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Ceramic fabrics can be used at heat shield components. I'm not at all sure about the effects of their porosity, though, in that application. These are largely alumino-silicate materials, with a solid phase change in the vicinity of 2350 F (1290 C). Take the material higher, and it embrittles and cracks apart upon cooldown. That's a lot lower than the typical meltpoint: 3200 F = 1760 C.
There's actually no reason that solid panels cannot be placed into contact as portions of a larger shield, almost regardless of the material used. All you have to do is stop the flow through the gap between the panels. You need some sort of gap-filler. Something like caulk would likely work.
Retro doesn't have to fire around the corner at the periphery. It can fire through ports in the shield, as long as the space behind is sealed, to stop gas throughflow. It does need to be multi-engine and canted a bit off-centerline. The cant angle stops the instability in the retro plumes.
GW
Two points: (1) partial pressure = volume % concentration x total pressure. I don't know myself whether flammability is more closely related to % concentration or to partial pressure, but I'd hazard the guess that is related to both, and probably more besides. That's a very complicated thing. Easy enough to experiment with in test chambers right here at home, though.
I would say that 42% oxygen is not as flammable as it sounds at low total pressure. 40% at 1 atm is something of a real fire danger with medical oxygen equipment. As for the proposed atmosphere, why include the argon? Just run a lower total pressure. Unless fire danger dictates otherwise.
POINT (2) suit pressure is fundamentally set by pressure breathing requirements, and would apply equally to full pressure suits, MCP suits, or any hybrid designs. The 1/3 atm pure O2 standard used by NASA for lo these many decades is overkill. You only need what you get on Earth: 20.9% O2 at sea level, which is 0.209 atm pure oxygen p-press, which is 3.07 psia. In point of fact, you don't really need to match sea level, in spite of the vapor pressure offset in the wet lungs. USN says pilots need O2 masks at 5000 feet, most everybody else says 10,000 ft. THAT sets what you use for breathing gases.
Say the USN is right. Total atm pressure at 5 kft is .8321 of sea level. That's 0.1739 atm partial pressure O2 in the air. At 37 C (body temperature), water vapor pressure in the (near-equilibrium) lungs is 0.0622 atm, leaving .7699 atm for the dry air, meaning you really have .1609 atm p-press O2 in the lungs. The suit has to match that, not other arbitrary criteria.
For a pure O2 suit (either or any type), you add back in the water vapor offset to see what dry O2 pressure you need in the suit. That's 0.2231 atm = 3.28 psia suit pressure. That IS the minimum. You should be as functional as any USN combat pilot at that pressure. That's not quite 23% of an atmosphere! Why do we need 33% of an atmosphere (4.85 psi), other than tradition not grounded in real science?
Even if you add a 10% kitty to cover leaks, that's still only 0.2454 atm = 3.61 psia. Use the 1.2 factor on that for habitat N2 p-press and you get .2945 atm = 4.33 psia. Your hab needs the same 3.61 psi O2 p-press and at most that 4.33 psi p-press N2, plus maybe some argon for fire risk reduction by dilution. So your hab pressure is 7.94 psi plus whatever argon you insist on using. If no argon, you are running 45% O2 at 7.94 psia (0.54 atm) total pressure. The low pressure should reduce flammability dangers some, if not enough, then by all means add some argon to the habitat atmosphere. No pre-breathe required!
The numbers are even lower if you use the 10 kft standard, even with the 10% leak criterion. USAF and airline and civilian/private pilots are all quite functional below that altitude without any supplemental oxygen.
BTW, the 1968 vintage MCP demo used 190 mmHg = 0.25 atm = 3.68 psia as its O2 breathing helmet and tidal-volume bag breathing pressure. Dava Newman's prototypes at MIT have reached or exceeded that compression. So, we CAN INDEED build suits like that right now, and they do NOT have to be as difficult to don as they were in 1968. It’s only corporate bottom-line politics that holds this back. That and inappropriate compression levels that are traditional within NASA. Tradition dies hard because people fear change, and some of them are making money on the status quo.
GW
I think the arguments about not settling in the first place you go, needing to see more than one place, are cogent. I also think it unwise and unethical to bet lives on technologies you are not virtually-100% sure of. Too many things are going to be very site-specific, such as ice availability. I also do not believe there will ever be more than one government-funded manned exploration mission to Mars. Not many in this community would agree with me, but most of government has become too stingy even to do its constitutional duties these days. That speaks volumes about manned missions to Mars.
