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Wasn't trying to be "rigid" about anything. I do tend to be very facts-in-front-of-me based, very empirical.
GW
Why use NASA mismangement? Use what already works in the private outfits.
GW
As good an item as a Skylab 2 might be, why not try another notion?
Dock a bunch of appropriate modules together into a long baton shape, a lot of them Bigelow inflatables with specific equipment cores. Put the docking adapters and the solar wings in the middle at the baton cg. Spin the thing end-over-end for artificial gravity, varying from 1 gee at the ends to zero in the middle. 56 m radius at 4 rpm is 1 gee. Use it to experiment with everything we do now, plus learning about artificial gravity and partial-gee effects (for the first time). It's also a basic technology prototype for the kinds of deep space orbit-to-orbit ships we will need.
Add a free-flyer module alongside that is your repair/assembly bay plus your zero-gee habitat. The assembly bay is where you experiment with lighting for temperature control in a zero-gee unpressurized "shop floor" environment. This is where you try out new maintenance procedures and new spacesuit designs, to make possible real self-repair and self-rescue techniques for long missions. The habitat is where you continue the zero-gee research we do now.
Using whatever is at hand at the time, experiment with and develop in-space refueling procedures, up to and including cryogens, as another free-flying-alongside item, just at a safe distance in case of an explosion. These would initially be things sent up, until the techniques are developed. Then we can incorporate them as routine operations into the spin station and the zero-gee free-flyer.
Given today's per-unit launch prices to LEO, this thing could be built of nominal 15 ton modules for a whole lot less money than ISS cost us. While more expensive than another Skylab, it does so very much more of what we need to do, if we really want to fly men outside cis-lunar space. It does more than ISS ever could, at a fraction of ISS's cost. (I don't have a good figure for that, but the direct launch costs are now factor 10 lower for the same thrown weight.)
What we have been doing up to now (from Skylab through ISS) demonstrably doesn't address all the issues we now know we must address for deep space manned travel. You have to do something new in order to address what has been heretofore unaddressed. Seems like basic common sense to me.
GW
Yep. XCOR has been flying piston-pumped engines in two rocket airplanes starting several years ago. These rocket engines end up with a maintenance lifetime resembling ordinary piston aircraft engines, or even better, approaching turbine.
They started with ordinary storables, went to LOX-kerosene piston pumped (that's Lynx), have done LOX-methane, and even LOX-LH2, all piston pumped. Sizes are still fairly small, I think the Lynx engines are each about 2700 lb thrust. But the technology is definitely scaleable, since they are turning the pump at a tiny fraction of its rated speed.
What's the significance of the photo of the pretty old Ryan? Is somebody learning tailwheel?
GW
Rock Em Sock Em Robots! I love it! Could help crews stay sane, doing that!
We ought to do that down here, too, to settle disputes! Get it out of your system sort of thing.
GW
I don't know anything about any MIT study (68 days). But, there are short-term and long-term survival issues. In the short term, they'll live as long as the food, water, and oxygen hold out. That could be for months to a year or so, given regular supply shipments from Earth. And that's where it'll fail: shipments from Earth will stop, or never take place. Precisely because they're expensive. I'd hazard the guess that's what the 68 day figure really represents: supplies run out, no more coming.
Self-supporting colony? Nonsense. Especially with a minimal-budget operation like this (it's a non-profit, after all). We cannot even run a closed-cycle ecology here on Earth successfully where conditions are far less lethal. What makes you think a greenhouse will work "first time up" on Mars, where conditions are so much more lethal?
Longer-term, assuming that the supply problem is licked: it'll be health issues attrition that gets them, plus accidents. There will be health issues from radiation and from low gravity, plus the effects of breathing gases different from air for long periods of time. These may or not be significant, compared to accident and ordinary diseases, we just don't really know yet. What happens after your only medical doctor dies in a space suit accident? There's no back-up. That's the problem you inherently have with small colony populations.
