If a very light-weight bubble/tent were erected around the space station, it could have several benefits.
If they drop something during an EVA, it couldn't get away to orbit back and smack into the station or some other satellite - reducing the space junk danger.
Properly designed, it could diffuse and internally reflect the sun's light. This would provide better lighting for work outside - less high contrast shadows.
You could inflate it lightly to help it hold shape. Convection could help even temperatures across the station. This and the more uniform lighting should reduce the need for insulation on space suits - no superhot or supercold surfaces.
Anything that needs to see out (windows, cameras, telescopes) or have access to vacuum would poke out of the tent.-- TomRC, Aug 27 2002 Staying cool on the space station http://liftoff.msfc...ews-stationcool.aspInsulation is not a problem [madradish, Aug 27 2002, last modified Oct 21 2004] NASA shuttle archives http://spaceflight....v/shuttle/archives/Lots of ISS not many satellites [madradish, Aug 29 2002, last modified Oct 21 2004] Lost in space http://www.interspa...t/lost_in_space.htm...when stuff gets away... [madradish, Sep 02 2002, last modified Oct 21 2004] Skylab Space Tent http://www.astronau...etails/sky21533.htmSpace Tent Helps Skylab reduce inside temperature during repair of heat shield damage. [hollajam, Sep 03 2002, last modified Oct 21 2004] Paint chip debris http://quest.arc.na...uited/9d2micro.htmlAstronauts face hazards of paint chips debris [hollajam, Sep 03 2002, last modified Oct 21 2004] Satellite Insurance http://www.spacedai...ron-insure-2002.pdfSatellite costs due to insurance might be lower with on-orbit assembly and test [TomRC, Sep 05 2002, last modified Oct 21 2004] I like (+). If the bubble was big enough and silvered on its exterior it might look quite nice from the Earth, too. A temporary moon.-- bristolz, Aug 27 2002 That thar's a good idear.-- ty6, Aug 27 2002 Where would the tent sit? Either it would obstruct astronauts on EVA, or it would obstruct solar arrays, antennae etc. Also, the windows on the ISS don't stick out, how can you have them poke out yet still enclose spacewalking astronauts?
UBs variation might work, but I don't think it would be worthwhile.-- madradish, Aug 27 2002 I don't think that loss of tools is that significant an issue. Any really important tools are tethered to the astronaut. Seems that it wouldn't offer any real benefits and would probably obstruct astronauts on EVA or other protruding objects. It would also make docking interesting.-- madradish, Aug 27 2002 Also this tent would not offer much privacy from neighbouring space stations.-- Aristotle, Aug 27 2002 Great comments - thanks. A couple of points.
The tent isn't intended to protect against existing space junk - just prevent dropped bolts/paintchips from adding to it. This would also allow more a flexible and efficient work style.
WRT the solar arrays, either leave them sticking out, or if they need work, put a tent around one of them at a time while working on that unit.-- TomRC, Aug 27 2002 The tent could be tried out as a "work tent" that can be erected around something to be worked on, or build stuff in the tent and then take the item out of the tent for addition to the station or for use. There are proposals that satellite costs and launch costs could be reduced substantially by packing components and doing final assembly in space - a work tent would be great for that.
Probably the tent should be modular, allowing easy reconfiguration - maybe velcro patches to hold it together. Unless the "inflation" idea is used, it doesn't have to be air-tight, and frankly making it airtight for inflation seems more trouble than it's worth. Just stiffen the panels with springy rods - for launch you can just roll panels up in tubes. Pull them out and they pop into shape.-- TomRC, Aug 27 2002 Seems to be solving a non-problem. Astronauts don't drop bolts or paintchips or screwdrivers because they don't use those things.
How do you get the shuttle into the tent?
I do like the idea of a big silver thing glinting the sun, though. I'll not fishbone you for that one.-- waugsqueke, Aug 28 2002 My fishbone remains. With all of the crap already up there, a couple of bolts won't make much difference. The cost in money and time of developing, lauching and erecting a tent like this would far outweigh any possible benefits.
//There are proposals that satellite costs and launch costs could be reduced substantially by packing components and doing final assembly in space//
I'd be interested to hear where you heard this. It may become true in the future, but at the moment the cost of getting trained astronauts to the satellite bits and having them put them together would *far* outweigh the costs of launching a preassembled satellite.
