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Space Science

Fly To Mars In A Plastic Ship 234

Posted by Zonk from the wouldn't-go-any-other-way dept.
saskboy writes "NASA reports that an old polymer may be the spaceship material of the future. Polyethylene is in household garbage bags, and it is also an effective solar radiation shield. I learned three years ago in astronomy class that polyethylene is used in the sleeping quarters on current orbiting space vehicles, but now NASA has developed a way to toughen the polymer into a product they call RXF1 which is 'even stronger and lighter than aluminum'. As you may know, radiation in space is currently a major obstacle to manned missions outside of the Earth's magnetic field, so better radiation shielding is essential to planned manned missions to Mars and beyond. Get the mp3 podcast of the article here."
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Fly To Mars In A Plastic Ship More

Fly To Mars In A Plastic Ship

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  • Plastic aluminum? (Score:5, Funny)

    by Anonymous Coward on Saturday August 27, 2005 @05:43PM (#13417931)
    but now NASA has developed a way to toughen the polymer into a product they call RXF1 which is 'even stronger and lighter than aluminum'.

    Is it transparent?? Plastic usually is/can be. Perhaps this is what they really meant by transparent aluminum. We should really make sure none of this time's whales have been recently stolen!

    Why, no I didn't read tfa.
    • The article shows a picture (I've read it now) and it doesn't look transparent. While that doesn't mean it can't be, my hope for this material has suddenly shot down quite a bit.

      Especially since it doesn't yet handle temperature very well. Hmm.. not a good material for a spaceship, I'm thinking.
      • Once you activate the shields, I'm sure it will be fine.

      • Re:Plastic aluminum? (Score:2, Interesting)

        by sdpuppy ( 898535 )
        I wouldn't be surprised if the main structure could be plastic, with a thin(ner) outer shell of some metal. You get the heat (and tinfoil :-)) shielding from the outer shell but most of the strength would come from the plastic.

        If I were designing that thing, I'd put a space between metal shell and plastic - then you have insulation (or a thermos - open the valve in space to evacuate. :-))

        • "I wouldn't be surprised if the main structure could be plastic, with a thin(ner) outer shell of some metal"

          Wrong order dude. The light weight shielding has to be on the outside or you miss the point. Sure there will be some of the very energetic particles that penetrate the outer hull but the vast majority of the particles will produce the secondaries in the outer hull, therefore the low-Z material must be on the outside (to get the desired effect).

          • Re:Plastic aluminum? (Score:3, Interesting)

            by Rei ( 128717 )
            Well put, although geometry can throw a wrench into the issue (people don't fly around in nice spaceworthy two-layer spheres :) ). My biggest problem was with the intro:

            Polyethylene is in household garbage bags, and it is also an effective solar radiation shield

            No, it isn't. It's an effective GCR shield, not an effective solar radiation shield - for solar radiation, you want high Z.

            Would you, perchance, have seen a study that actually for once addresses bremsstrahlung doses with more than a passing menti

            • Re:Plastic aluminum? (Score:2, Insightful)

              by Anonymous Coward
              Would you, perchance, have seen a study that actually for once addresses bremsstrahlung doses with more than a passing mention? Every time I see a study on radiation exposure for a Mars mission, after long detailed calculations on what would be needed to meet minimal health standards, there's usually a couple of lines to the effect of "These calculations do not include the effect of bremsstrahlung radiation, which can be expected to significantly increase the total radiation dosage." All of the studies I've
      • Generally if you want to toughen plastic against UV and solar light degradation, you add in some pigmentation. At the time of StarTrek, space ship speeds were high enough that little time was spent near stars, so there would have been less need for pigmentation.

        If that's something that would satisfy you as "transparent aluminum", then pigmentation in the current version shouldn't disqualify it.

      • Not likely (Score:2, Insightful)

        by Quadraginta ( 902985 )
        Polyethylene is almost never transparent because it crystallizes very easily with its nice simple ...-CH2-CH2-CH2-... backbone. The resulting microcrystals scatter light and make the stuff milky. If you want transparent polymers, you use a backbone structure that doesn't easily form crystals, for example polystyrene, where the big benzene rings tend to jut randomly left or right out of the backbone.

        I would guess that their new form of PE is a variant on long linear PE, with reduced branching of the CH2 ba
    • Transparent things are usually not very effective radiation shields.