Taken together, all of that says you send your one and only exploration expedition to Mars and you visit multiple sites with it. Anything less is just Apollo-style flags-and-footprints nonsense. You send enough stuff to do the basic mission even if all the ISRU stuff fails completely, simply because "it is the first time", and nothing else is ethical. You pick the "best" site of those you visit, set up your mini-base and all your ISRU gear, and leave your core-of-a-base there when you pick up and go home.
If ISRU propellant production really works, then you can fuel your landers as suborbital vehicles to visit even more sites. That's fantastic "gravy" beyond the basic mission. That's the smart way to approach this.
I think this sort of thing ought to be done by the "buddy system" for crew safety: divide up your crew so that one part goes exploring, while the other part watches over them with a reserve vehicle that could be a rescue craft. On a first (and likely the only) exploration mission, the best place to base initially is from is low Mars orbit. You need enough landers to have the reserve rescue vehicle, even if one of them has already failed. Later in the stay, when you set up your mini-base at the "best" site, you can base from that site on the surface.
No point going all that way, and having to abort your explorations, just because you were too stingy with the expense of sending lots of landers. You have to stay anyway, until the orbits are "right" to come home. So, go prepared. That's just basic common sense. Besides, engines that push landers can push things to Mars, too. A modularized approach to vehicle design makes great sense, if you multi-purpose your assets like that.
That whole concept leads you directly to a modularized orbit-to-orbit transport design, and re-usable one-stage landers. It leads you to on-orbit assembly by docking in LEO. Life support requirements for a 2.5 year mission lead you to the rest.
GW
Hi Quaoar:
If a folding heat shield can successfully be made, yes, it could protect a cluster of objects behind it. The key notion is one heat shield to protect all the objects.
You cannot survive as a cluster of objects each with its own shield. Each object sheds a shock wave impinging upon adjacent objects or connecting structures. Shock-impingement heating is simply not survivable with any technologies or materials that we have. Almost caused a fatal crash with the X-15 rocket plane in the 1960's.
The folding heat shield is a new technology item. No one has done it yet at full entry heating. It'll take a lot of testing and experience before that approach can be "trusted", especially with lives. Sure would be a nice thing to have, though. I think it can be done.
GW
Lander size depends upon what you attempt to do with it. If you do a minimal sort of Apollo-like stay, a small lander is OK. 5-7 mm dia near-cylindrical shape. The more tumble-home the sides have, the less heat protection they need on Mars. Such things could likely fly on a Falcon-Heavy.
If on the other hand you try to leave a functioning base camp, running on automatic, for the next mission to use, then we're talking about real construction of real permanent buildings. You'll need bulldozers or front-end loaders, concrete-like mixers, and a whole host of other construction equipment, plus a variety of bulky materials shipped from earth. Landers like that fall in the 15-30 m diameter range, and 30-100 tons at the very least.
It's mission objectives that drive this. Everybody has a different mission they'd like to see done, which is why opinions about the landers vary all over the map.
GW
In my post (#54 above), the radiation shielding is for the gardeners, not the plants. The specific worry is the extreme solar flare event. Those are lethal outside the Van Allen belts here, and Mars has no such belts. The data we have obtained at Mars does not, I repeat not, cover that event.
Like Robert Dyck, I do not think we need to build underground greenhouses. And most of the time at "reasonably low" elevations, cosmic ray radiation isn't much of a problem. For really temporary stuff, some sort of clear plastic inflatable should work. Maybe a few months. For something usable long term, you need "real construction" of some kind. Plastics just "die" when exposed to UV light and to vacuum.
The only problem with a clear roof is the solar flare radiation event. This is by far more a problem for the gardeners than it is the garden. But, if your roof is a shield, then your greenhouse becomes just another place to shelter from the flare event. "Suspenders-and-belt".
GW
Impaler:
What you describe (launching empty vehicles) is certainly an option. My figure-of-merit is shroud or payload diameter = 1.5 x first stage diameter for something that can fly stably out of the atmosphere. Bigger "hammerhead" configurations do not fly well.
I think small hand assembly has been deemed impossible up to now, precisely because of the idiotic spacesuit designs we have used since 1961. The gloves have gotten ever fatter and stiffer. They rip off fingernails now, quite frequently, as the shuttle and ISS astronauts describe it. So, it's far worse now than it was with the first spacewalks in 1964. At least in 1964 it was possible to pull the trigger on a small hand-held reaction pistol.