I have heard astronauts describe the awesome feeling of hanging in space on an EVA and feeling the hugeness of it. This tent would effectively remove that experience. I think this belongs in the redundant bin.-- madradish, Aug 28 2002 I doubt that space junk is not much of a collision issue, and won't be for a while. On second thought that's what people said about the "endless oceans"... I have read that large-scale orbital industrial processes and manufacturing would have advantages, in particular a system involving lunar mining with sled launches directed toward the Lagrange points of gravitational equilibrium, where static ore nets would gather the raw materials flung at lunar escape velocity on a vectored trajectory for orbital refinement. I'm with you [madradish] on the the basic points. And the bone.-- panamax, Aug 28 2002 [madradish] This is not an expensive thing to design or make or launch - simple to design and make, lightweight. So it won't take a lot of benefits to make it worth doing.
Ever wonder by a satellite smaller than your car can cost hundreds of millions of dollars? They have to be carefully designed (and simulated and tested and documented and triple checked, etc) to work right the first time, without any human there to fix minor problems when it changes from it's compact payload configuration to it's operational configuration in orbit.
Now imagine designing a satellite with the assumption that a human being is there to give a sticky arm a kick, to pull some fragile parts out of packing and plug them in. Not only is your design job easier (cheaper to do), but by packing the fragile bits of the satellite, you can launch it at higher G's, which is also cheaper.-- TomRC, Aug 28 2002 Nope, still not convinced. Anything sent to space costs too much to design and test. Every kilo sent up has to be justified, I still don't think this is. As for benefits, I have not yet conceeded a single benefit that would make this proposal worthwhile.
I'm not saying that launching satellites fully assembled is the best way to do it but *here and now* it is the most cost effective. Absolutely you can fit more unassembled satellites into a given volume, and launch them at higher G forces. But that is not going to significantly reduce the R & D costs. At the moment, the only way to put a satellite together in orbit is go persuade NASA that it is important enough to send a shuttle with trained astronauts up to do it. This would constitute a major part of a mission (which generally cost ~ US$1 billion each) and thus can hardly be considered the cheap option.
Even if there comes a time when satellites are launched in pieces and put together by technicians in space, I still don't think that your tent will help them particularly. Astronauts are very well trained and highly aware of the danger of letting objects go floating off, it's simply not the problem you are making it out to be.-- madradish, Aug 28 2002 [madradish] If assembling a satellite takes 5 work days - EVA, pre/post EVA, planning - the share of the cost of launching a station crew might be about $2M to $5M. Not cheap - but it should be easy to cover from savings on R&D and launch costs.
For more on this, see: http://www.spacedaily.com/news/satellite-tech-02a.html
WRT costs - see: http://www.howstuffworks.com/satellite8.htm
That cites the cost of a shuttle launch as $0.5B, BTW.
A space tent won't be the deciding factor in enabling on-orbit assembly - any more than any particular tool would be. It'll just be a useful tool - catching loose objects, creating a better-lit environment, moderating temperature differences on materials, etc.-- TomRC, Aug 28 2002 Tom, you also have to factor in the cost of launching the satellite in the shuttle. That would be a significant cost, and more importantly would limit what the shuttle can take up to the station. At the moment, with ongoing building, I think NASA would hesitate to take up satellites in preference to lab equipment, provisions etc.
In fact it is quite difficult to get a slot on the shuttle, particularly at the moment. These theoretical millions that you would save would probably be wasted in revenue that you could have gained by launching earlier with someone else.
I had a look at your links (which should be placed in the link section under the idea), I think the first one counts as WIBNI. Building satellites from the ISS would be great, but it's unlikely to happen on any sort of scale soon. I've provided a link to the shuttle archives so you can see for yourself that there aren't many satellites going up on the shuttle any more.
As to the price of a shuttle launch - NASA is famous for being cagey about this. Launch costs have a habit of ballooning and although 1 billion is definitely on the high end of the scale, it is probably closer to the true figure than the one you quoted.
Coming back to the tent, I've already covered loose objects and temperature modulation is pointless. Satellites are designed to work in the temperature extremes found in space, so are space suits. I don't think the lighting is a big problem, astronauts cope with this all the time. You'd be taking away the awesome view without adequate reason.-- madradish, Aug 29 2002 [Madradish]There's no reason to launch the packed satellite on the shuttle - the Russians deliver station components and supplies with conventional launch vehicles.
On-orbit assembly has not yet been technically and economically proven in practice, but that doesn't make it a WIBNI. There are no difficult technical barriers to doing it. There is at least one company moving toward it. And NASA would be politically smart create another solid use for the ISS.
