PB666

Forget about NTR and go with another type of system.

IOW there is no reason to have an isotope that has a half-life of 25,000 years when your probe will be out of communication range in 100 years and your thermocouple and the computer electronics on board died long before that. In space weight is everything, if you have to add 100000 times more uranium to get the same localized heat as 1 volume of polonium-210 for shorter spaceflight. For longer spaceflight you want something that generates hot alpha particles (they are insulatable by paper thin shielding). https://en.wikipedia.org/wiki/Plutonium#Power_and_heat_source. 238Pu has a power density of 570W/kg having a half-life of 87.4 years, whereas the shortest , and is a natural product of uranium decay. 232U is a synthetic product and difficult to obtain has a halflife of 69 years. THe closest natural isotope is 235U which has a half life of 700,000,000 years meaning you would need millions of times more Uranium, a specific type of heat retaining insulation to generate. MORE IMPORTANTLY, at this weight of 235U you surpass the critical mass (52Kg), this is a very bad thing for space-craft . . . .well not spacecraft specifically. . . but the poor unfortunate soul that constructed the RTG that blew up half the town. Long story short 210Po- heat your feet in your soyuz moon going space craft. 238Pu - run your experiments in voyager (HL = 89 years) 235U - Make'm big'm bomb or or create Chernobyl frankenwolves.(critical mass is low but half-life is high) 238U - A slow degrading isotope of Uranium goes by the tradename DU (depleted uranium) good for blowing the crap out of any tanks that you don't happen to like. Note: fast breeder reactors can generate 239Pu from 238U but this is irrelevant in space since the mass required to initiate and control the reaction are two great to make them practical.

There's no doubt in my mind to begin with, if you mix enough compost with martian soil those perchlorates will not last very long. The critical ingredient is not the earthworms, its the composing material they added. Compost does two things, for alkaline soils (e.i. martian metal oxides in the soil immediately become bases upon hydration) and Example Na2O + H2O ----> 2NaOH. NaOH + RCOOH becomes Na+RCOO- + H2O NaClO4 + Acid <--------> HClO4 HClO4 + 7H+ + electron donor (compost H:) ---------> 1/2Cl2 + 4H20 For example peat is an excellent source of protons. IOW, the earthworm part of the story is hype, they are just a canary in a coal mine. The critical ingredient is decaying organic material. Edit: I can put this another way, which might make the compulsive terraformers here unhappy, the Earth, at one time and still is, was very good at terraforming itself. It is the fact that once life begins and takes off, it can force the climate and soil where it wants to be. The ideal of earth as a living thing just as a eucaryotic cell has multiple lives within it, and the body has many cells, the Earth's surface is a living thing compose of biomes with various biotypes that cooperate (through both their lives and deaths) to create a living surface. If we remove this, we get something like Mars (too cold and small) or Venus (too hot and dense atmosphere). The old earth soil was this thin, methane was up there and spread loosely around. Now the organic material is a very dense and living layer decaying first by bacterial action, then by fungi, then by the activity of soil detritovores, then by the activity of plant roots, then by the decay of roots and plant leaves and start next cycle. In such a dense layer of organic material perchlorates or any kind of highly alkaline base cannot survive, since water is a prerequisite for soil, many soil oxides will decompose to base and the bases are unstable and become salts (like carbonates). Most of the biomass of the earth is now within the very top of earths crust.

