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Why not build landers in LEO from pre-fab components shipped up with these boosters. Plus, anything a Falcon-9 can fling, so can Atlas-5 and Delta-4. No need to suffer problems with flight rates of the companies supplying the services.
Make the lander chassis out of steel framing members (for strength to weight, plus absolute strength and toughness). Have it fold up like a trundle bed frame, so it can ride up inside a payload shroud.
Do the same thing with the heat shield panels: do them as separate segments, and fit these into a payload shroud or two. They unfold, and caulk together only once. Same for the outer aeroshell panels.
The cabin and propellant tankage items are pressure vessels. These can be shipped up in a series of payload shrouds limited more by thrown weight than by volume, as none of these need be anywhere near the heat shield diameter of the lander.
Fueling on orbit requires more "payload shrouds" as tankers. Or, these could be tanks that ride "naked" except for a streamlined nose cap, on the front of the rocket. Dock such tanks to your lander, and make the connections. The lander can push itself and a huge swarm of tanks to Mars one way, to support a bunch of landings, from low Mars orbit.
Another lander plus a swarm of tanks plus a human habitat could be the manned orbit-to-orbit transport, except that's a waste of a good lander. Just use the lander engines on a lander chassis as a propulsion module docked to your orbit-to-orbit transport.
GW
Great GW!
Why not posting in your blog a Mars lander assembled in orbit from pre-fab components?
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
Hi, GW. Tanks for your reply.
So the possible solution without new launcher are:
1) recycle an old Shuttle, send in unmanned in LEO with Canadarm and use it as an orbital assembly facility to build a 15-20 meter diameter lander. Is the best solution and a very good long term investment, but it's expensive and we know politicians and bureaucrats are penny wise pound foolish.
2) build a 5 meter diameter 15 meters height slender body biconic lander and launch it with a Falcon H. Have we some experience on slender body biconic reenter?
3) Assemble a cluster of five 5x10 cylindrical modules on a foldable umbrella shield. Advantage: is simple. Disadvantage: never tested.
4) Use many 5 meters diameter Dragon shaped landers: one for habitat, one for cargo, one for ascender. Advantage: is simple. Disadvantage: risk of collision during EDL, the landing sites of lenders are too far.
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
Can we use as a lander a cluster of five cylindrical modules (D=5m; h=10m), protected by a 30 meter diameter foldable umbrella heat shield?
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.
GW
Even without orbital construction capabilites, I think it's not impossible to build a 5 meters diameter cylindrical lander, with a foldable umbrella heat shield that can be lauched with Falcon H and conected to your modular spaceship.
I would agree with esperanto, because it is more or less international, unnational
Why Esperanto? It's an absurd language created by an ophtalmologist. Sindarin is a far better language, created by a linguist. Even Klingon is better than Esperanto: why not adopt it for Mars colonists?
AS a SF writer, I have a question on FTL drive to the experts of this forum: Alcubierre Drive (or any other hypothetical FTL-drive) will alter the position of our spaceship, but not her linear momentum (if not it will be an absurd reactionless drive): so if I use the AD to move from a star system to another, I have to match the relative velocity between the star systems with conventional rockets. It's correct?
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).
GW
Even if m2p2 works, I think it's better to have 20 cm of water around flight control station. EM shield may be subject to failure, passive water shield not: using both will result very safe. 20 cm of Water inside a double layer may be also a protection against microdebris impacts.
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
I prefer your modular spaceship because it'is reusable, but the very interesting thing in these works is the m2p2 cosmic ray shielding system: if it works, you can upgrade your Johnosn Express inserting a m2p2 module in the middle.
It's also a very good thing, that some people have realized that artificial gravity is not an optional: years long deep space reference missions without artificial gravity are very disturbing.
I found these very interesting works by Mark Benton and Ruth Bamfod
http://scholar.google.it/scholar?q=mini … CB4QgQMwAA
about a NEO asteroid mission with a spaceship, using an extesible truss module for artificial gravity and a very innovative mini-magnetosphere cosmic ray shield, generated via superconductive coils.
The spaceship spin on the transfer orbit plane: solar arrays and communications antennas are mounted on de-spun platforms
Here there are some very interesting designs by Robert Bussard about polywell powered realistic fusion spaceships: a shuttle SSTO and a lunar lander, with a water propelled high thrust regenerative cooled electro-thermal fusion rocket (15-20 km/s of exaust velocity); an inner solar system ship with a radiator cooled moderate thrust electro-thermal fusion rocket (55 km/s of exaust velocity); an outer solar system ship with low thrust thermal fusion rocket (200-400 km/s exaust velocity).
As to "figured-out-to-go-to-Mars", some of us think so. The arguments are really over how to ensure getting the crew back safe at high probability. That and cost. Actually, we could/would have sent men to Mars in the 1980's, had the space program not been cut in '72.