It is possible to think outside-the-box and do a mechanical counterpressure suit design, which is an evolved form of a partial pressure suit, adapted to long-term service in vacuum, instead of "just enough for a 10-minute descent". The test-proven successful elastic prototype of 1968 actually had thin, rather supple gloves, of about the same restriction as ordinary latex rubber surgical gloves. Small by-hand assembly would be easily possible with gloves like that.
If you pay careful attention to workpiece temperatures, there is no need for thermal insulation in the gloves, and you really can use thin, mechanical-compression gloves for vacuum protection. So, on-orbit fine hand assembly in LEO could be quite possible, and very soon, too. You do it inside a space frame covered with a bunch of sheets of aluminized Mylar. You hang a bunch of big electric lights inside, and use the lighting power that provides both (1) adequate visibility, and (2) radiation-equilibrium workpiece temperatures between about 0 C and 40 C.
For really fine work, mechanical compression gloves can be doffed for up to perhaps 30 minutes safely. This is based on a variety of experiments and experiences obtained over the decades. Barehanded work in vacuum for limited time exposures is entirely feasible, as long at thermal injury can be avoided.
I know nobody has already done this. But it could be done. And to do what we need to do for LEO vehicle assembly, it should be done, and soon, too.
GW
If you erect a clear-walled structure with a solid, regolith-covered roof in the middle of a small crater (or other depression), you can lay mirrors on the north side rim from east to west, so that sunlight bounces into the building through the walls.
You'll get quite a geometric concentration, because each mirror panel can be quite a bit larger than the projected area of the clear receiving wall. Mirrors can be nothing but aluminum panels.
Blow the dust off now and then with compressed Martian air. The vertical clear walls on the pressurized building will not generally collect dust. Can be 3 layers of glass, for good thermal insulation.
To compress Martian air, freeze it, put the dry ice in a closed vessel, and warm it. Sublimation in a confined volume is self-compressing.
This should work just fine at almost any latitude. Further from the equator requires more reflection panels to get the needed insolation into the building.
Better plan on auxiliary power to get you through a long dust storm: weeks to months, according to Mariner 9.
GW
According to CBS TV News tonight (Wed 11-12-14), "they" think the cold gas thrusters and the harpoons "failed" (no details), and that at least one ESA official is saying they "landed twice", meaning it bounced and touched down a second time by gravity.
The implication is that only gravity is holding it in place. It's down, but that means digging or drilling is problematical at best. One of the reports indicated there was some kind of screw hold-down mechanism in the lander's feet. Hope that works.
GW
update 11-13-14: now they're saying it bounced twice. The first one was a big, two-hour bounce, the second a small 6-minute bounce. No one yet knows exactly where it actually ended up, but it is in shadow, mostly cutting off solar power.
Falcon-9, Atlas-5, Delta-4, and (soon) Falcon-Heavy can launch modules to LEO in the 13-20 (soon 53) ton class, most of them around 10-15 tons right now. There's nothing about an orbit-to-orbit transport that cannot be assembled in LEO from modules like this. It's same as the way we built ISS, except the launchers far more-than-factor-10 cheaper than shuttle ever could be.
The problem is the Mars lander, which ought to look at least vaguely like a conical capsule, just a lot bigger. Perhaps 15-30 m diameter. That'd be too big even for the ridiculously-expensive SLS, so it'll need assembly from smaller components on orbit, which in turn eliminates the need for an SLS. That includes a sectionalized heat shield. Sounds risky, but we knew it worked in 1969 with the Gemini-B used on the one-and-only USAF-MOL flight. That was a reflown Gemini, by the way.
It'd be awfully nice if we had a supple spacesuit so astronauts in LEO could do small nut bolt and rivet work, as well as small wiring and plumbing connections. That makes assembling landers on-orbit in LEO much more feasible. We could have had one (a supple spacesuit) by now, the prototype tested OK in 1968.
GW
I hope the EM shield idea works, too. But if not, 20 cm of water wrapped around the flight control station makes a very good shelter for solar flare radiation. You have to have water and wastewater tanks for men anyway. So use them. And your food, which will in part have to be fresh-frozen (chunks of ice). Freeze-dried astronaut "food" doesn't last over about a year, maybe a year and a half.
