Shuttle Derived II - last thread crashed

RobertDyck · 2005-07-07 00:28:51

The problem isn't just the temperature Robert... you have to worry about ablation too, from the high-hypersonic Mach 30+ entry (massive asymmetric pressures too), which isn't just plain Hydrogen anymore... you've gotta worry about the super-mega-hot oxygen plasma in the atmosphere chewing at the corners of the fuel elements, spreading fission fragment oxide dust around...
Then there is the question, what happens on impact? If the fuel elements don't hit the ocean and hit anything but very soft ground, there is the risk that the fuel elements will shatter and disperse at least some. Heck, the elements themselves, even if they don't shatter, will contain enough high level waste to kill anybody within a city block... Its hard to describe in words just how much more deadly mostly & freshly spent highly enriched Uranium is compared to whimpy RTG fuel elements, or even more then commertial power reactor rod segments.
I just said it's your task to design a fuel element that won't pulverise on impact. Since you raised the concern of hot oxygen plasma, let's add that requirement. You're the nuclear advocate and a chemist; do you feel you're not up for it?
*Laughs*
Robert, I don't think you've got a clue what you are asking... dozens and possibly hundreds of professional materials scientists and chemists the world over (particularly at Sandia Nat'l Lab) are working on ultrahigh temperature ceramic compounds day and day out... its waaay out of my corner of the chemical sandbox.

So you don't want to work on anything? I said a few times that if you're not willing to do anything constructive yourself, you're not qualified to criticize. What exactly is your area of the chemical sandbox? Are you capable of exceeding it? I talk about aerospace engineering although I took computer science in university. I do have an advantage there: I wanted to be a "rocket scientist" since I was 7 years old. The correct term is aerospace engineer but that's the term kids used then. I watched the space program from Mercury-Atlas 8 when I was 3 months old. Last November I made a brief presentation to NASA about spacesuits; I was asked to condense it into a single presentation so I touched one reduced weight PLSS, thermal/scuff layer, helmet design, and operations for backup contingencies. Three years ago I presented a poster at the CSA workshop on a chloroplast based life support system, and presented it a year later at another conference. I'm still working to get lab space to prove the core concept works; a bio-lab said they will provide a lab and they do have the equipment but it's in storage, they're working to get building space. I'm also working on the envelope for a greenhouse, and have samples of film on order to build materials exposure test racks to be deployed at MDRS and FMARS. I already received half of the samples. I'll make 4 presentations at this year's Mars Society convention; one is Space Inflatables, dealing with the polymer film I found, its applications include greenhouse and a connection walking tube between habitats. I talked about asteroid mining here, that's another paper I'll present. My Mars mission architecture is another. The fourth is ISRU atmosphere harvesting. You're a chemist, perhaps you would like to comment on my presentation. I won't tell you ahead of time, you'll have to go the convention to hear it. I was thinking of presenting my ideas about spacesuits as well, but we have limited time and the moderator of the spacesuit taskforce wanted taskforce members to hear what the "heavy weight" researchers have to say. I will be at the spacesuit symposium.

So what is your field of interest? Interest is far more important than your day job, interest means you'll apply youself to the work and study. If you don't want to work on solid core NTR fuel elements, I can find something else. I'm really good at finding space related development projects.

GCNRevenger · 2005-07-07 08:16:36

"f you're not willing to do anything constructive yourself, you're not qualified to criticize"

*Coughs* Oh I think I very well can Robert... even in the scientific community, there is something called peer review.

My particular field is the physical chemistry of polymers, for want of a better designation, and since I have one foot in the materials science camp and another in chemistry... somtimes its just contracted to "polymer scientist" as the boss says. Getting enough background to be an effective researcher in the field of ultrahigh temperature lanthanide/actinide ceramics would take years of study even for me.

Like most "tertiary-education" level chemists, my interest is in my field... nobody would be crazy enough to do this to themselves for the money.

