we can
    eventually, with or without Einsteinian speed limits laid
    on us, if we really want to) the Solar System holds more
    than enough.

    It is my considered opinion that, without access to space,
    without opening space for people to use, industrial civliza-
    tion does not have much longer to live. At best, our near-
    future descendants will revert to the norm of history,
    which Alfred Duggan described as “peasants ruled by
    brigands,” and it won’t matter if the brigands retain a
    certain amount of high tech. At worse, our species will go
    the way of the dinosaurs–who enjoyed a far lengthier day
    and left the globe in far better shape.

    While I don’t entirely agree with Mr. Anderson’s pessimism about our industrial civilization, I do agree with him on the urgent need for mankind to get off this rock in a REAL way.

    I wish the bibliography given by Michael Michaud had included Poul Anderson’s IS THERE LIFE ON OTHER WORLDS? (Crowell-Collier: 1963) and Robert Zubrin and Richard Wagner’s THE CASE FOR MARS (Free Press: 2011).

  • craig November 27, 2015, 13:46

    In the short term, I absolutely favor maximal scientific output because the costs are so high and the budget is limited. If human exploration maximizes our understanding, then I’m all for it. But my general impression is that it doesn’t (outside of life support and related technology). I’m also leery of inhabiting Mars until we establish that there is no nascent life or we develop parameters for preserving it and studying it.
    The case for past water on mars is now very solid. We have every reason to think that life could have evolved there. The more that we learn about Mars, the less I want to see us rush off to land humans on the planet just for the sake of it.
    I think it would be better to focus on the moon as a first step. It’s much closer and inhabiting it has many of the same challenges and benefits. Considering that we’ve never done it before, the danger and the costs involved, it makes more sense.

  • Charlie November 27, 2015, 14:05

    There seems to be about three different possibilities here far human flight. One, upload human consciousness to a machine. Two, put people in suspended animation. Three, place them on a generational ship.
    The first to seem rather problematic and the third one all has the same problems of being able to keep people sane and alive for generations.
    Aside from the obvious problems that all these exhibit, even if people make voyages they’re going to go to worlds, which are not exact copies of our own Earth.

    I’ve often wondered whether or not this will result in the fact that you will not be able to adapt to these new worlds. Adapt, meaning that humans must change since that there no longer humans as we understand that. Is that what people are willing to do for this idea ?

  • Abelardlindsey November 27, 2015, 16:44

    What Friedman is really saying is that it will be our a.i. progeny that will go to the stars. I can buy that. Presumably he is on board with the predictions of Kurtz Weil and others on the development of strong a.i.
    I under what Friedman thinks about the possibilities of uploading human identities into such artificial substrates. He is correct that wet, squishy biological substrates are illsuited for life in space.

  • Abelardlindsey November 27, 2015, 16:52

    I think it was Friedman who said that if alien civilizations exist, that they would most certainly be post-biological machine intelligences. Is so, this would certainly dovetail with the content of his new book here.

  • david lewis November 27, 2015, 17:44

    Mars? In the next fifty years, or so, we “might” see humans return to the moon. That’s assuming we can maintain a technological civilization for that long – I’m doubtful.

    However, if we do then I would expect to see various branches of humanity spread out into the solar system. Some of those branches no doubt would be more alien to us than most Star Trek aliens are. One of those branches might make use of Mars. Sure it has a gravity well, but it’s nowhere near as bad as earth’s, and by then it would much less of an obstacle to them than it is to us. Most of the branches however would opt for space habitats.

    I wonder though…. If people so strenuously object to children having productive and high-quality lives in a world ship then what would they do when people decide to adapt themselves to living in the clouds of Jupiter, and have children who can’t even manipulate tools. Surely that would mean war.

    And it is to flee war that our descendants might one day decide to move away from Sol.

  • Tom Baty November 27, 2015, 18:12

    Forever is such a long, long time.

    None of us can know what the human condition will be like even in a hundred years, or five hundred years…let alone one thousand years.

    Kind of short sighted in IMHO.

  • Astronist November 27, 2015, 19:46

    “Friedman argues that we have only one technology that might someday take our machines to the stars – light sailing.” — Has he found a fatal flaw with the nuclear fusion pulse engine, developed in considerable detail in the Daedalus study and now being developed further in the successor Icarus study, or did he just ignore it?