Greater than 6% of the power of a nuclear power plant comes from fission product isotopic decay. Reading the posts . . . there seems to be some confusion between isotopic decay and neutron initiated fission. To understand how a fission reactor works take a long thin yard(meter) stick and try to balance on the blade of a very sharp knife. Any movement to one side or the other and the yard stick falls off. Fission of unpurified uranium is not spontaneous, yes it occurs but only slowly. To increase the rate of reaction fast neutrons need to be slowed by water or graphite. However once you get the reaction going you want to moderate, oddly this is also done by water (circulation in the reactor) and by control rods that contain neutron absorbents. The control features of a reactor broaden "the edge". If these features are removed the knife blade gets very thin and one can easily step into a prompt critical situation. If one moves to many control features into a reactor you can go the other way due to 136Xe poisoning. Here is a clear prompt critical situation. https://en.wikipedia.org/wiki/SL-1 Chernobyl was a mixed situation, but the 33+ GW explosion that took place was the consequence of poor fission modulation of a subset of pellets within the reactor, part of this was do to poor reactor design (this reactor design allow the build up of nucleated steam pockets) that was exacerbated by poor power to the cooling pumps that were required during reactor shut-down (as this was a shut down test and not a full shut down the exact qualification is ambiguous). The steam that built up around pellets that were not modulated by control rods allowed the pellets to go prompt critical, even though this did not include the entire reactor, it included enough of the reactor to create a catastrophic, epic, steam explosion. The heat of the <190 MW contributed by isotopic decay helped in that the improper cooling that lead to the disaster the isotopic decay was contributing the steam-pocket generation potential. But the bad in all of this was there were some pellets that were too far from the control rods at the time and although they were a small subset of all the uranium, there was sufficient number to create a local prompt critical, of the 33+ GW of power generated less than 1% was from decay heat. THis is to say that Chernobyl could have happened in an ever so slightly different set of circumstances without decay heat. The difference between SL-1 was during its prompt critical the proportion was so great that all the water immediately boiled and threw the uranium over a wide area completely stopping all reaction. At Chernobyl the fraction was small enough to preserve the Uranium which then melted basically to the core and created the situation we see today. The people who died at chernobyl primarily died from the secondary effects of a reactor breach (one man died from being scalded by reactor water), at SL1 the people died from the primary effects of being at point blank range from a prompt-critical explosion, (i.e being impaled by a control rod). Fukushima was almost entirely caused by the decay heat. In this is to say if your reactor has a 6% off power rating and your reactor can ambiently remove 1% of that power, that over time (say 24 hours) the heat of the decay will cause the reactors to blow off steam and hydrogen and eventually melt down. Why this has to do with space. Steam generation is the most efficient way of capturing the power generated by heat in the reactor. In general the water traps the heat, and the steam takes the power from that water and delivers it to one or two generators in a series and finally dumps the remnant to a cooling system before it is pumped back to the reactor. The steam/water separator depends on inertia and gravity. In addition nucleated steam on the pellets can become stable without gravity to remove the steam. For this reason steam reactors in space are highly limited in size and output.

https://en.wikipedia.org/wiki/Fregat#August_2014_failure

If you landed a fusion reactor on the CO2 poles it would sink like hot lead in an ice-cream sundae. The magnetic fields will only be applied when solar storms are a danger, and their field strength can be pulsed or even inverted. There is an alternative which is to place Coils on a set of tracks on the surface and have the simulate a solid core moving under the outer layers of the planet. You could have a orbiting wire array at L1 that creates a repulsive magnetic field that forces the plasma stream around the planet. Since that must orbit anyway the core could move closer to the sun when more force was needed and farther from the sun when less force was need. We could just dig way down into the planet from both poles and then create two large interconnected dipoles. Anyway I don't need to figure it out, there lots of times (100s of years) for it to be figured out or forgotten. Its kind of like fusion power.

Fusion is less far off the Venusian city blimps.

You have to have an awful lot in a loop to remain stable. The satellite tethers need to respond to fluxes in the gravitational field, the tether is releases and pulled back. Again lets go backwards. 1. Get a fusion reactor onto the surface of mars. 2. Find a reliable way to reach thick icey polar region of mars 3. Find a way to transfer power from the equitorial regions to the polar regions 4. get the water reliably back to the equitorial regions (I would think that by now everyone should realize this is 100s of years in the future . . .fusion maybe 75 years; getting mechanized engineers to mars poles; prospecting the energetics of extracting water from the poles, 20 or 30 years, finding a way to transfer power to the poles (requires ISRU, aluminum wire processing, building of towers, etc) at least 100 years after fusion power arrives. Then you need that +100t drilling equipment (something smaller will do). If you make it through all these steps then maybe 400 to 500 years from now you can pretend to make air on Mars.) by this time the drilling equipment should have improved markedly over current varieties. However I do expect these new varieties will use more hv and other wave form generators and much more energy and put a lower burden on the mechanical part of drilling cause the energy needs to be much higher. 5. Comet redirect is also an option. 6. get atmosphere stabilizing electromagnetic arrays in place. This is to say the technology is known, just not really doable at present or near-future. We could also say fusion technology is known, and fusion has been done for so briefly and inefficiently as to not call it fusion power. But they are progressing. There is no progression here on earth building cloud cities.

