-Velocity-

Also, the "best" heavy lifter is now greatly influenced by the cost, since funds at higher campaign difficulties are much more limited. I'm finding I'm using a heck of a lot more SRBs now. In fact, my latest "medium" lifter used SOLELY SRBs (29 of the biggest ones...) for the first two stages! I found out how much harder big rockets are to control when you don't have thrust vectoring! I am appreciating how the campaign is forcing us to do things we'd never considered doing before

I've heard that assertion before from fringe people and frankly, it is completely ridiculous and illogical. Many oil deposits are located in areas (oceanic crust) where the crust is young, only a few hundred million years. The oil and coal is located right int he middle of sedimentary layers of rock. How did it get there if it wasn't through biology? Oil can't melt its way up from the mantle like magma, and the high temperatures of the mantle would destroy it anyway. So either oil has a biological origin or the great Oil God simply dropped it out of the sky. This proves that it was something that was not born with this planet, but created afterward. Oil and coal are concentrated carbon, and carbon does not make up very much of this planet. The only way to concentrate it to such degree is through biological processes. Now is it possible to create oil without biological processes? Sure. Does that ever happen in nature? I donno. Even if to does occur though, all the fossil fuels we produce here on Earth are, in fact, FOSSIL fuels. No "primordial" oil would have survived Earth's early years, and we don't find oil in old cratonic crust anyways... a gigantic hint as to where it comes from....

For my VERY heavy lifters I longed used asparagus staging, with six stalks surrounding a central stalk. However, due to fuel flow problems I had to switch to vertical staging for my biggest lifter- it's almost impossible to get the stalks all draining correctly when there are multiple main-stalk tanks and nacelle tanks. Anyway, I'll post screenshots if/when I remember, but I got a vertically-staged 8,000+ ton (sans the payload) heavy lifter working without too much difficulty, once I finally abandoned asparagus staging. It could put about 2000 tons into LKO if I remember correctly (so the total liftoff weight was in excess of 10k tons). If you're wondering what the heck such a huge rocket could be good for, I used it for launching an "interstellar" probe that ended up with a final anti-solar velocity of like 120 km/s, don't remember exactly. I do remember that I could do a little bit better than this- I put way too many solar panels on it- so, 140 km/s or more is probably possible. This was stock, except for Mech Jeb.

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Sorry for probably posting a duplicate thread- YES, I SEARCHED MULTIPLE TIMES- but is there any resource out there that describes what each profession, and leveling them up, even does? At what levels do they get what skills, and what are those skills and how do you utilize them? It appears that the KSP wiki has not been updated to reflect beta yet. As an example, do I need to be bringing along scientists to collect EVA samples or something? Do they help improve science collected in any way? I understand that engineers can fix things- but what? Wheels and... ??? The game is starting to get complex enough in its own right to warrant a manual ASAP. I miss the old days, when all you needed was an understanding of orbital mechanics (Actually, I don't miss those days at all, the game is getting so much better now, but we need better documentation!)

I believe that gravitons have exceptionally low energies. If they're anything like photons- and there is a lot of analogous behavior between electromagnetism and gravity- then their energy is dependent on their wavelength/frequency, with shorter and shorter wavelengths resulting in higher and higher energies. To a certain extent, the shorter the wavelength and higher the energy of a photon, the more it begins to act like a particle- certainly, it becomes easier to detect as a quantized particle. Most gravitational forces are static or move and accelerate very slowly, so gravitons should be essentially undetectable, just as you cannot detect photons from static or slow varying electric and magnetic fields. The photons emitted by very slow varying or static fields remain "virtual" particles, undetectable as real particles, and by analogy gravitons ought to be virtual too in all but incredibly extreme cases that possibly only existed after the Big Bang, if ever at all. Just my take on it.

