As the Shuttle age draws to a close, there seems to be revived discussion in the media about where manned spaceflight is headed next.  The short answer is, of course, "nowhere," but we still see enthusiastic articles about returning to the moon, or visiting Mars.  The problem is, if you look at budgets and research programs, it quickly becomes clear that nobody's really interested in either of those objectives.

For instance, if NASA were actually interested in putting people on, say, Mars, for extended periods--or on the moon or indeed anywhere but low Earth orbit--they would logically have long ago embarked on a research program to learn what the biological effects of Martian or lunar gravity are.  Instead, they've invested decades and billions into learning how humans react to zero gravity--an almost useless scientific endeavor, because the clear lesson from the start of that program was that living in freefall is a bad idea.  Conclusion:  whenever people are going to spend more than a few weeks in orbit, provide them with artificial gravity in the form of a rotating spacecraft.  There's no reason not to; the technology involved in spinning things around is not actually rocket science.

No amount of data about how the human body reacts to zero-G is going to answer the important question, which is:  how does the human body react to extended periods under fractional gravity--like the moon's 1/6 G or Mars's .38 G?  If there's a potential show-stopper to colonizing other worlds, it's going to be how our physiology responds to fractional gravity, not zero gravity.

At what gravitational level does osteoporosis start in human bones?  What's the minimum level for maintenance of cardiovascular health?  At what level do embryonic and infant development begin to suffer?  Maybe these questions can be tentatively answered from studies in zero-G, but any conclusions reached that way need to be empirically confirmed.  In other words, what manned spaceflight needs as its next step is a variable-gravity research station.  The ISS is useless for learning what we really need to know; what's needed is a very simple, rotating station whose gravity can be tuned up or down to simulate life on worlds ranging from Mercury to the moon to Mars, or Ganymede or Titan.

It's pretty clear that NASA's not interested in doing such research.  There is an opportunity here, however, for the private sector to step in.  Once Robert Bigelow's inflatable space stations come onto the market, someone could attach one to a spent booster stage and rotate the ensemble.  They could then do the necessary experiments and sell the results to NASA or, say, the Chinese, who are sure to be interested.

I'm going to add this item to my list of things to do if I had a billion dollars.    But as long as the world's space agencies lack a variable-gravity station, you can be sure they're not actually serious about establishing a human presence on our neighboring worlds.

Solaren corporation has signed a deal with Pacific Gas & Electric to orbit a 200 megawatt solar power satellite by 2016.  I mention this not because the news is amazing (it was inevitable, really) but because their plan gives me some nice numbers to plug into my Verne gun calculations. 

You might remember my enthusiasm over Next Big Future's recent discussion of Project Orion and the spinoff notion of using nuclear bombs to loft very large payloads into space (wheeee!).  I called this idea the Verne gun in a feeble public relations attempt.  Anyway, Brian Wang's calculations over at NBF gave a figure of 280,000 tons as the lift-capacity of a single 10-megaton bomb.  At the time, I suggested using ten or so of these suckers to lift an entire continental powersat infrastructure into space.  But I didn't have hard numbers about how much mass equaled how much power.

Solaren have conveniently stated that their 200 megawatt, self-assembling power transmitter could go up in five launches of 25 tons each.  Solar power satellites are far more efficient per-solar-cell than ground-based plants, so they have a much smaller industrial footprint and almost no environmental footprint at all.  They run 24 hours a day.  So that means that the engineers at Solaren can do 200 megawatts of baseline power with 125 tons orbited.  To put it another way:

1 gigawatt baseline power = 625 orbited tons

Launching this much mass using conventional rockets is expensive, but obviously not entirely out of line, or they wouldn't be doing it.  But, here's a question:  how much baseline power (97% uptime) could be orbited using a 10 megaton Verne shot?  The answer: 448 gigawatts.  

The United States currently uses 4 terawatts of power per year.  About half of that is coal.  So four firings of the Verne gun could orbit enough power to obsolete the entire American coal-power system.

The big problem wouldn't be radiation from the launches (which would be effectively zero) but the astronomical insurance costs attendant on putting so many eggs in one launch basket.  Maybe a few dozen 100 kiloton shots would be better...