You dismissed the idea that loose objects are an issue - but loose objects ARE an on-going concern in any space construction work, and with satellite assembly it would be an even bigger concern. You don't want a key component floating off, forcing a retrieval or failed satellite. EVA is exhausting and stressful - fumbles do happen, especially given the clumsy spacesuits.
Temperature is a bigger deal for assembly than you imagine. Hot and cold metal parts may not line up - something as simple as a nut may not fit on a bolt if they are at different temperatures. Yes suits are designed with plenty of insulation - and as a result they (especially the gloves) are thick and clumsy. Anything that moderates temperatures would allow use of less insulation, making workers more efficient.
If you don't think high contrast light is much of an issue, try working on your car engine some dark winter night with nothing but the headlights of another car for light, and thick gloves on your hands so you can barely feel the parts.
If anyone wants an awesome view, all they need to do is stick their head outside the tent, or go inside and look out the window.-- TomRC, Aug 30 2002 <Rubs hands together>OK... Yep, you could definitely send components on a Progress or something. I misunderstood your //cover from savings on... launch costs// my mistake. I don't think it will be a whole lot cheaper to send a satellite up in pieces.
//There are no difficult technical barriers to doing it// Absolutely, there are also not that many technical barriers to sending people to Mars but it's not happening right now. It would probably be a smart move for NASA to start building satellites from ISS, but they are still too engrossed with putting the darn thing together. Also, on orbit construction was tried on a small scale on some of the early shuttle missions (ACCESS, EASE) and was found to be harder than anticipated. NASA will be building experience in this field with the construction of the ISS but it will still take some time for the techniques to be formulated and put to regular use.
Regarding the loose objects, I found a link that may explain it better than I am. Key tools and components are either packed or tethered, so they can't get away.
I concede that temperatures in space are a problem, but it is one that engineers have been faced with for decades now. I really wouldn't want to reduce insulation on space suits based on having a flimsy tent around people doing EVA, especially if it is intended to catch floating things. Any puncture would be extremely hazardous if not fatal, I would be inclined to distrust it.
The lighting is a pain, but the gold plated visor cuts out a lot of the excess light. I also think that if it was as big a problem as you are making it out to be, NASA would have found a workaround long ago.
//If anyone wants an awesome view, all they need to do is stick their head outside the tent, or go inside and look out the window.// Not quite the same though, is it?
I'm still curious to hear where you would place this tent in relation to the space station and whether it would be used only when an EVA is in progress.
It's good to debate with someone who is conversant with this field (pitifully few in Australia), feel free to email me anytime you have space related stuff to discuss... or just post it on the 'bakery.-- madradish, Sep 02 2002 Boys, this upscale chat is a pleasure to read. Why not have your light diffusing canopy on only the sunside of the shuttle? Looking like Christopher Lee's cloaking device in Clones...-- General Washington, Sep 02 2002 Clarifying [madradish's] point, the greatest reason not to have complete construction assembly in space is the lack of enterprise and bidding for assembly. Astronauts would have a cornered market if ony the few of them could do the job. Also there's a long way to go to replace a part that doesn't work out or is damaged during assembly. In addition, NASA has been designing preassembled satalites that conserve cargo space in transit for years. The ISS has major preassembled components that outsize demensions of the cargo bay but they are designed to unfold, telescope or pop-up into service once in place saving many astronaut man-hours and allowing relative effecient use of cargo space. If I remember correctly the ISS has photovoltaic panels the length of football fields but as thin as mylar. I don't recall if they unfold or unroll though.
[TomRC] However, I do agree that even just a turgid canopy of material could greatly improve productivity by defusing light better-[madradish] gold plated visors reduced glare but they do nothing for filling in shadows infinately the way diffused lighting can. Not even task lights can do it as well. I also agree that an envelope of the right material fabric could moderate heat loss/build up allowing for a more user freindly space suit design. I'm not talking room temperature comfort, just a tip of the scales in function to relieve the suit as the sole temperature moderator for the astronaut could allow for substantial *dextrous* improvements.-- hollajam, Sep 02 2002 <aims kick at GWs posterior> Boys? I wasn't last time I checked.
[hollajam] I don't believe that you were clarifying my point, rather that you were making one of your own. I don't think that this space tent would be worthwhile for improvement of lighting alone, and I still think that reduction of insulation in this context is too dangerous.
I would point to improvements in insulation as the best way of improving manual dexterity on EVA (and it definitely could do with improvement).-- madradish, Sep 02 2002 Since I was mistaken at the nature of madradish's point I'm glad that I went on to make the points I did about market bidding and astronaut monopolies in principle weighing against viability of space tent.
