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NASA found that a greenhouse large enough to produce food, is so large that it has a shortage of CO2. That's a nice problem to have, especially on a planet with a CO2 atmosphere. The Mars settlement will have to vent excess O2 to the atmosphere of Mars. That means plenty of capacity in case of a leak.
However, Biosphere2 had a problem. They built it in a desert to be isolated, but that meant no local soil. They tried to get cheap, to use sand and twigs instead of importing enough rich soil. The twigs would break down to produce organic matter, building soil. However the microorganisms that break down wood also consume O2. Because of that, they had a shortage of O2. They also found trees growing inside without wind were not strong, large branches broke off. To prevent that, they had to install large fans. Artificial wind from fans stressed trees sufficiently that they grew strong, branches wouldn't fall off. And they had a plant disease that destroyed their bean crop. They counted on beans for protein for diet of their "bionauts". Without beans, they were in trouble. They tried to kill the plant disease, but it always came back when the beans were supposed to develop.
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Martian colonists will need a series of separate agricultural spaces. In my novel, Martian settlements never had more than about 10% or 15% of their population or their agriculture in a single enclosure. Of course, once their main settlement got populous, that meant an enclosure 1,000 meters wide and 2,000 meters long, anchored to the ground with deep piles and cable anchors in the middle, with the dome soaring 500 meters or more overhead. The architecture depended on the same principles as suspension bridges. The dome was so high overhead one had a sense of being in an open space. The dome had transparent water bags built into its underside; the meter or 2 of water provided radiation shielding and counterweight against the internal air pressure, and could also be used for fire fighting or even irrigation. Excess heat in the dome could also be pumped up into the water bags on top to radiate the heat away. The domes were "open ground" with an ice table under them to freeze close the pores in the regolith and retain the air pressure. Buried plastic skirting covered the interdomal areas (which were filled with buried work areas) and allowed the capture of any leaking air. The ice table was several meters down, so there was plenty of room for agriculture and one could dig the ground to construct foundations for buildings. Such large domes did not require housing that could retain air pressure if the dome leaked. That's the sort of thing one can do if you have 50,000 or 100,000 people living in one community. A dome of 2 square kilometers, at 200 square meters of agricultural and residential space per person, can house and feed 10,000 people. It can even include a stadium for sports and cultural events.
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I have always envisioned it different. Rather than living in a dome, living in a pressurized building. Visualize a shopping mall, with multiple large buildings connected together and multiple units within each building. Each building a separate pressurized space that can be sealed off from others if it develops a leak.
And I envision agriculture as long narrow greenhouses. Each greenhouse about 12 feet tall at the centre, and 24 feet wide. It's important to have a 1:2 ratio due to sunlight. These greenhouses would be oriented perfectly east-west, with a flat mirror on both sides. The mirror would be as tall from the ground as the tallest part of the greenhouse, angled about 45° to reflect sunlight into the sides. The 1:2 ratio means as much sunlight from the mirrors as from directly overhead, so that means double sunlight intensity. Since 47% as much sunlight reaches Mars as Earth, and Earth filters some of the light through atmosphere but Mars filters a lot less due to very little atmosphere, that means total light in the greenhouse will be about the same. Making the greenhouse long and narrow means mirrors do not have to track the Sun. At dawn when the Sun rises in the east, sunlight will simply reflect off mirrors farther toward the west. At high noon it will reflect directly sideways into the greenhouse. At dusk when the Sun sets in west, sunlight will reflect toward the east. But with a long greenhouse, most of that light will still shine within the greenhouse. Mirrors will have to adjust with season, but due to Mars very long year, mirrors will have to change 1° every second week (14 sols). For a small Mars base, mirrors could be supported by a rod with notches. An astronaut would go outside to adjust the rods to the next notch, a chore once every second week. For a large settlement, some kind of motorized system, perhaps a worm screw. But if it gets stuck, it isn't a disaster. You've got 2 weeks to get it fixed. And if it isn't fixed in time, sunlight will be diminished just a little by angle being off only 1°.
I said the greenhouse would be about 24 feet wide, because that's the width of a typical double garage. And you don't need a ceiling higher than 12 feet. For an exploration mission, you may want to shrink that a little: 20 feet wide, 10 feet high. A ceiling higher than plant leaves is useless, and it doesn't make sense to make it higher than you can reach.
