Space! The Final Frontier! Why do we care?

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95 Responses

  1. Troublesome Frog says:

    I’m majorly in favor of scientific megaprojects as a good thing for government to do. Even the giant “wasteful” ones are usually small potatoes compared to any number of other crazy things we do with our money, and they’re the types of things that private industry just can’t reasonably be expected to do. We bitch and moan about the costs of a big physics project, but we rarely annualize the cost and compare it to other things that don’t cause us to bat an eyelash.

    I also think that a lot of people underestimate the importance of astronomy to our understanding of our own world. There’s a limitless sampling of huge-scale high-energy stuff happening out there for us to observe. In order to observe that same type of stuff here, we’d have to build ridiculous (or impossible) test equipment, and we often wouldn’t even know what questions to ask if it wasn’t for our ability to look at an oddball phenomenon in space and say, “WTF?”

    When all you’re doing is pointing a telescope (even a very expensive one) at the relevant set of astronomical bodies, the cost of admission to that treasure trove of data is incredibly low when you amortize it over all of the observations you can perform. And people still think of the researchers who do it as little more than stamp collectors.Report

    • Mad Rocket Scientist in reply to Troublesome Frog says:

      Case in point, fusion. Our space borne solar observatories not only expand our understanding of the sun, they also give us mountains of data & insights into sustained fusion reactions.Report

      • I hear this claim often — an implied “solar observations possible only from space contribute in some fashion to the design of confinement systems for terrestrial fusion systems.” Can you provide a pointer or three to actual papers or books where experts in the field make this claim? Eg, an expert citing a specific instance where detailed study of the sun’s gravity confinement system and behavior of the fusion reaction in that system led to specific changes in the design of our magnetic, electrostatic, or inertial confinement mechanisms?Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:

        Fair point. I don’t have any papers I know of that indicate that space borne telescopes are the only ones that can offer terrestrial nuclear insights. Rather, the L1 observatories offer better understanding of solar weather & allow for a greater understanding of the structure of the sun itself than what we can do with surface telescopes.Report

      • morat20 in reply to Mad Rocket Scientist says:

        Space telescopes are inherently better because (1) they’re not on shifting ground and (2) they’re not having to peer through atmosphere and pollution. There’s also (3) in that entire classes of telescopes work better the further apart you can put smaller telescopes, which is a bit limited on earth but less so in space.

        Seriously (1) is a real issue. Do you know how much time, money, and engineering goes into trying to keep those things stable while idiots drive around in cars and trucks, vibrating the earth and throwing off measurements — serious astronomy often is so precise that vibration from nearby cars and trucks, or even other equipment in the lab, can distort the images and readings.

        As for atmosphere — 60 miles of air distorting images and scattering wavelengths, not to mention light pollution and other forms of EM pollution.

        The Hubble is what, 30 years old? It’s been upgraded a few times, but the images and results it sends back are still absolutely impossible to get from the ground.

        The Webb telescope — well, the Webb is to Hubble as a PC from 1982 is to a modern desktop PC.

        As to studying the sun: Got no idea offhand if space measurements are better, but I’d be shocked if they weren’t — especially measurements made outside the earth’s own magnetic field, and imagery from outside the bulk of the atmosphere. There’s a lot of clutter in the way…Report

      • All relevant points — there are some things in space that can’t be measured in detail without going there. Eg, observing comets’ tails and the solar corona from the ground in various ways tells us some things about the solar wind, but putting satellites up allows actual particle collection, etc. I’m challenging — if that’s the right word — the commonly stated position that studying gravity-confined solar fusion through the intervening huge mass of hydrogen and helium is an important learning tool for achieving fusion using other confinement methods here.

        Over the last couple of decades I’ve noticed what I think is a trend in “hard” science fiction to tie practical fusion power to the ability to generate gravitational fields by some mechanism other than mass. I’ve long thought that such authors might get lots of details wrong, but because of their interests could be treated as a general indicator of the mood of the real experts. My interpretation of the trend is that there’s a growing feeling that magnetic and inertial confinement may never be good enough to yield large net energy output at an affordable price.Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:


        It might be that such magnetic fields can not be done well with the materials we have, i.e. unless we get room temperature super conductors, we are going to find a ceiling at some point.

        The cold of space may offer us more flexibility with the super-conductors we do have, if we can bleed off the heat effectively.Report

      • morat20 in reply to Mad Rocket Scientist says:

        Over the last couple of decades I’ve noticed what I think is a trend in “hard” science fiction to tie practical fusion power to the ability to generate gravitational fields by some mechanism other than mass

        If we could do that, fusion would be an afterthought. “Oh yeah, I suppose we sorta solved that by accident.” It’d be fundamentally like coming up with a way to repair each and every cell in the human body, keeping it healthy and young and undamaged (and restoring any damage to pristine health) and then thinking “Oh, in addition to perpetual youth, immortality, and perfect health I guess we sorta cured cancer.”Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:

        If we ever prove the existence of gravitons, & figure out how to generate them (or as Michael says, gravity fields), we’ll advance pretty fast.

        Hell, just being able to produce artificial gravity without spin would be a leap.Report

      • James Hanley in reply to Mad Rocket Scientist says:

        All fine and good, but when are we gonna get a true smell-o-scope?Report

      • North in reply to Mad Rocket Scientist says:

        A leap is putting it lightly. Build a couple ton wheel attached to a generator assembly, slap a gravity field on half of it. Generate electricity off the rotation until the mechanical parts wear out. Repeat.Report

      • Troublesome Frog in reply to Mad Rocket Scientist says:

        If we ever prove the existence of gravitons, & figure out how to generate them (or as Michael says, gravity fields), we’ll advance pretty fast.

