You have yet to provide a cite describing this thermal cracking process.
Wikipedia wrote:ThermochemicalThere are more than 200 thermochemical cycles which can be used for water splitting, around a dozen of these cycles such as the iron oxide cycle, cerium(IV) oxide-cerium(III) oxide cycle, zinc zinc-oxide cycle, sulfur-iodine cycle, copper-chlorine cycle and hybrid sulfur cycle are under research and in testing phase to produce hydrogen and oxygen from water and heat without using electricity.[81] A number of laboratories (including in France, Germany, Greece, Japan, and the USA) are developing thermochemical methods to produce hydrogen from solar energy and water.[82]
That is as much research as I am going to do for you.
KitemanSA wrote:are under research and in testing phase
So "in testing phase" has morphed to "(2x1087kg) you would have ~ 2.2E6/12 m² ~ 1.8E5 m². So: 32.6hr/kgm²/1.8E5m² = 1.81E-4hr/kg or 5.5E3kg/hr. Let us call it 5Mg/hr. "
Sorry. The only thing this "research" demonstrates is that your wits have been addled by fan boi kool aid.
Besides failing to cite thermal joules and kg output, you continue to delude yourself that Saran Wrap needs no support.
You might try this experiment:
Cover 40 acres with a single layer of Saran Wrap.
Now wave your fan boi Harry Potter Wand. Presto! Your 40 acres of saran wrap magically assumes the shape of a parabolic dish.
HopDavid wrote: Sorry. The only thing this "research" demonstrates is that your wits have been addled by fan boi kool aid.
Hmmm, doth #2 apply to you?
fanboi or fanbois 1. Derogatory. A person with an irrational attachment to a particular item or brand name, and an equally irrational dislike for competing brands or items. This behaviour is often seen during discussion threads pertaining to ISPs, computer hardware or motor vehicles.
2. A person who has a strong dislike of a paticular item or brand name may incorrectly refer to another who uses that product as a fanboi.
TDPerk wrote:If you assemble the edge fused pieces and spin it, it will do just that. For almost no structure.
How is this folded into a faring of plausible size? How is unfolded at arrival to LEO?
I can imagine this being done 20 meter diameter square solar sail such as Ikaros. A 40 acre paraboloid is a different matter.
Assuming you can spin out a 40 acre saran wrap paraboloid, how is station keeping accomplished? How is the mirror turned to stay in aligned with the sun? If attitude jets are attached to such a tenuous structure, attempts to move the structure will just tear it.
And once again I will note 285 kJ thermal cracking a mole of water remains unsubstantiated.
fanboi or fanbois 1. Derogatory. A person with an irrational attachment to a particular item or brand name, and an equally irrational dislike for competing brands or items. This behaviour is often seen during discussion threads pertaining to ISPs, computer hardware or motor vehicles.
2. A person who has a strong dislike of a paticular item or brand name may incorrectly refer to another who uses that product as a fanboi.
If an idea truly has merit, a thoughtful devil's advocate can do more to bring the idea to fruition than a thousand enthusiastic cheer leaders.
As an example, I played devil's advocate in a thread on mining propellant at the lunar poles. I argued metal is very brittle in the extreme temperature of lunar cold traps. Warren Platts was able to point to nickel alloys that work well in those temperatures. I now use his cite to argue heavy equipment made of nickel alloys can work in these environments.
I would love to see an actual method for cracking orbital propellant with so little mass. If you did provide cites, I would share them in future conversations on various forums.
So far you have provided nothing useful to back up your arguments.
My attempts to prod you to provide evidence has returned only crap. Until you flesh it out, crap is what your day dream remains.
HopDavid wrote:
Assuming you can spin out a 40 acre saran wrap paraboloid, how is station keeping accomplished? How is the mirror turned to stay in aligned with the sun? If attitude jets are attached to such a tenuous structure, attempts to move the structure will just tear it.
Too true. The solutions posed are pretty ridiculous and I'm surpirsed to read them in what is essentially an engineering forum.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis
Station keeping is trivial. You don't. You move the cracking apparatus.
Even unfurling it is trivial, you spin it and the unfurl is after the spin is begun.
There is no opportunity for turbulence, and there is no reason to believe the tension produced by spinning will not be effective in preventing tangles.
HopDavid long ago showed he passed the point where skepticism was productive, and instead is merely a sabot pitching pathology
And yes, hydrogen can be split effectively from water by heat and reactive surfaces, it is for example done in every biogas system on the planet, the feedstocks never being perfectly dry.
molon labe
montani semper liberi
para fides paternae patria
Seriously, that's not an answer. The answer is, you can't do station keeping with something that large and fragile. What you're talking about would be pushed around by solar wind and regularly misaligned by gravity acting on various parts. Also, you waste huge amounts of area by not pointing directly at the sun. You have to have a solution to station keeping.
What you could do is make many smaller such assemblies in order to minimize the forces on them and make them movable, but you'll still need some sort of light weight frame and you'd probably need many thousands of still enormous assemblies.
Remind me what was the point? Where did you intend to get the water?
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis
This item is only 1,500 feet across, and spun relatively rapidly. Hoop stress would clearly be more than enough to prevent buckling relative to the axis, prevent the need for continuous station keeping, and provide rigidity for what turning (precession works) is required. I suspect tidal forces may keep it aligned axially.*
The only vaguely challenging issue I can see is a need to resilver the inner surface without roiling the material with point loads--but at 1500 ft diameter, this is clearly within the realm of structures already built which face far higher loads.
To claim this is a very challenging, or even close to insoluble engineering problem, that to think otherwise makes one a "fanboi"; that's not reasonable skepticism...
...it's just being a prick.
*And if they did not, a single mast and stays would get it. Probable 10 tons max for that (could be 2), and 50 or so for the surface (could be 10). Figure 6 Falcon Heavies for the whole thing, if one is profligate with mass.
Last edited by TDPerk on Thu Jan 05, 2012 12:18 pm, edited 1 time in total.
molon labe
montani semper liberi
para fides paternae patria
We must be DESPARATE for something... ANYTHING... to natter about.
"You can't do Mars cuz the launch window is too small"
"You could launch a bunch of stuff over two years from Earth and just leave EO to Mars every two years."
"But, but all the propellant would boil away!"
"Not if you store it as water" (Note that the propellant is assumed launched from Earth over the two year period)
"Ohh, but you couldn't crack it into propellant. It would take 30 days/Mg using the ISS solar panels. It is just not REASONABLE."
"Thermal crack it. Kapton fim mirrors the weight of the ISS SP would allow 5Mg/hr, much faster" (Note, no specific call for a SINGLE massive mirror, just reflective area of that mass.)
"OOOO, but, but, but you couldn't control a mirror that size!"
WHAT SIZE? One mirror 500m across? Maybe 100 each 50m across?
Spin Deployed and Spin Stabilized structures have been around a while. I do not see much if any issue with use of them.
I also like swarming concepts, ie the use of many smaller cheaper devices to do the job of one larger stupid expensive one. Plus the inherently have more redundancy and work cycle.
In this case I think the discussion should focus more to movement of the raw material to the devices, and subsequent capture and storage of process products for future use.That would seem to be the bigger challenge at this point.