That tunnel was designed for two trains and a highway so . . . . . . .But yeah, if you cant get a 200t Wendelstein X onto mars you don't have to worry about tunneling anyway. I'm ordering my S210 today, watch your feet, . . . . . .

Dump it after apogee surpasses 1.5 million miles it will wander around the solar system a bit. We can have a media storm about when it will come crashing back to earth, you could also dump it on a course that causes it to collide with the moon. 800-900 ISP is kind of poor, NTRs have very heavy engines and they run on hydrogen.

We can, but to have enough they would have to be big and be capable of creating large magnetic field, that is particularly difficult. Just to make a point, Any decent sized laucnh system is now capable of getting a few hundred satellites into orbit, and all you need is 5700 dv to get them to mars. So basically you get to LEO, refuel then go to Mars. That has nothing to do with the problem at hand, because you would need 1000s of satellites capable of creating a magnetic field around mars, which means the power supply and some sort of very long booms for creating a dipole that can link to other dipoles. Again this is future space not a lets do this tomorrow. Ok for example if you had polar satellites you could have a series in orbit at one altitude, then another series at another altitude, even connected by a long thin wire that float magnetic dipole as they move creating a facsimile of a N and south Pole. There is new technology for creating surface dipole at great distance, so this could be at north and south polar regions. Again each series would need 100s of satellites to keep the wire from crossing into the atmosphere. It could theoretically be done, not saying it should be done, just saying that adding water to mar's surface is rather futile until it has a magnetic field. I believe that there is frozen carbonic Acid underlying the permanent Ice at the poles and lots of it. Carbonic acid is not particularly hard to deal with, heat to about 50' at STP and bubble with N2 and CO2 will come out as long as there is not to much base in the water. The problem is that in areas most likely to accumulate water, also are the places most likely to deposit clathrates and then CO2. So accessing these you have layers. Thats credible if only if you have not been fooled by the fusion reactor in 20 years. Lets say at the end of this century. Not to worry, it will be long before we have the capability to do the other stuff. (like generate a facsimile of a magnetic field). The swiss have dug a 80 something km tunnel. Yes but point taken, its another energetic proposal. OK so lets be frank, if we want to argue that we are going to have cloud colonies on Venus, we do not even have cloud colonies on Earth, and the technology to have a venusian cloud colony ranks up with the abrewhatshisface warp drive. So getting more down to earth we have Mars and mercury. The mercury issue is simply a brute force issue (cranking out those dV), if you can create technology for the moon, you can do so for Mercury (just much more expensive but cheaper to operate when you finally get there). Handled these two then there is Mars. Mars is freaking dry. Do we have the technology to make it wetter, the answer is yes but its tremendously expensive and requires things we are trying to invent but are not yet invented. So yeah, 21st century. Mars has enough problems as it is without Nuking the poles. Dry Ice makes an excellent insulator, this is because is primarily flake, by getting under the ice you can use the latent heat of mars on one side and insulating capacity on the other to grab at the water you need, at first. Of course the problem is how to get that back to the colony. Its all expensive. So getting that going may 23rd century. Finally, life on the surface of Mars probably does not exist, but if you go digging 1000s of miles underground with trapped water from the early history of mars, you might be in for a surprise, like archea level bugs in the mileau.