        Looking for more invisible stuff? What useless pie in the sky nonsense. Slash it. We have wars to fund, prisoners to store, and ethanol to subsidize. We don’t have the cash to waste on your hobbies.Report

      • morat20 in reply to Mad Rocket Scientist says:

        A leap is putting it lightly. Build a couple ton wheel attached to a generator assembly, slap a gravity field on half of it. Generate electricity off the rotation until the mechanical parts wear out. Repeat.
        Sorta depends on how it’s done. First, it’d probably take a lot of energy. A *lot*. So even if you could run fusion off of it by basically creating a massive gravity well and fusing hydrogen like the sun does, a great deal of the energy released would probably go to sustaining the reaction.

        I don’t think anything short of fusion would get you nearly the power you needed to sustain the gravity manipulation and produce any useful energy.

        Unless there’s a fun space-time hack you can do to increase apparent mass or something. But since gravity is a big question mark at the extreme small and large scales (and then there’s dark matter, which we’re pretty sure exists but can’t seem to find) that physicists in general have been reduced to trying things and hoping the result is weird enough to give them a place to start.

        I know at least one place that makes anti-matter is trying to get it to stick around long enough to reliably measure how fast it falls, to see if gravity interacts differently with it…Report

      • North in reply to Mad Rocket Scientist says:

        Fair enough Morat, I was being flip anyhow. I have no confident in our odds of creating artificial gravity though it’s a lack of faith born of ignorance. I just am not able to muster the interest in the maths.Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:

        Last time I did some reading, we have evidence of the existence of a few dozen sub-atomic particles, but the various approaches to the Grand Unified Theory generally posit that there are a lot more (upwards of a couple of hundred, I believe).

        We create magnetic fields by causing electrons to flow through a conductor. It stands to reason that there are other useful fields we can create by passing different sub-atomic particles through different conductors. One of those fields may be gravitational.

        Provided we ever find proof of said particles, can study them, and find a way to generate them en-mass as we can with electrons.Report

      • morat20 in reply to Mad Rocket Scientist says:

        Well, if the Higgs field works as they think, being able to manipulate the Higgs would allow one to manipulate mass, since the Higgs is what gives mass in the first place.

        If you can manipulate the relative mass of something, there’s all sorts of fun potential there.

        I doubt it’s possible, but who knows? Too many open questions. It’s funny — one of the benefits of the Webb space telescope might be particle physics — peering into the past, and to see larger and finer scale patterns in space might actually knock something loose. The Big Bang, in the beginning, was particle physics at it’s most fascinating, energetic, and crazy. 🙂

        There’s already some fun arguments over some apparent patterns (they verge on statistical noise, so right now half the people working on them are trying to prove it’s just variance and the other half are trying to figure out what caused them, and I bet conventions are fun) in the CMB.

        (I’m particularly fond of the notion that one pattern could have come from a brane collision — basically our universe bumping off another one. betcha it’s noise though…)Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:


        Let’s save String theory & Membranes for another discussionReport

      • Build a couple ton wheel attached to a generator assembly, slap a gravity field on half of it. Generate electricity off the rotation until the mechanical parts wear out. Repeat.

        If you can extract more energy from such an arrangement than the energy needed to generate the necessary gravity fields, you have to tear down thermodynamics and rebuild it. Gravity-confined fusion doesn’t have the same conservation problem, since the excess energy is the result of converting mass.Report

    • Fnord in reply to Troublesome Frog says:

      I think it’s possible to consider Hubble et al useful pieces of technology that involved space while still being skeptical of significant portions of the space program (particularly the manned space program) as “vanity megaprojects”.Report

      • morat20 in reply to Fnord says:

        We spend a lot less on space — and on manned flight — than you think. Sure, it looks like a ton of money, but frankly we were blowing NASA’s entire annual budget (everything from science to engineering to manned space flight) a month, every month, in Iraq.

        I think NASA’s newest budget (the 2015 proposed one from Obama) is 17 billion, which covers everything NASA does. Sure sounds like a lot, but it’s like half of one percent of the federal budget.Report

      • Mad Rocket Scientist in reply to Fnord says:

        The moon landings were in a lot of ways vanity projects, but they really did push the bleeding edge of our technology at the time. Not a lot of space vanity projects since.Report

      • Michael Cain in reply to Fnord says:

        The moon landings… really did push the bleeding edge of our technology at the time.

        And in an important sense, LEO still does. One of the interesting systems analyses that can be done combines the energy available from reasonably safe rocket fuels, the structural strength of materials for building tanks and rocket housings, the mass of all those things, and Earth’s radius and value for surface gravity. One of the conclusions is that if gravity were only modestly stronger (a bit less than 20% IIRC), or the planet was somewhat larger with the same surface gravity, achieving orbit using chemical rockets launched from a standing start becomes impossible. Absent some breakthrough — reasonably stable chemical fuels that release more energy than anything we know about now, materials that are enormously stronger for their weight than what we have now, some way to launch from miles up and moving fast in the proper direction — lofting a pound to LEO is going to remain difficult and expensive.