With artificial gravity, waste disposal and treatment are far easier, and you can do conventional cooking with conventional frozen, fresh, and canned food. Plus your health stays good far longer. There is no need for more than a few days here-and-there doing zero-gee stuff, using zero-gee toilets, and eating astronaut "food".
I don't really see a problem with galactic cosmic radiation until we start sending colonists. Exploration crews just don't fly twice. One trip will hit career exposure limits in about 3-4 years in peak cosmic ray exposure years. You might get to fly twice if both trips were during minimum exposure years.
GW
Free oxygen is too valuable to waste on Mars. Take a machine similar to home oxygen equipment to concentrate the O2 into a closed but room pressure space as near-100% O2, and suck on that with a fairly conventional air-compressor-like machine to compress the O2 into high-pressure bottles for storage / use later. Believe me, it'll find good uses.
I think the first mission should erect some sort of base habitat building to be left on Mars, plus any greenhouses or other facilities where ISRU or gardening are to be attempted. That mission should have all the supplies it needs from Earth on that mission, no matter whether every single ISRU or garden experiment is a failure. Not to do that is unethical in the extreme.
That mini-base should be left running on automatic when the crew returns home, sending data, and waiting for "mission number two" to come and utilize it, whoever that might be. The easiest habitat building is an inflatable buried under regolith with a bulldozer. Greenhouses might not be so easy.
GW
Well, maybe the plastic body parts. But they didn't print the wires, they sure didn't print the electric motor, and no way in hell did they print the batteries.
And, I really doubt any of the fasteners were printed. I know metal can be printed now (although I do not understand how), but it is printed with the properties of castings or sintered parts, not the properties of real forged steel, not by a long shot.
Impact and fracture toughness depends upon both tensile strength and elongation/ductility. You get neither in a casting or a sintered part, not even one made of steel. You have to have those properties in the electric motor, the fasteners, and much of the suspension and wheels. Period. And the wires inherently need lots of elongation. Castings and sinterings in copper or aluminum have next-to-zero elongation.
GW
Actually, that's pretty close to the same ideas I've been proposing since the 2011 Mars Society meeting. It's an orbit-to-orbit transport with adequate life support, appropriate landers if Mars, all to be launched and docked together in LEO. It spins for artificial gravity.
GW
RobertDyck:
I understand completely about mission architecture bias.
I'm not sure there will ever be more than one government-funded mission to Mars with men, though. Not the way any of the agencies have behaved in recent decades.
It would be nice if that one government exploration mission did things in a smarter way, so that private or public-private partnership follow-on missions to establish a permanent presence looked more feasible. You do that by leaving usable assets behind that others can use later. Like landers in orbit. Like a small base building of some kind on the surface. Like an operating ISRU facility. Etc.
I think once you have a reusable Mars lander worked out, a decent Earth ascent-to-orbit scheme worked out, and some kind of orbit-to-orbit reusable transport worked out, that will fill the bill for the necessary human transport system, which can also be the same fleet that does cargo transfers. I've seen elements of all three proposed for a long time now, just not seriously funded.
And yet, any orbit-to-orbit transport and Earth-ascent-to-orbit system suitable for Mars can be suitable for anywhere in the inner solar system, even with today's propulsion. Landers for the moon and Mercury will be different, and you don't need a big lander for Venus or the asteroids. But that's the smallest part of the mission. An orbit-to-orbit ship design capable of transferring men with good life support, or massive amounts of cargo, that's the "biggie".
I haven't seen one of those proposed since the 1950's. Not by anybody in any sort of government agency. And yet it is the key thing.
But no, we're spending virtually all our money on a shuttle-derived Saturn 5 moon rocket to launch a new Apollo-on-steroids capsule suitable only for cislunar-length journeys, and with very little radiation shielding ability. And we're still lying to the public about how that capsule is the vehicle that takes men to Mars, when it quite simply cannot.
GW
Sorry, I can hardly figure out how to write text here. Inserting some kind of image? I have no clue. At my age it's rather unlikely I ever will.
What I had in mind was 5 modules arranged in a linear array, perhaps connected with cables (or trusses), and maybe some kind of adjustable-length personnel transfer tunnels between them. The middle one is at the spin center of what amounts to a baton-shaped object. That's the zero-gee module. The two end ones get the most a=V^2/R, the intermediate ones get less.