IMHO, we should be looking at bases manned intermittently for relatively short periods, not colonization. Use the bases to figure out how to really live off the land. Then do the colony, and do it in a big way, so that the no-back-up problem of a small population doesn't bite you.
GW
Don't be misled, I'm not one of the "electric universe" enthusiasts. I don't think they're at all correct in attributing everything to electrical phenomena.
But I do think we are wrong to routinely ignore the possible electrical effects among all the other explanations for the weird things we see. Spacecraft charging was (and still is) a real design issue. So far, that's the only verified instance, but why dismiss it in other scenarios before investigating?
GW
I'm thinking "high-power" solar electric propulsion means one of the newer panel designs with more watts per kilogram of hardware, coupled with a bigger electric thruster of some significant-factor-larger thrust level. Of course they can do it. They should do it.
GW
I would think if you built the engines on those propulsion sections to be long-life reusable (whatever that might actually mean), there would be little need for refurbishment after every use, until that operating life runs out. Thus you could just do in-space refueling and supply-loading at the L1 point. Returning the stage to LEO for refurbishment should only be occasional. You get to send more propellants and supplies most of the time, if you're not ferrying inert stage weights around.
Maybe such engines exist and maybe they don't yet. Spacex at least thinks they have one in the Merlin 1D's. We'll see. At small thrust sizes, maybe XCOR has one in their piston-pumped Lynx engine. That's because the highest risk of failure in rocket engines has to do with turbopump machinery. They at least think they can scale up to larger sizes, too. That extends to methane and hydrogen, not just kerosene and LOX.
One or the other of those approaches, or maybe something else, will give us the long-life, low-maintenance liquid rocket engines we need to make this transportation happen efficiently. And I think it's not very far off. Both companies I mentioned are making good progress.
My suggestion does imply that we develop in-space refueling well enough to make it both safe and reliable with mild cryogenics. Most folks are talking LOX and methane these days. The Russian refueling is with simple storables, NTO and one of the hydrazines, if memory serves. NASA has never learned how to do any of this for itself, though. It's this issue, probably more than long-life engines, that limits our ability to do replenishment at L1 instead of coming back every time to LEO.
We'd have to start with exactly your suggestion, but we'd have to work on long-life engines and in-space cryo-refueling to make it more efficient, which is my suggestion.
Given what I have been saying about NASA declining elsewhere, I think I'd look to the private companies to actually get this done. If one of them sees value going to the moon, something like what we are discussing is the better way to do it. It'll happen then, and not before.
GW
Expecting things from NASA to make rational sense at the strategic level is not realistic, for reasons I have offered elsewhere on these forums. I tried to pull all of that together into an article title "Stagnation in Space?" posted 1-17-15 at http://exrocketman.blogspot.com.
Mr. Bolden is not (and never has been) free to actually-manage the selection-of-projects of the organization he is in charge of; all its high-dollar items, down to procurement of items from vendors, is mandated by Congress, whose members are pathetically-obviously incompetent to be making such decisions.
Between that and the effects of growing too bureaucratically large, you are essentially witnessing the death of the American manned space program. This has been going on for some decades now; it just takes the giant a long time to fall over. It could still be reversed, but I see none of that going on, which saddens me greatly.
I think what you will see is an end to all American government-funded manned space flight in the next several years, without ever really going anywhere, not even back to the surface of the moon. The government-funded science and planetary probe efforts will continue, as the public actually supports some of that. But manned activities will transition to private entities, and to other countries like China.
I really hate being a pessimist, but that is what I see going on.
GW
Responding to Spacenut in #82:
Want a small "shipyard" we could build almost right now? Take a look at what I posted in the article "On-Orbit Repair and Assembly Facility" dated 2-11-14, located at my blog http://exrocketman.blogspot.com. This includes an unpressurized but thermally-stabilized and well-lit work bay, and very supple MCP suits to eable the necessary dexterity. I intended it for LEO, but it would work for this L1 refurbishment application. You only man it and use it when you need it. In point of fact, I would now put one on any Mars mission orbit-to-orbit transport design, as a part of avoiding the costs of a dead crew.
