This is kinda a dick headline. The real credit should be to Bigelow for building the BEAM. Its a very impressive solution and I believe the first full scale habitat inflatable in space. I guess the SEO people at techcrunch know words like 'SpaceX' gets results, but this article is like saying "American Airlines sends Obama to Chicago." Instead of "Obama visits Chicago." The transportation isn't the story here. The cargo is.
Kudos to the team at Bigelow for making it this far. Let's hope for a successful deployment. Inflatables have often been assumed to be how we'll build habits off planet. They're light but durable and could soon be deployed on the moon with our current technology to act as a semi-permanent base. Imagine a dozen of these tied together. The lift cost would be a fraction of what a 'hard' habitat would cost.
Or from less ambitious perspective, one of these acting as a commercial space hotel. Space tourism works better with a destination.
I'm super passionate of space habitats and have done extensive reading about them. This is not a habitat in the real sense of the word. It provides a more spacious environment for the ISS. Therefore, it's just an extension to the already existing science laboratory (not habitat).
For humans, a habitat should replicate earth's environment. Gravity is the first thing that comes to mind, but there are other things it should provide.
I hope in the near future we work on actually building/sending habitats in space with the goal of actually living there, and not only for scientific research.
Development of inflatable volumes is a reasonable step towards us becoming a spacegoing species. If you have a decent bag and enough air to pressurise it, you can have as much room as you want in space. There's no external pressure working to collapse it.
Of course, there are questions to answer about safety, shielding against debris and radiation protection, but that's the point of doing the research. I love this kind of stuff. It serves to remind people that space travel isn't just launch vehicles. Part of, as you say, providing a place in space for humans to live, is providing spacecraft that aren't utterly cramped.
Inflatable habitats actually scale worse than ridged structures. The problem is as you inflate a structure the air pressure is constant but the surface area increases. And you must carry the load around the edges.
The advantage is actually in mid-sized structures where you can more easily compact them for transport where rigid structures are sent up in a single piece for strength.
PS: This is also why you need buttressing around above ground pools. For comparison 1ATM = 33.9 feet of water. Above ground pools rarely go above 1/3 ATM at there base. Granted, they are also not made out of Kevlar, but the same basic problems apply in space.
Interesting. I would expect that both air pressure and the tensile strength of your enclosure would scale directly in proportion with the area of the enclosure.
But some thought experiments about enormous pools - ponds, really - make me think that you're correct.
Indeed, looking it up, in a sphere, the stress (in units of pressure) is equal to (pressure x radius) / (2 X thickness). In a cylinder, it's worse - axial stress is the same as a sphere, but hoop stress is (pressure x radius) / (thickness)! You also have to think about increased stretching in the hoop direction compared to the ends of a flat-plate cylinder, which should probably be a sphere or complicated ellipsoidal shape to best deal with the stress.
Applying these equations, an ideal steel (assume an alloy with tensile strength 700 MPa) sphere with 1cm thick walls would have a maximum radius of 138.2m. A cylinder would have half the radius. Using Kevlar (tensile strength 3620 MPa) increases the radius by 3.62.
Doubling the thickness doubles the allowable radius but also increases the mass of our sphere from an already staggering 136 metric tons (3 Falcon Heavy payoloads) to an astonishing 546 metric tons, or more than 10 Falcons Heavy.
Kevlar is, of course, lighter than steel by about 5 times, but that many tons of Kevlar will not be cheap. That's about 0.5% of the total world annual production of the stuff!
We won't be going up to inflatable planets anytime soon.
You could have multiple membranes wrapping one another, each with a lower pressure than the last until vacuum. That way you substantially reduce pressure forces, and improve ballistic resistance.
Make it big enough, and vaguely cylindrical, and you could spin it up to provide simulayed gravity - you'd just need internal webbing to prevent it bulging from centripetal forces.
This all adds mass of course, but it still be lighter and more compact than an equivalent rigid structure.
Your mistake is in assuming we're simply optimizing for volume and nothing else.
Factor in each of size, cost, and deployment complexity, and it's clear many feel that inflatable structures represent huge potential wins.
Besides, it's not like you actually need to build single, huge volumes. Space-based habitats built of multiple, smaller linked structures makes more sense, anyway, as it enables module isolation in case of failure.
We are still thinking in terms of tiny structures. Picture a space station with 100,000+ people.
From a safty standpoint you want modular structures. But, you also want to minimize the areas directly linked to space. Thus you end up with something like a nuclear submarine vs an ever expanding ant hill.
Remember apartment builds give every room a view, but that's high risk in space. You can also reuse walls, between areas to cut down on mass without compromising if there is a leak.
It should also be noted that this will not be actually inhabited by the resident astronauts - it contains a heap of sensors to monitor retention of pressure and atmosphere etc, and astronauts will enter it a handful of times (wikipedia suggested around 30-40 times during its mission last time I looked) - so it's just laying the groundwork for a potential further attachment in the future
Then what is the point of having the habitat in space in the first place? Should we block off the windows, too, and replace them with posters of the side of some terrestrial apartment? Hamstring the solar panels because the atmosphere would block a lot of energy?
Living in space should be different than life on earth. Humans need some things to be similar to survive, so give them those things - possibly including some time in gravity - but we don't need a few more square feet of living space equivalent to a vacant lot.
I agree that living in space does not need to perfectly replicate the feeling of living on Earth. Humans should be supplied with the things they need to live and gravity might be one of those things, but only when it comes to long term health concerns.