  • I want to say one word to you. Just one word. (Score:5, Funny)

    by Mr.G5 ( 722745 ) on Saturday August 27, 2005 @05:43PM (#13417932)
    Plastics.

  • ...and when the mission is over (Score:5, Funny)

    by tinrobot ( 314936 ) on Saturday August 27, 2005 @05:47PM (#13417953)
    You can toss your spaceship in the blue bin for curbside recycling!

  • a new fashion (Score:5, Funny)

    by igny ( 716218 ) on Saturday August 27, 2005 @05:48PM (#13417955) Homepage Journal
    NASA has developed a way to toughen the polymer into a product they call RXF1 which is 'even stronger and lighter than aluminum'.

    Yeah, and polyester hats should be much more fashionable than the tin foil ones.
    • Dude, polyester rocks. I wore this lime green polyester shirt for years until I gave it away. Now, aside from the sheer tackiness of it, what was most remarkable about this shirt was that it was in the same near-pristine condition when I gave it away as when I received it. Those fibers are tough.
    • I wear both. The plastic hat to block solar radiation (alien beams) and the tin foil to block out radio waves (human beams).

      You can never be too safe.

  • Metals are becoming obsolete (Score:3, Interesting)

    by Sir Homer ( 549339 ) on Saturday August 27, 2005 @05:48PM (#13417962)
    With carbon fiber [wikipedia.org] being as strong a steel at a fraction of the weight, and plastics that are bulletproof, and it becoming more and more likely that polymers will be used to build next generation cars, bridges and buildings as well as spacecrafts.

    • Re:Nature's way... (Score:5, Informative)

      by khallow ( 566160 ) on Saturday August 27, 2005 @06:19PM (#13418123)
      I don't think so. Metals still have a series of characteristics that aren't matched by plastics and advanced fibres. For example, steel is much harder than plastics (or the resin portion of carbon fibre), chemically compatible with concrete (another unfashionable material that isn't going away), handles compression loads well, easy to work with and machine, cheaper (IMHO), and recyclable. Things that handle significant localized forces like most screws or nuts, probably will remain metal. Weight critical applications (cars and spacecraft) will probably eliminate most uses of metals.

      But most architecture just isn't that sensitive to weight. For example, steel frame houses have significant earthquake resistance and are just more durable overall. Most bridges cover modest spans and can continue to be steel and concrete. Further one has to consider the problem of wind force. If your structure is very light for its surface area, then it'll experience increased jostling due to wind. Then you need to engineer some sort of means for stabalizing the structure, maybe guy ropes or some sort of internal computer-controlled weight that counters these motions.

    • I suspect not. (Score:2, Informative)

      by Quadraginta ( 902985 )
      I understand one of the disadvantages composite materials have, besides the fact that they cost more and are generally harder to work with, is that their aging and failure modes are hard to predict. If you build airplane or spaceship parts out of metal, you can do small-scale short-time testing of the material and accurately predict the lifetime of the part, its probable failure mode, how its properties will decline as it ages, and the warning signs of imminent failure.

      This is not true for composites. Acc

      • Re:I suspect not. (Score:3, Informative)

        by DerekLyons ( 302214 )

        Recall the RSS panels on the Space Shuttle, which failed in Columbia and in the CAIB test under surprisingly small impacts. This is not, I think, because the original engineers had their heads up their asses and didn't design for an impact with a bird or some such. I suspect it's because these composite parts are now 25 years old, and subtle changes due to aging have ruined their original design impact resistance, and have opened up unsuspected new failure modes.

        You may suspect that - but you'd be wrong.

  • No, seriously, what's the point of a manned space flight to Mars? What can they do that robots can't? Is it really worth the cost and the risk?

    • The risk? (Score:4, Insightful)

      by reality-bytes ( 119275 ) on Saturday August 27, 2005 @05:57PM (#13418014) Homepage


      There is no risk to you.

      Nobody is asking you to go to Mars and it just so happens that some people still have the spirit of exploration and adventure and will volunteer to go knowing the dangers involved. (I know this to be true because I would raise my hand for the chance).

      If America can't find someone to volunteer and do it for the spirit of exploration, China, a few years later will order someone to do it for prestige.
      • (I know this to be true because I would raise my hand for the chance).

        I would cut off my hand for the chance!
      • Yeah, but why would NASA bother sending volunteers there, knowing you'd be going blind from cataracts by the time you were in a position to do much to replay the investment in training and time?