GW
Hi Void:
Lots of theory possibilities, with few facts to support or contradict them. Perfect for an academic investigator. Nice work if you can get it. Wish I could.
There is this starting to come out about asteroids and comets: both types seem to be extremely variable in their construction and in their volatile content. I think before we are through, we'll find there is no distinction, that there are no asteroids vs comets. There is only a broad spectrum of very heterogeneous bodies that range from dry to icy. Just my opinion, few yet agree.
And some of the weird phenomena that we see may actually derive from electric effects in addition to the physical/chemical stuff we have been considering. After all, the solar wind is a plasma. And it could easily change its charge state balance as it flows outward from the sun. There's celestial bodies to scrape off some of the electrons as it flows by. Also just my opinion, very few yet agree.
GW
Responding to Void in #78: The original group doing nuclear explosion propulsion at General Atomics San Diego in the 1950's actually flew a subscale model, even though they weren't supposed to. It flew fine on pulses of ordinary high explosives (presumably dynamite). 1-meter long model. So, yes, chemical explosion propulsion is possible, at least in an atmosphere where there are blast wave effects.
In space, no. There is not enough thermal radiation released by chemistry to push anything. It takes nukes to do that. There are no blast waves in space.
The old 1959 Orion explosion-drive design used fractional-kiloton devices for surface launch where there were shock waves, and multi-kiloton devices in space, where the nuke shaped-charge effects caused a thermal radiation spike through a reaction mass (incorporated into the device) which was converted to extreme high-speed plasma. That plasma blob plus the thermal radiation spike are what put the "push" on the pusher plate in space.
That being said, how about putting your "bucky bombs" into a liquid as a dense slurry, and using that as a monopropellant?
GW
Responding to KBD512 in #77 above: Why not leave the landers at L1, and shoot the supplies straight there? Why drag the inert mass of the landers back-and-forth from LEO to L1? Otherwise, I love your idea!
GW
Trying to answer RobertDyck in #76 above: I don't know enough about SLS/Orion and its configurations and capabilities to say. But it makes no sense at all if it cannot reach lunar orbit and return home, without a lander. (It originally had a bigger service module when they were talking about taking an Altair lander to the moon.)
I'd hazard the guess they intend to get the LEO departure burn and the lunar orbit capture burn out of the booster upper stage. Then the service module can do the departure burn for the fall back to Earth. If it can do that, then it can reach L1 or anywhere else near the moon where they end up parking that redirected tiny asteroid fragment.
Sure is a lot of bother and cost to reprise nothing more capable than Apollo 8 using shuttle-era hardware. But I guess it helps keep the likes of ULA alive.
GW
Actually, there's no reason at all to think that just because Earth has a 1-bar atmosphere today, then it had a 1-bar atmosphere 1-4 billion years ago. That's assumption, not fact.
One possible solution to the "dim young sun" problem is inherently-thicker planetary atmospheres providing more greenhouse effect. These would be thicker in the far past because the interiors of the planets were much hotter then, and there would consequently have to be more volcanic outgassing.
If that was true here, why not Mars? And the rest? Theory only, no facts, but it does make sense.
Assumptions, especially unspoken ones, often lead us astray. I guess that's why they spell "assume" the way it is, because of what it makes out of you and me: "Ass u me".
Sorry, bad joke.
GW
As far as I can tell from what I read in the scientific journals, the thinking is that Mars had a fairly big ocean "initially". Ice-covered, or not, nobody knows. But there seems to have been lakes and rivers "all over" at that time. That ended the best part of 3 billion-or-a-bit-more years ago.
For solar wind reasons, Mars lost its atmosphere and most of its water to space. This appears (!!!) to have something to do with lack of a planetary magnetic field to shield the atmosphere. Perhaps the tectonics died earlier in the smaller world that cools off quicker. Nobody really knows.