        Unfortunately, most of the proposals for getting around the problem seem to cost upwards of a trillion dollars or more just to try on a realistic scale.Report

  2. Will Truman says:

    For my creative project, I’ve been reading a lot about the solar system (and looking at animations which make my little girl ecstatic). Specifically, I’m looking into the terraforming possibilities because for the project I need to figure out a very hypothetical “If a bunch of humanoid alien refugees were to set up in our solar system, how and where might they do it?” So I’m going through planet by planet, moon by moon, dwarf planet by dwarf planet.

    In the process, I’ve become very grateful to NASA and excited about what more we will know thanks to their efforts and the efforts of similar organizations. So, if nothing else, it’s good for the arts! Knowing stuff is important for the arts! Among other things.

    Longer term, though, we’re extremely likely going to need to figure out how to get off this rock. At some point in the distant, distant future. The more we know and the earlier we know it, even if we have millions of years to figure it out, the better.Report

  3. North says:

    An excellent summary MRS. A question: is it true that cold is not really the big problem in space but rather heat? I follow a fantasy author (Linda Nagata) and she was writing about how all those spidely vanes on the ISS are primarily used to cool the station off and went into a long talk about how enormously insulating space is and how very difficult it is to deal with waste heat. It kind of turned my space view upside down of course since all the sci-fi talks about you freezing very quickly when your life support runs out.

    I would also like to observe that from an atheist/agnostic/humanist perspective the development of space is an evolutionary (and I might even assert a moral) imperative. It is an undisputed fact that the fusion furnace that powers our intricate biosphere is a finite one. The termination of our biosphere due to stellar death will not be a particularly gradual one; evolutionary pressures will prove utterly inadequate to address this challenge. Non-higher intelligent life has no adaptable option for surviving such a doomsday scenario (and again it is a scientific fact that this event is inevitable). We human beings are the Terran biosphere’s solution to that no win situation. It is only through human intelligence; expanding into space and learning to bridge the almost unimaginable vastness between the stars (and carrying our biosphere with us) that all life on earth has any prospect of escaping the thermal and nuclear incineration that stands as an inevitable exclamation point at the end of the story of planet earth which concludes “and then everything burned up in the expanding corona of the aging sun”. If one were searching for an answer to the “why do we exist” question I’d submit that this is a far better answer than most; we exist to save our entire biological world from firey oblivion.

    Defeating the Terran gravity well is an indispensable first step on that great species spanning quest. That it also promises the potential of incredible material and ecological advancement for us as a people and a biosphere is just gravy on top. In a purely rational long viewed world such a project would surely be an enormously important priority.Report

    • Mad Rocket Scientist in reply to North says:


      Yes, waste heat is a bugbear. Thanks to the Laws of Thermo-damn-namics, everything we do produces waste heat that must be dealt with (yes, that is entropy). Heat moves via three primary mechanisms:

      -Conduction (solid to solid transfer – your cooking pot on the electric coils of your stove).
      -Convection (solid to fluid or fluid to fluid – This is how your car engines gets rid of waste heat, via the radiator)
      -Radiation (heat transmitted as electromagnetic waves).

      In space, the only way to unload waste heat is via radiation. You can do it with very large heat sinks (large thermally conductive plates that stick out into space) as the ISS does, or via more technical ways (like a cooling laser). I just finished a book (A Sword Into Darkness) where the first generation Space Navy ships had almost a third of their length dedicated to supporting just cooling vanes.Report

      • North in reply to Mad Rocket Scientist says:

        I thought as much. Thank you for the post though, it’s brilliant. I never realized the electrical generation potential of a space elevator. I didn’t think I could love the idea of the things more than I already do.Report

  4. Boegiboe says:

    Thanks for writing this, MRS!

    Why does the spacecraft at GEO have to be a full space station before the shot lines goes out. Why not launch a bare minimum robotic spacecraft and bootstrap additional equipment as cables are added?Report

    • Mad Rocket Scientist in reply to Boegiboe says:


      You are welcome, I enjoy writing stuff like this!

      As to your question, space station is a term of convenience. In the minimum, it would need to be a large satellite with 20+ tons of shot line onboard as well as all the equipment to deploy it while station keeping. The shot line may take up to a year to fully deploy to the earth (makes sense to go slow to avoid twisting, tangles, collisions, etc), so a decision will have to made at some point as to whether it is more economical to lift an unmanned robot and send people to it if there is a problem, or just lift a station with a crew on site to fix things quickly.Report

      • Patrick in reply to Mad Rocket Scientist says:

        Ship some robots to the asteroid belt. Find a nice big appropriate asteroid, put a solar sail on it, and sling it around and park it in earth orbit. Then disassemble it into the raw materials in order to make the line.

        Now, this requires getting manufacturing gear up into space, but if the big problem is weight, why not find raw materials that are already outside of the gravity well and use those, instead of lugging them up from terra firma?Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:


        I’d have to look through the catalog of current lifting rockets, but I don’t think it’s really a problem to lift 20 some odd tons of shot line to GEOS, especially if you are already going to be lifting much more to get the deploying platform built. Basically the cost of launching a few asteroid catchers would probably equal the cost of just lifting the shot line.