        It's not kindness that makes them concerned about radiation damage. It's practicality.

        People smart enough to handle the job are valuable enough to keep healthy. People who aren't, aren't.

        Nothing personal intended here. It's just that few people know the effects of radiation as well as the government -- it's not ju

    • Re:But what's the point? (Score:5, Insightful)

      by The Master Control P ( 655590 ) <ejkeever@nNETBSDerdshack.com minus bsd> on Saturday August 27, 2005 @06:08PM (#13418067)
      Initially, it'll be the same point as the original manned missions to the moon: Proving that we have a bigger collective dick that the Soviets / Chinese while happenning to also do some science on the side. After that, our government and NASA will return to their usual psychotically-risk-averse stupor.

      We desperately need to get some competition going on in space exploration or nothing's going to get done. Come on China...

      • Re:But what's the point? (Score:5, Insightful)

        by ZosX ( 517789 ) <zosxavius@g m a i l .com> on Saturday August 27, 2005 @06:37PM (#13418231) Homepage
        How is this even flamebait?! What the parent said is true. We would have never have sent a man to the moon if we were not in a technological superiority race with the Soviets. While I will admit that going to the moon is an AMAZING feat for humanity to marvel at for a long time into the future, the actual scientific value of such a mission when compared to its cost is greatly diminished.

        That being said, we need to go somewhere other than earth orbit. If we keep going on into the future without looking at ways to live without earth we will be doomed to eventually perish here. The planet keeps getting smaller and smaller and the population keeps increasing. Eventually in the relatively near future we will either die en masse from starvation, lack of resources, etc, and (hopefully) leave some survivors, but we could easily become extinct as well. Technology is only going to help us now. If such a mass extinction of humans occurs they will have little fertile land to live off of and very few animals to hunt. We need to kick ourselves out of the womb before we as a race die like a stillborn fetus.

        The mother can only sustain our greed for consumption of natural resources for so long.
        • > While I will admit that going to the moon is an AMAZING feat
          > for humanity to marvel at for a long time into the future,
          > the actual scientific value of such a mission when compared
          > to its cost is greatly diminished.

          What about its financial value? I may be remembering wrong, but I thought the Apollo program paid for itself when you count revenue from inventions like velcro, Tang, and the myriad other materials and gadgetry (not to mention stimulting the nascent computer industry). IIRC the
    • "what's the point of a manned space flight to Mars? What can they do that robots can't?"

      Actually go there.

      What if all the great explorers throughout history simply sent robots (assuming they had them). We'd all be living in isolated tribes sleeping in huts.

      Humans (for good and bad) physically explore.

      We go places.

      Send all the probes and robots you want, but if there is a rock big enough to land on and explore in our solar system my bet is that we will eventually go there.

      At the moment space exploration is
    • robots should go to mars first, unfortunately bots can be quite dumb, so it might be a good idea to have someone there who has less than 16 hours reaction time to react quickly.
    • NASA currently has two robots wandering around on Mars. They have been wildly successful, instead of working for 90 days like they were expected to, they are still going after more than 500 days. On the other hand, they have only travelled about 2 or 3 km. What has taken each of the robots a year and a half to do, could arguably be done by one person in a morning (with a break for morning tea.)
    • ever see firefly? The earth will get used up one day. then where will we be?....... dead. we need to start developing tools to leave earth and the solar system.

      the asgard are not going to help us out on that one.
    • We've already sent robots - and they've done about what they can.

      Every new robot sent is going to get increasingly fewer returns. What a human can do is - anything. They can climb down in a gully we want to go to now, without spending a few billion more on a craft that MIGHT make it to the surface. Just because NASA has had a lot of success does not mean each new robot is assured of a landing, and once there will not break - especially if you are going in a canyon (when you can easily slip or loose signa

  • Nasa (Score:4, Interesting)

    by 3.09 a hour ( 812839 ) on Saturday August 27, 2005 @05:55PM (#13418001)
    Why in Bush's name are we cutting fuding to nasa? After this alumna-plastic and http://www.jpl.nasa.gov/news/features.cfm?feature= 490 [nasa.gov] aerogel, seems to me they are doing cutting edge USEFULL research.
    • Research makes the baby Jesus cry.

      Won't you think of the baby Jesus?

    • Re:Nasa (Score:5, Informative)

      by FleaPlus ( 6935 ) on Saturday August 27, 2005 @07:14PM (#13418422) Journal
      Why in Bush's name are we cutting fuding to nasa?

