Putting the life back in science fiction


21st Century Space: two views

I’m supposed to be writing about the upcoming election right? Because my job as an American citizen at this pivotal moment in our nation’s history is to help spread all the psychological warfare tactics being deployed by all sides to get us to be afraid and either vote or not.

Screw that. By the way: Vote! That’s all I’m going to say right now. It’s not that I’m not busy with local politics (hence the silence on this blog). Rather, it’s that I suspect that your adrenal glands are getting worn out by the psywar, so I wanted to give you a little respite. Over the last month, I’ve read two very different visions of space for the 21st Century, and I wanted to share them.

One is the US Space Force’s “Capstone Publication”: Doctrine for Space Forces. It’s an interesting mix of apparently thoughtful “how do we fight a war in space” analysis (which happens to be useful for SFF types at least), combined with a certain amount of macho posturing and “boots in the sky rhetoric,” to make it look like they’re more than a bunch of satellite jockeys working from home and keeping their cats off their laptops. Which I’m sure they are. This is good stuff to read if you’re interested in the putative realities of warfighting in near-Earth orbit and how it fits together with all the other various and diverse ways we have of hurting each other. But much of it is perhaps too familiar for precisely those reasons.

On the other side is something (apparently) completely different: JP Aerospace, aka “America’s Other Space Program,” a little outfit in the Sacramento area that seems to be developing its space hardware as a non-profit running on donations and contracts. The JP is John Powell, and I’m a bit late to his game. For the last 20 years or more, he’s been promoting what he calls “The Airship to Orbit Program” (you can buy his 2008 book at his website. Or Amazon–it comes out of the same warehouse. It’s worth reading, not just for the program, but if you want to learn about all the upper layers of our atmosphere). His vision of how to get to orbit is a slower, safer, three-step operation using ginormous airships.

Stage one is an A-shaped “Ascender” that’s around 900 feet long. The arms of the A are helium or hydrogen-filled polypropylene balloons inside a wing-shaped nylon sleeve, while the crossbar of the A has a couple of electric-powered high altitude propellers. It’s a semi-blimp with a keel that’s a large carbon fiber space frame truss, while the top of the wing-bag is a carbon fiber deck that mounts thin solar panels and carries the pipes and pumps for moving the lifting gas between internal gas bags. Semi-blimp means its halfway between a blimp (which has no hard internal structure other than the nose cone and possibly fins) and a dirigible, which has a full internal structure. Or you could call it a keeled airship. This beast can carry about 20 people up to 140,000 feet in about two hours. Basically, the Ascender takes off, points its nose up 70 degrees (it’s basically a huge, slow flying wing) and ascends to 60,000 feet on buoyancy alone. At that point, the wings and propellers take over so that it can fly the rest of the way up. It has to be so huge and light to fly at high altitude in very thin air.

At 140,000 feet (space officially starts around 330,000 feet up), the Ascender docks with Stage 2: Dark Sky Station. This is a starfish shaped, rigid-keeled airship/station. Each arm of the star is around 2 miles long, and it can house 100-200 people indefinitely with resupply. Its gasbags are inflated with hydrogen, but there’s so little oxygen at this elevation that combustion is not an issue. The Dark Sky Station (dark because the sky is black at this elevation) is a combination tourist attraction, transshipment hub, and research center. People visit to see the sights, drop a paper airplane, catch Stage 3 to orbit, or go up there to do astronomy, aerobiology, or unload cargo that needs to go to orbit whatever. It’s a commercial venture.

Stage 3, the Orbital Airship, is assembled at the Dark Sky Station and flies to orbit. This is another A-shaped, keeled airship, except each wing is around 6000 feet long and there’s no cross-bar. It has electrical propulsion units (design TBA, but anything from VASIMR to advanced ion is possible), and it’s so large because it has to fly in *really* thin air. It climbs to 270,00 feet on a mixture of buoyancy and wing lift. Above that, level, it flies using its wings for lift, gradually picking up speed (over most of a day or 5) at the top of the atmosphere until it achieves orbital speed at 17,500 mph and is flying on propulsion alone. At that point, its job is to either rendezvous with a spacecraft or space station or possibly release satellites. To get back down to the Dark Sky Station, the orbital airship merely tips its nose up, and its enormous surface area acts as a really nice, gradual aerobrake without heating too hot. It drops and slows until it can match velocity with the DSS and do it again. This ship is not designed to ever land. To fly at that altitude, the gas bags are about the consistency of vegetable bags at the grocery store, and the nylon skin is not much thicker. It would break apart in the lower atmosphere, but it can get lift out of what would have been a decent vacuum at sea level in the 19th century. It’s also so big and ponderous that even a simple turn would take something like an hour to execute. This flies like an oil tanker, not a jet fighter.