I rather doubt they would have made it home alive, knowing what we know now about microgravity diseases and radiation exposures. It was a 17 km/s free return, at something like 15 gees. Not something you can survive after 2.5 years' accumulated microgravity disease.
GW
I think artificial gravity is a MUST, untill we will have GM deep space compliant astronauts, microgravity and (possible) radiation reasistant. I'm surprised there are still people who design Mars manned mission without some kind of AG.
The actions of USAF, the White House, and that court, all demonstrate exactly what I have been saying:
BA = 1 / DC where BA = bureaucratic arrogance and DC = demonstrated competence; applies to any organization, public or private
HA >>>> H where H = number of horses and HA = number of horses' asses; applies to absolutely anything
GW
I'm Italian and I was ever a pro-American douring all Cold War I, but in case of Cold War II, I ask myself how can US win again with such a short sighted leadership?
The real problem with Atlas-V is the engines: they're Russian. Guess what gets embargoed next.
It's happened
Depends on whether you walk in the radiation shadows or not. Radiation has to come a particular direction, a Ganymede day is seven times as long as an Earth day, so that means for 3.5 days you would be protected from radiation from the bulk of Ganymede.
Jovian satellites are in syncronous rotation so the east trailing emipshere will ever take more radiation than the west leading emisphere, because radiation belts rotate faster than moons. But currents in radiation belts are very very complex ( http://en.wikipedia.org/wiki/Io_plasma_torus#Role_of_Io ) and Ganymede has its own magnetosphere with open line in the polar region and closed line on the equator where they generate another radiation belt.
http://en.wikipedia.org/wiki/Ganymedian … netosphere
So it may be very difficoult to predict if there are safe even and where they are.
Astrobiologist are very interest in looking for safe evens on Europa, because they hope to find intact biological material coming from subglacial ocean: this work is on the topic http://www.astrobio.net/exclusive/3010/ … -radiation
One possible way to create fusion power on an ice world would be to use the cleaner H3 Hydrogen bombs to repeatedly heat the waters of an underground lake. Then venting the lake heat to either vacuum skys or in the case of Titan to atmosphere.
If done correctly, the radation produced could be isolated to that lake, and perhaps a layer of clean ice above the somewhat radioactive waters, serving as a shield for the machines and humans above the submerged lake. This might be a real good one for Titan I think. Perhaps one side of the Moon having this power source, and the other side being more for civilian habitation.
If you used your super greenhouse gass as disolved in Nitrogen, and also had this heat leakage into the atmosphere, perhaps all the methane could be vaporized, and so also serve as greenhouse gass.
After all fusion reactors are just pulsed fusion. These would just be big pulses. And with that technology, yes build space propulsion also, as you have suggested.
Ganymede is interesting, but if you then have a nuclear pulse Orion type space craft, then you should be able to go to Titan instead, and with 1+ bar of surface pressure, and a plentiful energy source, then, a new home for a human civilization. Probabbly at least as good a bet as Mars, especially if it turns out that Mars cannot support a 1/3 bar atmosphere even with heating.
We don't need fusion power in Jovian Satelllites: we can get all the power we want from radiation belts, extracting ions energy with an electrostatic or magnetohydrodinamic direct conversion generator.
It may be interesting to discuss about the best way to colonize Jupiter's Moons: surface colonies Vs. space habitats.
Europa and Ganymede may harbor indigenous life in subglacials oceans: in this case, may be wiser to not contaminate their ecosystems and build O'Neil's cilindrest in their L1 or L2.
Very interesting. As I expected a denser gas lowers the pitch of your voice. Not sure I would want to sound like that though, I prefer the Donald duck sound that comes with helium. 6 times heavier than air. I guess there must be a reason you don't see planets with sulfur-Hexafluoride atmospheres.
We cannot use sulfur exafluoride as a buffer gas, because it is too much havier than oxygen and displace it from the lower zones.
How much helium 3 is there on Ganymede? I would imagine that, like most other claims of helium 3 resources, the concentration is incredibly low.
Helium3 is not useful without a working fusion machine. Tokamak is too massive for space application at the moment the candidates may be Bussard's Polywell and Lerner's Dense Plasma Focus. But they are still far from breakeven.
The bulk of reasearch has been done in 60-70thy, and all the rocket has designed for the materials of that times.
With today materials we can build better and better rocket. I imagine some kind of "hairy core" NTR, stable, restartable and easy to handle like a solid core NTR, but with the Isp of a gas core: the core may be a bush of graphite fiber or carbon nanotube, coated with uranium 233 zirconium hafnium ternay carbide that heat hydrogen (or water steam) for nuclear fragmentation, so the propellant can reach more than 5000°K while the fuel is still 3000°K, resulting a more than 1600 s of Isp without the uranium loss of a gas core.