If you use a dome, then that means simple ambient light. No mirrors to double light. Some crops thrive in shade, cocoa trees produce cocoa pods that contain cocoa beans. That's where chocolate comes from. They're an understory tree, on Earth require a tall tree to provide shade. But on Mars could grow in a dome with no mirrors and no shade tree. In nature they grow 50 feet tall, but plantations trim them to 25 feet to make harvesting practical. Other smaller crops also thrive in shade: Lettuce, Broccoli, Cauliflower, Peas, Beets, Brussels Sprouts, Radishes, Swiss Chard, Spinach, Kale, Beans. (I copied from a website, they had caps.) Other crops need full Sun, so will need the mirror thing: tomatoes, peppers, squash. Grain needs full Sun: wheat, corn, etc.
Last edited by RobertDyck (2016-10-24 11:58:01)
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In my novel I started with smaller enclosures that were long and thin with reflective blankets that could be raised or lowered on tracks attached to the dome (which was half as high as wide). At dawn, the blanket on the east side is lowered and the sunlight going above the plants is reflected back to them by the reflective blanket in the west side of the enclosure. At noon both blankets are removed and the plants just get the straight overheat sun. In the afternoon the reflective blanket on the eastern side goes up. The enclosures are oriented north-south. The resulting sunlight may be a bit less than terrestrial average, but there won't be cloudy days on Mars (except in dust storm season, when supplemental lighting may be needed in any design, or special crops will have to be planted). But when the population got larger, I assumed that genetic modification produced crops with more efficient photosynthesis.
Martian agriculture will be different from terrestrial agriculture in that the carbon dioxide content can be controlled carefully, and that may speed up plant growth as well. We don't have enough research to know all the details.
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I'm with you on this kbd - I have never been able to understand what the problem is with multiple launches and, where necessary, orbital assembly. The great advantage is that you don't need to develop huge, innovative rockets and, also, you can pre-land equipment to the landing zone, thus ensuring you
Of course it does mean you have to be fairly confident of your ability to land everything in the same drop zone of perhaps 25 sq. kms. But there is no evidence that we don't have that ability.
Of course Musk's approach is more appropriate to his overall goal of transferring tens of thousands of people to Mars quickly. But I do have doubts about that.
NASA and Congress squandered all available funding on their reprise of the Apollo program. Every thinking person involved in the manned space exploration program knew ahead of time that there was no way they were going to another planet without dramatically improved in-space propulsion and closed-loop life support. There was never a reality-based requirement for super heavy lift rockets because chemical propulsion is so inefficient as to make a flags-and-footprints manned mission to Mars cost-prohibitive. That lie was concocted and sold to the American public and to Congress as a ploy to obtain more funding. It failed spectacularly.
The only point in time when some minor justification for SLS existed was during the STS program. The STS program is history, as is the justification for SLS. Another decade has been lost and we're still no more capable of any real space exploration than we were a decade earlier. Nobody in NASA's administration had the backbone and self-discipline to admit to reality and devote serious sustained funding to the kinds of technologies required for actual space exploration.
We need to de-fund SLS and Orion to devote all available funding to the following projects:
1. In-Space Propulsion (fusion driven rocket) and aerocapture (magneto-plasma variety)
These two technologies take the proverbial axe to propulsion mass requirements. No other technologies remotely approach what these two technologies would do for the manned space exploration program.
2. Closed-Loop Life Support
This technology represents another substantial mass-savings for long duration missions.
3. Better Batteries, Better Solar Panels, Small Fission Reactors, Lattice-Enabled Fusion Reactors
Yet another mass-savings program.
4. Active Radiation Shielding
And another mass-savings program.
5. MCP Suits
And one final, though comparatively minor, mass-savings program thrown in for good measure.
The combined effects of those programs would make super heavy lift rockets unnecessary. Space colonization has a different set of requirements, but still benefits from development of those technologies listed.
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Dear kbd: You are assuming, of course, that this fusion engine thing isn't a boondoggle. If we haven't managed a fusion reactor in 50 years, why assume we'll manage a fusion engine first? Either way, you need to confine plasma at high enough temperatures and pressures to allow fusion to occur. We haven't managed to do that yet with 100+ tonne machines and huge supplies of electricity.