    Stephen A.

  • Black SciFi November 27, 2015, 20:08

    The resources needed for any manned deep space space travel in the foreseeable future will need to be diverted to 1 or 2 mega projects here on earth.

    1) Moving the worlds coastal populations 50-100 miles back from the coasts due to sea level rise. The good news is that such a series of projects will ensure full employment planet wide and the buffer zone created by such a move should restore the balance of nature.

    2) Wasting time building sea dams and sea walls, for sentimental (I love NY?) + (NO-LA sea wall is just stupid, IMHO) reasons as a short term and ultimately useless solution.

    This impending reality, sea level rise, will divert resources from any big ticket manned space exploration projects. The kicker is that Cape Kennedy will be underwater and need to be rebuilt somewhere, or not.

    I think our scientific potential should be more focused on what will be the “habitable zone” on earth rather than spend the same “generational potential” concerned with deep space habitable zones.

    Let’s be clear, it might take more political capital to move our populations from the coastlines to a safe/sustainable distance than to convince the same populations to spend valuable resources on another trip to the moon and beyond.

  • Jer November 28, 2015, 1:26

    I am not convinced that the Old World order, its politics, its current corporate entities, and larger institutions will spearhead or even solidify large-scale human habitation/ exploration outside of cislunar orbit. As with most groundbreaking acts of discovery and ambitious exploration, it has been accomplished by broken rules, charismatic initiatives, misguided objectives, and morally ambiguous visions. Such will be the movement into space beyond LEO – from asteroid-exploiting multi-conglomerates to developing country totalitarian systems to multi-billionaire cult-vision initiatives. A Wild West of exploitation, annexation (in the sense of taking over what was to be classified as non-ownable), conflict, and incredible risk. This disparate sprawl will create the long and lonely path -similar to the Transcontinental Railroad- which will then be followed by the adventurers, tourists, enterprising and eccentric academics, and finally the most driven mainstream ex-pats. An unplanned and unstructured exodus/spray forth of humanity. But first, the resources – recently accelerated by recent legislative initiative:
    Once all the ingredients for infrastructure are in place outside of LEO, including all the resources not needed to be brought up from Earth, such will be the creation of that next step: small, medium, and large spacecraft/ modified intrasolar bodies/ unmanned supply/recon vanguard craft will push to solar system edges and beyond. This will all be free of planning, solid government leadership/support, and -likely- oversight. We will see our first crew leave the mars’ solar orbit, outbound, to either colonize far, research near, or expedition somewhere in-between before the end of the century — hardier of biology and equipped with life-support and propulsion tech depending upon a large-scale energy sources unrealized by us in the first half of this century.

  • Brett November 28, 2015, 1:53

    Mars settlement feels more like an “interim” project than anything else in terms of off-world expansion. Once you have the robotic capabilities to have them remotely grab and process space materials into habitats in space for humanity, then that’s going to be better than any colony planet-side off of Earth unless we’re positing a Kim Stanley Robinson-style scenario where we need “exposure” to a planetary biosphere to be healthy.

    I’m a bit skeptical that baseline humans will ever settle off-world in large numbers, although groups may take a go at it if or when it becomes affordable. And any interstellar travelers will be either robotic or transhuman.

    @Black SciFi

    The resources needed for any manned deep space space travel in the foreseeable future will need to be diverted to 1 or 2 mega projects here on earth.

    I doubt it. Crewed space flight wasn’t canceled despite a lot of very big budget-line costs that happened at the same time (the Vietnam War, expansion of the Great Society, Iraq War and Afghanistan, etc). It won’t be cancelled because of climate change, especially since climate change adaptation is going to be spread out over an even longer stretch of time.

    2) Wasting time building sea dams and sea walls, for sentimental (I love NY?) + (NO-LA sea wall is just stupid, IMHO) reasons as a short term and ultimately useless solution.

    What’s stupid about it? The Dutch have been walling off below-sea-level areas of land for centuries, and the coastlines around the major northeastern cities are already heavily modified (a big part of Boston’s Harbor was filled in over hundreds of years).

    I think we’ll absolutely try that before we just abandon these cities and move in-land, and it will probably work as long as sea level rise doesn’t get above about 10-20 meters this century.