But with 3 radial levels like that, you can directly compare experimentally the effects of gee and spin rate from zero gee to full gee. If you rig this for various baton lengths, you can use multiple combinations of inter-module dimensions and spin rates, so that you can investigate multiple levels of spin rate as well as gee, all with the same facility, over time. It's spin rate and required gee-to-be-therapeutic that we need to know.
GW
I have no idea how "3-D printing" is supposed to convert rock dust into building bricks. I don't even understand how to print casting-quality metals with "3-D printing". But I do understand heat, melting, and vitrefaction. That last post I understand. All it takes is an enormous energy supply of great power (those are two different things, by the way!!) to effectively melt regolith into bricks on the moon, on Mars, on NEO's, on just about anywhere the surface is mineral.
What THAT says is that we need to develop compact lightweight energy supplies of immense energy and great power. Then ISRU becomes truly feasible, especially for a big base, or even a colony. So also does electric propulsion become feasible for something besides satellite orbit maintenance and the occasional robot probe mission.
Does anybody really see that power supply development going on in a way that might actually yield results? I do not. Be careful who you vote for. As it is now, they fund in a big way the guys who aren't doing these things. Look at the deeds, do not listen to the words.
GW
I've been skeptical myself, because I see no hint of a viable plan for survival in anything I've read about this. It looks to me like a one-way suicide mission. And if that's what it is, intended or not, it will set back human space exploration for decades at least.
Actually I had similar (but not as severe) qualms about Dennis Toto's flyby mission with a married couple. Except now that he's hooked up with NASA, his mission will never fly. Precisely because it was intended to shame NASA into actually doing something about men on Mars.
GW
Thanks, Impaler! Your cogent argument makes the very same case I have been trying to make for a long time: separate the functions of Earth ascent, orbit-to-orbit transport, and Mars (or anywhere else) descent in to 3 very disparate vehicles (or more, I'm not convinced that only one type of vehicle is suited for Earth launch). Give up the Apollo-on-steroids approach in favor of something that makes both technical and financial sense. Then go about creating the technologies and infrastructures needed to accomplish this (something absolutely not happening right now, at least at NASA et al, because they're still driven by the Apollo-on-steroids notion, mostly driven so by politics of big money).
GW
Just updating y'all on what I have heard about both failures. These are just public news releases, so who really knows the pedigree?
SS2 apparently pitched up when the tails feathered uncommanded, while under rocket power at about Mach 1 and near 50,000 feet. It completely broke up very rapidly, "ejecting" both pilots directly into the thin air, in street clothes and without oxygen, wearing chutes that require a manual ripcord pull. One managed to deploy his chute, the other did not.
Orbital believes a turbopump assembly failed on one of the two Russian antique engines, causing their rocket to lose thrust and start to fall back. That's when the range safety self-destruct was triggered.
GW
Why not do it right? 5 Bigelow modules connected by cables, parked not far from ISS, and spinning. Let the actual astronauts experiment with it.
The odd module is the center, and provides a safe entry point to get on and off the spinning lab.
By changing lengths and spin rates, you can investigate 4 to 40 rpm, and 0.2 to 1.1+ gee easily, and get the tolerable gee gradient information, too. We've got until at least 2020 to do this. How much could 5 Bigelow modules possibly cost, when supplied from ISS?
GW
Actually, when you get right down to it, a radioisotope generator is a nuclear reactor. One that uses decay instead of fission, and presents roughly the same risk of radioactive materials dispersal in some kind of accident.
Also actually, we've been launching reactors and radioisotope generators into space for decades now. All probes to Jupiter and beyond are powered this way, as solar is just ineffective that far from the sun. And, a great many of the spy satellites circling the earth are powered this way, and have been, since the beginning in the 1960's.
The Cosmos 954 crash in Canada in the 1970's was a Russian spy satellite powered by a plutonium reactor. There's a whole lot of those cores in very high orbits around the earth today. That was the design disposal method for that series of "Cosmos" craft. Not many folks want to face this fact, but it is true.
Kinda makes the fears about a nuclear explosion drive ship seem silly, doesn't it?
One day, we humans will have to go to high orbit and retrieve that radioactive junk for proper disposal. But there's time. Centuries, in fact.
GW
I saw the same news story. Surprised to see NTSB making comments this fast, but at least it may put the kibosh on some of the media circus. I updated my posting to reflect this development, this morning.