I'll stick to chemical, thank you, until fusion advances to the point where someone can actually demonstrate something that almost works. New Horizons left the Earth at a velocity of 36,373 mph and passed the orbit of Mars in 81 days (longer than I said; I just checked). That requires a delta-v from low Earth orbit of about 19,000 mph. With methane/oxygen, that's a mass ratio of about 6 to 1. Even with the Falcon Heavy ($90 million to launch 54 tonnes to LEO without reuse) you could launch about 50 tonnes to Mars with $450 million of propellant; expensive, but a lot cheaper than spending $10 billion developing fusion or fission engines. In ten years Musk won't have the price down to $20,000 per tonne, but there's a good chance he'll have it down below $1,000,000 per tonne, maybe three quarters or half that. And that's assuming you want to send things to Mars at such high speeds. If you want to use a 6-month trajectory, you need maybe 100 tonnes of propellant and staging for every 50 tonnes you send to Mars, and at $1 million per tonne to LEO that's $3 million per tonne to get it to the Martian surface, which is cheaper than launch to low Earth orbit now.
Chemical propulsion works fine, if the cost to low Earth orbit drops enough. Once that happens, it's hard to justify developing the other stuff until you're at the point where the development cost of the alternatives comes down.
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Just a little small detail, we haven't achieved break-even with our fusion programs yet, how are we going to build a fusion rocket I we don't even have that? SLS uses existing technology, it is not a fusion rocket, it is not a space elevator, as you said, it is a reprise of the Apollo Program and it will get us back to the Moon! if we wait for fusion, I may never see a person walking on another World ever again. Fusion will come in time, and we re working on fusion even as we speak, but as they say, "Don't count your chickens before they've hatched," and they haven't hatched yet!
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Dear kbd: You are assuming, of course, that this fusion engine thing isn't a boondoggle. If we haven't managed a fusion reactor in 50 years, why assume we'll manage a fusion engine first? Either way, you need to confine plasma at high enough temperatures and pressures to allow fusion to occur. We haven't managed to do that yet with 100+ tonne machines and huge supplies of electricity.
I'll stick to chemical, thank you, until fusion advances to the point where someone can actually demonstrate something that almost works. New Horizons left the Earth at a velocity of 36,373 mph and passed the orbit of Mars in 81 days (longer than I said; I just checked). That requires a delta-v from low Earth orbit of about 19,000 mph. With methane/oxygen, that's a mass ratio of about 6 to 1. Even with the Falcon Heavy ($90 million to launch 54 tonnes to LEO without reuse) you could launch about 50 tonnes to Mars with $450 million of propellant; expensive, but a lot cheaper than spending $10 billion developing fusion or fission engines. In ten years Musk won't have the price down to $20,000 per tonne, but there's a good chance he'll have it down below $1,000,000 per tonne, maybe three quarters or half that. And that's assuming you want to send things to Mars at such high speeds. If you want to use a 6-month trajectory, you need maybe 100 tonnes of propellant and staging for every 50 tonnes you send to Mars, and at $1 million per tonne to LEO that's $3 million per tonne to get it to the Martian surface, which is cheaper than launch to low Earth orbit now.
Chemical propulsion works fine, if the cost to low Earth orbit drops enough. Once that happens, it's hard to justify developing the other stuff until you're at the point where the development cost of the alternatives comes down.
SLS will be able to send larger space probes to Uranus, Neptune, and Pluto, We've never sent orbiters to those planets. I would like to see a Titan lander and rover too. Big enormous rockets would be a good help in getting those things there! I think the ITS is further down the pike, we will have the SLS sooner, and we've spent a lot of money on it, hardware exists, we should use that hardware to do some useful things. I think a larger space telescope would be just the thing for finding those exoplanets, I would like to find some planets orbiting Alpha Centauri A and B. Maybe I will find if those planets exist before my natural lifespan runs out. In 21 years I'll be 70 years old, and judging by the pace of our space program, we'd better get cracking!
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Martian agriculture will be different from terrestrial agriculture in that the carbon dioxide content can be controlled carefully, and that may speed up plant growth as well. We don't have enough research to know all the details.
Many greenhouses have already increased CO2 content. Especially Alaska, where it's cold so they need a greenhouse to extend growing season long enough for vegetables to produce. Since it's a sealed, heated greenhouse anyway, increasing CO2 is easy. And a greenhouse is expensive, heating is also expensive, so Alaska operators want to maximize production. Some greenhouses in Canada also do this. My city has a few heated greenhouses, although they're mostly to prepare ornamental plants for the spring season. Plant response to CO2 is well documented.