Now about the practicalities: JP has flown over 100 development missions consisting of balloon rigs and sounding rockets, and built Ascenders up to 160 feet long for the USAF, so he’s not blowing smoke. He’s designed high altitude propellers and demonstrated that they work on rigs launched up to 100,000 feet. He’s flown a number of small dark-sky stations (10-30′ wide) and demonstrated that the five-armed starfish is the most stable design. He’s recycling a lot of the same designs and technology for all three designs, and he’s testing them out as he gets funds to fly missions with his crew of merry space pioneers. One of his basic workhorse designs, the two-balloon, two propeller “tandem” design was developed and flown for around $30,000. While he ran his company on government contracts prior to the 2008 crash, he’s currently running the whole thing as a non-profit. He’ll haul your stuff up into the upper atmosphere for quite affordable rates (or free if it fits in a ping-pong ball), and he does several launches a year, testing his technology a piece at a time and flying other people’s stuff to pay the way.

A couple of other design challenges: how can balloons fly at Mach 22 (escape velocity), and what happens when something hits an airship?

Balloons flown by the NASA and the USAF have already gone Mach 10 in the high atmosphere/near Earth orbit, so it’s not impossible. No one apparently knows if a balloon with mile-long wings can pull off the stunt, but our intuitions about friction and lift get weird in near-vacuum conditions.

The other common concern is “what if it gets a hole?” And the simple answer is this isn’t a problem. The gas is in multiple bags, not one . This is a normal dirigible design going back a century. The problem with having one gas bag per wing is that gas can slosh around, and once it gets to one end and the ship goes vertical, things get hairy. Blimps have multiple gas bags inside the outer envelope as do dirigibles. They also normally have air ballast bags inside them to keep the gas where it belongs (outside air performs the same function as water ballast in a submarine).

Anyway, getting back to safety, if a gas bag gets holed, it can be replaced in flight. They’ve been testing having large gas bags on reels and unreeling them as they get inflated. It works well enough. Another line is the WW I bombing of London by Zeppelins. It took some time to figure out how to shoot down the dirigibles. The problem wasn’t hitting them with bullets, it was that the bullets simply passed through, rather than igniting the hydrogen inside. The holes leaked slowly enough that the airships didn’t go down, and sometimes the bags could simply be patched in flight. The Zeppelins weren’t shot down until the British figured out special incendiary bullet pairs to pierce the bags and physically ignite them from the inside. Then, once they got the right fuel-air mixture from the holed bags, the hydrogen finally ignited and brought down the Zeppelin.

In the case of a meteor hitting an orbital airship at Mach whatever, the space debris passes right through, and the crew patches up the hole. The ship’s shape is inflated by nitrogen (at very low pressure, I suspect), so it’s a matter of patching holes and replacing stuff. The carbon fiber truss is probably also fairly easy to replace, and it looks like the ships will have multiple trusses per keel. According to his book (and the enclosed pictures), a 100 feet of the truss he uses as airship keels weighs around 20 lbs. Having multiple trusses and carrying spares on the ship isn’t that hard. Patching it in a freezing vacuum gets interesting, but that’s not the same as the shuttle breaking up over Texas.

So that’s two visions of space overall. On one side, we have a very colonialist take of shredding treaties and militarizing space before the other side does it to us. Which sounds depressingly familiar, but I’m a well enough trained nationalist to feel a faint patriotic stirring at the thought of boots in the sky. On the other side, we’ve got this scrappy little outfit with a really different take on how to get to orbit, that’s shoestringing successes at a tiny fraction of what the rocketeers are charging to light candles and launch stuff. They may be dreamers, kind of goofy, and definitely not suits, but they’re getting stuff done for cheap, which is more than we can say for most aerospace companies.