        Remember, once the line is connected, the rest of the cable will be laid out using crawlers that are towing a ribbon from the ground up.Report

      • I’d have to look through the catalog of current lifting rockets, but I don’t think it’s really a problem to lift 20 some odd tons of shot line to GEOS…

        According to Wikipedia’s list of orbital launch systems, of those currently in operation, the maximum weight to geosynchronous transfer orbit is 12.98 metric tons (call it 14.3 short tons). Other articles suggest that about half the weight in GTO can be delivered to GEO. Of currently operational systems on their list, the heaviest load to LEO is 27.5 short tons; depending on the weight of framing and such, you can probably get your shot line that far, and carry up enough rocket/fuel in separate launches to move it to GEO.

        Several retired heavy lifters would have been able to deal with the problem. Some of the heavy lifters “in development” will solve it again, assuming that they actually get built. Even building a one-off heavy lifter to get the initial thread to GEO is one of the easier problems that a space elevator project has to solve.Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:


        Thank you for doing the research I’m a bit too busy/lazy (circle one) to do.Report

  5. James Hanley says:

    Fascinating post, MRS. It’s about time someone put this Ordinary University thing to good use.

    The cable will carry an enormous amount of electricity, more than enough to power the base, the station, and the cars, with plenty to spare.

    Any idea how much is “plenty”? Enough to power a city? A small town? A drive-in movie theater? Do we have–or are we likely to have–the technology to capture that extra and put it to domestic/industrial uses?Report

    • North in reply to James Hanley says:

      Well, if the energy is generated by virtue of the elevator being in essence a long length of conductive carbon in a massive EM field then it would stand to reason that the energy output would be nearly constant and at a pretty consistent level (it’s not like the earths EM field turns on or off much). That sounds eminently harness-able to my entirely neophyte ears.Report

      • James Hanley in reply to North says:


        To clarify, when I think harnessable, I think about how (probably ignorant) enthusiasts used to talk about things like nuclear powered vacuum cleaners, and how today we still don’t directly harness the power of fission, but use it the same way we used coal to power a steam engine in the 19th century. Hopefully we can have a rather more sophisticated capture method for the energy produced by the cable.

        And unless I’m wildly misunderstanding, it would be really clean energy, right? Except maybe for being a bit of a bird hazard?Report

      • North in reply to North says:

        Yes, it’d be the definition of clean energy if I understand it correctly. The earth’s EM field exists, period. Sticking the cable up through it would have pretty much zero ecological impact, I don’t know if it’d even represent that much of a bird problem -certainly no more than say a single tall building and definitly much less than a windmill (no moving parts).

        An electrical generator uses some kind of engine (chemical, wind or steam driven) to generate a magnetic field around a conductive length*. The length running through the field develops electrical difference and we harness that to create a current. In the case of the space elevator the engine is the trillions of tons of spinning molten iron of the earth itself, the field is the earth’s electromagnetic field generated by that spinning and the elevator cable would be playing the role simply of the conductive length. Nothing is being created or diminished that doesn’t exist already except the conductive length so it would quite literally be electricity produced out of nothing. I can personally think of no more ecologically clean source of electricity; solar panels create toxic waste when they wear out, hydro floods land and impedes river flow, windmills chop up birds and generate noise, biofuel distorts economies, flattens ecologies and turns liberal politicians into drooling morons.

        *I am an utter noob when it comes to this stuff so I’m probably using some wrong terms.Report

    • Mad Rocket Scientist in reply to James Hanley says:


      How much electricity? I honestly don’t know, since it will depend on how many cables there are & how thick they are, etc. But suffice it to say that it will be likely be a large value of Mega Watts. From what I’ve ready, it will be enough that we will need to deal with it in the name of safety. I’m not an electrical engineer and my training in that area is pretty thin, so how well we can utilize, or at least insulate against, such electrical potential is a question probably better answered by someone else.

      I have seen rantings by people who claim it will be so much that the elevator itself will be too dangerous. Of course, these are the same people who think such an elevator would strip the earth of the Ionosphere, so I’m not sure how much weight to give them.Report

    • morat20 in reply to James Hanley says:

      NASA tried an experiment with a space tether in 96, and generated about 3500 volts across a 20,000 meter tether.

      I’m not sure how exactly a ground to orbit one would work, or how much it’d generate, but NASA’s problems with space tethers (free floating ones) have generally been “Whoops, more than we thought” types.

      Frankly, solar power is actually easier. It’s amazing how much power you can generate when light hasn’t diffused across so many kilometers of is pretty huge. A space collector gets something like half again as much energy per square inch of sunlight, and other than about three hours a year, is in constant sunlight, so it’s 24/7 power.Report

      • Mad Rocket Scientist in reply to morat20 says:


        Now if we could just make solar cells that weren’t so damn fragile…Report

      • morat20 in reply to morat20 says:

        We can. We don’t use them in space because they have more mass and why bother, because anything that’d break fragile is gonna break tough, and we don’t use them here because in general they cost too much.Report

      • Troublesome Frog in reply to morat20 says:

        What’s the deterioration rate of a solar panel being pelted by debris in orbit? Fragile is only a problem if you don’t get your money’s worth before you have to replace them. Fragile could conceivably be OK if it came along with “inexpensive to make” and “inexpensive to lift into orbit.”Report

      • morat20 in reply to morat20 says:

        Really, really slow.

        Solar panels are made up of tons of cells and it’s not like if one fails, they all fail. And there’s really not that much small debris. It’s generally pretty honking big, and hits are rare and very, very tiny.