Guelph University did research with hypobaric chambers to characterize plant growth in reduced pressure. They found spinach grow at the same rate down to 10 kPa, but below that wilts and stops growth. But once pressure is restored, the plant perks up and continues growing. For one experiment they dropped pressure down to Mars ambient, left it there for an hour, then restored pressure. Plants perked right up. Growth rate is the same regardless of pressure, but the lower the pressure the more water transpires through leaves. Plants require more and more water with lower pressure, but in a sealed greenhouse all water that transpires just condenses on cold walls and runs back into the soil. So in a sealed greenhouse they don't actually consume any more water.
So we have a lot of research already. I feel the next research needs to be a human mission on Mars itself. Mars now!
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The problem with STS is that it'll cost $1 to $2 billion per launch, most likely. No one knows, yet. Falcon Heavy can launch 54 tonnes WITHOUT propellant transfer from the outer cores to the center core. If they add that feature again (which they had planned to use, but dropped) I suspect Falcon Heavy will be up to about 70 tonnes to LEO. With reuse of all three cores (the new block-5 Falcon is supposed to be designed for 10 reuses) you can probably get 30 or 35 tonnes to LEO for what; $30 million or so? We don't know, yet. Under those circumstances, I doubt the STS will fly very many times.
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So what are you saying? NASA should sit on their ass and do nothing? You can't do anything with Red Dragon, it's way too small.
I already posted elsewhere a YouTube copy of a film I saw in 1968. This NASA film promised a human mission to Mars in 1978. That was 10 years later, NASA did the Moon within 10 years so that sounded reasonable. Especially considering they would use Apollo infrastructure. But it didn't happen. Then they said later, then later. On July 20, 1989, George H. W. Bush ordered NASA to send humans to Mars. But NASA asked for way too much, Congress would not authorize that. Robert Zubrin and his partner came up with a practical plan in the last quarter of 1989 and first half of 1990, presented to NASA in June 1990. We could have gone. Mars is overdue, and there is no real progress. We have SLS, big and expensive but SLS block 2 practically is Ares from Mars Direct. We could go. Not with Orion, but with a more reasonable spacecraft. Or NASA could continue to spend billions to accomplish nothing.
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Given the history, why would anyone expect anything “reasonable” from a government agency (NASA) that (1) has gone insanely risk-averse, and (2) has bloated to ridiculous size trying to be all things to everybody? The extremized risk-aversity prevents them from telling members of Congress that they are incompetent to be mandating technical development efforts, because they fear further funding loss. That alone precludes anything new that is significant.
No group in that condition will ever be able to accomplish anything of significance beyond what they have done before, and with some serious doubts about even that. We have orbited men since 1962. But we have not gone back to the moon since 1972. Or didn’t anybody notice?
SLS lacks an adequate service module delta-vee, and it lacks entirely the lander, to return to the moon. As it stands now, with that too-big Orion capsule and its current under-powered service module, it's not even a good moon rocket (in the sense of reprising Apollo flag-and-footprints), lander or not.
At around $1B per launch, that's a poor buy at best. Especially when all you ever get back (in ANY sense of that word) is the Orion capsule, and you won't get to reuse or re-purpose that, except as a museum piece. This isn't about launch capability, this is about the giant corporate welfare state at its very worst. Or hadn’t anybody noticed that just about all high-$ government projects have not met their requirements in some decades now?
Falcon-Heavy is too small to send men to Mars by NASA- or Zubrin-style mission plans, unless you instead do major orbital assembly by lots of launches with it, which is not a NASA- or Zubrin-style mission. But that's exactly what I assumed with my 2016 Mars plan posted on "exrocketman". Which just goes to prove that a gigantic launch rocket is NOT an absolute prerequisite to go to Mars, although it might make things cheaper (although NOT SLS!!!) and easier, if you actually had one.
Whether Musk ever actually successfully builds his giant booster and spaceship concept, who knows? He tends to do what he says, in one form or another. But his history says it takes him about half again as long as he thinks to actually get the job done, because he always underestimates just how hard it will really be. That's down at the $B ranges where he can self-finance. Mars is bigger than that, so he needs others participating, including outfits like NASA.