These worlds aren’t mutually exclusive: JP Aeronautics did build its early Ascenders under contract to the Air Force. In the book Powell says that the biggest Ascender he built for the USAF was destroyed because the officer in charge ordered them to fly the airship in a high wind (which the prototype wasn’t designed to handle at that early stage). The resulting fiasco destroyed the airship, after which the USAF cancelled the contract and JP figured out how to launch balloons in high winds regardless. However, in an interview, Powell says that some of his work was given to the military and ended up in places he doesn’t know about. So it’s possible that the USAF (or even the Space Force) is flying ultra-high altitude airships based on JP Aeronautics designs. They may even be manned observation platforms. After all, even the Stage One Ascender is designed to operate at 140,000 feet, while the SR-71 allegedly has a ceiling of 85,000 feet and the U2 operates below 70,000 feet. Yes, these airships are slow. However, they don’t have a lot of metal in them or much that can burn, so it’s not clear to me how you track or even shoot one down. If a missile puts a hole in an airship that’s 900 feet long, unless it shatters all the keel, it probably can just be patched in flight.

But I think the vision of JP Aeronautics is a bit closer to sustainable than the jet, rocket, and missile crew are. While the airships would need square miles of plastic sheeting, they’re low-energy and electric-powered. In the worst case scenario, they can be inflated with hydrogen too. Figure out a way to make them out of sustainable materials and they can still fly. It’s a lot harder to do that with a metal and ceramic rocket.

Couple these airships with Brian McConnell and Alex Tolley’s spacecoach, and you’ve got the rudiments of a sustainable solarpunk space transportation system. And perhaps that’s an alternative vision you can play with for a bit, before descending back into the high stress memescape the politicos want our day to day lives to be.


22 Comments so far
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Back when AtO was published I was intrigued by the idea. I still think teh orbiter is unworkable, but there is nothing out there to test the idea. I have conversed with an ex-employee of JP Aerospace who says the founders are very smart people, but whether that means it has been even simulated IDK. Their argument is that inflated vehicles have descended from extreme altitudes, but that doesn’t mean that they can ascend.

For me, the high altitude sky station was more interesting. It is a cheap way to gain access to near-space conditions and could fulfill a number of roles in both military and civilian spheres. It even has gravity so that normal operations can be carried out if you want, yet offers a space conditions outside of a pressurized crew compartment. Getting back to the ground is also much easier. This is the project I would back as I see no fundamental showstoppers. It would also make a great hotel.

Comment by alexandertolley

I’m not clear on whether you read Floating to Space or not, but there are some of your answers in there. One tricky part is “extreme altitude.” 140,000 feet is above where most (all?) balloons have ever gone, and JP Aerospace routinely only goes to 100,000-ish feet with their test rigs. If they can get up and down to 140K on a regular basis, then you’ve got your Dark Sky Station,, even if it’s an RC rig. And I agree with you that this would be a good facility to have.

Building a V-shaped airship with 6,000 foot wings at 140,000 elevation is, in my book, one of those “neat stunts,” because the wings of the orbiter are longer than the wings of the station. Doing the assembly and inflation without destabilizing the station takes some very clever engineering. As for flying with mile-long wings at Mach 22, that’s a whole other question. The part I don’t think anyone knows is whether the plasma in the exosphere or thermosphere is homogeneous enough that something that big plowing through it won’t get torqued or bent. We know how to send smaller things through such media, but we don’t really know how to fly something that’s got more in common with a bridge than a plane.

Fortunately, Powell’s honest enough about the unknowns and risks If you haven’t heard him interviewed, check out https://www.thedrive.com/the-war-zone/32082/we-talk-giant-boomerang-shaped-airships-space-and-phoenix-lights-with-jp-aerospaces-founder

And finally, if someone wants a SFF spaceship, I think you’d agree that these airships are no more batshit than a laser sail the size of Texas, or the idea of rockets landing on Mars and taking off again without refueling.

Comment by Heteromeles

Interesting idea.

A safety aspect question: What about solar winds — as in fast travelling ionized particles zapping very thin sheets of plastic?