This just popped up on space.com http://www.space.com/28320-asteroid-mining-bacteria-microbes.html Sounds a little crazy. But what if they surrounded the asteroid in a big air-tight bag to keep the volatiles from leaking out? First that would be a big balloon. But secondly- where would they get enough water in the first place? This doesn't strike me as practical or plausible on first examination. However, what if instead of injecting the bacteria into the asteroid, they could inject the bacteria into a smaller section of the asteroid they separated and put into a bag? All this seems more complicated and less practical than some kind of chemical extraction, but I'm not a chemical engineer. - - - Updated - - - Not true, at least, not yet. Right now, at processing factors, like uniformity, the resulting expense of the necessary silicon process equipment, and the availability of process equipment limits the size of silicon wafers, really. We can make bigger wafers than the equipment can operate on. They thought that that we would have already moved on to 16" wafers by now, but the most advanced foundries are still on 12", because the new equipment to process 16" wafers is so expensive, hard to develop, and still experimental. Having no gravity could actually make silicon microfabrication more expensive and difficult, but I've necer studied the problem.

Maybe this is comforting to you, but many people view other species as having value in of themselves. Also, mass extinctions do destroy; they destroy millions of years of genetic heritage and reduce biodiversity. Organisms do not live and die in vain; they all contribute to the billions-of-years genetic history of life. The genes of a living creature tell an incredible story of biochemistry that we are beginning to learn how to read; every time a species goes extinct, then a huge amount of that history is irreplaceably lost. Future history is also lost- all the species that the extinct species could have possibly evolved into are also lost. Heck, for all we know, any random higher animal species (most likely mammal or bird) could lead to its own intelligent civilization in 20, 30, 100+ million years. Earth has at least 500 million years left.

I thought that teleoperation implied real-time control, but I might be wrong.

You can't teleoperate asteroid mining; the asteroids could be will frequently be tens of light-minutes away.

Mars probably doesn't have enough volatiles left to sustain an atmosphere for a long time. Melting the ice caps would get you some, but it would re-freeze. It would be far better to deliver more volatiles by redirecting comets to impact Mars. Siding Springs would have only required a slight nudge a century ago, though it was anomalously close. Yes, Mars loses its atmosphere much more quickly than Earth, but it still takes hundreds of millions of years, even without a magnetosphere. I'm not sure what the radiation level on the surface would be, but a thick atmosphere would greatly reduce it. The biggest problem I can see with cometary redirect would be that by the time we'd be ready to do it, there would likely already be people living on Mars. At which point, you obviously can't go smashing big rocks into it anymore. It also begs the question of why you need to terraform it in the first place. And no, cometary impacts would probably not blast off more atmosphere than they add. If Mars lost some or much of its atmosphere from impacts, they were from impacts with asteroids, which have almost no volatiles, so asteriod impacts can only subtract, not add.

The paper is not incorrect, but it's another example of the popular science news media completely overblowing a completely mundane topic, and also of people who somehow still cannot grasp that light is both a wave and a particle. When a wave propagates, it can diverge in different manners. In 3 dimensions, a wave that is NOT diverging is a plane wave. Its wavefront is planar. The wavefront progresses at the propagation velocity of that particular kind of wave. However, really you're never going to observe any true plane waves in nature, though many wavefronts can be approximated as planar. For sources far away, wavefronts you observe are usually going to be diverging spherically (but over short distances can still be approximated as planar- for example, if you climb a ladder at night, you should not expect the stars to become measurably brighter because you're closer to them). The magnitude of the wave will decrease by 1/r, thus meaning the energy in the wave will decrease by (1/r)^2, leading to the "law" that the intensity of distant sources of light will decrease by a factor of 4 if you double the distance. However, there are other ways that waves can diverge too, such as if the medium is bounded in some way. Imagine you're a whale. The sound waves you produce are bounded by the ocean surface (a pressure release surface with a reflection coefficient of -1) and the ocean bottom (a pressure doubling surface with a reflection coefficient of 1)- as long as there is not a thermal layer (which can also reflect sound). Relatively close to the whale, the sound the whale makes will diverge spherically, but at distances much beyond the distance between the sea surface and sea floor, you actually get into a cylindrical divergence regime. The sea surface and the sea floor acts as a crude waveguide, preventing the sound from escaping in three dimensions, and reducing the rate at which it decreases with distance. Instead of 1/r for the sound intensity, you get 1/r^0.5. Whales use this waveguiding effect to help communicate long distances. (In reality, I think I've simplified this a bit and that whales actually frequently use two thermal layers or a thermal layer and the surface as the bounds for their planar waveguide, since the seafloor and sea surface are far apart and there is usually a thermal layer anyway.) Why I bring this up is that because of this wave guide effect, the wavefront of the sound is NOT aligned with the sea surface- the wavefronts are bouncing between the top and bottom surfaces. This means that, transverse to the surface of the ocean, the sound is NOT propagating at the speed of sound in water. It's instead propagating at the "group velocity". The group velocity is determined by the angle between the wavefronts and the ocean's surface. Only at 90 degrees is the group velocity equal to the speed of sound. Sorry for the long, drawn-out examples, but the end message is that light is a wave, and the same wave theory rules apply. If the wavefront is not aligned with the group propagation direction, then the speed of the light-MEASURED IN THE GROUP PROPAGATION DIRECTION- will not be c, even in a vacuum. I never considered that this applied to gaussian beams too (lasers emit gaussian beams), but of course it makes sense that it does. From what I'm reading all this research group did was reduce the intensity and/or duration of the beam till it was a "single photon", and noted that the group velocity remained unchanged. Whooptie-freaking-do. However, while the science is unimpressive (well, there is no real science), the usefulness of this paper is to help point out to people working on precisely pulsed laser systems that they should not blindly assume that the laser beam propagates exactly at c. To be honest though, what I am still confused about is why the velocity would not be exactly c at the center of the beam. Maybe I'll have to think some more on this.