NASA ignored Red Dragon for a couple of years, and now suddenly wants to participate in Musk's 2018 Falcon-Heavy/Red Dragon shot, which they are supporting in kind, but not with $. I think they finally understand at executive management levels that Musk is indeed leaving them behind in the dust. Maybe there's an embarrassment factor that will induce them to help him with that Mars ship concept.
Who yet knows?
There's always more than one way to accomplish a job. Different starting assumptions lead to very different outcomes, that’s pretty much an axiom. Just because the outcome with different assumptions looks so different than what you thought, does NOT make that outcome or those different assumptions wrong.
Only making inappropriate assumptions incompatible with known constraints will turn out wrong. The Mars objective does NOT specify the assumptions you need to make, contrary to what I often see implied in these discussions. Or sometimes overtly stated.
Known constraints: addressing microgravity disease, dealing with radiation exposure, enough space in which to stay sane, and enough food/oxygen/water to live through the trip. Musk's version looks a whole lot more probable to me than anything I have ever seen out of NASA, not in over 50 years.
If Musk’s big ship should actually fly, I think it could do the job, and many other jobs, too. But it will have a “checkered” test history. They all do.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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One thing that worries me about Musk's plans is that they are just too big for NASA to "buy." It's one thing for NASA to agree to send a series of 6-man exploration crews to Mars, something else entirely for NASA to agree to fund a multi-billion dollar project to land 100 people at a time there. I wish Musk's architecture were more "evolvable"; that it start smaller and grow. I think he'd get more cooperation in the long run, and his scheme would be more credible. And there may be ways to make it more evolvable, by using fewer refueling flights per launch to Mars and launching smaller crews and cargo loads at a time.
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Just a little small detail, we haven't achieved break-even with our fusion programs yet, how are we going to build a fusion rocket I we don't even have that? SLS uses existing technology, it is not a fusion rocket, it is not a space elevator, as you said, it is a reprise of the Apollo Program and it will get us back to the Moon! if we wait for fusion, I may never see a person walking on another World ever again. Fusion will come in time, and we re working on fusion even as we speak, but as they say, "Don't count your chickens before they've hatched," and they haven't hatched yet!
You're not trying to produce electrical power with it, Tom. You're not even trying to contain the superheated plasma. You're intentionally allowing the plasma to escape from the magnetic bottle. As previously stated, there's a big difference between trying to contain a superheated plasma and produce electrical power, which implies Q > 1. You only have to generate enough juice to charge capacitors to compress a pellet and achieve fusion using a thin metal foil wrapper to contain the fusion products, produce a superheated plasma, and use an electromagnet to cause the plasma to be ejected from the combustion chamber.
1. Suck (lithium foil from lithium fuel tank)
2. Squeeze (electromagnetically compact lithium foil onto D-T pellet)
3. Bang (fusion)
4. Blow (electromagnetic rocket nozzle directs the superheated plasma away from the combustion chamber)
It is not a continuous reaction that requires more output power than input power to sustain the reaction and it does not try to contain the superheated plasma. We're counting on containment failure to produce thrust and we are not interested in achieving Q > 1 because it's not recharging the capacitor. We're talking about doing that once every ten seconds. If we could do it faster, that'd be great, but unnecessary and we'd have to figure out how to dump the excess heat.
Make sense?
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When I look at projects like SLS, Orion, and Mars 2020, I think there's something else behind this. It can't be just trying to keep voters employed, there has to be something more. Are Congressmen getting kick-backs into their election campaigns? Is this just spending programs to fund their elections? If that's the case, there are actual productive things NASA and their contractors could do that would cost that much money.
GW: I know you don't like politicians designing equipment, but look at history to see why. Under Constellation NASA worked on Ares V. It was originally going to use SSME, but salesmen from Boeing/Rocketdyne convinced NASA to use RS-68 instead. It was 50% more thrust, and cost:benefit was already optimized for an expendable launch vehicle. RS-68 didn't have as high Isp as SSME, but the engine was designed to be less expensive, and that was balanced against additional cost for propellant and tank. Total launch cost for the first stage was the criteria. NASA was convinced, they chose RS-68. But the engine guys at NASA wanted to develop a new engine, they wanted an engine that was SSME with 50% more thrust. When NASA management said no, their excuse was RS-68 had to be man-rated. NASA management fell for it. But rather than man-rating the engine, they proceeded to redesign it. Every feature of SSME that was not on RS-68, they installed. Their goal was to increase Isp to equal SSME. They intended to build a new engine that was SSME with 50% thrust, the engine they wanted to build, but do so under the cloak of "man-rating RS-68". Since NASA bureaucracy couldn't control them, Congress took direct control. However, so far timeline and cost don't look any better.
