Older science fiction is full of large domes on Mars and The Moon. These seem to have gone out of fashion, and there's a lot of work on semi-rigid inflatables.Most of the Bigelow Habitat mass is accounted for by shielding - against micro-impacts and radiation.But on the moon, or Phobos, that can be provided by regolith. A treble walled fabric can suffice. - An inner layer to prevent accidental damage- A pressure layer- An outer layer, to contain the shieldingJust add regolith between the outer layer and middle layer to get wahtever thickness you desire.The mass of the pressure vessel increases with the cube of the diameter. Using materials like spectra, 100m diameter is possible in 100 tons, 50m diamter 12.5 tons (though actually at that size, you'd stop shrinking wall thickness.This makes a way to create comparitively massive habitats with very low mass, using regolith as shielding. There's a focus on having Phobos (or Deimos) as an exploration destination. http://forum.nasaspaceflight.com/index.php?topic=18339.0, as it seems likely to have water, and plenty of regolith for shielding.But no artifical gravity.So, would it be possible to launch an inflatable dome or disc with a spinning wheel in the centre?Assume a Jupiter class 100 ton payload. This is taken to Phobos collapsed. It's anchored to the surface, and inflated. Then a robot hopper gradually scoops up regolith (which is meant to be flaky), and covers the habitat, perhaps with 5-10m of regolith. (I'm not sure if the outer layer is needed to prevent regolith from falling off - as it the regolith weighs almost nothing, it might be better to just keep on pouring and bury the whole thing. The robot hopper could be mounted at the centreof the habitat.The habitat is disk shaped, 50m in diameter, and perhaps 25m high. Inside, is an inflatable "tread-mill", axially mounted, supported on magnetic bearings. This rotates at 4rpm to provide Mars level gravity around the edge. (Humans are selected for withstanding this.) The floors are rigid inflatable.Would it be feasible?
No.-If only the circumference is habitable, why waste weight building the interior? Just rotate a hoop within an inflated tube covered in shielding.
Second; to keep the structure balanced as crew/supplies move about, sufficient static rotational weight or fluid counterweight is needed. Which comes back to an inflatable floor's insufficient load bearing.
-Any extraterrestrial base is a major undertaking unless it's launched pre-fab like the ISS or Altair. If artificial gravity is also an objective, IMO it would be better to send and spin completed habitats in an optimal orbit around the chosen body. Shield tiles, water, fuel, crops, science, etc could still be retrieved from the surface base, but habitat and base construction is vastly simpler.
No.-If only the circumference is habitable, why waste weight building the interior? Just rotate a hoop within an inflated tube covered in shielding.-"The floors are rigid inflatable." First; I have to question just how rigid they'd be and if they could support the systems. Second; to keep the structure balanced as crew/supplies move about, sufficient static rotational weight or fluid counterweight is needed. Which comes back to an inflatable floor's insufficient load bearing.
For any large structure on a body covered in regolith, I'd recommend a concrete plant http://forum.nasaspaceflight.com/index.php?topic=18641.0 to produce the foundations, shielding tiles, main structural components, launch/landing pad, etc.
I think covering the habitat in regolith would be simplified by just finding an appropriately sized crater and putting it into the crater. You would also have significant radiation protection before you finished covering the habitat with regolith.
Here is a high resolution image of phobos taken from mars express: phobos (link).That bar on top with the 5km marking is about 400 pixel wide. So the resolution is about 12.5m per Pixel. A 50m diameter toroidial habitat like the one proposed by alexterrell would be just four pixels across. There are literally hundreds of craters that would have exactly the right size. This also provides some sense of scale for those that think of phobos as a tiny object. Compared to everything we can hope to achieve in the next few decades it is so large that it might as well be a planet.