    This impending reality, sea level rise, will divert resources from any big ticket manned space exploration projects. The kicker is that Cape Kennedy will be underwater and need to be rebuilt somewhere, or not.

    They’ll just launch out of New Mexico. They already are doing that. Or they’ll do sea launches, assuming they get that to work.

  • Michael Spencer November 28, 2015, 8:27

    Dr. Friedman is simply extrapolating the observation that heavier than air isn’t possible.

  • Alex Tolley November 28, 2015, 13:22

    The current issue of Smithsonian’s “Air&Spoace” magazine (Jan 2016) has a nice article on telepresence to control robots with very short latency. It makes Mars exploration much easier and safer if the crewed vehicle only needs to reach Mars orbit, and landers with robots do the exploring and sample collection, all controlled from orbit.

    Now just suppose that “new physics” shows us how to move information near instantaneously, rather than at c. All space activities could be done using telepresence, even exploring the nearer stars, once the robots have crawled to their destinations at fractional c. No need for worldships, as human minds would be “present” through communication devices, and embodied in machines, whether or not, humaniform. This is a big IF, but a possible alternative vision for humanity in space if achievable.

  • william f collins November 28, 2015, 15:06

    I was somewhat perplexed by Dr Friedman’s premise or conclusion: human space exploration mostly limited to planet fall on Mars? While I can understand the debate over interstellar travel – between the possible,the likely and the fantastical – , I see interplanetary space travel/exploration/exploitation of resources as inevitable (I hope) no matter how long it takes to accomplish. Of
    course, an interplanetary spacefaring civilization will have economic incentives as a primary driver. What sort of economic and political structures will emerge over the course of the next 100 to 200 years, well, I can only speculate what they will look like. I am assuming that asteroids, comets, or moons can be exploited for their natural resources. I am assuming with somewhat less confidence that there will be large or significant numbers of people living in space in self-sustaining habitats – in orbit or on the surface of moons/planets.

  • Malcolm Davis November 28, 2015, 19:13

    ‘No’ is the short answer to the question posed at the beginning of the article. I fundamentally disagree with Friedman’s thesis in terms of his approach to human exploration beyond Mars. He advocates machines only beyond Mars, but this is a very short-sighted perspective that ignores the potential synergistic value of machines and humans working side by side for exploration and the gathering of knowledge (the ‘science’ part of why we go to Space), as well as exploitation of resources to allow colonisation across the Solar System. If you want to understand my preferred vision for the next 100 years of human space exploration, watch the ‘Wanderers’ movie ( http://www.erikwernquist.com/wanderers/film.html ) which shows a very positive and inspiring perspective on humanity’s future in Space. Incidentally, the movie is narrated by Sagan.

    This vision is far more appealing and inspiring than Friedman’s rather depressing perspective of humanity forever stuck on two planets, and being forced to stand aside for machines to go further. Watching such exploration, even through very advanced VR is actually no substitute for really going in person. But more fundamentally, such a passive approach does not allow human expansion and colonisation across our Solar System and eventually beyond. The long-term goal, perhaps for one thousand years, should be humanity as a spacefaring civilisation spanning across a significant portion of our galaxy. Friedman would deny humanity that future, and relegate us to a species which is merely a passive remote observer rather than an active explorer. Thanks – but no thanks – I want to be an explorer.

    Friedman says it is impossible to go beyond Mars, but really does not explain why. When someone says something is impossible, my response is to say ‘right, lets work out how to make it possible!’ (and yes, that includes faster than light travel). Its a science and an engineering problem that asks for a solution. It may take some time to find that solution, but in my view nothing is impossible if human ingenuity combined with advanced technology is applied. Humans and machines can work together as a team. Alone, humans struggle in harsh environments, and by themselves, machines are not as smart as humans and lack intuition, judgement, and decision-making skills of human beings. Machines should blaze the trail, and go to places we can’t but humans should be there at the front of an expanding wave of human exploration and colonisation that does not stop at Mars.

    There are two ways for humans to explore the solar system beyond Mars and achieve the vision set out in ‘Wanderers’. One is a stepping stone approach that uses forward bases and facilities to launch a new wave of expansion. We establish bases on Mars and use modern 21st Century manufacturing (i.e. 3D printing, nanotechnology) locally to build all that we need to go to the next destination (for those of you who have played games like Civilisation, this is that approach). So we don’t take everything we need to get to Callisto, Ganymede or Titan from Earth – we go via the Moon, Mars and the Near Earth Asteroids, and use local resources to take the next step.