      Erm, where did you get that info from? Bush does many shitty things, but cutting NASA funding isn't one of them. In fact, NASA is one of the few non-defense government agencies which has actually seen funding increases. Bush even threatened to veto [msn.com] a huge appropriations bill unless legislators increased NASA's funding by a billion dollars.

      The official info on NASA's budget can be seen here [nasa.gov].

  • Yes, but... (Score:2, Redundant)

    by Ieshan ( 409693 )
    "even stronger and lighter than aluminum"

    Yeah, but really geeks want to know, is it transparent?
  • Plastics make it possible?

  • Outgassing and thermal properties (Score:5, Insightful)

    by G4from128k ( 686170 ) on Saturday August 27, 2005 @06:19PM (#13418125)
    I'd want to see how the material handles long-term exposure to vacuum and large temperature swings before using it in any space-borne structural applications. Most plastics contain plasticizers that help improve flexibility and handling properties, but which slowly evaporate leaving the material brittle (anyone ever see what happens to a plastic milk jug left in the sun for a year?). Moreover, plastics tend to have structural properties that are very temperature sensitive -- at modestly high temperatures, plastics slowly stretch to failure, at modestly low temperatures, they fracture. The "temperature" in space is strongly dependent on whether the surface is facing the sun or not. It's baking hot on the sunny side and freezing cold on the shady side -- not a good environment for plastics.

    The history of material science is the history of failures such as the catastrophic failure discovered in Liberty ship hulls in cold North Atlantic waters (learning that some steel alloys are brittle in low temperatures) [disastercity.com] to the Comet airplane crashes (learning that aluminum fatigues from repeat cycles of stress) [wikipedia.org]. I can only hope that NASA does something like LDEF [nasa.gov] with this material before depending on it to hold its properties for several years of space-exposure.
    • (anyone ever see what happens to a plastic milk jug left in the sun for a year?)

      No, sorry, can't say I have. I don't know the properties of cars left up on blocks in the front yard, either.

    • Re:Outgassing and thermal properties (Score:4, Informative)

      by dbIII ( 701233 ) on Saturday August 27, 2005 @07:26PM (#13418492)
      Liberty ship hulls in cold North Atlantic waters (learning that some steel alloys are brittle in low temperatures)
      Incorrect - that was well known before the Liberty ships were constructed but since it was wartime a lot of corners were cut in the design and construction. The Liberty ships are a good example because there were so many of them of similar design (4694) and so many that developed major cracks (1289) so we have plenty of information about what happened. The two major problems were the use of steel that normally wouldn't be used for low temperature service (hit it with a hammer at 0 C and it will crack very easily), and designs developed for riveted ships being applied to welded constuction without modification. Square sharp cornered hatches provided a point where stress was concentrated and cracks could start easily. One of the T-2 tankers, the Schenectady, actually cracked completely in half in the fitting out dock one night before the ship had even been launched. If you can track down the book "The Brittle Fracture of Steel - W.D.Biggs 1960" or "Brittle Structure of Engineering Structures - E.R.Parker 1957" there is plenty on these, newer texts typically just include a couple of photos and a couple of lines of text.

      The standard for testing whether steels are brittle at low temperatures that we use today was known about and insisted upon by Lloyds of London in the 1930s - it was just taking shortcuts and a two year refusal to acknowledge that there was a problem that resulted in so many of the "liberty" and "victory" ships having problems. Some ships developed major cracks but were kept afloat - since the crack started at hatch corners on deck. One ship used in Antarctic waters in the 1950s developed a crack that opened up to well over a foot across each time the ship went over a large wave in a storm. The ship made it back to port when the crew drilled holes in the deck and bolted steel beams over the crack to hold the deck together. Since these were welded ships they were effectiveley one peice of metal, so a crack starting on deck could go all of the way around to the keel, which is why some of the ships broke completely in half.

      Having square sharp cornered windows did the same thing with the Comet airliner - they also failed due to metal fatigue starting from a stress concentration. In the case of the airliner the fatigue properties of Aluminium (yes, americans spell it differently) were not considered to be important enough in the design process.

      Back to polyethelene - the effects of radiation on this material are very well known. Despite years of research the best material for some parts of artificial knee joints remains the polyethelene exposed to radiation to produce more cross-links that was developed in the 1950s.