It's basic trigonometry. If you wanted to resolve features, say, 1 km across on Pluto, that means your telescope has a resolving power of 1x10^3 meters / 6x10^12 meters = 1.67x10^-10 radians (this is the small angle approximation for tangent that you should hopefully remember from high school). The only other equation you need is to apply the Rayleigh resolution criterion (http://en.wikipedia.org/wiki/Angular_resolution)- Resolution = 1.22*wavelength/telescope aperture. For visible light, 500 nm is a good middle-of-the-spectrum number for wavelength. So, it's 1.67x10^-10 = 1.22*5x10-7/d d = 3660 meters = 3.66 km. That's a big mirror.

No, I don't think that infinite is impossible to understand. Everything in the universe follows rules, and those rules are possible to understand. Nothing that derives from those rules are impossible to understand, you just have to find the right way of htinking about it. For example, quantum mechanics starts to make a lot more sense if you just drop the silly notion that particles are actually particles.

There were some folks saying a few years ago that since it appears space is flat, that must mean the universe is infinite and that somewhere out there is an exact copy of Earth, on which lives an exact copy of you. Given infinite star formation events, after all, there should be an exact copy of Earth, and even the entire Milky Way galaxy out there. I too find this absurd. Here I thought that the leading theory for the formation of the universe was that everything began in a Big Bang, and the the universe initially was an extremely small (atomic scale) closed sphere of space-time with incredibly high energy density, and that inflation blew it out to macroscopic proportions. Where did I go wrong with that? Because if that's true, then an infinite universe with infinite matter is impossible, because the universe started out with a finite size and finite energy density. The only way around that is if there were there regions casually disconnected from us by the expansion of space where new matter was created. How does that work?! Expanding faster than the speed of light allows a finite universe to become infinite?!!? The only way in which I understand the universe being infinite is if you were to try to transverse it. The farthest regions are expanding away from us faster than the speed of light, so we cannot reach them. If you were to travel across the universe in a spaceship going 99.99999% of c, what you would observe is a universe that appears to be spatially infinite. You could travel forever in any direction and never return to where you came from. However, while you would observe that the universe appears to be infinite it its spatial dimensions, you would not observe it to be infinite in its quantity of matter, because as your voyage progressed, you'd observe the density of matter decrease with time as the universe expanded.

Astronomers have believed for decades that the early solar system was a much more crowded place. There may have been like, 7, 8, 10 large inner planets- who knows, maybe more- right after the main phase of planetary accretion was complete. The four inner planets left today are just the survivors in a game of gravitational billiards. If Mercury DID survive a giant impact that blasted off much of its mantle, then the debris that escaped Mercury's influence was most likely ejected from the solar system or impacted other objects. Who knows, maybe some of it is still around in the form of a few small asteroids. Anyway, the point is, to think there's some connection between the object that purportedly hit Earth to form the Moon ("Theia"), and an object that possibly might have hit Mercury, is not logical.