    The other approach is to invest money into R&D on more advanced spacecraft technologies and propulsion so that we can go from Earth to Titan or Pluto fast. Not faster than light, but a lot quicker than we can now. Nuclear Thermal or Nuclear Electric is a good place to start, and we develop spacecraft systems to protect a crew from the hazards of the space environment in a fast transit. Chemical rockets and gravity assist become very horse and buggy, and new approaches take over opening up the broader solar system beyond Mars in the same way railroads opened up settlement on a large scale of the United States in the 1800s. Sixty days from Low Earth Orbit to Jupiter space is what I’m envisioning. Thats not impossible, its an engineering challenge, a science problem, and a political and financial issue to resolve.

    I think either approach can prove Friedman’s thesis to be fundamentally flawed. There is no way that humanity should accept some sort of arbitrary limit on its future and relegate exploration purely to robots, whilst we sit fat and happy and content to watch through VR. Such an approach would prove to be disastrous for our civilisation, leading it to a dead end of stagnation, apathy and ignorance (people get bored, take off the VR goggles).

    All it will take will be one human to set foot on Ceres or Juno or Pallas in the 2040s to prove Friedman wrong. Perhaps a good start would be for key policy makers to start thinking about a crewed Ceres mission, either from Earth, or from facilities established on Mars. Lets call the main spacecraft that goes to Ceres the ‘Louis Friedman’ just for effect.

  • Brett November 28, 2015, 19:34

    @Alex Tolley

    It won’t be an inspirational as having people walking on the surface of Mars, but I agree that it’s probably easier and better from an exploration perspective. And unlike a Mars landing mission, a Mars Orbital Mission plus telepresence also gives you a lot of preparation for doing other telepresence missions with robots – with asteroids, with the Moon, maybe with the outer planets someday, and so forth.

    I mean with Jupiter we pretty much have to do it because of the radiation – any crewed ship would have to hang out around Callisto unless it had extremely good (and heavy) radiation shielding.

  • Roger November 28, 2015, 19:57

    In my view Louis Friedman has very much hit the nail on the head – but only for the near short term. What might that be? … Several hundred years to half a millennia but who really knows. But never say never, especially when it comes to the impulses and desires of human kind.

    There are countless economic and political hurdles to expanding beyond earth, but the short comings of our present day science and technological solutions are the real limiter in getting us beyond Mars. Again, in my view, not until science & technology can provide safe, efficient and thoroughly routine human-centric travel to extreme distances and back, will we be able to conquer this solar system, our solar neighborhood and regions beyond.

  • Rangel November 28, 2015, 20:58

    I believe virtual reality and robotic exploration will be key yes, however manned missions (and expansion) will happen at the same time but very slowly as technology and safety for space habitats advances. Also people seems to understimate space access on the future, i believe private space companies (that “just born” right now) will eventually lead mankind expansion, or at least the needed technology and means.

    I should also note that we keep making a mistake: thinking about the far future using the current human/government mind, did people forgot the way we face things change over time? While some decisions seems naive or too optimistic/pessimistic right now, it can change completely in the future, meaning we should not use current people/politics/economic realities as base for a talking about the future.

    I believe people realized humans are in danger for living on a single planet, which will bring us to Mars soon or later, the interest can be seen from the rovers, orbiters and other missions we launched last decades and planed future missions. So humans are expanding step by step, meaning all focus are on the first potential steps and we will only glimpse the next after we reached the first one, that currently are the Moon and Mars.

    Also it isn’t hard to think on the next step after Mars, it will be the moons of Jupiter, very likely Callisto (for a human habitation) since it is the only moon outside Jupiter’s radiation belt, from there we will be able to explore further Ganymede and the oceans of Europa (very good reasons to make an outpost). Dwarf planet Ceres may be a option before that, but somehow it doesn’t seems likely except if we start to mining the asteroid belt (we need a reason). And this step is for the far future in my opinion, after new propulsion tech are made to get there faster.

    Anyway it doesn’t matter how long it takes, i bet we will expand into the galaxy colonizing new worlds, giving life to several branches of humanity in differente star systems/regions of the galaxy. For now i am excited to see the near-future: the Moon and Mars.