RobertDyck · 2005-07-07 12:46:39

I'm serious about the criticism. I have short patience with nay-sayers who criticise everything with no constructive alternative. Your comments aren't quite that bad, but close. I still haven't quite figured out what you do support. To "peer review" my feeling is you have to do work in the field. I'm trying to get you to do that.

If you are the polymer expert, then perhaps I can ask your advice about the film. I got excited about manufacturer spec's about PCTFE, including their claim one of its highlights is UV resistance. I thought its high transmission of UV-B (200nm to 300nm) was one reason. However, when I tried to look up the numbers I found the molecule http://www.accudynetest.com/surface_ene … ml]surface energy is quite high, on the order of nylon. Specifically, Polychlorotrifluoroethylene (PCTFE) surface energy is 31 dynes/cm, Nylon-11 (polyundecanamide) is 33, while Fluorinated ethylene propylene (FEP) is 18-22 dynes/cm. NASA uses FEP for the outside of satellites in Earth orbit, it's UV degredation is quite well characterized. The real kicker is when I found a document http://www.radtech-europe.com/download/ … ]Radiation Processing of Fluoropolymers. This states

Poly(tetrafluoroethylene) (PTFE) undergoes chain scission under normal conditions. This is exploited commercially, and that will be discussed later. However, there is an evidence [5-7] that irradiation of PTFE above its melting range (603-613 K) in a vacuum results in a significant improvement in tensile strength and elongation at 473 K and in an increase of tensile modulus at ambient (room) temperature. This clearly indicates cross-linking in the molten state, similar to effects caused by irradiation of polyethylene. At temperatures above 623 K, thermal depolymerization is increasingly accelerated by irradiation and prevails over cross-linking at yet higher temperatures [8]. A fairly detailed discussion of the process is in [9].
Fluorinated ethylene propylene (FEP) a melt-processible perfluoropolymer, when exposed to ionizing radiation at ambient temperature, it degrades in a similar way as PTFE, with the resulting reduction of its physical properties. However, if the polymer is irradiated above its glass transition temperature (80 °C) [10], cross-linking predominates and the result is an increase in viscosity. With doses above 26 kGy (2.6 Mrad), the ultimate elongation and the resistance to deformation under load at elevated temperatures are improved and the yield stress is increased. However, the improvements are offset by some loss in toughness [11].
Poly(chlorotrifluoroethylene) (PCTFE) degrades when exposed to ionizing radiation in a similar fashion as PTFE at ambient and elevated temperatures. Unlike PTFE, when irradiated above its crystalline melting point, it still exhibits chain scission [11].
Copolymer of ethylene and tetrafluoroethylene (ETFE), an alternating copolymer of the two monomers can be cross-linked by irradiation. Further improvement is achieved by the use of prorads (radiation promoters) such as triallylcyanurate (TAC) or triallylisocyanurate (TAIC) in amounts up to 10% by weight [8].

I include ETFE since greenhouses use that as the premier quality film on Earth. However, Dr. Penelope Boston raised the question of UV resistance, claiming it can't withstand UV in Utah (MDRS) much less on Mars. On researcher working on Advanced Life Support at Guelph University raised the question of outgassing ethylene. Trace quantities of ethylene cause premature ripening of fruit, so ETFE can only be used with plenty of ventilation; a sealed greenhouse on Mars won't have any ventilation.
I include PTFE since that starts the discussion of chain scission and cross-linking. My understanding is that cross-linking causes stiffness and cloudiness of transparent material.