        ESA and NASA have both done studies, and the power loss is minimal over the operating lifetime of the array. In fact, IIRC the worst damage they’ve suffered was one particularly lucky strike that caused a bit of a power surge on some probe.Report

      • Kim in reply to morat20 says:

        fragile is very much a problem, if it creates more space garbage.Report

      • morat20 in reply to morat20 says:

        Solar panels don’t break that way. They pit. It’s like glass backed by aluminum and coated with a thick layer of sticky tape.

        Or, you know, how you tape windows during hurricanes so a puncture just breaks the glass, not sends it all into your room.

        Sure, if you drop a pane you’ll break it and might even shatter it. But in space, that’d be simulated by an object of equal mass and dimensions to the array slamming into the array at, well, a good clip really. On earth, stuff accelerates downward at what, 10m/s2?

        Solar cells pit like car windows in space — at worse, a chunk is taken out. But the cracks don’t spread because the array isn’t one sheet of glass, so it can’t spread out past the edges of the cell.

        At the least, that’s what direct studies of solar arrays in space have shown, both in low earth orbit and on vehicles we’ve sent looping around.Report

      • Mad Rocket Scientist in reply to morat20 says:

        True, but unless we can make them extremely cheaply, they won’t be able to produce enough power to satisfy needs (although in space, we may be able to make them extremely cheaply).

        Now the solar mirror mining bit I mentioned down thread could also be used to run a solar thermal plant very effectively.Report

      • morat20 in reply to morat20 says:

        Price per watt on solar has been falling for over a decade. It’s pretty cheap now (it’s not so cheap getting them to orbit) and it’s only going to get cheaper.

        Because of the launch costs, the orbital stuff is generally as efficient as possible (they push 40 to 45% efficiency, roughly double general commercial solar, and they get 50% more solar power per square inch on top of that due to not having an atmosphere in the way.)

        The drop in prices might slow down as China’s economy starts to sputter, but I don’t think that’ll matter. Solar leasing agencies and installers are building up pretty steadily, and there’s a lot of clever work and engineering that might have been dropped as not immediately competitive with subsidized (by China) cheap solar, but might pay off long-term once the market settles a bit.

        Energy’s cheap in space, as long as you’re inside Jupiter’s orbit.Report

    • Boegiboe in reply to James Hanley says:

      I didn’t want to quibble with a side point of MRS’s piece, but since you asked, I don’t believe useful electrical power could be generated. The current would be generated by motion of the cable and time variation of the magnetic field. Put another way, the ribbon has to have a changing intensity of the magnetic field to generate a current. However, the magnetic field intensity is fairly constant for horizontal, twanging motion.

      I think the main concern would be safety, as MRS says in another comment. For instance, solar weather can cause the magnetic field to expand and contract–vertical motion of the field relative to the ribbon–so those changes would induce currents. How do you ground the station against current coming from its grounding wire?Report

      • Boegiboe in reply to Boegiboe says:

        Sorry, I left out a bit of logic: The current needs to be predictable to be very useful. If twanging did cause an oscillating current, something could be done to take advantage of that.Report

      • Mad Rocket Scientist in reply to Boegiboe says:

        Actually, from what I understand (again, not an electrical engineer, nor a geophysicist), the magnetic field of the earth does move, and not with the earths rotation, so it is actually a conductor moving perpendicular to a magnetic field. Hence it will produce a considerable electrical potential.

        That said, solar storms could spike the current in the cable. Again, something that must be engineered against. These are values that can be estimated rather well right now, and once the shot line is in place, we will be able to get a much better idea how much the full cable can carry, and thus be able to engineer against that, either through insulation or grounding or tapping.Report

      • Boegiboe in reply to Boegiboe says:

        I think you meant “not just with the Earth’s rotation.” Predictability of the field direction as a function of latitude, longitude and altitude but not time is heavily relied upon in some space systems.

        But looking up some stuff online, the magnetic field does move faster than I realized before. I’m not sure it would be enough change to be useful, but I will submit that it is more believable to me now than when I wrote my earlier comment. Thanks!Report

      • Michael Cain in reply to Boegiboe says:

        Sorry, I left out a bit of logic: The current needs to be predictable to be very useful.

        Unpredictable voltage differences and the resulting current flows are something that the elevator design has to handle, whether useful power can be extracted or not. For the most part, we’re talking about the construction material being carbon nanotubes or similar, which are very good conductors. At various points along the 22,000 mile conductor (from the surface of the Earth to GEO, ignoring the probability that the necessary counterweight will extend far above GEO) there are going to be large voltage differences.

        The typical difference between the potential in the ionosphere and ground is 250 kV. The potential difference between parts of a thunderstorm may reach 10 MV. Typical currents during the discharge of a lightning strike are 30 kA. The power output of an average lightning strike peaks in the terawatt range, but that only lasts for a few milliseconds. The problem is serious enough that some elevator advocates insist that lightning frequency should be the primary consideration for the where to locate the anchor site.

        Building and operating a space elevator isn’t just the initial strength-of-materials engineering problem; it’s a whole bunch of difficult engineering problems.Report

      • Mad Rocket Scientist in reply to Boegiboe says:

        Difficult, yes, but doable with the state of the art of today.

        The initial site will probably be in the Pacific, somewhere calm. Let’s not make the first one harder than it needs to be.Report

  6. Mad Rocket Scientist says:

    Regarding orbital manufacturing:

    @morat20 comment about solar cells made me think of this.