Or sunlight – could this airship capture enough sunlight to power a generator or charge a battery? If yes, then it might be handy to keep around a space station as a back-up power supply … between guided tours. An armada of these could be used to cover/block out ‘excess’ sunlight over/to major cities on the planet while also charging batteries for use on its space station.

Lots of potential applications depending on whether such ships would be solely piloted by onboard crew, drones or a mix of both.

Comment by SFReader

Suppose they used beamed power for ionic thrust in the very thin atmosphere. See Myrabo’s Lightcraft concept.

https://en.wikipedia.org/wiki/Lightcraft

Comment by alexandertolley

Easily. Even the ascender first stage has about 1600’x50′ available for thin film solar panels. The others have about a mile of solar panels on each arm. Given that the ships are positively buoyant when starting (buoyant lift>weight), I think there’s enough energy generated to keep things going. That’s one thing I like about this design, actually, is the absolutely huge areas for solar panels.

Comment by Heteromeles

I am having trouble posting a reply.

Comment by alexandertolley

Weird. There’s nothing pending. Try again or email me, and let’s see if we can get it published

Comment by Heteromeles

Still nothing…

Comment by alexandertolley

In 3 pieces:

The reason I am skeptical that the orbiter can “float to orbit” is based on my limited understanding of the approach. As I understand it, the orbiter uses a mix of static and dynamic lift that allows for a continuous slow acceleration to eventually reach orbit. The vehicle is therefore constantly balancing dynamic and static lift.

Comment by alexandertolley

2 of 3:
The problem is that lift effectively ends at the Karman line. At this point the air density is so low that the velocity needed is higher than orbital velocity, so centrifugal forces are, not lift forces are in effect. For the orbiter, this implies that there is no way to keep rising and therefore it will be accelerating against a v-squared increase in drag at it highest possible attainable altitude. Low thrust engines of whatever type will simply end up with a maximum velocity at that altitude, which will be well below orbital velocity. As I am not an aeronautical engineer, this may be a poor analysis, but I have yet to see any analysis that shows that a high-drag vehicle can slowly continue accelerating at the top of the atmosphere until it reaches the needed orbital velocity.

Comment by alexandertolley

Ah, here’s the confusion. There are two sources of lift: buoyancy (putatively to 270,000 feet before it cuts out entirely) and the engines, which cut in at 180,000 feet and take over at 270,000 feet, along with lift from the wings, which are t be shaped for hypersonic flight. Not sure it will work, but there are three sources for lift, not two. It’s a wing as well as an airship.

Comment by Heteromeles

Let me try again. The orbiter ascends to its maximum height (~ 270,000 ft) with static lift (buoyancy). The air is thin, but not absent. Now you need to accelerate to Mach 25. Unless you can get higher with dynamic lift from the wings, you are going to be pushing a high drag balloon through the air. The drag increasing as v-squared. This would normally require a high thrust engine, like a rocket (e.g. X-15 spaceplane). But that is not what JPA wants. They want a low thrust engine that will slowly reach that speed over a period of days. But that requires the drag to be reduced, which means gaining lift to reach a higher altitude. But that is limited by the available lift at the Karman line, about 330,000 ft. IOW, there is no way to gain lift beyond that altitude, but the vehicle is still pushing through rarified air, with low thrust engines and a high drag balloon shape (however well-shaped). I claim that therefore the ascent to orbital velocity cannot be achieved. The vehicle will fail to reach even that Karman level height as its lift will be low due to its low speed. To my mind, JPA is assuming the physics at the Karman line are not relevant to balloons, but AFAICS this is not the case. Another way to consider the case. The vehicle is traveling at Mach 25 at 330,000 ft with no further lift possible. Can low thrust engines even maintain that velocity? No. The drag will reduce its speed and the vehicle will sink down. The denser air will increase drag, further slowing the balloon and reducing its height. The stable point will be where the thrust will generate enough lift and velocity to keep the balloon above its static buoyancy height, but with a low velocity depending on its thrust and the balloon’s drag.

If the vehicle was doing reentry (which the book claims is a proof of concept), the drag is exactly what you want to reduce speed. Here the large area and low wing load is helpful, preventing the craft from a too steep reentry and burning up.