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Robert,
It started during the civil war. The north needed weapons, needed them desperately at any price. They printed money to buy them. That is when the US developed a rich ruling class. The trick was remembered. I will say no more, other than in spite of the apparent unfairness of the situation, I still make out pretty good with my table scraps, and choose not to be a bad dog.
Done.
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Quite. No one wanting to get to Mars quickly is relying on fusion technology - Musk certainly isn't. He's the Edison of our age - a supreme pragmatist.
Dear kbd: You are assuming, of course, that this fusion engine thing isn't a boondoggle. If we haven't managed a fusion reactor in 50 years, why assume we'll manage a fusion engine first? Either way, you need to confine plasma at high enough temperatures and pressures to allow fusion to occur. We haven't managed to do that yet with 100+ tonne machines and huge supplies of electricity.
I'll stick to chemical, thank you, until fusion advances to the point where someone can actually demonstrate something that almost works. New Horizons left the Earth at a velocity of 36,373 mph and passed the orbit of Mars in 81 days (longer than I said; I just checked). That requires a delta-v from low Earth orbit of about 19,000 mph. With methane/oxygen, that's a mass ratio of about 6 to 1. Even with the Falcon Heavy ($90 million to launch 54 tonnes to LEO without reuse) you could launch about 50 tonnes to Mars with $450 million of propellant; expensive, but a lot cheaper than spending $10 billion developing fusion or fission engines. In ten years Musk won't have the price down to $20,000 per tonne, but there's a good chance he'll have it down below $1,000,000 per tonne, maybe three quarters or half that. And that's assuming you want to send things to Mars at such high speeds. If you want to use a 6-month trajectory, you need maybe 100 tonnes of propellant and staging for every 50 tonnes you send to Mars, and at $1 million per tonne to LEO that's $3 million per tonne to get it to the Martian surface, which is cheaper than launch to low Earth orbit now.
Chemical propulsion works fine, if the cost to low Earth orbit drops enough. Once that happens, it's hard to justify developing the other stuff until you're at the point where the development cost of the alternatives comes down.
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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The way I look at it is this - how much tonnage do we need to get on the surface of Mars for a crew of say six to survive there for a couple of years. Last time I looked I convinced myself it was probably only 20 tonnes (in addition to an descent/ascent craft). But 40 tonnes would probably make it much more comfortable. This is most definitely NOT beyond our technical capability. What is lacking is the political and organisational will (with the wonderful exception of Musk of course).
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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So with the Red Dragon we could preload any site we would wish on Mars in 10 landers or less and lighten the crewed lander back to a realistic mass for its trip to the surface. So what is in the itemized list of what that 20 tonnes would be?
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I have an interesting idea. Again, I don't see the colonial transporter being the first human mission to Mars. That's a later phase. You at least need living quarters and life support for the first 100 settlers, waiting for them before they arrive.
Going back to my proposed mission plan. Again my plan is a modification of Mars Direct, but getting more modified all the time. I said use ISS as construction shack for Earth orbit assembly. And a reusable vehicle that would go from ISS to Mars orbit and back to ISS. It would park at ISS until the next Mars mission is ready to depart. As a reminder, my last configuration looked like this...
First mission:
- 1 SLS Block 2B for MAV (direct launch from KSC to Mars surface)
- 1 SLS Block 2B for lab & pressurized rover (direct launch)
- 1 Falcon 9 v1.2 for ITV
- 1 Falcon Heavy for TMI stage
- 1 Falcon 9 lander & unpressurized rover
- 1 Falcon 9 for DragonSubsequent missions:
- 1 SLS Block 2B for MAV
- 1 Falcon Heavy for TMI stage
- 1 Falcon 9 lander & unpressurized rover
- 1 Falcon 9 for Dragon
Now here's the interesting thing. I'm not sure a single Falcon Heavy can lift a single stage sufficient for TMI. It depends on the mass of the stack. And we know lift capacity for Falcon Heavy launched expendable to 185km orbit, we don't know how much it can lift to ISS when all 3 core stages are recovered. But Elon's colonial transporter integrated the upper stage with the spacecraft. And a tanker launched to refuel the spacecraft in LEO. Using that same idea, integrate the Falcon Heavy upper stage with the TMI stage. And a separate tanker could be launched on another Falcon Heavy to refuel the TMI stage. A second tanker that looks like the Mars Colonial transporter but smaller.