However, In support of my convictions for it.. it seems NASA astronauts have already 'been-there-done that' with a heat moderating parasol tent waaaaay back in '73 on Skylab. It worked so well that astronauts quickly modified it with 55ft. poles and made it into a bonafide A-frame tent of all things!
[Link]
<gyrating, rocking end zone celebration with self in window reflection><(soft-n-sweet) "wup-wup ooh ba-bay">> It reduced Skylab's inside temperature by 29 C (50 F) while Skylab was compromised by heat shield damage and suffering temporary power reduction. As for using a 'parasol' as a light diffuser; The concept would be as natural as coming up with the idea of using light colored fabric to make a tube tent for your light bulb display. It might help to think of such a simple device deploying similar to one of those beach goer's toss and pop-up type shade screens. Not neccesarily an UberGrandeBubble enclosure turgid by convection.
<setting up for free kick> Seems //paint chips// are real hazards for astronauts working in space after all... [Link]-- hollajam, Sep 03 2002 [hollajam] use the link section (under your idea text) for links, the url will not work in annos.-- Zircon, Sep 03 2002 I think it's a fish-- bristolz, Sep 03 2002 thanks, hollajam.-- yamahito, Sep 03 2002 [Yamahito],<curtsey> Much obliged.
[UnaBubba] //define sturgid// I haven't a clue UnaBubba but I'll have a go at it for you..
sturgid (stur'jid) -adj. [Colloquial-*Kansas*(?)] to swell 1) bastard child of /stern/ and /rigid/ combined> sturgid 2) reference to fish(?) as in: long dead sturgeon-- hollajam, Sep 04 2002 //Seems //paint chips// are real hazards for astronauts working in space after all...//
No one said that they weren't. UB covered that issue in his 2nd anno.-- madradish, Sep 04 2002 [madradish] Aside from [TomRC's] first anno, the only reference I could find to paint chip debris was that of [waugsqueke] //Seems to be solving a non-problem. Astronauts don't drop bolts or paintchips or screwdrivers because they don't use those things.// I understood that to be something like, "{Spacecraft} don't need paint jobs therefore no problem with paint chips" When in fact paint chip debris is a concern. My link was to provide a source to correct the misconception. I just happened upon it while looking for 'space tents'.
I think points in [TomRC's] idea have novel contributions to be considered. I don't think a full vehicle enclosure is the way to achieve those benefits for one obvious reason of needing to fire thruster rockets occasionally to adjust position. [UnaBubba's] idea of using two stage film for the lighting and heating factors assures my resolve in the value of a modified canopy's utility.-- hollajam, Sep 04 2002 [hollajam] Thanks for the references to the sun shade on Skylab and paint chips. Also the description of the problems Skylab encountered with automatic deployment after one thing went wrong are a good illustration of how on-orbit final assembly could have avoided problems.
One other financial factor I don't think anyone has mentioned - insurance. While most of the insurance cost for a satellite is due to the risk of a rocket exploding, some of the cost is due to the risk that the satellite will be damaged on launch, or otherwise fail to function. I would guess the added insurance cost just covering immediate on-orbit deployment failure is probably somewhere around 1%-5% of the launch vehicle and payload costs. (Insurance rates are now on the order of 16% of those costs - see link.)
If on-orbit assembly and test eliminates deployment failures and reduces subsequent failures originating from launch stresses, insurance rates should fall substantially.-- TomRC, Sep 05 2002 [hollajam]...
<snip>//It's hardly likely to prevent damage by orbiting junk, which is zipping along at around 60km/sec.//<snip>
Sorry I didn't make myself clear enough. As you observed, the parasol on Skylab was similar to what Tom is proposing. I just don't see why they wouldn't be using this already if it were at all useful. NASA engineers are hardly stupid.
Tom, you could be right about the insurance. I have some friends in the industry who may have an opinion on this. I don't think that it would eliminate deployment failures however. There is still too much to go wrong, and humans aren't infallible.
You seem to be mainly arguing for on orbit construction rather than the tent now, and I still want to know where and when the tent is supposed to come into play.-- madradish, Sep 05 2002 If you could get enough O2 up there, you could even eliminate the need for those long and perilous oxygen lines, although they'd probably be kept for safety anyway.-- NickTheGreat, Sep 07 2002 [madradish] The space tent would surround the on-orbit assembly area and create more desirable work conditions - better lighting, better thermal balance, better safety from loss of tools or parts.-- TomRC, Sep 16 2002 random, halfbakery