      • Inferior steel and poor maintainance (rust) is the reason why fairly new merchant vessels are still routinely disappearing. They get into some rough seas and the keel snaps. Glub, glub. The vessels are comparatively cheap and insured. The small crews come from developing countries and there's no big, dramatic oil spill when an ore carrier sinks. It doesn't make the news and nobody cares.

        • Re:Outgassing and thermal properties (Score:5, Insightful)

          by back_pages ( 600753 ) <back_pages@NoSpAm.cox.net> on Saturday August 27, 2005 @10:44PM (#13419161) Journal
          Inferior steel and poor maintainance (rust) is the reason why fairly new merchant vessels are still routinely disappearing.

          This statement simplifies the problem to the point of being incorrect. I don't profess to have nearly the wealth of knowledge as the parent poster, but I have recently read and recommend The Outlaw Sea by William Langewiesche, which examines the modern merchant marine in fascinating detail.

          Strength of materials or maintenance procedures has basically nothing to do with the loss of merchant ships in modern times, except for the banal observation that both are involved when a ship sinks. So is water. The cause is closer to deregulation and an unchecked free market in the shipping industry.

          I don't think that a NASA-developed plastic space ship is going to experience deregulation or rampant capitalism. It seems pretty likely to me that someone is going to, oh, I don't know, check to see if the material is suitable for use in space before building a space craft from it. Just tossing that out there. By Slashdot standards, I'm probably insightful.

          • pretty likely to me that someone is going to, oh, I don't know, check to see if the material is suitable for use in space before building a space craft from it
            And after the shuttle o-ring design problem caused fatalities management is likely to listen to engineers about the suitablility of the materials for at least another couple of decades.
    • Personally, I think the way to test it is to use it as the hulls of some satellites that won't really need them after getting into orbit, but which will need occasional servicing. Then they could take a sample every time they went up to service it.
  • Looks like all that time making rockets out of washing-up-liquid bottles as a kid wasn't such a waste of time!

    I'm off to send my CV to NASA... now where are my crayons?

  • what's the melting point of the modified polyethelene? that would certainly bear into my deciding whetheer to make a space hull from the material.

    • You'd have more trouble with the freezing point of the plastic. Space is very, very cold on the lee side. Therefore, plastics will tend to become brittle in space. Also, you'd probably use different craft for landing and only use this one in orbit.

  • Polyethylene (Score:5, Interesting)

    by chroma ( 33185 ) <chroma@@@mindspring...com> on Saturday August 27, 2005 @06:24PM (#13418156) Homepage
    Polyethylene is one of the most commonly used plastics in the world, and is found in plastic grocery bags, cutting boards, milk jugs, disposable cups, and about a million other things. It's very stretchy, and thus is unlikely to break. It's tough, so that when it gets a hole or crack, the structure keeps its integrity. That's why I use it for armor on my fighting robots [tinyplanet.com].

    According to MatWeb [matweb.com], Ultra High Molecular Weight Polyethylene (UHMW-PE) has an ultimate tensile strength of about 40 MPa [matweb.com], while 7075 alloy aluminum has an ultimate tensile strength of 524 MPa [matweb.com]. The article claims that this new PE-derived material has a tensile strength 3x that of aluminum. I find a 40x improvement in tensile strength a bit tough to believe.

  • I for one... (Score:2, Redundant)

    by israfil_kamana ( 262477 )
    ... welcome our new plastic-encased overlords.

  • Plastic Kits (Score:3, Funny)

    by MrSteveSD ( 801820 ) on Saturday August 27, 2005 @07:17PM (#13418437)
    Actually this is going to make spacecraft a lot cheaper. NASA will be producing future vessels in kit form with components attached to a large plastic framework. Construction will be a simple matter of twisting off the right parts and gluing them in place.
  • toughen the polymer into a product they call RXF1 which is 'even stronger and lighter than aluminum'

    It would be more useful to be building cars out of this.

    • The specifics of how RXF1 is made are secret because a patent on the material is pending.
      My hunch is that it's just a fiberglass or carbon fiber composite, with polyethylene as the binder. In which case we already are building cars out similar materials. Then again, I'd doubt that's actually new. I'm working with parts right now that are fiberglass and nylon. Either way, the article overhypes it.

  • Plastics (Score:3, Informative)

    by cyberfunk2 ( 656339 ) on Saturday August 27, 2005 @08:46PM (#13418868)
    While plastics are incredibly useful and durable .. from a chemical point of view... I'm much less likely to trust them in terms of long term stability.