Both Mars and Earth seem to have had some sort of near-fatal impacts during their formation. This is supposedly how Earth got its moon. And the lowlands around Mars's northern polar regions looks suspiciously like a basin left by such an impact. That's where the ocean was. Maybe that's why the two planets are as similar as they are.
For whatever reason (nothing is sure) life started on Earth within a billion years of formation. Some say as soon as there was an ocean. I don't think anybody really knows yet, but that idea makes sense to me. The same thing would have happened on Mars, if any of our ideas are in the least correct.
Here, it took over 3 billion years to go from single-celled life to multi-cellular life. No one really knows why, or just how adverse conditions were, etc. Lots of theories, almost no facts.
But if that is "typical" (a huge guess at best), then life on Mars never had the time to get beyond the single-cell stage, because it dessicated and the surface "died" for lack of air almost 3 billion years ago. If what we believe is actually correct. Again, lots of theories, very few actual facts.
All that being said, if I were sending probes and expeditions to look for life, I'd be looking for microbes, and I'd be looking underground. Perhaps miles underground. There's life here that deep.
And I'd be looking for microbial fossils on the surface, especially where the lakes, rivers, and ocean once were. Fossils that might resemble those oddball structures found in the Allan Hills 84001 meteorite-from-Mars. Fossil hunting is hard to program into probes, as is drilling down miles. Those are things that men do better. You have to drill deep, and you have to bust-open rocks without powdering them. I have yet to see a probe do either.
And so THAT is the science reason to send men to Mars. The human reason is "to explore" as we have done since before the stone age. What else do you need to go?
GW
NASA is no longer free to do what makes sense, and has not been, since Apollo was cancelled in the midst of the landings in 1972. That was over 4 decades ago.
The SLS/Orion is only a moon rocket, and not a very good one at that, since the Orion service module has inadequate delta-vee to do what the Apollo service module did. They cannot really even reprise Apollo with that system, one dictated by Congress, and based on what gets built in whose districts. This is in turn based on what the same outfits (now gobbled-up into a monopoly) have been doing for the last few decades.
So, you should not be be surprised that almost nothing about SLS/Orion makes any sense at all, including its per-launch cost (a rather big step backward from where we are right now).
That being said, maybe (and it's a big "if" !!!) SLS/Orion can take crews to cis-lunar space. Maybe.
Which is why "going to the asteroids as a step to Mars" has completely devolved to a 2-weeks-max-long mission to a tiny asteroid in lunar orbit. That asteroid is to be captured by a robot (still yet to be defined) and released into that lunar orbit. That manned mission is basically nothing but Apollo-8 with a slightly-bigger crew: going to the moon without any means of landing. And I'm not even sure they can really do it with SLS/Orion, because they lack so much delta-vee.
Congress basically killed the front-burner mission for NASA decades ago: manned spaceflight to other worlds. All the big dollars are being wasted on boondoggles for this or that Congressional district. Aeronautics and science take a minor role with minor funding. Only the planetary program has achieved successes popular with the public, primarily because it was too low a cost to be worth turning into boondoggles.
ESA and the rest are no better off. Don't look for any government agency to send people to Mars in the 2030's or even beyond. None of them really want to take the risk to go. Whether any visionary private entities want to belly up to the bar and do this, remains to be seen. Not everybody who wants to go has the right ideas about how to do it.
And that Mars One suicide mission is definitely not what I had in mind: it violates "precept one" - nothing is as expensive as a dead crew.
GW
BTW, the "imperical" in the title of this thread should really be spelled "empirical". That assumes what is meant is to follow results/facts-based designs rather than something imposed-from-above arbitrarily. Which actually is where we are with NASA having stuff imposed by Congress, as in SLS/Orion as the latest, and dating back to a semi-reusable drop-off tank and booster design for shuttle about the time Apollo was cancelled.
GW
From what little I have read and understood, didn't the Dawn probe to Vesta and Ceres have ion thrusters? And the ESA probe with its lander on the comet? And the JAXA probe Hayabusa? I think all of those were solar electric plus conventional propulsion, were they not?