This is so we don't have to shrink the lander to an all-soft pressure tent, with nothing but capsule seats for astronauts when landing on Mars. The lander could be a hard wall habitat of descent size, something like the Mars Direct habitat. Again that's heavier, requires a larger TMI stage.
The MAV would also be too large for direct launch by a single Falcon Heavy. But could be assembled in LEO. The lab could be deleted, one reason for making it separate is to keep the lander small. If the lander is larger, then a separate lab wouldn't be necessary. However, would still be a nice backup. I would still make the lab inflatable, because the inflatable could be moved to the lander/habitat and connected. Lab equipment moved separately and set up inside.
I could work out details. Again, this would use equipment designed like the Mars Colonial Transport, but smaller. And this would perform initial human science missions, construction of the first base, and finally construction of living quarters with life support to receive the first 100.
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Tom Kalbfus wrote:Just a little small detail, we haven't achieved break-even with our fusion programs yet, how are we going to build a fusion rocket I we don't even have that? SLS uses existing technology, it is not a fusion rocket, it is not a space elevator, as you said, it is a reprise of the Apollo Program and it will get us back to the Moon! if we wait for fusion, I may never see a person walking on another World ever again. Fusion will come in time, and we re working on fusion even as we speak, but as they say, "Don't count your chickens before they've hatched," and they haven't hatched yet!
You're not trying to produce electrical power with it, Tom. You're not even trying to contain the superheated plasma. You're intentionally allowing the plasma to escape from the magnetic bottle. As previously stated, there's a big difference between trying to contain a superheated plasma and produce electrical power, which implies Q > 1. You only have to generate enough juice to charge capacitors to compress a pellet and achieve fusion using a thin metal foil wrapper to contain the fusion products, produce a superheated plasma, and use an electromagnet to cause the plasma to be ejected from the combustion chamber.
1. Suck (lithium foil from lithium fuel tank)
2. Squeeze (electromagnetically compact lithium foil onto D-T pellet)
3. Bang (fusion)
4. Blow (electromagnetic rocket nozzle directs the superheated plasma away from the combustion chamber)It is not a continuous reaction that requires more output power than input power to sustain the reaction and it does not try to contain the superheated plasma. We're counting on containment failure to produce thrust and we are not interested in achieving Q > 1 because it's not recharging the capacitor. We're talking about doing that once every ten seconds. If we could do it faster, that'd be great, but unnecessary and we'd have to figure out how to dump the excess heat.
Make sense?
So what happens if you put this on the Launch pad and try to launch if from Cape Canaveral? An explosion every ten seconds?
"Boom, one Mississippi, two Mississippi, three Mississippi, four Mississippi, five Mississippi, six Mississippi, seven Mississippi, eight Mississippi, nine Mississippi, ten Mississippi, Boom!" and then repeat. I don't think this would produce enough thrust to get off the launch pad, you would need at last the bottom stage of the ITS to get it into space first, and then it can have the leisure of having a nuclear explosion every ten seconds.
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Quite. No one wanting to get to Mars quickly is relying on fusion technology - Musk certainly isn't. He's the Edison of our age - a supreme pragmatist.
No one wanting to get to Mars at all is relying on landing a spacecraft weighing more than the Space Shuttle on its tail on the surface of another planet without a landing pad, unloading a propellant production plant capable of producing 1900t of propellants on Mars from a cargo hold 30M in the air, and then returning that spacecraft to Earth for immediately reuse without extensive refurbishment.
NASA and SpaceX both need better in-space propulsion solutions. A bigger chemical rocket isn't the answer for exploration purposes and the ITS is already beyond the practical weight that Pad 39A can support, so that means sea launch.
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So what happens if you put this on the Launch pad and try to launch if from Cape Canaveral? An explosion every ten seconds?