On the other hand, the word "habitat" literally means the natural home of an animal or plant, and a gravity-free inflatable balloon in space is about as far from the natural living space of a human. It's going to be a long, long time before anyone can recreate Earth-like conditions in space.
Living in zero gravity tends to be very bad for long term health because bone and muscle mass start disappearing.
Radiation shielding is a huge problem. Inflatable habs provide almost none, so they're dangerous in LEO and potentially fatal further out.
And then there's danger from micro-debris.
So inflatables could be good for short trips - space hotels, especially - and for extra storage. But they're really not a solution for long-term occupation.
How about inflating them with water, and then living inside another air inflated bubble inside? Like a giant cell. Radiation shielding, micrometeorite shielding, plus water is pretty important too. Other gear can float inside the water behind their own membranes like organelles, some use the water to radiate heat away, some use water for other things like making macronutrients (carbs, fibre, protein, & fat), or processing waste.
I've seen people propose this before, and it's always bothered me, because when they say they're "storing" water it suggests the water will be there until the needed for some other purpose.
But if you're using water for radiation shielding and you then dedicate it to some other purpose, you no longer have radiation shielding.
That's only the cost if you use disposable rockets. About the same cost/kg of flying if you're throwing away the 777 after one flight. Reusable rockets are magnitudes cheaper per launch.
Or there's robotic in-situ water mining - Ceres has a shallow gravity well and probably has as much water as Earth. Easy? No, but space is always going to be hard.
Probably not what you had in mind, but I found Neal Stephenson's novel Seveneves to be very thought provoking on the subject. I had never thought of inflatables before I read that.
Ohhh, the soft walls, the lack of windows, and a lockable door between it and the rest of the space station? What is not to like? Might as well try out some of those "hotel room" features to help Bigelow design a better room for space tourists.
I was really excited to see Bigelow's ideas here, and have enjoyed seeing stories of their test modules floating around in orbit. It seems to make a lot of sense if you want something that transports small, and grows big when it is deployed (no joke intended). I remember thinking it was like one of those "pop up" tent trailers you see at the campground. Easy to transport but very spacious and useful once set up.
I'd like to see one designed that could be manufactured in orbit, or on the moon. That could jumpstart space manufacturing and expansion like nothing else.
Or you could launch them and fuel cheaply with a space gun, along with Robots to bash the components together into a functioning structure, and leave the mucky rocketry bit for your g-sensitive meatbags.
How is sending up raw materials better than sending up completed parts? At best, the total weight is the same, but if you're doing manufacturing in space, you also have to send up tools.
I would assume the parent comment's idea is based off of an assumption of some sort of ISRU (in-situ resource utilization). Which, to be fair, is tricky.
It should be noted that this is for NASA to the ISS, and not for human use. They'll check it out occasionally and maybe use it for storage after a while.
Still, it seems like the way of the future for human living spaces. I visited the Air and Space Museum in DC and the Skylab was amazingly roomy compared to ISS modules.
I hope everything works out with this test. B330, the larger variant, could be launched on a Falcon Heavy and add 35% to the volume of the ISS in one go.
I've always thought that Mars missions should 'drag a bag' behind an atomic rocket. The best shielding is the inverse-square law. Put the habitable part of the mission vehicle several miles from the fissionables! At the end of a tether.
But directly behind the rocket is where most of the energy goes.
I'd also be curious how the tether would avoid getting cooked by the rocket exhaust. I think a long mast, putting the riders in front of a large mass of fuel, would be much simpler.
But you're right, it is a lot easier to design an ultra-light, super-strong tether than a giant mast.
Two habitats with an engine in the middle spinning around like a top could provide gravity, and absorb the engine impulse. Under no acceleration the three bodies would be co planar, and under acceleration would deform into a cone shape.
That's a smart design! If you spin up to 0.5g and accelerate at 0.5g (which, while not enough for takeoff, is plenty for interplanetary travel) the tether angle would be 45 degrees, more than enough to get out of the exhaust plume.
Another free benefit would be that on a change of acceleration, angular momentum would be conserved. Rotation would increase or decrease to keep the acceleration felt by the occupants approximately constant!
From what I've seen the Project Orion and later designs concluded that was the most efficient design. Imagine a parachute (hemisphere) with the place where the explosion happens in the center and the (heavily shielded) capsule behind it, so fully 50% of the explosion is providing forward thrust. You don't have a single tether passing through the heart of the exhaust, rather you've got several going around the outside (like the frame of a cone tent, with the capsule at the apex). This was apparently easier than designing a rigid "pusher plate" with the right shape to capture a lot of thrust.
Yes that design has been proposed before. The mass savings from using a tensile structure can make up for the slight loss of thrust efficiency. There was a somewhat plausible design in Avatar.
Its possible that the exhaust could be made to disperse without losing much thrust - like a defocussed electron beam. Just so long as its cool enough when it hits the habitat. Which could have an aluminum-foil shield or some such...
Some details and photos of the BEAM here:
https://en.wikipedia.org/wiki/Bigelow_Expandable_Activity_Mo...
http://bigelowaerospace.com/beam/
Kudos to the team at Bigelow for making it this far. Let's hope for a successful deployment. Inflatables have often been assumed to be how we'll build habits off planet. They're light but durable and could soon be deployed on the moon with our current technology to act as a semi-permanent base. Imagine a dozen of these tied together. The lift cost would be a fraction of what a 'hard' habitat would cost.
Or from less ambitious perspective, one of these acting as a commercial space hotel. Space tourism works better with a destination.