If it works on missions of 7 years to a decade or more to bodies like that, why the hell would it not work going to Mars? The only reason it hasn't already been done is that nobody thought they needed it for Mars.
But I think that's wrong.
SEP sends cargo to Mars orbit from Earth orbit just fine. SEP plus conventional sends men (use the SEP to cut transit times). You'll need a lander, you'll need artificial gravity-by-spin to stay healthy, and you'll need a lot of packed supplies since closed life support is just simply not ready (and likely still won't be if we go between 2025 and 2035). You'll need a solar flare shelter, use some of the packed supplies and propellant for that. Given that you will be sending a lot of mass anyway, there's simply no excuse for a cramped habitat for the crew.
The surface supplies and landers and landing propellant supplies can all be sent unmanned separately, and slowly. All you need for the manned part is an orbit to orbit transport, with as reduced a transit time as we can build.
While figuring out how to piece all this together into a real design proposal, you do need to remember one thing as of supreme importance: there is nothing as expensive as a dead crew. Applies to civilian/private efforts as much as to government agency efforts.
The second thing to remember is that there will likely be one and only one government-funded trip to Mars. You'd better leave a functional base on that very first trip. Otherwise, it will be decade upon decade before any private outfit returns.
GW
My point about wearout applies to flight vehicles, for which minimum weight is critical. Houses are anything but minimum weight, so comparing houses to flight vehicles is a rather egregious non-sequitur.
Besides, not all houses last. Custom-builts tend to hold up well, while the crackerboxes they put up as tract homes tend to fall apart in under 2 decades. Same applies to appliances, none of which are min weight designs.
Metal structures have a fatigue life that you have to observe. They say composites do not have fatigue, but I do not believe that (we haven't had them that long yet, to have the necessary long-term experience to know). Fatigue life shows as a negative-slope curve on a log-log plot, with abscissa number of cycles, and ordinate cyclic stress level. If the stress is low enough, the slope breaks to zero (stresses under that level are OK for "infinite fatigue life").
Few flight vehicles today (air or space) have structures so lightly loaded as to have the "infinite fatigue life". The last one I know of was the wing structure in the DC-3, from 1935. Most of the space technology we discuss here derives from missile heritage, which was all one-shot stuff. The low inert weights are achieved by loading the structures to yield and even beyond, factor 5-10 or even 10+ beyond the "infinite fatigue life" stress levels.
Aluminum is the worst of all about this effect. Between yield and ultimate you get to load the thing only a tiny handful of times, maybe even only once. That's really short working-life stuff, defined as cycles of one kind or another (number of landings for airplanes, usually). Pressurizations for tankage. You get the picture.
Like I said somewhere above, ISS will be worn out and endangering its crews by about 2025 or so (just like Mir did before it), unless it is rebuilt or replaced in some way. If it were me, I'd build replacement modules as the issue arises, launch each one to the station, use it to replace the corresponding worn-out module, and then de-orbit the junk ,module. Another one starts failing, do it again. And again, etc. Same thing applies to the solar panels, too. Same age problem, plus degradation of polymers and crystals by intense UV.
Doing it piecemeal like that gets you two really important advantages: (1) low political visibility (more probable funding), and (2) you could add a centrifuge module and finally study what level of partial gee is actually therapeutic. That last is crucial for long term deep space travel and off-world bases with men.
Launching a series of 15-20 ton modules one at a time over several years can be done with the current launcher fleet, for >10-factor launch cost reduction under what we paid using shuttle to build it originally. Later this year should be Falcon-Heavy's first flight. That one could launch 50-ton items for factor-30 savings over costs with shuttle.
Those costs and payload capabilities being what they are, I fail to see the purpose in wanting to restore the shuttle, other than nostalgia. And I also fail to see the purpose in the new giant NASA rocket, because it represents an increase in launch costs over what we now how, not the decrease it should have been. What we have right now (US, European, and Russian launchers) is simply way better. Different from previous and pre-conceived notions, but better.