    In space, it will be very easy to manufacture nearly optically perfect lenses & mirrors. Much better and far easier than we can on earth. Keep that in mind.

    Let’s say we need a whole lot of metal for something. Send out some drones and have them boost an asteroid back to earth (we can get a pretty good idea of asteroid composition from observations). While the drones are busy with that, start building big mirrors, and on the back of each one, attach a maneuvering unit. Position them as an array out in high orbit. Put a very powerful computer nearby with telemetry links to each mirror. Bring in the asteroid put it on the same orbit as the mirror array. Start the asteroid spinning. Aim the mirrors at the asteroid so they reflect sunlight to it’s surface at a point. Slowly heat the asteroid.

    What will happen is over time, the asteroid will heat up and begin to melt. It’ll probably out-gas here & there as volatiles boil away, so it may need to be stabilized a few times, but in the end, what you will have is a spinning ball of molten asteroid, where the various elements will have spun out into layers of material. Once ready, turn off the mirrors, let it cool enough to handle, and start peeling off the stuff you need.

    It won’t work for every element out there, but it’s a low effort way to mine an asteroid for the things it will work with.Report

  7. Dan Miller says:

    What are the failure modes of this? If it comes down (due to accident or act of war, e.g.) wouldn’t it lead to 36,000 km of cable wrapping around the earth and generally destroying things on a massive scale? I’m getting this scenario from a Kim Stanley Robinson book but it seems like a valid concern.Report

    • morat20 in reply to Dan Miller says:

      No. The ribbon cables are both very broad and very light. Frankly, the bulk of it would just burn up and air resistance would lead to the cable hitting the ground with about the force and deadly energy of a dropped sheet of paper thanks to air resistance. (Seriously, the proposed designs of these have them weighing about a kg per kilometer of cable).

      Now the cars would be a different matter, although again — likely to burn up if they’re up past a certain point, and the station itself could technically fall if the thing snapped at the right spot, but all you need there is a ribbon cutter located a bit lower that you could activate and it’d be fine. (And again, station would probably burn up even if you didn’t bother with elementary safety mechanisms).

      Snaps at the anchor would just see the whole thing float upwards a bit.

      In any case, as the thing fell with cars on it, it’d break into a lot of pieces that would mostly burn up, and it’s more the cars you have to worry about as them hitting might do some damage, but given the massive reduction in cost-per-kg, you’d except them to have parachutes and such.

      It’s not that it can’t be destroyed and billions or trillions go up in smoke (although it’s worth noting that the FIRST elevator is very expensive. Each elevator after that costs a fraction as much), but it’s mostly going to be lost cargo and “Crud, we have to build another”.Report

      • Mad Rocket Scientist in reply to morat20 says:

        Remember that the space station is keeping orbit on it’s own, the cables are not doing any work.

        In reality, if there was only one cable, and it snapped, the station would need to adjust the counterweight accordingly (or release it). The space station itself, unless it is built without any gyros or reaction thrusters, is the most survivable part.Report

    • Mad Rocket Scientist in reply to Dan Miller says:


      Good Question! It really depends on where a break occurs, how many parallel cables we have, & how well we’ve learned to move about space efficiently. Any break is bad, as one could imagine, although the nanotube ribbon is remarkably tough stuff, and the cars themselves could constantly inspect & even repair the cable as they went about. Still, it is a potentiality that must be prepared for. Essentially, the closer to the earth a cable breaks, the better. A break near the earth would be bad for any cars below the break, but above the break they may be able to keep climbing, or at least not fall until the broken ends could be secured. A break near the station would, if not dealt with, result in a long cable wrapping about the earth, but the cable itself is incredibly lightweight, so the surface damage that could do would be minimal. Ideally, a broken cable would result in spacecraft moving out immediately to grab the free ends & move to get them back together until a repair could be made.

      The biggest danger would be the lower orbits, where there just may not be enough time to respond before things crash.

      What would happen is pretty predictable, especially with computer simulations doing all the math. It’s really a question of being able to respond fast enough to a break.Report

      • Dan Miller in reply to Mad Rocket Scientist says:

        Huh, OK. I hadn’t quite wrapped my head around just how light this thing would be (really, just a kilogram for a kilometer of cable that’s capable of tethering a counterweight and lifting cars? That’s fricking amazing!).Report

      • morat20 in reply to Mad Rocket Scientist says:

        Carbon is pretty awesome that way. Of course, actually making that particular type of carbon is..problematic. Although they’ve gone from “a centimeter” to “tens of centimeters” in just a few years.

        I think given the methods they need to make it, they need to be able to make (and verify free of microscopic flaws) foot-long or so segments.Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:

        Check out that link I included to Nanotube ribbon. Back in 2011 they were making 20 feet per minute of the stuff.Report

      • morat20 in reply to Mad Rocket Scientist says:

        It’s gotta be flawless. Every millimeter. The quality control needed for a space ribbon is insane. It’ll probably raise the cost-per-meter by an order of magnitude or more to ensure it’s good enough, if not outright need a new generation of scanning machines and software to search for problems.Report

      • Mad Rocket Scientist in reply to Mad Rocket Scientist says:


        Yep, but that’s just details. We know how to make the stuff in large batches, and have since 2011. The leap has been made, now it’s just filling in the details.Report

      • Kim in reply to Mad Rocket Scientist says:

        This calls for More Vodka!Report

  8. Damon says:

    The sooner we get this built, the sooner our Alien Overlords will take notice of us and conquer us. Welcome to earth. I’ll take you to our leaders, please eat them.Report

  9. Don Zeko says:

    As a total non-scientist, it seems like the radiation/fallout concerns around a nuclear rocket subside if you can launch it from a space elevator rather than a much lower altitude. Seeing as you’re the expert, MRS, is that nonsense?Report

    • Patrick in reply to Don Zeko says:

      Fallout requires material to be in the fireball, so that would eliminate the fallout more or less.