Response of fluoropolymers to UV radiation
Fluoropolymers as a group exhibit exceptional resistance to UV radiation. The strength of the C-F bond makes them resist to pure photolysis. Moreover fluoropolymers, in general, do not contain light-absorbing chromophores in their structure or as impurities. For example, PTFE did not show any deterioration after 30 years of continuous exposure in Florida.
The outdoor durability of a fluoropolymer is directly related to its fluorine content [32]. Typically, fluoropolymers do not change after a long outdoor exposure (5-10 years) and only very sensitive analytical methods can find even the minute changes. Nevertheless, it was established that the rate and degree of deterioration depends strongly on the wavelength of the UV radiation with wavelengths shorter than 300 nm being the most damaging. Perfluoroplastics are very stable, but PCTFE tends to degrade rather rapidly under the UV light [33]. The effect of structures of several untreated and gamma-irradiated fluoropolymers on their response to UV radiation is reported in [34]. The most interesting finding was that PVF, PVDF and ETFE respectively exhibit increasing UV resistance. PVF undergoes significant degradation, ETFE does not show any changes and PVDF exhibits an intermediate response.

I'm rather concerned about the statement PCTFE degrades rather rapidly under UV light. Use of the word "the UV light" implies it refers to the same frequency band as the previous sentence, wavelengths shorter than 300nm. I tried to look up reference [33] "Wall. L.A. and Strauss, S., J. Research (National Bureau of Standards) 65, p. 227 (1961)" however http://www.nist.gov/nvl3.cfm?doc_id=89& … r]National Institute of Standards and Technology, as it's called now, only has on-line articles since 1982 and submitting a request is restricted to NIST staff.
I'm now thinking the solution is laminated film: FEP outside with http://chapters.marssociety.org/canada/ … Spectrally selective treatment, and PCTFE inside. I could go over temperature, chemical resistance, transparency, outgassing, and gas impermeability requirements; but UV resistance has me worried.

SpaceNut · 2005-07-07 13:10:57

I include ETFE since greenhouses use that as the premier quality film on Earth. However, Dr. Penelope Boston raised the question of UV resistance, claiming it can't withstand UV in Utah (MDRS) much less on Mars. On researcher working on Advanced Life Support at Guelph University raised the question of outgassing ethylene. Trace quantities of ethylene cause premature ripening of fruit, so ETFE can only be used with plenty of ventilation; a sealed greenhouse on Mars won't have any ventilation.

I would think that the ventilation of the greenhouse would be a natural thing; for you would want to keep the atmosphere inside the unit flowing with fresh CO2 and syphoning off the O2. In order to keep healthy plant growth going and to reuse what mother nature creates.

John Creighton · 2005-07-07 14:13:15

I'm serious about the criticism. I have short patience with nay-sayers who criticise everything with no constructive alternative. Your comments are quite that bad, but close. I still haven't quite figured out what you do support. To "peer review" my feeling is you have to do work in the field. I'm trying to get you to do that.

I think calling GCNRevenger is slightly demeaning towards his contributions to these forums. Pear review is a valuable service and it is important for the presenter of new ideas and alternatives to be able to address the criticism. GCNRevenger seems to be a very well educated and well read person who looks for legitimate technical problems in ideas which are presented. Truly sound ideas must be able to withstand criticism and review and GCNRevenenger provides that service well. Yes we need people to look for solutions and GCNRevenger does do a little bit of dabbling in rocket configurations but remember people have a limited amount of time and many efforts today are undertaken by large teams of people. You seem to be able to accomplish a lot Robert but try to keep you expectations reasonable about what a few people can accomplish.

SpaceNut · 2005-07-08 12:12:50

Thou it will still be a few weeks away, the 60 day review of CEV options are still leaking out as being Da Stick as referenced by space.ref and others.

New NASA launchers based on shuttle booster

The vertical design won out over a alternative parallel option based on a concept called Shuttle-C, where a cargo payload would sit on the side of the tank. NASA had studied this concept in the 1980s but abandoned it after discovering the design saved no money when compared with conventional cargo rockets.

I guess that there was a huge cost in the cargo container unit, though I really do not see why it would be all that expense. Unless it is the cost of the Shuttles main engines.

Admiral_Ritt · 2005-07-08 12:51:26

The vertical shutle derived stack I saw seemed to require Larger SRB's Are these developed yet?