The problem with martian water is that it is retained in paleogeologies that have been preserved. Climate forcing is readily apparent on Mars, because of its lower gravity than Earth these forcing mechanisms have more consequences. The heat from the sun is not great, but water once evaporated is free to liberate hydrogen in equatorial regions or sublimation in the polar regions due to the lack of a magnetic field. it is possible to create a magnetic field or around Mars using 1000s of satellites that convert solar power and also ground stations that reinforce the feild, this however would not be either comprehensive or stable . Thus water in the equatorial regions is inherently unstable over time, where as water buried in the polar regions and covered with CO2/water clathrates and dry ice will be more stable. So the problem with water on mars is getting power from the places that have power to the places that have water so that water can be accessed. Already discussed in other threads is the problem with fusion reactor weight and heat dissipation, both problems for getting a fusion reactor onto mars (although it could be delivered in pieces and assembled on mars) Since you probably don't want people to be living in the cold polar regions, you need to deliver the water from the places that have water back to places that don't. A second way to do this is to actually heat the poles using radiative heating, either from space (polar climate forcing) or by transferring power from the equator to the poles. Thus forcing the water and carbon dioxide off the poles and back into that atmosphere. This has the added benefit of warming the climate at both the poles and the equatorial regions. ONe still has to deal with solar winds. One could dig a tunnel from the poles to the equitorial regions that permit the flow of water back to the equator. In the process you might also stir up dormant life forms on Mars, which means that you will have xenobiology to worry about. But one could dig deep cisterns that keep the water in places that can then be used by humans, cisterns covered with plastic to prevent evaporation (of course the cisterns would be kept at 4'C because at martian pressure and room temperature water would boil). The bottom line is that any colonization system on Mars would need a water plan, and invariably these plans require alot of energy to execute.

You still have not done the math. Its not a few percent., SKE is specific kinetic energy specific potential energy as two components of specific mechanical energy. Spacecraft Orbital mechanics is ALL about energy management particularly when you are moving between Hill spheres. If you only concern yourself with velocities and dV you fail, simple as that. Again, I am point out to you the inherent inefficiencies in ION drive systems that give rise to the problem 1. Lack of thrust on the endplate give rise to huge endplates 2. Lack of a credible power source (except for small satellites, in which case solar will do) 3. Futuristic power sources that are incredibly heavy and produce untenable amounts of heat These give rise to the choice one needs to make concerning 1. Burning between SOI using non-optimal burn points 2. Burning at optimal burn points but requiring insane amounts of time. 3. A compromise between 1 and 2 starting with choice a. burning from AtP optimal -90 to 90 degrees (doubling the time but significantly cutting the loses) to b. burning a few degrees clost to AtP optimal and losing little but taking alot of time. or c. Do a spiral out burn and wasting half the dV. Read it again, when you do the math and figure out where the numbers came from, then we can talk about it further.

Needs more HVAC/duct tape on the nose cone.

lol, no.

No, No, No....5760 dV is for a very specific model, its a launch that places the outbound burn at completion that intercepts Mars without the need for a plane change burn and then with minor correction places the craft to LMO were it burns to circularlize without any system entry slowing burn. Specifically you leave earth and try in orbit to intercept mars LMO at its orbital apo. To achieve the 5760 you have to launch from a particular time of day, +/- 10 degrees achieve minimum orbit at 140,000 then make your escape burn average to a certain time of day something like 135 Atp, preferable at as high a g-force as possible with no spiraling. If you spiral out of orbit or spiral into Mars orbit the dV goes up markedly. You can achieve the same with an ION drive as long as you estimate how many kicks you need, the backtrack that number of days alterning the place of the launch and burn by 0.985 degrees per day. Its not the best way but the model allows you do kick with no increase in cost, spiralling cost extra dV. Noting that a kick is a spiral but a spiral that preserves pE as closely as possible with constant burning you loose dV. Correcting an error of a previous post because its demonstrates your misunderstanding in these matters. At SOI you get to (Must keep) any specific kinetic energy that you gained during our burn but that you did not loose to specific potential energy. (See thread on this, it was specifically put out because of misunderstandings that you have). SKE = V2/2 SPE = u/r (for any radius). For any circular orbit SKE = u/r and SPE = (1.4142 * V)^2/2. Consequently burning to a planet at LEO along a optimal vector can both add dV (in terms of post scape velocity) and inclination velocity in excess of what is added at LEO. If you for instance burned to barely escape earth and then at mars burn to reach HMO and then burned again to circularize mars these are your DV assuming we nailed the plane change at liftoff window and dv1 - 3240. Burn to escape Earths SOI and no more (spiralling cost even more) dv2 - 3663. Burn to Mars and no more combining dv1&2 into a single burn with associated plane change - 3884 (you saved 3019 dV) dv3 - 1986. Burn to match velocity just inside Mars SOI dv4 - 1499. Circularize at Mars LMO. (Spiralling in costs more) combining dv3&4 into a single - 1877 (you saved 1608 dV). You said using the rmin "Oberth" did not result in any remarkable savings . . . you are wrong. . . . .by converting all but a mid-trip correction burn (which is usually only a couple dV) you save 45% of the dV required to get to Mars, if you are a space tug hauling non-perishable items to mars you just cost your money (xenon gas is very expensive) and you reduced his PL by 40% and in addition you just earned your competitor business. To put it otherwise you increased the companies variable cost by 81% over what it might have been if you planned your burns carefully. The last burn you make to Mars from a spiralling orbit is for-all-intents and purposes is dV2, this means that you have already spent at least dV1 to get to that point, whereas by repeatedly kicking at say 150-300 km I am basically emulating a model orbit exit by using the elliptical nature of orbits to give more optimal burn time. I should mention that if you watch You-tube videos of KSP long time players you will see that they make burns along multiple axis in order to maximize the burn and avoid waste. You will find many posts here about players complaining that the trip to Moho cost alot more than stated on the dV map of the Kerbol system. This is the reason why. The dV map assumes that Hohmann transfer are made with only 2 burns. For planetary systems like Jool the process is more complicated because achieving LMO may not be desirous unless it can intersect a given planets orbit. https://en.wikipedia.org/wiki/Specific_orbital_energy

