Bigelow Shoots for the Moon
I'll add some more commentary later, but for now a fascinating scoop by Alan Boyle.
Labels: Lunar Commerce
posted by Jon Goff at 6:20 PM
22 February 2007
Name: Jon Goff
Home: Tehachapi, California, United States
Home: Tehachapi, California, United States
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10 Comments:
Wow- No machinery, to be done by no more then two people, burying the unit under 2-3 feet of soil on the top (who knows how much you'd need on the sides to get that depth on the top!).
I wonder if he doesn't go into details because of lack of time (as he states), or is there something of a trade secret involved?
Assembled at L1, and then flown enmass to the lunar surface? How sturdy would this system have to be? If you put something like 4-5 units together, how freakin' large would that be? How much flex would this flying bedstead be, that it could be flown down from orbit to the surface?
David,
It'll be interesting to see what his regolith handling idea is. Of course, even if that ends up not working out, there are plenty of other ways to skin that cat (though many of them will be very painful until we get further up the learning curve). I've got a few regolith handling ideas myself, but we'll have to see.
As for the idea of landing his station in one piece...as a VTVL guy that kinda scares me. It can probably be done, but with that many non-crossfed propulsion modules, redundancy becomes a real challenge. I think that the dangers and worries of ground assembly are being overestimate and the ease of rocket landing the whole thing is being underestimated. But the whole idea of using future Bigelow modules at L1 and on the moon is a good one. And however the thing ends up being lowered, that's going to be one *huge* market for orbital propellant delivery if he does things right.
~Jon
Lunar regolith is pretty amazing stuff. Have you read about the microwaving capabilities of it? Apparently you could conceivably create steel highways by 'mowing' the lunar surface with microwaves. It limits dust issues and obviously makes travel easier.
Jon,
Why can't he use one rocket to deposit the thing on the surface? The rocket has a few nozzles canted away from center, and a cable or cables that hold the habitat. It's the same scheme NASA wants to use to land the next Mars rover.
And it doesn't seem very ridiculous to me. Anything going down to the surface is going to be soft landed with rockets anyway. Doing it in one shot isn't going to use any more fuel than doing it piecemeal. They'll probably have the thrust necessary from one of the boosters used to lift the thing in the first place. Can a Falcon 9 lower stage make it to orbit with no upper stage to weigh it down?
I don't see how landing in one shot solves the levelling problem. It would appear to me that all it does is require the levelling problem to be solved in a few seconds instead of weeks, which is potentially bad.
Burial can be done by landing at the bottom of a crater and detonating the perimeter, causing a landslide which flows over the habitat. If they need a specific amount of overburden and no more (weight problems), this technique is going to be difficult.
I think it would be possible to land four bigelow modules connected to a central hub with a propulsion module with considerable redundancy.
Just have tanks and a few redundant large thrusters at the hub, and a bunch of tiny roll control thrusters at the ends of the four modules.
That should give you plenty of redundancy.
i wonder if rolling brushes could use to bury the thing ? You know, like street cleaning machines pile away dust. Theres little control on how and where it lands though, with 1/6th gravity making it a bit dangerous.
anonymous said:
"I think it would be possible to land four bigelow modules connected to a central hub with a propulsion module with considerable redundancy."
That's certainly one possibility although I would stress that they would want this to flow around the central hub (one would want the habitats to be interconnected).
Since the news broke I've been doodeling a bit trying to fill out the gaps and second-guess the untold. I've mostly been thinking about possible habitat layouts and their various pros and cons regarding landing, shielding, access solutions, and placement.
As with the +-shaped layout suggested by anonymous a square-shaped one should be easy to land using a central propulsion module connected to the structure with tethers. However the rigidity of the habitat modules (with or without a central beam running through them) might allow for completely different approaches.
The same rigidity makes me think that within limits BA won't be too concerned about uneven landing ground. My guess is that they would want to use some system of landing legs or similar that are easily adjustible or perhaps even self-adjusting and levelling upon landing. If so they would fill most of the empty space below the habitat modules the same way they make the layer of regolith shielding.
Anyway does anyone else envision moving "raw" regolith onto a structure as death by a billion papercuts? I'm wondering about how they will evade the sandblasting effect of pushing/dropping/blowing regolith onto the habitat modules and whether they'll cover the modules in an extra "expendable" layer.
Another detail that will be interesting is how they deal with shielding versus access. The simplest is to only partially cover the habitats but that would probably make most of the effort futile. The best I can think of (warning: might not be very good) is short stubby (quite possibly inflatible) endcaps on the outside of the entry with an angled "roof" to keep the 3 feet (or more) of regolith from sliding down (envision a cone lying on the side) thus allowing the modules to be completely covered.
One might want to make those endcaps a tiny bit more complicated by making them into T-junctions to be covered in regolith so as to in effect completely surround the modules on all sides by a layer of regolith.
Anyway does anyone else envision moving "raw" regolith onto a structure as death by a billion papercuts? I'm wondering about how they will evade the sandblasting effect of pushing/dropping/blowing regolith onto the habitat modules and whether they'll cover the modules in an extra "expendable" layer.
Remember that the regolith that is already there will shield against the rest. Plus, it can't come in with a lot of force otherwise most of it won't stay on the module.
Those are good points and it may be that I'm overestimating the abrasiveness of regolith. I must admit I've come to think of it as more like tiny razorblades than sand and that might be going a bit too far ^_^
I've seen on the Lunar Lander PPT file that NASA Watch has up today a number of lander scenarios that have a roof over a landing field- what we older types might have know as a 'Quonset Hut' design (Named after a Naval Airstation in RI that developed them for WWII). With a low slope like they envision, if you had little wing flaps on the fabric that would catch the soil, the fabric would better hold the regolith better then a sloping roof alone would do.
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