Space probes have managed to operate in that radiation environment, without problems. Also the Moon is tidally locked with Jupiter, this means the high radiation will be on one hemisphere only. The radiation consists of charged particles trapped in Jupiter's magnetic field. Since Ganymede has little orbital inclination with Jupiter's magnetic field, then following the right hand rule, the charged particles will be coming up from behind Ganymede in it orbit, that means if you are in the leading hemisphere, you'll have the moon between yourself and the direction from which the radiation is coming.
Yes it's correct. Radiation have been measured in orbit and probe has never landed on Ganymede. Theorically one emisphere has to be radiation free.
But why Ganymede and not Callisto?
Callisto is very similar to Ganymede and has amost the same resources, but is outside radiation belt.
The only reason to prefer Ganymede, may be to extract energy from radiation belt and use it to power your subglacial habitat. We can imagine two kind of devicies, magnetohydrodynamic and electrostatic (the first may be towers of coils the second a field of charged grids) that produce electric power slowing down ions. Such a colony can realy on almost unlimited energy source...
So about 70 meters of ice, probably you could live with less than a full bar of atmosphere under the dome too. I always heard that Earth gravity was 9.81 meters per second squared.
Yes, but before going in your 70 meters deep in the ice habitat, you have to build it. You have to explore surface to find the right location and this is very very difficoult in a high radiation environment: you have to travel in a heavly screened 30-40 tons rover and you cannot walk outside.
On Callisto there are not such issues: you can explore surface on a 5-6 ton rover, you can go out in spacesuit and you are free to choose to build a surface dome or a subglacial habitat.
But then, why not do that on Callisto? The gravity difference isn't that bad; Callisto is about 13% of a g, while Ganymede is 15%. There is a difference in surface area, but when we're talking whole planets that's hardly significant, or at least it won't be for a good long time.
It would sure be nice to not have that much surface radiation. It would simplify everything a lot.
I do find that 1 rem per year surprising, though. Is Callisto protected by Jupiter's magnetic field?
Yes. Callisto it's outside radiation belt, but Jupiter magnetic field is still strong enough to deflect galactic and solar cosmic ray.
I think the safest way to expore Jupiter System, is landing astronauts on Callisto and tele-robotically explore Ganymede, Europa and Io.
We need water, can't live without it.
Radietion levels on Jovian satellites:
Io 3600 REM/day
Europa 540 REM/day
Ganymede 8 REM/day
Callisto 1 REM/year
Why do you choose Ganymede?
Thanks, Quaoar, that's one of the reports I never saw decades ago. I saw the Ragsdale Mars mission stuff, and I saw the United Aircraft reports on the stuff they did. A version of that spherical engine is what was proposed, back in about 1969, for the then-planned 1980's manned Mars mission. United Aircraft was of the opinion that 35:1 LH2:U flow ratio was as good as perfect containment, at the U burnup rates they were looking at.
Another version of that same spherical engine operated at higher power, but with a waste heat radiator because they thought regenerative cooling would not be adequate. Vehicle thrust to weight was somewhere between 0.01 and 0.1 gees, but the Isp was 6000 s, not just 2500 s. United Aircraft thought the tradeoff point for radiator-or-not was about 2000-2500 s Isp reactor power levels. Their thinking was even higher engine T/W ratios than NASA, without the radiator, perhaps 30:1.
Point is, this thing could have been ready for test flights back in the early to mid 1980's, if it hadn't all been killed by 1974.
GW
I found even this interesting work on a Droplet Core Rocket that can reach 2000 s of Isp. In this roket, the uranium droplets are centrifugated and recycled with a liquid lithium flow system: it may be cheeper than Gas Core where the core is vented out after every burn.
https://discover.tudelft.nl/recordview/ … 9920001887
I found also this review about all kind of NTR
http://www.google.it/url?sa=t&rct=j&q=& … 8261,d.ZGU
Most of them are designed in 1960-70. I think that using modern high temperature resistant materials, running at low pressure to achive high hydrogen dissociation and using a particle bed architecture or a FOIL (Fission Fragment Assisted Reactor) even a solid core can reach 1500+ s of Isp.
There are a lot of articles of gas-core NTR, but mostly are very superficial: only some schematic design and very few data on real technical fasibility.
Now I found this very robust study, where all critical issues like vortex formation, core-propellant heat transfer, propellant seeding, wall and nozzle cooling are properly addressed.
http://ntrs.nasa.gov/archive/nasa/casi. … 003405.pdf
It's to note how simple and practical is the fuel injection system: an uranium bar in a cadmium protected pipe: when a segment of of uranium protrude outside the pipe, it quickly vaporize and mix with the vortex forming the core.
It's all very simple and can be done with existing technologies and materials. I guess almost 10 yr of R&D (if properly founded) and we will have a 1500-2500s Isp rocket, that can explore all the solar system.
Callisto is better: water rich like Ganymede, but outside the radiation belt and still inside Jupiter magnetosphere, that protect it from cosmic ray, so surface radiation dose is very low, almost 1 REM/yr.
Callisto is also at the border of Juppiter gravity well, so departure burn will be not too much delta-V expensive.