I know the folks at JPA are far smarter than I am at this, but I have seen no analysis that says they are correct. Given what appears to be a low-cost way to gently “float to space” one might think the military has looked into this, even if just doing computer simulations. I know of no such work outside of JPA’s claims.

Comment by alexandertolley

Last thoughts. Can a plane “fly to orbit”? Imagine a plane with zero net weight and zero drag coefficient. The engines would have to be non-airbreathing. In this case, the zero drag allows the craft to continue to accelerate whatever the thrust level. Its wings would be useless above 330,000 ft, but the centrifugal force would increase its height just as if it was making an increasingly eccentric orbit. The key is the drag coefficient.

Therein lies the problem for JPA. Can they make the ascender with an extremely low drag coefficient? The Drive interview indicates that they understand this is necessary. I very much doubt it, as we would see examples of this in a range of vehicles. Airliners with very low drag would have huge cost advantages. We see this with the adoption of winglets to reduce wing vortices, and of course with ever more efficient engines. But a huge gamechanger would be to make the body very low drag, both the form drag of the blunt nose and the skin drag from friction. The latter can be reduced by sucking the air into slots over the skin. The form drag can only be reduced by making the front surfaces as aerodynamic as possible. For the JPA orbiter, drag reduction will have to be heroic. Maybe they have some clever idea of how to do this with a high altitude balloon. However, I am very skeptical.

Comment by alexandertolley

Well, there are a couple of things. One is that its hypersonic, so the wing cross section would have to be some sort of wedge forward. From what little I understand, manipulating the shock waves coming off the boundary layer separating off the front edge is critical. What shape works best for that? Got me. Also, I don’t know how much force this exerts on the edge, so I don’t know if an inflatable can deal. Then there’s the problem no one mentioned, which is the potential torquing effect of turbulence on a wing over a mile long. The third thing is the barometric equation. Air pressure declines non-linearly with height, so there’s a complex dance between going higher for less drag and still getting enough lift to make it worth the trouble. I think it’s worth being really suspicious, but I also suspect that we don’t know enough to know for sure that it’s impossible. On the other hand, as you’ve noted, a Dark Sky Station is still useful even if there’s no next stage, so if JPA can get that far, they can at least research the next stage. And that would be cool.

Comment by Heteromeles

I think they’d agree with you, actually. See that TheDrive interview I referenced in the original post. No one flies anything winged above 100,000′ to my knowledge. I think there are air density and temperature numbers above that, but beyond that, JPA wants to set up tests (using inflatable mach gliders launched by sounding rockets, inflated high, and flying down as fast as they can get it going) to characterize the flight conditions and figure out if it’s possible to create a hypersonic wing that can get up to Mach 22 below the Karman line. If not, then they can’t get to orbit. If so, they can.

Comment by Heteromeles

3 of 3:
The Dark Sky station, OTOH, suffers no such theoretical problems and offers a unique platform that no other technology can exploit – near space conditions at altitude but with 1g. This makes living in the pressurized quarters very easy, and also allows low cost access as even balloons can reach it. Even I could comfortably make the trip and enjoy a stay there.

Comment by alexandertolley

Nice to see you back.
I love the idea of a slow climb to the dark sky stations … especially if there are lots of them available over most cities…or places where cities once were. Like murder on the Orient Express, you have time to develop a good story line isolated from the normal world below and the stations above assuming you can fly or float from station to station…

Comment by ArtDeco

The unobtaium is zero coefficient of drag paint or fabric…

Comment by ArtDeco

Seems there’s a tendency to use/assume only one energy source – both in terms of type and placement.

Why not go hybrid: light weight high energy materials & design craft plus external boosting stations (satellites) that can feed (pulse) energy into your craft at key phases along the upward trip.

Comment by SFReader

If you read xkcd, here’s a link for space elevators

Don’t know if this will go to spam …

Comment by ArtDeco

This blog post on Floating to Orbit is far more complete and interesting. I came across it looking for something else.

https://www.science20.com/robert_walker/can_giant_airships_accelerate_to_orbit_jp_aerospaces_idea-225058

Comment by alexandertolley

I agree that this is an excellent post and well worth reading. It convinced me to by Floating to Orbit to see what the whole thing was about, and I probably should have referenced it.

Comment by Heteromeles




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