  • Charlie November 29, 2015, 4:14

    I’m unable to get the expense angle and seeing how they can remove a large number of people to the surface of Mars. Frozen embryos? Perhaps that might work. What we’re going to need, if we understand the science of genetics properly, is we’re going to need a large diversification genetically speaking, if we expect the human species to be genetically fit, and to resist and reading which would cause a lot of weakness.
    There’s also going to be the question which might be exacerbated in such a hostile environment such as Mars of whether or not there will be political stability in a Martian colony. We might have to unstable earthlike planets instead of a backup system. As we all envision, it politics, which will be present has its way.

    I’ve been thinking that a better solution. With regards to a lot of problems that are man-made is to have a drastic reduction in the population of earth that is proportional to the numbers of people that now occupy each country. A reduction in population, with his massive the economic impact of technologies which are increasingly encroaching upon people’s livelihoods and abilities to find meaningful work. If you are the people, the more likely you’ll be able to find a suitable job. Additionally, the stress on natural resources would obviously be far less than. I believe they were going to have to look a lot harder in word before we look a lot extensively outward as has been promulgated in endless discussions on this board here.

  • Ashley Baldwin November 29, 2015, 7:34

    E=mc 2 . The very fabric of the Universe is energy . Get enough of it and there are practically no bounds on what you can do. The Kardashev classification system of civilisation development has energy use as its central tenet . Whether it is at sub light speeds in a multi generation Ark ship or via some distant future “Eureka” moment that exploits the more esoteric equations of General relativity on worm holes and warp speed ,the very essence of the human psyche is to explore and expand. Energy is the driving and limiting factor . Harness enough and it isn’t a question of where so much as when. I would like to interpret the message of this book as a challenge rather than a prediction.

  • James Benford November 29, 2015, 10:15

    I’m happy to see Michael’s critique of the Friedman book here. His points are quite valid! I too have doubts that we will never go beyond Mars because technology development is always greater than what we anticipate.

    I might add that Michael’s comment that lasers for interstellar propulsion will not be available until perhaps the next century. That’s certainly true. Lasers are far less developed in power, efficiency and optics than microwaves and millimeter waves are. Microwave and millimeter waves could be used for such a system with today’s technology because of the their high efficiency and high levels of device power, which are commercially available at about a dollar a watt. Moreover, the antennas, although larger, are also far far cheaper. I showed in my JBIS paper 2 years ago (Starship Sails Propelled by Cost-Optimized Directed Energy, JBIS 66, pg. 85, (2013)) that, if you take all the cost factors into account, laser systems, millimeter wave systems and microwave systems have roughly equal capital cost to build. Operating cost for microwaves are much lower because microwave devices are far cheaper and far more efficient electrically efficient than millimeter and laser systems.

    But the major advantage microwaves have is that they are available now. High-power lasers are still a gleam in the eye of their advocates. This was true years ago as well.

    My point is that beam-driven propulsion to interstellar speeds need not wait for the development of lasers. The technology already exists for building millimeter or microwave systems, from components that are already available commercially. They will be large, they will be expensive, and will very likely require assembly in space eventually. But those are engineering matters that we can do. We need not wait for fundamental technological improvements to begin to advance beam-driven propulsion.

  • Michael November 29, 2015, 12:35

    I have never been an advocate for the settlement of Mars, just to cold, but a powerful magnetic field could be setup through it which would protect orbiting colonies. The cold poles allow superconductors that together with the magnetic properties of the planet would create a huge protective field. Now if we want to get out of the solar system we may need to go inwards towards Venus and Mercury, Venus has enormous amount of deuterium (150 times enrichment) and Mercury plenty of water, materials and sunlight to build powerful lasers.


    As with all things given enough time and effort obstacles can be overcome, I mean at one point in time there was only one man on Earth who worked out we can get to the moon but we got there. Sometimes it only takes one man or women to see the light and the rest will follow.

  • Eniac November 29, 2015, 14:08

    James Benford: I agree that particularly the energy efficiency of microwave transmitters makes them extremely attractive for beams, be it propulsion or energy transmission. I wonder if you could comment on the use of swarms of small antenna to also eliminate the complexity of large antenna systems.