Without knowing the actual reabsorption rate/reaction rate or the mechanisms involved, in the limit of small changes in the concentration of oxygen, the absorption/reaction of atmospheric oxygen will likely occur in a linear fashion with time. Over longer time periods, it may start to approach an expotential decay of some sort. But it's possible that within the range of oxygen levels that would support humans, absorption and reaction of oxygen would be linear enough that a linear approximation may get you in the ballpark. If you assume that the current oxygen levels represent an equilibrium between oxygen production by plants and oxygen absorption and reaction, then you need to find out how much oxygen is produced by plants yearly. If you make the assumption that without plants, oxygen absoprtion and reaction would continue at the same rate, then you can thus get a ballpark estimate of how long it would take for oxygen levels to drop below habitable levels, by using the aforementioned linear approximation by subtracting the oxygen production rate of plants from the atmosphere until levels fall below habitability. This will probably under-estimate the time it would take, but that's OK, since we're just looking for a ballpark figure. In reality, the moment plants die then there is a quick drop in oxygen levels (probably only by a fraction of a percent though) because much of the decay of plant matter will involve reactions with oxygen. ANYWAY, in summary, look up the rate of oxygen production by plants, and make an estimate based off of the assumption that we're currently in an equilibrium state between oxygen consuming and oxygen producing processes.

It doesn't matter how many lakes or rivers or oceans or rain clouds it has if all that liquid is not conducive to supporting the extremely complex chemistry that life requires. Our best guess is that liquid hydrocarbons do not. Not only do they not support the range of chemistry that water does, they exist at much colder temperatures so any chemistry would proceed slowly. What is more exciting to me is the possibility that life could exist in the Titan's "lava" and "magma", which would be largely liquid water. For pure water, it doesn't look like this is the case if there is no internal heat. I pulled the phase diagram for H2O from Wikipedia to illustrate- In Titan's case, I believe we already have confirmed that the mantle contains huge amounts of liquid water. Titan has a big mountain, "Mount Doom", that is believed to be a large cryovolcano that erupts liquid water based "lava".

As it is electrically charged, it won't penetrate very far. Neutrons are dangerous because they do not interact via the electromagnetic force and thus and sail right through the outer atoms of your body, delivering ionizing radiation deep inside your body when they finally strike a nucleus and interact via the strong force. In contrast, alpha radiation, which is helium-4 nuclei, generally only burns your skin since alpha particles are electrically charged, and so they feel electrostatic forces from both the electron cloud and nucleus. (The wide separation between electron cloud and nucleus means that the range at which electrostatic forces are cancelled is much, MUCH larger than the range at which the strong force is cancelled- the effects of the strong force is just confined to the nucleus and a very small radius around it, while the electromagnetic force is not largely cancelled until a few atomic radii.) Since a proton has twice the charge per mass as helium-4 does, I would expect protons to penetrate even less distance into solid matter than alpha particles.

No, it has nothing to do with global entropy, it has to do with local entropy. What they're saying is that it is a general property any system to arrange itself so that it can create as much entropy as possible. In nebulae, this means that stars form to convert rest mass into radiation and neutrinos. On a world with the right chemicals and the right energy sources, this may mean that life will frequently emerge to catalyze entropy-producing chemical reactions. I'm not convinced myself. Entropy works through probability- there are more "disordered" states than "ordered" states. But the steps that you take to get from ordered to disordered are not all equally probable. If life is highly improbable, then couldn't the probability of increasing entropy through the actions of life be smaller than through non-biological means?