This Griffin dude seems in a hurry. If we wanted to get to
Mars I can think of few better ways of speeding the
process up. Being able to hurl 330 MT into space in 3 launches is just the ticket.

I predict, (barring a "fireball" on the pad incident) A Mars
mission will be launched by 2019-2020.

GCNRevenger · 2005-07-08 13:55:47

"I have short patience with nay-sayers who criticise everything with no constructive alternative. I still haven't quite figured out what you do support. To "peer review" my feeling is you have to do work in the field. I'm trying to get you to do that."

Yeah yeah... I think that if you are really serious about seeing some of your ideas and considerd for an actual mission, then it pretty much has to survive scrutiny of its viability. This is entirely reasonable given the fantastic costs involved with spaceflight or any other large scientific/aerospace project. It is not, however, something to be despised... it is helps to refine ideas to the point where the probability of sucess is high enough to risk limited reasources on.

To get all defensive and "but if you don't contribute, then you don't count" is nonsense, anyone who is reasonably intelligent and essentially understands the tenants of your ideas are more then competant to question them, reguardless of their educational background. My own work will, one day, be questioned by people who are not well versed in polymer chemistry, but that does not disqualify them from being a critic.

What I want and advocate is for humanity to get off this rock, the long and the short of it, and learn to live elsewhere for a variety of reasons... material wealth from scarce atoms available in space, a frontier to restimulate humanity like Bob says, insurance in the event of planetary catastrophy, whatever... But to see that it is done, then we need to be serious about the means required and available to do it, so I like to critique ideas that I believe stray practicality too far, and when insight strikes to inject my own plans & thoughts about practical human space travel. The Moon just so happens to be the best site for material wealth, and Mars the best site for a colony, using exsisting or predicted near-term technologies.
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Use "Heat Mirror" as a means to protect a fluropolymer outter layer for your green house from UV and trap heat? The problem with that is that Heat Mirror (silver oxide) may not stick to fluropolymers very well. Heat Mirror used in today's windows is deposited (probobly via vacuum vapor deposition, perhaps by solution spay/dip) onto polyester films. Perhaps there is a colorless version of Mylar you could use... probobly has good permiability characteristics.

BWhite · 2005-07-08 14:56:14

What I want and advocate is for humanity to get off this rock, the long and the short of it, and learn to live elsewhere for a variety of reasons... material wealth from scarce atoms available in space, a frontier to restimulate humanity like Bob says, insurance in the event of planetary catastrophy, whatever... But to see that it is done, then we need to be serious about the means required and available to do it, so I like to critique ideas that I believe stray practicality too far, and when insight strikes to inject my own plans & thoughts about practical human space travel. The Moon just so happens to be the best site for material wealth, and Mars the best site for a colony, using exsisting or predicted near-term technologies.

I concur, pretty much 100%

RobertDyck · 2005-07-08 18:04:11

Use "Heat Mirror" as a means to protect a fluropolymer outter layer for your green house from UV and trap heat? The problem with that is that Heat Mirror (silver oxide) may not stick to fluropolymers very well. Heat Mirror used in today's windows is deposited (probobly via vacuum vapor deposition, perhaps by solution spay/dip) onto polyester films. Perhaps there is a colorless version of Mylar you could use... probobly has good permiability characteristics.

Is "Heat Mirror" pure silver oxide? The government web site said "silver based compound" and the manufacturer web site says "metal/metal-oxide". I just called V-Kool while composing this message, the guy I talked to said they use nickel, silver, and gold. Their technical document says it's a multi-layer sputter coating, "Metallized on the non-slip coated side with an metal/metal-oxide coating stacks". Substrate (on either side) is sputtered PET - "clear biaxially oriented PET". The outer most layer is a hard coat: "Ultraviolet cross linked acrylic clear coating." Mounting adhesive is 1.5 micron - Acrylic pressure sensative (PS). Dupont has a version of FEP film with one side cementable. Could we use FEP 200C outside with metal/metal-oxide sputter coated and PCTFE inside?