Its a great place to launch extrasystem craft because you can launch empty cans on solar ION drive ships, then fill them up with Argon, the kick each time you pass the sun at PE continuing to do so for a year or so when you get an Apo about the orbit of jupiter the next pass you use all the rest of your fuel and press for high speed. You could even use shuttles to refuel the ships each pass if you use X:1 orbit that greet Mercury each time. While I don't recommend the use of steam in space literally at termination you put a boiler and run a bunch or radiators on the back side and you have a steam turbine. 10 to 16.2 kW per meter. Thats enough to run three homes.

Too bad they could not find a parachute.

The standard ISP for HiPEP is 8900 sec. In addition I ran your numbers, to develope the 5600 spiralling dV you need to escape, requires 3 days using the acceleration you gave, but since you wasted half your fuel by using a spiralling path and lower ISP, your net load went from 180,000 PL to 140,000 PL (200,000 to 160,000 if exchanging at Mars). Congradulations you just discovered the payload efficiency tradeoff for ION drives. Unfortunately the head of the space tug company your work for just fired you. This has been tested are revealed many times. If you use your thrust to circularize (make more circular) then you have to pay an additional cost to circularize, you cannot keep that energy when you leave, it goes into the planetary system.

You really should read past postings in the group. The topic of hydrogen leakage has been discussed ad nausea. Its the reason when I say x-space craft use RL10b-2 at some great distance from earth I also mention that no provision or some mass provision was give for collection and concentration of hydrogen. IR detectors are used in Jet craft for targeting surface to ground missiles. They can be (and proabably have already been) made more sensitive for use in space on satellites as they are not quite as surrounded by background radiation. The OP did not make any provision that the target world did not have developed satellites. So now I argue that the world has 50 J. Webb telescopes and 100s of satellites in GTO just looking for aberrant IR signals and peculiar asteriods that have weird hot and cold spots. Just to make a point we detect single photons of red-shifted light that have traveled for 13.8 billion years, detecting something a few 1000 kilometers away is small relative to this. This is how your scenario plays out, race Q on Ganymede takes off with a full load of hydrogen. On day 26 it is bombarded by a cosmic ray storm and looses about 1/10th of its hydrogen. As it makes its way to Mars (a trip that takes 1.9 years) it looses about 5% per month. Somewhere around the sixth month the spy realizing that he will not have enough fuel to hide unfolds his solar panels and radiators and begins scavenging all the hydrogen that he can. Just then the target world and its 1000 circumsolar asteroid findng space craft detect a strange signature. They immediately begin panning that area of the sky, now about 10 m Km from the target planet and 8M km min from the telescopes. Sure enough a strange reflection of the solar panels are caught just long enough to plot a course. The course will intercept the target. The target planet then trains all variety of sensors looking for the coincidence of x-ray, uv, visual, and Ir photons from regions of space without sources along the path. Since they are not looking at a single wavelength or a single time but following a path they pick up a very fuzzy signal that suddenly increases as it approaches the world. They train there lasers to the part of space where stars momentarily disappear and blast with many lasers with microwaves that correspond to the frequency absorption of Vanablack, sudddnely a very intense IR signal appears, they keep blasting until the target explodes. No spies were detected, but very stranglely that area of space smells like bar-b-que to death row inmates who get spaced.