    It seems to me that a relatively dense 3-d swarm of millions of transmitters, properly phased, could generate a pencil beam of a million times the power of each individual transmitter. Same with a billion, or even a trillion.

    Thinned-array curse, you say? Let me do a quick demo calculation: Say we fly a million transmitters in cubic formation, 100 meters on each side. In the direction of the beam, there will then be 100 transmitters per square meter, allowing for a wavelength of ~10 cm while retaining a dense array. For a billion transmitters, it would be 1 cm, and it gets better the larger the swarm.

    If this worked, we could quite easily, with today’s technology, deploy such swarms and scale them indefinitely just by mass-producing more transmitters. They would in effect be space-based devices converting sunlight to microwave pencil beams scalable to ANY desired power level, with an efficiency of around 20-40%, dictated mostly by the solar cells. The ultimate in reliability by redundancy, and no mega-structure engineering issues, whatsoever. Just a very simple craft (a flying, solar powered microwave oven, in essence) and formation-flying, which is not all that difficult.

    Is there a flaw in this concept that I have missed? Or should we form a company to start designing these, now?

  • Robert November 29, 2015, 14:29

    I am beginning to believe that our Western culture is simply not organized in such a way to make human development of space an imperative. Perhaps a symbolic landing on Mars and a few other places someday but nothing beyond that unless for some reason the technology evolved to make the process almost trivial. A breakthrough amounting to a simple rocket engine with about two orders of magnitude increase in performance for the same mass of engine and fuel or better would be needed to make solar system travel routine. A completely new kind of chemistry or some simple and robust form of fusion would be needed. Large scale beam type systems seem way too cumbersome and expensive.

  • Jim Strom November 29, 2015, 14:45

    Whether to agree with Mr. Friedman depends on the time he is considering, which is not clear.

    A theme in these comments is certainly true: social problems create uncertainty for space exploration, and science in general. Anyone who cares about scientific progress … do dream of Centauri, but also work for an Earth where that dream can be more than a wish.

  • Dani Eder November 29, 2015, 18:11

    @Malcolm Davis > “One is a stepping stone approach that uses forward bases and facilities to launch a new wave of expansion. We establish bases on Mars and use modern 21st Century manufacturing (i.e. 3D printing, nanotechnology) locally to build all that we need to go to the next destination”

    Dr. Friedman seems unaware of the “seed factory” concept ( http://en.wikibooks.org/wiki/Seed_Factories ). This is a starter set of core machines, which use local energy and raw materials to make parts for more machines, until you have a complete factory. Then you produce habitat domes, exploration rovers, or whatever else you want, including new seed factories.

    As Mr. Davis points out, this leads to a stepping stone approach to expanding through the Solar System. But the laws of nature are the same everywhere, and seed factories will work on Earth as well as they would in space. So the first place to apply them is here, and solve the problems we have today, such as not enough renewable energy to displace fossil fuels.

    I’ve started an article that describes this approach in more detail:


    The core difference is between a linear approach based on fixed agency budgets, and an exponential approach based on one generation of factories producing multiple starter sets, which grow into the next generation in new locations, eventually spreading everywhere.

  • James Benford November 29, 2015, 21:03

    Eniac: Yes, antennas can focus on a small spot by the technique of phasing many small antennas, and synthesize an “effective” area equal to the diameter spanned by the antennas. So get a beam-spread characteristic of a large antenna by using a phased array of small antennas. But how close do they need to be? The “thinned array curse” (sometimes the “sparse array” curse) is very simple. If a transmitting antenna is filled by an area-fraction F (where F is less than 1), then the power that is lost by emission into side lobes of the beam (and hence is NOT directed into the main beam) is proportional to 1-F. So, fine, but the antennas must be very close to each other and in phase, of course.

    Using sunlight is fine, but must be boosted from the few volts of solar arrays up to the keV voltages of magnetrons. That voltage multiplication hardware is the heaviest part, so will dominate the mass. For a GW, would need about a million of them. The cost-optimized of the system will determine both the power and the antenna size of a system element.

  • Harold Daughety November 30, 2015, 2:15

    There have been comparisons between exploration the New World and the exploration of space. One point that has not been brought up is that economic motives encouraged individuals to risk their lives but a major motive for governments to financially back these voyages into the unknown was to spread Christianity throughout the world – with horrible results in most places.