My real question regards your knowledge of polymers. Would this stand up in the UV environment of space.

Tekni-films makes PCTFE film laminate, it's sandwiched between 2 thinner layers of PVC film. They use Aclar brand of PCTFE from Honeywell. Could PCTFE film be directly bonded to the metallized surface? How does Tekni-films bond PVC to PCTFE? Why do they sandwich it? Is PCTFE soft and scratch prone? Should we add an inner scratch-resistant liner?

::Edit:: Honeywell also makes PCTFE film with the brand name Clarus, aimed at aerospace and military applications rather than pharmeceutical. Clarus has been used for outer protective film of electroluminescent lamps, touch screen displays, resin mould release film, packaging for corrosion-sensitive military stuff, and outdoor signage. It stands up.

::Edit:: To quote Robert A. Heinlein, any opinion no matter how expert is only opinion unless expressed in numbers. Scratch resistance is expressed in hardness. On the http://www.welchfluorocarbon.com/techdata.htm]Rockwell scale PCTFE is R105, Tefzel is R50, and FEP is R45.

GCNRevenger · 2005-07-09 20:05:41

Early versions of heat mirror probobly were pure silver oxide, but "late model" ones use a combination of elemental oxides to block different (wider?) portions of the spectrum most likly. As far as UV resistance, the question is does it need that acrylic "top coat" in order to stay adhered to the PET. If it does need it, then the question becomes can that acrylic layer handle the UV & oxidizing dust environment. If it doesn't, and the metal oxide coating is thick enough to block most of the UV, then yes it should be stable. (more to come later)

RobertDyck · 2005-07-10 01:49:57

http://www.v-kool.com/Pdf/VK70spec.pdf]V-Kool 70 is metal/metal-oxide layers sputter coated on adhesive (thermally-cured polyester compound). Then it's sputter coated on each side with clear biaxially oriented PET, 13 µm front and 23 µm back. The back then has 1.5 micron Acrylic pressure sensative (PS) to act as a mounting adhesive to bond to glass. This is applied window film. The front has a hard coat of UV cross-linked acrylic to act as a scratch-resistant coating. These layers make me think PET is only used as a bonding agent for acrylic.

Couldn't we simplify this by sputter coating metal/metal-oxide directly onto the cementable surface of FEP 200C? The '200' refers to 2-mil thickness, the 'C' means one side cementable. Couldn't we then heat bond 1-mil PCTFE directly onto the metal/metal-oxide surface? This would produce 2 layers of polymer instead of 5, with less mass per unit area. In metric that's 50.8 µm FEP and 25.4 µm PCTFE. These thicknesses of film are available directly from the manufacturer, so it only requires applying the metal/metal-oxide and heat bonding the laminates together. 1-mil FEP has a bursting strength (Mullen) of 11 psi @ 25°C, so 2-mil FEP alone should have a bursting strength of 22 psi; plenty to hold in pressurized air, especially if the Mars science mission uses 5 psi.

Service temperature for http://www.mcp.co.il/pages/products.html]C-PET is -40°C...+220°C, A-PET is -40°C...+65°C. Different forms of PET have different upper service temperature, but none are rated colder than -40°C. http://www.uniqueprinting.com/adhesive.htm]Pressure sensative acrylic adhesive has a low service temperature of -65°F (-53.889°C). That's reasonably cold considering Mars pathfinder recorded a low of -77°C over 3 days, but Viking 2 recorded a low of -111°C over more than a Martian year. Polyester has a lot of variety but I don't see one that can handle cold lower than -40°C.

SpaceNut · 2005-07-11 05:06:14

Here is what I can remember from semiconductor build from Metal on metal oxides; in that they tend to make capacitors. which I think could lead to to a static charge build up along the surface of the greenhouse material if not given a return path to ground.