I don't disagree with you but I will make a couple of points with regard to gravity that make gravity as a force stand out. 1. Gravity is not a force, even though we treat is as if it was. When you stand on the ground its not gravity pulling you to the ground, its electrostatic forces in your shoes and ground that push against your inertia, if these did not exist you would easily form an elliptical orbit around the Earths point mass. Gravitation is the warping of space-time cause by the anisotrophic distribution of energy in space. The problem is that space has at least one form of non-zero energy rest state, and it may have other forms. 2. Gravity in its purest form (Quantum space-time) was once the strongest force in the universe and composed of a particle that was presumptively most of the energy of the Universe during early inflation, but now gravity (space-time), which we all agree, to be a field that propogates through space time is the weakest of all forces. . .So small in fact its not possible to detect its particle, just its peculiar effects. How does quantum gravity go from the strongest force in the universe to the weakest force in the Universe with gauge invariance? if Quantum gravity can vary then why cannot space-time similarly vary. Oddy if you try to detect gravity in different ways you get a slightly different result, and although we know what Standard gravitational parameter for the earth and sun to about 10 digits, the gravitational constant is only seven. All the other basic constants of the universe are know to at least 10 digits. Thus gravity as a force stands out for several reasons. It should be subject to ongoing critique as to the core of its nature.

Fission based expulsion systems typically have low ISP. 1st the Power/mass is low and second the end products are heavy and do not gain much speed.

Bottom line is that he creates a set of consistencies but does not explain the require time variance in space-time. He could be right, but does not know enough or have enough insights to gauge variance to do the math. Part of the problem with early theory of relativity is that Einstein did the same, and later found the mathematical solution, but now in a post-relativity physics should anyone be allowed to do the same. Remember he advocated a cosmological constant. I still think the idea of a cosmological constant is wrong and even if it was right its not consistent over time and not what Einstein thought it was . . . .It was a guess. My point is that OP-author may or may not be right, but people need to stop looking for massive particles and start looking at gravity itself.

Right, fission just doesn't shut down! I was going to mention this. In a fission reactor a high percentage of the fuel is undergoing a low rate of decay, water and graphite are moderators, but even as one removes the rods or raises the graphite, the downstream short-lives isotopes are still decaying for days after. Fusion is different, in a fusion reactor reactants are pulsed into the reactor, undergo fusion and then expelled. In this process they lose heat. There are three primary products, helium, dueterium, and tritium (half-life is 12 years), On a quantum scale this can happen, what would happen on graphene is that it would cool and the ripples would decrease intensity and stop, therefore there would need to be a heat source to restore the rippling.

How is the waste gas accelerated. And my presumption with Space nuclear is that you start with alot of hydrogen and a little Deuterium. As the fusion reactor goes over time it generates deuterium from hydrogen which is then used to fuel the reactor. If you expel the reactants into space prior to purification you waste the neutrons. Anyway how is the waste gas accelerated? rf? Lasers? Magnetism and Charge variance? As stated previously every metal has its breaking limit temperature, that temperature determines the ability to accelerate. To get higher than that you need to use EM or its surrogate charge propulsion and magnetism. In fusion you have to create a plasma and pressurize it, this can be used to expel the gas. THE BIG PROBLEM IS: you have to bring a power supply or battery along that can get this process going _and then_ after its completed you have to recharge. Are you using solar cells (for example while off-cycle kick burning out of orbit around a planet). Constituitive space craft operations are nothing compared to the cost of sustaining and using MW of power in generation.