    If some ideology, philosophy, whatever (excepting religion) could be developed to light a fire in people for space exploration, it will go forward. There is a glowing ember already, just needs to be fanned into a blaze. I feel that establishing Moon/Earth L4 or L5 colonies, established free of government oversight and finance, would lead to expansion to the moon and elsewhere. There are people willing to take a one way trip to Mars – and there are plenty that would go to a space habitat if given a fair chance to survive: I would go tomorrow and never return. I can’t think of a more exciting finish for these old achy bones.

  • Alex Tolley November 30, 2015, 12:44

    Beaming. So assume 10kg per transformer unit, at $1000/kg launch costs. and a million units = $10bn, or about half Nasa’s annual budget. If SpaceX and its peers can get the launch costs down to $100/kg, the array cost falls to ~ $1 bn, a very reasonable upfront construction cost.

    I like the idea of producing many small units as this allows scale economies in manufacturing and more flexibility with launch vehicles. This is exactly the approach John Mankins envisages for space based solar power satellites (“The Case for Space Solar Power”).

  • TLDR November 30, 2015, 13:27

    I think we need to start acting like we don’t have a Planet B. Home worlds are not disposable.

    That said, by the time we have a credible Mars program together, we will have a much better view of habitable exoplanets nearby. This will fuel scientific imaginations, I think, for generations.

  • ljk November 30, 2015, 13:33

    We need to secure the planetoids and comets first. Millions and billions of floating chunks of raw resources in low mass packages floating throughout the Sol system for relatively easy utilization. If we are serious about the human colonization of our celestial neighborhood with the later goal of moving outward to other star systems, then we will want to go to those worlds first.

    Mars is still a priority in the human expansion into space, please note. It is just that the Red Planet will be made even more suitable for human existence if we already have those smaller worlds I mention above to get resources from to make Mars and other places more livable as part of the overall permanent colonization plan.

  • ole burde November 30, 2015, 13:52

    Friedmans speculations hardly deserve any serious consideration from a rational point of view …the way to relate to them is in the realm of psycology : Why would anybody invest so much energy in convincing us about what we can not do , wil not do and should not do ? Perhabs it was just too traumatic for him to experience the present lack real progress in manned spacflight , so he had to hang his personal hopes somwhere else …..poor guy , reality was too much for him!

  • TLDR November 30, 2015, 15:22

    I’m not as keen on colonization as some are here. It’s – to me – a mostly “gee whiz” concept to see “boots on the ground”, with all due apologies of course.

    To me, there are more important focuses for science in space.
    – Asteroid defense: We still don’t have a reliable program for detecting and intercepting asteroids that endanger Earth.
    – Finding ET life in our solar system: besides Mars, there are a familiar list of moons that might potentially harbor forms of life, and their discovery would turn modern science upside down in a very exciting way.

  • Eniac November 30, 2015, 22:11

    James Benford: The key element of my suggestion regarding the thinned array curse was that the antenna be spread out along a third dimension. In other words: A phased array does not have to be flat.

    Try to envision the 100 x 100 x 100 cubic antenna swarm I mentioned in my earlier comment. If you look in the direction of the beam, you see 1 million antenna spread over a 10,000 square meter area. This is one antenna per square 10 cm. It would allow a wavelength of 10cm while still being dense.

    Yet, each antenna has 1 cubic meter wiggle room, because they are spread out along the beam. Is this going to work?

  • william f collins December 1, 2015, 1:24

    I hope and believe that only the development of an interplanetary economic/political infrastructure will turn our civilization into a space faring one – that will explore and exploit the resources of our solar system. Private sector investment in space will have to involve huge potential for profits (and loss). Public sector funding has so many competing factors- health care, wealth disparity, ocean exploration, etc. – in fact, all of the space faring Nations – USA,UK, Japan, India,France, China- are in the process of building very expensive aircraft carriers or fighting terrorism or dealing with climate change, et al. I will keep on encouraging my grand-daughters in their fascination with STEM activities – building robots and computer programs-
    As my 8yr old granddaughter says, “I am interested in the future,” as she aspires to create a time machine.

  • Brett Bellmore December 1, 2015, 11:12


    The basic problem with the cubic array concept, is that it’s only going to work if each individual antenna can focus it’s beam tightly enough to miss the antenna further out along the Z axis. Otherwise you’re going to get shadowing and diffraction. But, in order to do this, each individual antenna has to be multiple wavelengths in size, which kind of conflicts with their being spaced at roughly wavelength intervals when the Z axis is ignored.