"Boom, one Mississippi, two Mississippi, three Mississippi, four Mississippi, five Mississippi, six Mississippi, seven Mississippi, eight Mississippi, nine Mississippi, ten Mississippi, Boom!" and then repeat. I don't think this would produce enough thrust to get off the launch pad, you would need at last the bottom stage of the ITS to get it into space first, and then it can have the leisure of having a nuclear explosion every ten seconds.
Do you read more than the first sentence of responses?
The Fusion Driven Rocket (FDR), like SEP or NEP, is only for use in space.
A chemical rocket delivers the FDR to orbit. The FDR is attached to the payload like a conventional upper stage rocket motor.
The FDR operates off of very high speed electromagnetic implosion. The "fuel" for nuclear fusion is Deuterium-Tritium (D-T), but the propellant is Lithium (Li). The propellant is like Reynold's Wrap. Electromagnets wrap the propellant over the fuel using electromagnets. The act of wrapping the propellant over the fuel causes the D-T pellet caught in the magnetic field to implode, initiating fusion for a split second. This vaporizes the Li foil propellant, which absorbs most of the neutron radiation thrown off by the D-T fuel pellet, and produces exhaust velocities of 20km/s to 30km/s.
Solar panels provide the electrical power (27kWe to 350kWe, depending on how fast you want to go; 90 day transit vs 30 day transit), capacitors store and discharge the electrical power, and electromagnets direct the electrical power. Fusion provides zero watts of electrical power for the reaction, which is another way of saying that the solar panels and capacitors initiate fusion. There is no self-sustaining reaction or continuous reaction.
FDR's intentionally lose containment of the superheated expanding plasma created during fusion and directs it out the back of the rocket using an electromagnetic rocket nozzle. Thus far, we've had a 100% success rate with losing electromagnetic containment of superheated plasmas. Experiments have already shown that electromagnetic foil liner implosion fusion works. The question is no longer "Will it work?" That's already been proven. The question now is "How well can we make it work?"
To the people stating that this requires a multi-billion dollar development program, Dr. Slough gets $10M per year from NASA until 2020. To build flight test hardware, he needs approximately $50M per year for a period of about three years. Does anyone here want to bet that development of a flight tested LOX/LH2 upper stage for SLS will cost more than $200M?
Last edited by kbd512 (2016-10-25 10:44:28)
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Musk's ITS/MCT/"whatever" second stage spaceship is the equivalent of a large ocean-going container ship. It is far bigger than it needs to be for any sort of initial explorations on Mars. It is intended as a large, generalized "transport truck" to be used for all sorts of missions we haven't even thought of yet. The historical parallels are the Dutch Fluytscip of about 1500, and the B-747 air freighter of about 1970. That's what I was trying to convey about assumptions, he's solving a vastly-different problem than just "first men on Mars".
Imagine what a vehicle like that could do if re-engined down the road somewhere with a working fusion rocket! But there's no need to wait for the fusion rocket, why not get started now, and adapt later? You get more done that way.
The things about million-man colonies and 100 men per flight are a distraction. That's future stuff decades upon decades away, don't be confused by it. But the same large vehicle serves, even "up front" when men first go, as we have known since the mission proposals of the mid 1950's. Think half a dozen people, and near a 100 tons of supplies, equipment, and machinery. That's difficult if done 5-50 tons at a time. Easier if done 100+ tons at a time.
From Europe, North America was neither explored, nor colonized, by folks crossing the Atlantic in rowboats or other tiny craft. Full-sized ships were used. That's the historical parallel. Why beat your head on the wall, when history already tells us what we need to do? Only the detailed technologies and difficulties change, the broad outlines remain the same, across millennia.
But what kbd512 describes for the fusion rocket is a high-risk/high-payoff gamble. There's nothing wrong with that, and prudent agencies do fund such things (example: USN funding Polywell fusion technology, as a high-risk/high-payoff alternative to what mainstream high-energy physics has been unsuccessful at, for 6+ decades now).
But I see no point in waiting for any of these improvements, just because they might be so much better. Neither did Ferdinand and Isabella of Spain wait for better propulsion technology, they funded Columbus to go with the ordinary windjammer ships of the time.
Same was true for the Dutch, the Portugese, the French, and the Brits. They just went with what they had. It worked. Life support was right at the scurvy limit, but it worked.
Why not us?
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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