    I've seen these things dissolve in the slightest bit of an organic solvent (e.g. Dichloromethane or acetone)... and seen them melt with a souped up hairdryer (heatgun) at less than 200 degrees C. I wouldnt feel particularly safe with these materials shielding me from one of the harsher environs known to man (space).

    Maby it's just my experience of seeing these substances take damage a lot, but i'd be real uneasy to trust my life to them over a bar of aluminum, which you can easily dip in water/organic solvents and heat to rediculous heats without so much as loosing it's bright metallic glint, let alone the all important structural integretiy.

    If they're going to use plastics as a main part of the airframe, they're definately going to have to do some shielding from heat/radiation (U.V. light by itself can be quite destructive to certain plastics).
    • Lots of plastic is used in space.

      Mylar for example is extensively used as reflective material. You might recall the apollo lunar landers were wrapped in it, as shielding.

      Spacesuits are extensively made of plastic. Nylon, teflon, kevlar and dacron are used.

      As others have pointed out, temperature in space is not as severe as one might think (otherwise, the earth would be a giant oven or freezer -- the sun's heat has to go _somewhere_ after all, and it doesnt just vanish into another dimension after reaching t

  • Coming soon to a pair of scissors near you (Score:4, Funny)

    by EEBaum ( 520514 ) on Saturday August 27, 2005 @08:49PM (#13418878) Homepage
    As frequently happens with NASA tech, I expect this will make its way into the private sector.

    How long will it be until they're packaging our scissors, walkmans, and USB hubs in this stuff? You thought those packages are hard to open NOW!

  • Here's the important part of the article (Score:4, Informative)

    by eaolson ( 153849 ) on Saturday August 27, 2005 @10:36PM (#13419134)
    The article several paragraphs says,

    RXF1 is remarkably strong and light: it has 3 times the tensile strength of aluminum, yet is 2.6 times lighter -- impressive even by aerospace standards.

    "Since it is a ballistic shield, it also deflects micrometeorites," says Kaul, who had previously worked with similar materials in developing helicopter armor. "Since it's a fabric, it can be draped around molds and shaped into specific spacecraft components."

    So this stuff is a fabric, so the implausible tensile strength numbers are probably for the individual fibers, not for a solid piece of the material. (The photo has him holding a "brick" of the material though.) Spider silk is as strong as high strength steel, and is very tough, but no one is suggesting building spaceships out of it. 2.6 times less dense than aluminum gives it about a density of 1, which is what polyethylenes typically are.

    So they've managed to build a tough fibrous material. That's good, and it might make for a good micrometorite shield, and possibly a radiation shield. But it's not going to be a replacement for steel, titanium, or aluminum.

  • The radiation safety field has been using plexiglass (polymethylmethacrylate) as shielding against high energy beta particles for decades so its not very surprising that another polymer of a similar type can be used to shield against intrastellar particles of a similar type. The thing to understand is that although they liken the structure to that of a garbage bag, the higher the energy of the particle, the thicker the material needs to be and since those particles have very high energy in space, it is lik
  • Mix together garbage bag material space habitats and Bruce Sterling's idea that you would _want_ cockroaches in order to eat the sluffed off skin and stuff and it looks like interplanetary settlements will be about as glamorous as I envisioned life in a vacuum-sealed can would be.
     
  • ...buying all those Lego toys from kid! now I can be the first to Mars by building a Lego spaceship!
  • But I also love the fact that you can get your PIN number is space and use it at an ATM machines in space!

    Confused?

    Get the mp3 podcast of the article here.

    Or:

    Get audio of article here

    Or

    Get MP3 of article here

    The word podcast was complete redundant in that sentence. I mean, really.

    If any word should be found #ditch shot execution style, it should be 'podcast'. Please, make it go away!

    Back on topic: Compared to aluminum, polyethylene is 50% better at shielding solar flares and 15% better for cosmic rays.

    You a
  • Ahem, there's radiation and there's RADIATION. Plastics are good at stopping low-energy radiation because they have lots of hydrogen in them, and hydrogen has a good cross-section to interact with yur basic alpha beta radiation.

    But out in space you have to contend with COSMIC RAYS, which are a whole other kettle of fish. They're much more energetic. So much so that if your typical plastic stops a cosmic "ray" (they're usually particles), the plastic emits a spray of even less desireable radiation.

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