The discussions of possible rocket failure modes are still valid, but apparently don't apply to this incident with Spaceship Two. From what I can find, the fatal ground test accident 7 years ago was an NTO tank explosion, not a hybrid motor explosion. So far, their hybrid motor has a pretty good track record in testing.
GW
Stressing the body in zero-gee by using resistance exercise might work, for a little while. That's what they did on shuttle, and it's what they do on ISS. Most ISS crews are limited to 6 months, some crews apparently will be risked for up to 1 year this way. That's way short of what would be required for any sort of Mars mission, or any sort of in-situ mission to an NEO.
What THAT says is "it's all about the artificial gravity, stupid!"
That's the very thing we have never looked at on ISS, and the very thing that never appears in any of NASA's mission plans involving SLS and Orion. Now, do you understand why they wants robots to tow an asteroid (a very small one) to the moon, so they can go back to the moon with nothing but a 2-week moon mission, and call it an "asteroid mission"?
There are groups within NASA that are looking at manned Mars missions, yes. But the things that are seriously funded have NOTHING to do with sending men to Mars. THAT tells you what the REAL priorities are, no matter who says what about them otherwise. These priorities are set by Congress, which is about as competent to decide space program priorities as your average lab rat. Or maybe just your average cockroach.
It is no different in any of the other countries. We all do this completely wrong, around the globe.
Now, I don't know what level of gee might be therapeutic for maintaining the health of crews that must return to Earth. No one does, for sure. Those experiments have never been directly done. We evolved at 1 gee, but I saw some rather-credible stuff earlier in this thread that said 0.3 might be enough. So, we have bounded the answer as 0.3 gee < req'd gee < 1.0 gee. We know FOR SURE 1 gee will work, but higher gee is more expensive. Period. Hard fact of life.
I consider the gee gradient issue unresolved. All we know is that faster spin rates inherently cause higher gradients. There is as yet no answer on this that is in any way credible. Other than "mimimize the gradient". Those experiments MUST be run.
There are short term answers that say large rpm will be OK, but zero long-term experiments have been done. There's a lot of 1950-1970's experience suggesting that 3-4 rpm is about the long-term max for untrained civilians. There's no proof of anything, though. Those experiments still need to be run. Period. End of issue. We have not yet even bounded that problem.
Assuming that 4 rpm is acceptable for multi-year exposures, then 1 gee requires a 56 m radius, and 0.3 gee needs a 19 m radius. You either do that with cables, a truss, or a docked-module baton shape. What other choices are there? I see none.
Go with the one with the least vehicle inert fraction for whatever ship design you are looking at. Simple enough. There's probably different selections that are "best" for the different possible ship design approaches. "Surprise, surprise", as Gomer Pyle would say.
Any space agency or private corporation looking to send men to Mars using chemical (or even nuclear thermal) rocketry should be doing the experiments to resolve these issues. To make electric propulsion feasible for faster trips, to circumvent the microgravity problem, will require technological breakthroughs on power supplies, breakthroughs that have not happened yet.
A rule of thumb regarding technology development, which is always a proper thing to be doing: attempt vehicle designs only with existing ready-to-apply technology. If you make technology development success a requirement for your vehicle program, you WILL NEVER fly.
Welcome to the real world. Sorry to be the bearer of bad tidings. But at least I can point toward the most fruitful way forward: go find out (best possible speed) how much gee is enough, AND how much spin rate can we stand, both answers for very long term exposures(years).
GW
NTSB investigators don't have "field days" with anything. These are dedicated professional folks, and they will get to the bottom of it. It's the pundits, media, and political critics that are having field days.
FAA does not investigate air crashes, NTSB does. FAA may make or remake some rules based on what NTSB determines. Or maybe not.
Having two of these disasters, unrelated as they are, within days is causing quite a stir in the media. All sorts of irrelevant questions are being raised, and too many irrelevant conclusions being drawn. It's actually kind of sickening watching all that useless fuss going on.
I looked at what I could find in terms of verifiable accounts and photos, and there is not enough to draw any conclusions yet, for either Spaceship Two or the Antares rocket. I put what I could find, along with an explanation of some aspects of hybrid and solid rocket engineering, up on "exrocketman". It may be a long while before enough is known with certainty to update what I posted there.
GW
http://exrocketman.blogspot.com
"Two Commercial Spaceflight Disasters in One Week", dated 11-1-14