    The alternative, I suppose, is making the individual antenna much smaller than a wavelength of the frequency being transmitted. There are tricks for doing this, but they tend to seriously impact efficiency, ruling out their use in power beaming applications.

    Your proposal might be feasible for a radio telescope, though.

  • Javier Garcia December 1, 2015, 12:26

    I fully agree with Alex Tolley comments.

    I think in the first place that virtual reality is not really. And even i the case that we could invent in the next 1000 years an instantaneous way of communication through space distances, it is not in the human nature to sit and see. We are a race of rangers.

    In this sense, there are right now projects of space tourism. Rich enough people, are willing to pay mountains of money in order to feel what ingravity is. They want to say “Hey, I was there, out i the space”. They don’t just want to sit on a comfortable couch at their big houses and, with a virtual reality equipment, try to figure out how the space is like. They want to be there.

    So I am sure they will also like to “be” in Mars, not only “feel” like they are in Mars.

    Economic reasons for going to Mars and beyond are there: tourism, mining, etc..

    But there is a logical reason that has nothing to do with politics or economy. Sooner or later, another mass extinction will crash the earth. Maybe it will be in 10 million years. But it will happen. And by that time we better have a wide range of space colonies. Because even if a meteorite rain hit the earth in, let us say 100.000 years time, having only a small presence on Mars will not save the humankind.

    More over, and at a bigger time lap, we will be forced to get out of our solar system. There are a number of reasons. Being in multiple star systems is a much bigger guarantee of surviving as species.

    Finally, it is true that, for present human beings, traveling to the stars is a mayor challenge. But I bet in 1000 years, human beings will be more different from us, than Neanderthal men are from us. Having extended life spans to thousands of years, and enhanced physical and mental endurance.

  • ljk December 1, 2015, 17:41

    Here is the crowdsourced Integrated Space Plan with a detailed chart on where we may go in space in the next 100 years:


  • Eniac December 1, 2015, 20:50

    Brett: You make a good point. I tend to think that a properly phased transmitter would do more to reinforce the beam than to disrupt it, so that the effects you mention amount to minor losses. One way to think about it is that at least part of your argument would also apply to a planar phased array, which we know works. I don’t really know, though, or even how to find out.

    It may take a tree full of cell phones with hacked radio chips to really know…

  • Black SciFi December 6, 2015, 2:40

    Any technology invented by a space faring nation that approaches the speed of light would justify a tactical nuclear strike. That, my dear friends is the reality of the world we live in. I keep going back to the “heal the earth” meme because without adequate wealth distribution there will be no peace. Without peace all our scientific focus will be on inventing bigger, better, faster weapons.

    A quick look around JPL, or any of the other NASA development or missions teams, will tell you that we aren’t using an “Nth” of the potential brain power available to humanity. The fact that we are giving away visas to import brain-power speaks volumes about the idle minds here in America.

    If you plan on going to Mars or anywhere else in the next 1k years then these issues must be addressed and solved. Otherwise, the best we can do is more robotic missions to the same locations because they’re affordable.

    The best example of spinning our wheels is the 5M theories about dark matter published weekly. Let’s move on and try to make the earth whole again so we don’t HAVE to find another habitable planet. You never know what dual use (ecology/space missions?) may come from the inventions needed to repair our planet.

  • Larry Kennedy December 6, 2015, 11:16

    While I don’t see things with the same degree of trepidation as Black SciFi I certainly agree to there being major issues to be addressed here on Earth. I also agree that some of these could dovetail neatly into our long term dreams of space. One is the obvious dual use of small space high yield crops with recycling of water and nutrients.
    Another dual use technology is a self replicating industrial unit. We of course already have such a thing. Our world wide industrial complex performs that function when combined with self replicating biological units. So why not get together with NGOs or governments and figure out how small this unit can be made, with the least use of rare high grade ores. Let’s demand sustainable energy while we’re at it. The social use of driving this down to the size a few thousand people could sustain could be huge. At that point it would also become manageable to continue development of smaller less labor intensive units. In this way long term Earth sustainability and long term space colonization could both be enhanced.