Further to the discussion about Brian Wang's treatment of Orion and its offshoot, the Verne gun, if you look at the comments to my previous post, Adam Crowl suggests that peak acceleration for Brian's gun would be about 3700 gravities.  He also suggests ways of reducing that, primarily by using a nuclear charge to energize hydrogen gas and have that push the ship.  (I'm not sure that's the most efficient way to go, though, because the Orion design depends on the efficiency of energy transfer to the pusher plate and requires close proximity to the charge.)

In any case, this figure of 3700 g's suggests something: some things would be able to take it (like hardened electronics, tight rolls of thin-film solar cells, and liquids like water or rocket fuel) but others (like people and furniture) would not.  In one of Brian's latest posts, he talks about the Mercury laser, which might make practical laser-initiated fusion happen.  This piece makes me wonder what the total mass of the system minus the supporting building structure would be (because that bears on how practical it would be for fusion powered spacecraft) but also reminds me that laser launch systems have only been waiting for this one development to become practical. 

So here's the plan:  launch a few hundred thousand tonnes of rugged stuff using the Verne gun, and send up the rest a tonne at a time using a laser launch system.  You can even run the laser launch system off renewables if you want to be green; and after the first few launches, you end up running it off beamed power from the first solar power sat you put up.  True bootstrapping through hybrid launch technology.

I have to admit I got a bit ahead of myself in the post below, in which I renamed the nuclear cannon the Verne gun and described some of what you could do with it.  As it stands, the idea would only work for cargoes that could withstand tens of thousands of g's of acceleration---which in practice would amount to fuel, raw iron and a few other simple items like that.  Still valuable to orbit, but a bit limiting.

So, here's a proposal to refine the idea a bit:  the sabot.  In this variation of the Verne gun, you don't try to reach escape velocity.  The blast that sends up the ship only needs to loft it about 100 kilometers---above the atmosphere, but not into orbit.  The bulk of the ship's mass is in fact acceleration padding--a sabot or shell around a more conventional rocket-powered craft.  After an initial acceleration (still on the order of hundreds of g's at least) the sabot separates from the cargo at 100 kilometers, lightening the load and permitting the contained rockets to fire.  This lighter craft then enters orbit under rocket power.

An alternative to rockets would be to catch the ship at the top of its trajectory using an orbiting tether (a huge one, if we're catching tens or hundreds of thousands of tonnes!).  In either case, the acceleration shielding for the initial launch falls back into the ocean and what enters space is pure cargo.

Using a sabot might allow us to launch more fragile cargoes than the straight shot version.  I now doubt that you could launch, for instance, solar power sats without a sabot, though sending up a space elevator would probably still work.

Toby Buckell informs me, by the way, that Niven and Pournelle used the idea of the nuclear cannon in their alien-invasion novel Footfall.  Let's get precedent straight here---as far as I know, they did it first in science fiction.

Recently I talked about one of my favourite blogs, Brian Wang's Next Big Future.  He and his team are a veritable fountain of ideas, and this week they've outdone themselves with a series of pieces on Project Orion and its offshoots.  Now, I freely admit that they've done all the heavy lifting here (so to speak) but I'm going to take one of their ideas and run with it anyway.

A couple of the salient posts on Project Orion are The Nuclear Orion Home Run Shot, and Pieces of a True Nuclear Cannon.  Now, Orion was the 1950s-era American project to build a nuclear-bomb powered spacecraft.  Three facts stand out about the project:

1. It could have worked, and would have put unlimited amounts of mass into space for less than $1 a kilo.
2. The biggest vessel contemplated by the Orion team would have weighed 8 million tonnes, and would have been bigger than the Great Pyramid.
3. The sucker wouldn't have incinerated, flattened, and irradiated nearly as much real estate as you might think.

Still, for some reason the project was canceled around 1964.

In contemplating the glory that almost was, it's tempting to imagine what could have been accomplished with Orion.  One thought I had was that, well, maybe you could just use it once:  do the full-out 8-million tonne monster and use it to launch, in one shot, enough solar satellite infrastructure to obsolete every North American coal plant overnight.  According to a rational moral calculus, if Orion works it should be used in such a way, because the number of people who would die worldwide from the beast's fallout would be trivial compared to the number saved by reductions in air pollution from coal.  (Three million people die from air pollution each year; what they point out over at Next Big Future is that Orion could be calibrated to limit its fallout deaths to no more than a few dozen per launch, even for the biggest ship).