I'm not sure I buy this theory either, but it IS somewhat interesting. However, there's a decent counter to your above statement. Life should not be capable of coming into being in all conditions. In addition, some conditions should be more favorable to the formation of life than others, and should give rise to life first. Earth may be an example of this. Additionally, life on Earth has now evolved space travel, and, with luck, will soon be spreading to other planets, asteroids, and maybe even deep space. If humans can pull it off, the development of space travel and the colonization of offworld habitats will be the among the greatest achievements by Earth life in the history of life, right up there will the colonization of dry land, multicellular structures, and photosynthesis. A lot of people set humans above other life forms and see us as somehow different, but the fact remains we are just Earth life, cousins to all other living things, and so most certainly yes, Earth life appears to be on the doorstep of evolving the ability to send "spores" across the gulf of space to colonize previously unreachable and uninhabitable environments. We're living at a very, very special time, and I just wish more people saw it the way I do. We have the ability to accomplish one of the greatest achievements in the 3.6 billion year+ history of life on this planet, if we can just pull ourselves out of the mud. So, anyway, to make a long story short, life may be much more ubiquitous in the not-too-distant future, at least in this solar system.

You'd get your thrust from gravitational radiation pressure, in other words. A static gravitational field cannot be used to accelerate you away from an object, as the gravitons emitted by a static field have zero energy and so a static field would just attract you. This is similar how the photons emitted by a static electric field have zero energy (wavelength = infinity) and are thus never able to make the "jump" from an undetectable virtual particle to a detectable, quantized, real particle. But yes, you'd see the energy drop as the wavelength of the gravity waves decreased due to "redshift". The question is, CAN you absorb or reflect gravity waves? I believe the answer is yes, certainly. Conductors and dielectrics change the electromagnetic waves passing through them by having charges that can move in response to the electric and magnetic fields in an electromagnetic wave passing through it. So a piece of matter that has masses (gravitational "charges") that move in response to the passing gravitational wave should likewise modify gravitational wave propagation through it. So you should have materials that can absorb gravitational waves or slow them down. Boundaries/surfaces should also exist that have non-zero reflection coefficients too, so that allows the reflection of gravitational radiation too. All such effects are going to be incredibly, immeasurably weak. Gravity interacts extremely, extremely, extremely weakly with matter, as compared to the electromagnetic force. Gravity is so weak that we almost never even observe the gravitomagnetic side of it, and only the fact that there are no negative gravitational charges allows us to observe it at all.

You'd be much better off using all the fissile material to build giant Orion vessels to evacuate as much life- and even more important- industrial equipment and supplies- from Earth as possible. You've got to get your @$$ to Mars with enough supplies and backups to give you hope that you can figure out how to live sustainably there before the supplies run out and everything dies... because we don't know how to do that right now. At least you wouldn't have to worry about the radioactive fallout from launching Orion ships from Earth's surface, because no one would give a crap anymore.

Gravitons have WAY less momentum and energy than a photon, which is why we never can observe them. They are so low energy that they behave like waves all the time, and never like quantized particles, like higher energy photons can. There is probably no known process that can produce gravitons with high enough energy to actually appear like quantized particles to any known or even conceivable detection system. Photons have way more energy and momentum and are much, much easier to produce in large quantities. The red/blue shift effect would be exhibited in a increase or decrease in the observed frequency of gravitational radiation- gravity waves. Gravity waves carry so little energy that no one has ever directly observed any, though we may be getting close. We know gravity waves must exist because theoretically they are required, and we've observed close pulsar pairs that are spiraling inward towards each other at exactly the rate predicted by the conversion of their orbital energy into gravitational radiation. I will note that I am not certain as to whether all physicists are certain that gravitons exist. There might be theories of gravity that do not invoke the use of gravitons, but honestly, a universe where gravity is a fundamental force with a force-carrying particle, and not some weird other thing, seems to me a much more simple (and thus, likely) explanation. Gravitons are massless force carriers that travel at c, exactly like photons, so they appear to travel at c from all reference frames. So exactly as you cannot travel faster than light, you cannot travel faster than gravity.

Could you make an "reactionless" drive by moving mass/energy in such a way to preferentially launch gravity waves in one direction? Gravity waves carry energy and should carry away momentum. There should be a gravity wave radiation pressure. You'd be exchanging momentum with the objects behind you, through gravity waves. Even if possible, the thrust you would get would be incredibly, incredibly, incredibly tiny. You'd be vastly better off just shooting a laser out the back of your spacecraft and using the momentum of the photons you're emitting to provide thrust- and that momentum would still be pretty tiny, but at least it would be measurable.