Fly To Mars In A Plastic Ship

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."

Comments

Plastic aluminum?

[Anonymous Coward]

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.

I want to say one word to you. Just one word.

[Mr.G5]

Plastics.

...and when the mission is over

[tinrobot]

You can toss your spaceship in the blue bin for curbside recycling!

a new fashion

[igny]

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.

Metals are becoming obsolete

[Sir Homer]

With carbon fiber 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.

I beg your pardon.

[reality-bytes]

 

it's an audio file with the intent of being news listened to on a portable audio device

Sorry to bring you up there, but my system weighs around 40kg now with the fluid cooling and it's anything but portable; even If I could work off with it, It'd rip the IEC out of the UPS after 4 feet.

Nasa

[3.09 a hour]

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 aerogel, seems to me they are doing cutting edge USEFULL research.

Re:Nasa

[FleaPlus]

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 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.

The risk?

[reality-bytes]

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.

Re:Not a Podcast!

[flowerp]

RSS URL is feed://science.nasa.gov/podcast.xml, smartass

I am subscribed with the iPodder app. Again, how is this not a podcast?

Re:But what's the point?

[The Master Control P]

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:Nature's way...

[khallow]

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.

Outgassing and thermal properties

[G4from128k]

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) to the Comet airplane crashes (learning that aluminum fatigues from repeat cycles of stress). I can only hope that NASA does something like LDEF with this material before depending on it to hold its properties for several years of space-exposure.

Re:Outgassing and thermal properties

[dbIII]

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.

Re:Outgassing and thermal properties

[back_pages]

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.

Polyethylene

[chroma]

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.

According to MatWeb, Ultra High Molecular Weight Polyethylene (UHMW-PE) has an ultimate tensile strength of about 40 MPa, while 7075 alloy aluminum has an ultimate tensile strength of 524 MPa . 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.

Re:But what's the point?

[ZosX]

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.

Plastic Kits

[MrSteveSD]

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.

Coming soon to a pair of scissors near you

[EEBaum]

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

[eaolson]

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.