GW
140 tons of anything is only "huge" if you insist on launching it with one rocket. We don't have to do that anymore. Launching and assembling large masses is no longer insane, because launch prices are much lower now than when we built ISS. An order of magnitude lower, or maybe a bit more. Around $2500/lb flying full with the current fleet, vs $30,000+/lb with shuttle.
If you cannot make a recycling or closed life support system work (at least in time for the mission), then you fly with bigger, heavier stored supplies, if you want to go at all. The sense I have is that closed life support is still very experimental, and largely unsuccessful, as of yet. I rather doubt that picture will change in only 1 decade, if you want to go in 2025, say.
If you make your mission dependent upon developing that (or any) technology, you never will fly. Someone else will. That's not to say we shouldn't work on the technology, because we should. But when you intend to fly, you use what is ready "now", or you won't fly. It's hard enough to just make the vehicles work with all-existing stuff. That's school-of-hard-knocks talking, and it's a very important lesson.
As for ISS, by about 2025 to 2030, it will literally be falling apart (and endangering crews) as Mir did before it. These things wear out, as I said before. If nothing else, metal fatigue sets in. But working/moving parts are the real trouble. Your hatches will quit sealing, for one. And the electronics/electrical will be the first systems to start failing. At least that's been the history of it since man first starting building flying machines.
GW
Hi Bob:
I hear (and sometimes see, if there's a low cloud layer) Spacex tests every day. Their facility is 6 miles from my front porch. Spacex is very close-mouthed about details released to the public, but I suspect they are using the new down-in-a-hole giant thrust stand now.
The bright fire at night from the older tower stand I no longer see very often. This bigger stand is where they will test Falcon-Heavy, if they haven't started already. The new stand is configured so that -Heavy tests won't be any louder than -9 tests were up on that tower stand.
GW
What's completely forgotten in this conversation is wear-out. Which is not the same as obsolescence! Wear-out is fundamentally why shuttle was retired somewhat prematurely. If we (all of us humans) want a space station for any purposes at all past about 2025, we'll definitely need another one. This one will become unrepairable the same way shuttle was headed, and that is very dangerous to crews!
The next space station ought to experiment with artificial gravity as its primary reason-to-be (something this one should have, and did not). That eliminates at one fell swoop about 2/3 to 3/4 of the medical/health worries for going to Mars (or even the main asteroid belt) with men (or women). Further, it ought to be powered such that movement to different orbits is also possible. That essentially becomes experimentation with a manned orbit-to-orbit transport craft, too. A single craft like that could take men on many missions to multiple destinations, a good way to amortize costs.
Forget government space programs doing this. They're not going anywhere any time soon. If NASA goes to Mars with men, which is not a likely prospect at all, they will mount one and only one mission. The whole shmear will be cancelled after the first landing, similar to Apollo, if they ever go at all.
So, watch for visionary private entities like Bigelow and Spacex to do space stations and manned deep space missions. And probably starting sooner than 2025. And I'm not talking about one-way suicide missions as that Mars One stuff appears to be.
GW
Has NASA learned how to do a SRM joint right yet? NO. The solid manufacturers back then knew (the one left today does still know, I hope) how to do this right, but dince the beginning contractors get threatened with loss of contract if they disagree with arrogant-but-ignorant NASA "experts" (same goes for all the government labs, not just NASA). Nobody at NASA since its inception in 1958 ever built a solid propellant anything. All that stuff was bought from contractors.
Sometimes it's easier, cheaper, and/or safer to just fly-with-what-you-got, even avionics. The B-1B is a case in point, and its deciding factor was cost. 2/3 of its price is avionics, and even today you cannot turn on all 3 critical systems simultaneously. That's why they NEVER flew it in combat in any high-density SAM environment, not since it entered service. And they still won't, today. Because it cannot survive in that environment without all 3 critical systems. That was a USAF mistake, claiming the systems integration job when they should have paid Rockwell to do it. Rockwell actually knew how, USAF did (and still does) not.
GW