GCNRevenger · 2005-07-11 17:54:15

"Then it's sputter coated on each side with clear biaxially oriented PET, 13 µm front and 23 µm back."

Probobly so they don't have to sputter onto glass, which is a real pain, since it needs to be done under vacuum most likly. Cycling an airlock for glass sheets doesn't lend well to continuous processing. Putting a big roll of PET film in the vac chaimber is much more efficent.

"Couldn't we simplify this by sputter coating metal/metal-oxide directly onto the cementable surface of FEP 200C?"

Probobly. Is 200C transparent?

"Couldn't we then heat bond 1-mil PCTFE directly onto the metal/metal-oxide surface?"

No. You might ruin the "flatness" of the metal coating that way most likly and disrupt its properties, particularly since you would need a temperature near or above the glass transition point most likly.

The best option would probobly be to use a low-temperature adhesive, which avoids the need for high temperatures. Getting one to stick to fluropolymers might be tricky however. Different types of polymers don't generally mix even when melted, so simply pressing them together when hot doesn't generally work that well either.

RobertDyck · 2005-07-11 23:07:37

"Couldn't we simplify this by sputter coating metal/metal-oxide directly onto the cementable surface of FEP 200C?"
Probobly. Is 200C transparent?

Yup. I have an 8.5"x11" sample of http://www.dupont.com/teflon/films/H-55 … tml]Teflon FEP 500C in my hand right now. The only problem is I can't tell which side is cementable. The http://chapters.marssociety.org/canada/ … f]spectrum shows FEP is more transparent than glass. (http://irc.nrc-cnrc.gc.ca/cbd/figures/060f01e.gif]Additional glass spectrum extended deep into IR. Also shows solar spectrum and terrestrial warm objects.)

"Couldn't we then heat bond 1-mil PCTFE directly onto the metal/metal-oxide surface?"
No. You might ruin the "flatness" of the metal coating that way most likly and disrupt its properties, particularly since you would need a temperature near or above the glass transition point most likly.
The best option would probably be to use a low-temperature adhesive, which avoids the need for high temperatures. Getting one to stick to fluoropolymers might be tricky however. Different types of polymers don't generally mix even when melted, so simply pressing them together when hot doesn't generally work that well either.

I suspect the PET of applied window film is the adhesive that binds acrylic. But PET and any polymer I know that isn't a fluoropolymer can't withstand the cold of a Mars night.

I found http://www.southwall.com/products/xir_laminaed.html]XIR laminated glass has even lower UV transmission than Heat Mirror or V-Kool. I found the plastic films transmit only 2% of UV, 56% of that is blocked by glass so they can quote 1% transmission. Fluoropolymer film won't block much UV so we would be left with 2%. XIR laminated glass uses PVB binder between two layers of glass. PVB itself blocks 99% of UV-A in the range 320-380 nm. Quoted figures for XIR are combination of glass, PVB and spectrally selective coating; the result is 0.02% UV transmission for Low-e clear, and 0.00% when applied to Amiran brand glass. We wouldn't have glass, but the combination of spectrally selective coating (metal/metal-oxide) with PVB (polyvinyl butyral) would mean 2% of 1% of UV gets through, which is the 0.02%. PVB is the binder for automotive laminated glass: safety glass for windshields. Could we use PVB to bind PCTFE to the metal layer? What is the service temperature of PVB? (I can't find it.)

GCNRevenger · 2005-07-12 18:37:25

PVB as a "glue" between layers? Probobly. I don't know if its physical properties suffer at very low temperatures.

Yang Liwei Rocket · 2005-07-14 11:20:36

After the Shuttle....comes another shuttle

NASA urges shuttle offshoot

officials say that a shuttle-derived vehicle would be cheaper and quicker to develop than its alternatives

NASA is telling Congress that the nation should build launch systems based on shuttle components as part of President Bush's plans to send astronauts back to the moon, FLORIDA TODAY has learned.

http://www.floridatoday.com/apps/pbcs.d … pps....007

is it a good plan, maybe this can push NASA forward ?