      Even inside the atmosphere, a large nuclear weapon detonated where the fireball doesn’t touch the ground doesn’t have much in the way of fallout, because there’s no dirt to get irradiated.Report

    • Mad Rocket Scientist in reply to Don Zeko says:

      @patrick is right. Still, if you were launching a nuclear rocket from a GEOS station, or from the more distant counterweight station, you’d want to have it move far away from anything before lighting off the main drive, as the drive plume will probably be very unhealthy, and very very long.Report

  10. Major Zed says:

    Why? Why? The survival of the human race, that’s why! If all of us stay on this one tiny rock, eventually we’re doomed. Spread out. Get powerful enough to deflect comets, withstand gamma ray bursts, and survive assorted other extinction-level events headed our way. It’s a race against the clock.Report

    • Patrick in reply to Major Zed says:

      Mostly this.

      Sooner or later, through a megavolcano, or a climate shift, or a major impact, or a gamma ray burst or whatever, we’re going to be a pretty dead rock, here on ol’ Earth.

      It would be nice to spread out a little bit. It would be nicer to spread out a *lot*.

      There’s a whole lot of Universe out there. It’s entirely possible that we’re the only cognition capable folks around to appreciate it. Seems a waste not to go check it out.Report

    • Matty in reply to Major Zed says:

      I don’t think a space elevator is going to get us out the way of a gamma ray burst. The area affected by those things is really, really big. To quote “a typical GRB pointed at the Earth from 3 kpc (or about 10,000 light years) or closer constitutes a serious threat to the biosphere.”

      I know I’m just quibbling and colonising the solar system would work for avoiding a lot of other risks just probably not that one.Report

      • North in reply to Matty says:

        The elevator is the first step Matty. Visiting the airport isn’t going to get you to Berlin by 6:am tomorrow but it’s an integral part of the process.Report

      • morat20 in reply to Matty says:

        Low-earth orbit is, literally, 90% of the cost and effort to getting anywhere in the universe.

        Once you’re in LEO, everything else is…ridiculously cheap. All it costs is time, really.Report

      • Mad Rocket Scientist in reply to Matty says:

        Well, it’s a potential first step, and one we can do in the very near future*.

        However, if tomorrow the LHC finds the Higgs Boson, or some other particle, and we learn how to generate & manipulate the particles relatively easily, we may suddenly have a reaction-less drive that will make such an elevator moot.

        *The ballpark cost for doing this is on the order of $10B. Forbes Top 10 could each put forth $1B, hardly notice the contribution at the end of the day, and make this happen (provided the political issues could be handled).Report

    • North in reply to Major Zed says:

      Yes Major Zed, I could not agree more. It is a historical, biological imperative.Report

      • James Hanley in reply to North says:

        Maybe I’m weird, but I just don’t get that.Report

      • Mike Schilling in reply to North says:

        Maybe you’re channelling C. S. Lewis? (He explicitly rejected that argument in Out of the Silent Planet as greedy and ungrateful.)Report

      • Mad Rocket Scientist in reply to North says:

        It’s the same imperative that pushed people across oceans.Report

      • Glyph in reply to North says:

        And sounds so much nicer than “avarice”.Report

      • North in reply to North says:

        James, it’s the same basic impulse to my mind as stepping out of the road when one see’s a vehicle coming.

        Mike, is not for humanity itself then surely for the sake of the rest of the planets life which we would presumably carry off planet with us. But C.S. Lewis and I disagree on many things, this clearly one of them.Report

      • James Hanley in reply to North says:

        So we’re not talking “imperative” in a moral/ethical sense, but just in the sense of “that’s what that type of critter is going to do, come hell or high water, and there ain’t no way you’re gonna stop it”?

        I’m good with that. That makes sense to me. But the “we must do it or our species is doomed” just doesn’t resonate with me. And it’s not out of any sense that it’s “greedy” or “ungrateful,” but just that I seem to lack this species-sense that some others have. In a half century or a little over, I’ll be dead. A century after that there’ll be nobody left on earth that I ever knew, and if there were, through death I’d be oblivious to their fate anyway.

        If a comet blasts the earth and over 7 billion people die, leaving just enough to repopulate, that’s an incomprehensible tragedy. If all 7 billion+ die, leaving none to repopulate the earth, that’s a slightly greater tragedy because even more people died–the loss of the species itself, to me, adds nothing to the degree of tragedy.

        As I said, maybe I’m just weird about this issue.Report

      • James Hanley in reply to North says:

        it’s the same basic impulse to my mind as stepping out of the road when one see’s a vehicle coming

        You’re applying individual-level analysis at the group level. Of course you have an impulse; you have a brain and a nervous system. The group does not have a brain or a nervous system, so it cannot have an impulse.Report

      • Glyph in reply to North says:

        the loss of the species itself, to me, adds nothing to the degree of tragedy.