Still, there would be some place on Earth that would suffer from such a launch, and one thing we've learned is there is no truly "empty" land.  Even if our moral calculus could be extended to other species that would be saved by greening our power, it would be better if there were some way to launch such huge masses without exposing the biosphere to nuclear explosions and fallout at all.

There is.  I call it the Verne gun because frankly, a name like THE ATOMIC CANNON would just not go over well in certain circles.  In any case, the principle is the same as Verne's original idea, but using modern technology:  you set off a nuclear charge underground where the blast, heat, radiation and fallout can all be contained, and use Orion-type technology to direct its energy into orbiting a very big, very heavy spacecraft.  This vessel would experience hundreds to thousands of g's of acceleration--you couldn't put humans in it.  But Wang calculates that a 10 megaton bomb could put 280,000 tons into orbit with zero radiation escape into the biosphere.  Since dozens of bombs were exploded in exactly this way from the 50's to the 70's, we know this can be done.  And Orion's researchers proved nearly every one of their theories about Orion.  What they couldn't test at the time can now be simulated accurately by today's supercomputers, without the need for a test program.

Such an orbital gun could be used multiple times.  Here's what you could do if you could put 280,000 tons into orbit in one shot:

• Put 1.5 terawatts of clean solar power into orbit with less than ten launches.  Obsolete coal and petroleum power production with green baseline power, using less than a 10th the number of solar cells as you'd have to install on Earth to capture the same amount of sunlight.
• Orbit an entire space elevator with one launch.  Set it up, retire the gun, and get on with a clean space age.
• Do the same thing with an orbiting greenhouse infrastructure.  Drop solar-powered mass drivers on the moon to feed a continual stream of building material to the building sites.
  
• Orbit fuel depots to drop the price of conventional rocketry to orbit through the floor.  One shot and access to space for NASA becomes 10 times cheaper.
• Send up a telescope so big that it can image the continents of planets circling other stars.
  
• Put up one or more of those cool gigantic orbiting space station wheels that are showcased so dramatically in the movie 2001:  A Space Odyssey.
• Send an entire colony's worth of material to the moon or Mars.  With a second shot, put up an interplanetary cycler ring, tether launch system or other permanent mechanism for shuttling people to and from the colonies.
• Toss a couple hundred thousand tons of nuclear waste into the sun, where it won't bother us anymore.  (Trust me, the sun won't notice.)
• Launch an empty Orion ship, send its fuel up the safer space elevator, and send an expedition to Saturn, or a probe to the next star.
  

I'm not going to suggest orbiting a sunshade to head off global warming, because that's no solution for problems like ocean acidification.  --In any case, you can certainly think up other cool stuff we could do; and notice that some of these options, like orbiting fuel depots or a space elevator, can easily bootstrap us out of having to use the gun more than once or twice.

Oh, and of course, there's one more thing you could do with it, but since you'd need to get signoff from all the members of the nuclear club to use it at all, this one's a bit less likely:

• Orbit a huge frikkin death star platform with ATOMIC LASERS and MISSILE RACKS and RAIL GUNS and aim them at anybody you don't like.
  

The Halifax Chronicle Herald has an article about the military's new future-oriented analysis, and how I'm going to be writing a novelization of the material, just as I did for Crisis in Zefra several years ago.  Public reaction seems to range from supportive and admiring to derisive and outraged (as in, 'they can't even tell what they're doing next week, how are they going to look thirty years into the future?')  

Apart from the fact that I'm getting paid to do this, I think it's a good idea for other reasons:

Most businesses and governments only look ahead a few months, Mr. Schroeder said.

"That’s like painting your windshield black and driving out on the highway, as far as I’m concerned. You need to be able to look as far ahead as you can, even if it’s foggy and you can’t quite make things out."

For me, the thing that decisively signals a split between old-style politics and something new, is President Obama's reluctance to give up his blackberry.  In retrospect, it's astounding that someone in such a position should not have personal access to instant messaging of this kind.  It suggests that there are always filters around the president--i.e. that someone else is filtering his view of reality--and limiting his ability to act.  The presence of 21st century tools in the White House would be highly significant; as I wrote in Lady of Mazes, "technology is legislation."  Technologies like instant messaging are likely to have a profound impact on process that, at least in the near term, is almost certainly going to be attributed to other causes.

The fact is that you haven't just elected a president.  If he gets to keep it, then you've also elected a blackberry; and nobody yet knows what that is going to mean.