Method for assembling and landing a habitable structure on an extraterrestrial bodyDocument Type and Number: United States Patent 7469864Kind Code: A1Abstract:A method for assembling and landing a habitable module on an extraterrestrial mass is claimed. At least one inflatable module and a second module are placed into orbit about an extraterrestrial mass. Connecting nodes, propulsion busses, and landing pads are also placed into orbit. A habitable structure is constructed from the modules, busses, pads, and nodes. The structure can be robotically constructed. The habitable structure is then landed onto the surface of the extraterrestrial mass. The landing can be remotely controlled and the modules can be non-occupied.Inventors: Bigelow, Robert T. (US)Application Number: 11/363346Publication Date: 08/30/2007>
Shear-thickening fluid reinforced fabrics for use with an expandable spacecraftDocument Type and Number: United States Patent Application 20080296435Kind Code: A1Abstract:A shear-thickening fluid is used in conjunction with fabrics utilized in an expandable spacecraft. The combination of the fluid and the fabric allows the fabric to resist penetration by hypervelocity particles in space.Inventors: Cohen, Dan (Las Vegas, NV, US)Application Number: 11/807830Publication Date: 12/04/2008Filing Date: 05/30/2007Assignee: Bigelow Aerospace >
Regolith container for use with a structure on an extraterrestrial massDocument Type and Number: United States Patent Application 20080000168Kind Code: A1Abstract:A regolith container for use with regolith on an extraterrestrial mass is disclosed. The filled container covers a portion of a spacecraft to provide the spacecraft with a measure of protection against space debris and radiation. The container can be compartmentalized to reduce the loss of regolith should from the container if a single compartment is penetrated.Inventors: Bigelow, Robert T. (Las Vegas, NV, US)Application Number: 11/479276Publication Date: 01/03/2008Filing Date: 07/03/2006>
One issue: how does phobos rotate on its axis? You would want the centrifuge to have the same axis of rotation or there would be a lot of twisting on the bearing.Does everything in space have an axis of rotation? Or can they tumble in a more complicated way?
Cant the ares V launch something with a radius of 10 or so?What about a bycycle-powered treadmill that fits in this. That way you have it for the journey as well. Then you bury it when you get there.Also you can have passenger seats (plus desks and terminals) so that you get a couple of hours exercise each day, and some more hours doing desk work (eg teleoperating robots) also under gravity.And for that matter, if the whole thing breaks down, you could probably get some exercise and impacts just running around the circuit. I think a high impact competitive sport could also help. The strength of an impact doesnt depend on the gravity, but how hard you are trying. Perhaps something like basketball, but using a medicine ball and a drum instead of a court.
Bigelow has some ideas on how to do this patented or in the process.
As seen from Phobos, Mars would appear 6400 times larger and 2500 times brighter than the full Moon appears from Earth, taking up a quarter of the width of a celestial hemisphere.
names Jake!!! this guy in my class called curtis has a massive egg head and likes men!!!! hahahahahahahahahahahahahahahhahahahahha
Even for only twenty tons I reckon you would not want it twisting on its axis every 7 hours. Maybe a polar location could give you easier line-of-sight to earth anyway.
Of course, if you went for a 50m diameter sphere, you could put the rotating ring on any axis you want.
Of course, if you have it on a horizontal (phobos) axis, you'd get a slight variation in g. I suspect this might feel like a gentle , long frequency swell in an ocean liner. Probably not an issue compared to the coriolis effect. If you cancel out the inertia with a counter rotating mass, you still have the torque in the bearings, so if you're on Phobos, it's not really a help. If in orbit, then you'd put the spin in the same axis as the orbit.
Quote from: alexterrell on 09/13/2009 06:47 pmOf course, if you went for a 50m diameter sphere, you could put the rotating ring on any axis you want. You think bigger than I'm allowed to.
QuoteOf course, if you have it on a horizontal (phobos) axis, you'd get a slight variation in g. I suspect this might feel like a gentle , long frequency swell in an ocean liner. Probably not an issue compared to the coriolis effect. If you cancel out the inertia with a counter rotating mass, you still have the torque in the bearings, so if you're on Phobos, it's not really a help. If in orbit, then you'd put the spin in the same axis as the orbit.With a 7h 40m orbit I doubt you'd notice anything.Yes you'd still have the torque in the bearings but that should not be a problem for the bearings to handle. I'm more concerned with the problem of a ship with AG sitting on the surface being tipped over by gyroscopic forces in the very low gravity. Even under several meters of loose regolith the gyroscopic forces could possible move the habitat around since the downforce of 2 meter thick layer of regolith over a 15 m diameter hab is only a few hundred pounds.