RobertDyck · 2005-07-14 20:06:20

"Since you're a polymer scientist I asked your help with film for an inflated greenhouse or inflated walking tube between habitats. How can you do this for your day job and not know PVB?"
Excuse me dear Robert, but did you know that there are quite literally thousands of industrial polymer products? I do, and you know what? The physical properties for the majority of them in conditions they wern't intended for probobly have never been reccorded by anyone. It is very possible that the information you want isn't available at all.
"I gave you a project to prove yourself and meet the qualification. Can't you even look up a simple little statistic for a constructive project in the same field as your day job?"
"Gave me a project" sounds like you are my superior or something Robert, which is not the case, and I looked through the usual handy chemistry references as a favor, not a test. I am quite offended that you think I am perhaps "not on your level," which I most certainly am.
That "little simple statistic" would involve some days or perhaps a week or two of work and probobly several hundred dollars worth of supplies and instrument time, if equipment for very low temperature testing is even readily available... Which is probobly why nobody has botherd to do it on a obscure and expensive polymer of limited usefulness to get into the Polymer Handbook.
I don't think you even know the difference between a chemist and a chemical engineer anyway.
Now if you will ask very nicely, maybe I will take some nontrivial time out of my day to look for dead-tree chemical engineering references (rather then the straight chemistry ones at the office) at the library the next time I am by that way. I try and do something nice for you, and look how I am repaid.

You posted this in the "Early retirement for orbiter?" thread, but since it deals with an issue we addressed here, I'll respond here. I would like cordial relations with everyone in the Mars Society, but we've had arguments on this board for so many years that one individual commented on our "famous" debates at the 2003 Mars Society convention. I guess we're destined to lock horns forever. (Hint: Go to the https://www.marssociety.org/secure/regi … nvention.)

If it sounds like I think I'm better than you, let me put it this way. I am better than anyone who doesn't do anything. But it doesn't have to stay that way. Do something, anything Mars related and you will instantly be my equal. If it sounds like I'm challenging you, that's because I am. Let's be very clear: everyone who makes any presentation at the Mars Society convention or any symposium or other gathering is my equal. Anyone who actually gets funding for their project is better than me. (Hopefully I'll get funding soon.) Now let's see if you can be better than me: can you get funding for a Mars related project before I do? At least work on something. Anything. I asked your help for one project because you said this is your field. I would really appreciate your help, but if you don't want to work on it then work on something else. I've noticed your message count is higher than mine but you haven't been part of New Mars as long as I. If you have time for this many messages then you have time to do something constructive. It's too late to submit an abstract for this year's convention, but I seriously want to see you present something next year. And please come to this year's convention. You can criticize my presentations and bawl me out to my face.

GCNRevenger · 2005-07-14 22:53:54

"I am better than anyone who doesn't do anything. But it doesn't have to stay that way... you will instantly be my equal. If it sounds like I'm challenging you, that's because I am."

Blah blah, nonsense! This attitude is a great way to never get taken seriously, just like your absurd Shuttle-C development times or whatnot... Knowing about the subject at this level of science and engineering is enough, tangible accomplishment is unessesarry.

"If you have time for this many messages then you have time to do something constructive."

I did look in the references that were easily available, and I didn't find what you were looking for. Its very possible that the information you wanted doesn't exsist. Have I not already explained this to you? And you are asking an engineering question more then a chemical one, we don't have volumes or databases of such information about obscure materials laying around.