        Yeah, this def. seems weird to me, and would even if we weren’t talking about, arguably (in multiple senses of that word) the only sentient species we know of.Report

      • North in reply to North says:

        I don’t know James, I guess you and I are just different in that sense. I guess I’m coming at this from a different angle.

        I’m heavily agnostic, we’ve seen no evidence of life on other worlds -yet- and most certainly have no evidence of intelligent life on other worlds -yet- so it is not irrational to posit that so far as we know we’re the only intelligent life in this galaxy and potentially Earth is the only living world in the same. I attribute value to that life and to that intelligent life. To my mind for that entire ecosystem to perish, as it inevitably will, with our planet would be a tragic thing. Escaping the Terran gravity well and ultimately escaping the confines of the Solar System would alleviate that tragedy. Such an accomplishment potentially could see our biosphere and our peoples flourish on countless worlds potentially for the remainder of this galaxy/universe’s life. A significantly preferable outcome. Striving towards this outcome strikes me as highly moral.

        You’re applying individual-level analysis at the group level. Of course you have an impulse; you have a brain and a nervous system. The group does not have a brain or a nervous system, so it cannot have an impulse.

        I suppose I can grant that, but our biosphere does have a collective impulse, to adapt, to evolve, to live. I do not think it that it somehow irrational to consider human intelligence to be the expression of the most likely evolutionary pathway for a biosphere to escape the ultimate evolutionary challenge: the failure of its environment on a stellar level.

        I also find your indifference odd on this since you have children and I do not. Granting, as I assume you do, that this planet will ultimately die, would you not prefer that your distant descendants have an exit option available?Report

      • James Hanley in reply to North says:

        and potentially Earth is the only living world in the same. I attribute value to that life and to that intelligent life. To my mind for that entire ecosystem to perish, as it inevitably will, with our planet would be a tragic thing.

        Unless we escape our universe, and then the next one, it’s going to perish someday anyway. I personally don’t feel a difference between that life blinking out 10,000 years from now vs. 1,000,000,000 years from now.

        Granting, as I assume you do, that this planet will ultimately die, would you not prefer that your distant descendants have an exit option available?

        The problem is that it’s too distant. If I knew the big asteroid strike would happen during my kids’ lifetime I’d be distraught. If I knew it was going to happen in the lifetime of my still-hypothetical grandkids, I’d really be bothered. If I knew it was going to happen in my hypothetical great-great-great-great grandkids lives, I just don’t have any emotional attachment there.

        This isn’t an argument that others should feel as as I do, just an explanation of why I feel that way.Report

      • North in reply to North says:

        I think I am clear on your feelings Prof and I can understand the detatchment. I can’t claim I feel it intensly but on a rational level I find it compelling.Report

  11. Lyle says:

    The question of course is why carbon(Human) based explorers, why not silicon based. Silicon based explorers do not need oxygen, food etc. They need electricity which the carbon based explorers would also need to keep them alive and provide the oxygen etc. If you believe Kurzweil about the singularity by the time almost anything could get going silicon explorers will have the computational capacity of carbon based explorers.In addition silicon based explorers are more radiation resistant, and can go to a low energy state if activity is not warranted, whereas humans don’t really go into that deep a hibernation. My ideas are to build more automated rovers likley more autonomous than the current ones (which are living on 6-8 year old tech or much older depending on the rover). After all a human will have to live in a can, and will rely on instruments to get most information, so why not just remote the instruments.
    Of course this leads to my questioning, could we put several memory units (exabyte or larger in size) in outer planetary orbits oriented to 90 degrees to the ecliptic, to act as our monument for other civilizations (likley silicon based also) to find.Report

    • North in reply to Lyle says:

      Whether carbon or silicon based, Lyle both will have mass and the utility of an elevator to boost that mass into low earth orbit strikes me as self evident.Report

    • Mad Rocket Scientist in reply to Lyle says:


      Robotic explorers are always preferred at the outset, for all the reasons you list above, as well as the whole “nobody dies if it all goes biblically pear shaped” aspect, and the information a robot sends back can improve human survivability when we do decide to put Mark 1 Eyeballs on site. Still, North is correct, it is much easier to fling out a legion of robotic explorers from the top of the gravity well then from the bottom. The elevator still improves the economics of such endeavors by a huge margin.Report

  12. Mike Dwyer says:

    Question about stationing asteroids in orbit for mining: Will they maintain orbit on their own or would we have to add some kind of thruster array to allow them to maintain the orbit we want and not float away or fall to earth?Report

    • Mad Rocket Scientist in reply to Mike Dwyer says:


      If we were to retrieve an asteroid and pull it close to earth, we would insert it into an orbit. This isn’t difficult to do at all. You just get the speed, angle, & altitude right (all easily computable) and as the asteroid gets close to earth, it will slide into the desired orbit.

      Once you start working on it, and the mass changes, and volatiles outgas, you’ll need something to help it keep orbit or the orbit will begin to decay. Although if the orbit is distant, the decay rate may be so small that the asteroid will be consumed before it’s a problem. Alternatively, you could park it at one of the Lagrange points (L4 or L5) and work it there.Report

  13. Miss Mary says:

    Very interesting. Thanks for sharing. 🙂Report

  14. Mad Rocket Scientist says:

    PS Everyone, the new Cosmos started this week. If you aren’t watching it, you should be.Report