In fact, with the very nature of criticism in refining ideas and plans, that in itself is "doing something constructive. I like doing it, which is one reason I have such a high post count... that and the twenty-odd pages of Errorist's crazy ideas.

dicktice · 2005-07-15 11:05:00

May I butt in? RobertDyke, you are waisting your time challanging RCNR. You'll have more luck with Yang Liwei Rocket, who is more or a free thinker. I've derived a great deal from RCNR, who's generous to a fault with his opinions and advice: A true Engineer's (or Devil's) Advocate, in fact. My own work keeps bringing me back to the (now) Russian Buran shuttle history, and what might have become a Russian cooperative-programme, instead of the counteractive-programme under the old Soviets. A study of the design decisions that resulted in the Buran/Energyia spacecraft, supporting infrastructure, prototypes and test fixtures are too well documented to be denied. It's strange that no reference is made regarding what was successfully accomplished, in such different ways to NASA's approach to the Space Shuttle. They truly Alternative Histories, on account of all that secretiveness on the part of the crazy Old Soviets. Now it's NASA which is secretive, and the Russians who are open. Why is this? when the only threat to World peace is so-called Islamic Terrorism--where Spacetravel has no significance, as far as I (in my ignorance of Muslim notions of Paradise) am aware. I'm amazed that the Energyia modular heavy-lift launching system hasn't been appropriated by now, quite aside from Buran, for shoving the rest of the ISS elements up to LEO.

SpaceNut · 2005-07-15 11:13:09

NASA is considering retiring a Space Shuttle orbiter in 2007 and beginning modifications to one Shuttle launch pad at the Kennedy Space Center under a plan now being reviewed at NASA headquarters, according to senior agency sources.
If this plan is adopted, the chosen orbiter would only fly three or four additional missions after STS-114- Discovery or one of the other remaining vehicles would result in its transport to the National Air and Space Museum facility at Dulles International Airport in 2007.

What makes Nasa think that they will save any money with this plan? In my way of thinking if this notion could be done it would have already saved at least 6 billion or more from the last 2 years of non flight of the remaining shuttle fleet. They have had nearly 2 years and have not save a dime while not flying any of the shuttles. How do they think that not flying one of them would change that fact to allow for CEV money to be freed up.

RobertDyck · 2005-07-18 21:19:49

I received the referenced paper on PCTFE! It's entitled "Pyrolysis of Fluorocarbon Polymers", Leo A. Wall and Sidney Straus, December 15, 1960. Published in Journal of Research of the National Bureau of Standards -- A. Physics and Chemistry, Vol. 65A, No. 3, May-June 1961.

This paper reports UV degradation of PCTFE at temperatures close to pyrolysis temperature. The report states all polymers so far studied undergo photoinduced thermal depolymerization at about 100°C below pyrolyisis temperature. The PCTFE plot shows pyrolysis rate measured at 420, 410, and 400°C, and photoinduced thermal depolymerizaiton at 371, 366, 361, 356, and 351°C. There is a clear relationship to temperature.

The report also states it "showed a feeble though definite response to the ultraviolet light used. This polymer does not absorb light except at lower wavelengths and hence the result was not unexpected. The photo rate observed was probably the result of light absorption via impurities since, during successive runs on the sample, the photo rate markedly decreased." The tests used a medium-pressure quartz mercury lamp.

Does this mean degradation only occurs at short wavelength UV and high temperature? Will cold keep PCTFE safe?

GCNRevenger · 2005-07-19 17:15:57

If the paper is correct about impurities being the source of the UV absorbance, then yes it should. As long as you don't set a heat lamp, air heater, or hydroponics pump etc' on the material then its a safe bet (safe enough to move to the experimental stage) that there wouldn't be any signifigant UV degredation.

BWhite · 2005-08-01 08:32:03

http://www.thespacereview.com/article/421/1]Griffin vs Rumsfeld - - do we have peace?

SpaceNut · 2005-08-01 10:56:42

Well here is a little more on the derived versions for shuttle piece and or the delta/ atlas route in this article.
NASA's New CEV Launcher to Maximize Use of Space Shuttle Components

Much like the NASA's moon architecture in the orland sentinal.

Can we trust the side mount to not be damaged by the foam, or is the hull hardened against such damage?

New Mars Forums

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