KerikBalm

There are plenty of designs for operating a reactor in zero-G. http://en.wikipedia.org/wiki/SNAP-10A dating back to the 60's, even before the "flight ready" NERVA designs. The larger the solar panel, the more mass it is, you simply can't get good acceleration from a solar powered propulson system without lowering your ISP to horrible, horrible levels. There is a reason the Dawn probe (solar powered propulsion) took 4 years to reach Vesta... A hohman transfer would only take 6 months or so... but it didn't have the acceleration required to do such a maneuver.

Highly unlikely, if there is heat to warm the H20 to make it into ice, then there is a thermal gradient available, which can drive some chemistry similar to "black smokers" on Earth, which life uses for energy and is not nuclear in nature.

Anyone seen this film? Any good KSPer should be disappointed by the end.... The lander goes into a vertical climb, I wasn't clear if this was a programmed flight path, or somehow the result of the fighting and having no pilot... anyway... it climbs, and the engines cut out, it reaches apogee... and ... stops, whereas I was expecting it to plummet back down.. Shortly thereafter, he radios that he's in a stable orbit... wut? So I guess that was supposed to be a programmed orbital insertion burn, but then he can't rendevous with the mothership (insufficient fuel)? Nothing went wrong with the lander... does that mean the entire mission was doomed from the start because their ascent vehicle wasn't up to the task... That all said... I did like some of the scenes before the stupidity starts... just the martian landscape shots (even though it often looked too much like Earth, because, well, it was )

The precooler would be fine, the NH3 wouldn't be needed. The precooler is just to allow it to operate in air breating mode for longer/to higher velocities. Project Pluto (linked in the first post) was a ramjet that needed to be accelerated to a certain speed before it can work. Thermal turbojets are more complex, given that you need combressors and such. http://en.wikipedia.org/wiki/Aircraft_Nuclear_Propulsion http://en.wikipedia.org/wiki/General_Electric_X-39#The_nuclear-powered_X39 A nuclear ramjet would be lighter, but it also requires an initial "boost". So (somewhat ambiguous terms here, using the same terminology as in KSP for the rapier): Closed cycle takeoff, open cycle cruise phase to high altitude and hypersonic speeds, closed cycle to orbit. This is what Skylon would do with its SABREs, if I understand correctly (the sabers can't operate in open cycle from zero airspeed, correct) I was thinking NH3 initially, simply because its easier to store, and much denser than H2, *and* for a given power output, you can get more thrust with it (at lower ISP) for the same flow rate (in liters/sec, not mass /sec). Heck, maybe you could use Neon instead for "moar thrust" on takeoff, I don't know if the pressures in the reactor would be a problem (as I'm guessing the gasses deviate quite a bit from the ideal gas laws in there), but at least you know it won't be clogging or corroding anything. As I understand it, you can do direct cycle engines without leaking radioactive particles, but in practice its hard to make sufficiently durable coatings. Still, if you wanted to operate these things on anywhere but earth.... who cares about the radiation? Assuming a never before used reactor, it should be fine. Maybe not a reusable-on Earth SSTO, but a SSTO that can get large payload to orbit and beyond, but then never comes back to earth - detach precoolers and wings once in orbit, become a dedicated tug? be a reusable SSTO on Titan/crew return vehicle (run it on N2 gas taken there?) Lets send a nuclear thermal turbojet to Titan! I doubt Mars has sufficient atmosphere to run them as ramjets, though you could still condense the atmosphere for ReMass. Venus would probably be too harsh on it, and like mars its mostly CO2 atmosphere is not very good as a propellant.

"- You omitted the dV to land a fully fueled LM on the surface." He probably assumed its something like duna and stock aerodynamics, where you just pop chutes, and fire off about 10 m/s worth of dV to cusion the landing.... Aerobraking would save a lot of dV, (in theory at least 3.8 km/s), but that requires a heat shield, which is going to reduce the dV of the stage going to mars. And even so... Mars' atmosphere is really really thin... you'll still becoming in very fast even with chutes (which again add weight), and you'll probably need a dV of another few hundred m/s. For reference, the pathfinder mission, which was a small payload (the type you want if you want to land on just parachutes)... was coming in at 68 m/s - it would be even worse for a heavier craft. Then you need to figure in the gravity drag while firing the retrorockets... Its not all that much... the biggest problem is the consumables for the journey, and that you really want to be able to get your astronauts BACK to Earth. NERVA, we need NERVA (or prometheus nuclear-electric drives, ideally both)

The Apollo 15 rover could be operated by a robot just as well, its not like the thing was pedal powered. The Apollo 15 rover 210 kg with a 36km range on the moon (low gravity lowers power consumption) Opporotunity weighs 185 kg, goes farther, and is a mobile lab with wheels, not just a pure transport vehicle. Curiosity's "expected" travel distance should be compared with opporotunities expected travel distance... We'll see how far it actually goes, just wait. The lunar rover was for getting from point A to point B, and did not do on site analysis. The robot rovers do on site analysis, they are in no rush, if they pass something interesting, they stop and have a look. For the cost of sending 1 human, you could easily send hundreds of robots... even if the robots are slower. If terrain is limiting, build a better robot... like a mechanical spider. If you want faster robots, land a nuclear reactor, then they can operate at much higher power levels. Relying on solar and radioactive decay is one of the major reasons they are so slow.

You assume a "combat". There are multiplayer sandbox games where combat is not the objective. Think multiplayer minecraft in space. It could be fun to just cooperate building up a laythe base with a friend, for instance. No, it doesn't. Compete != battle Race to X with a budget of Y. Players are given a budget, the one that collects the most science wins... etc. Now it may be that it becomes common to carry a detachable probe, and try to fly it into your opponents spacecraft... but that would be just 1 of many viable strategies.

Basically, there are only 4 engines you should use in the game if part count and cost are not an issue: Turbojets: for use in the atmosphere of Kerbin/Laythe 48-7s: for use when high thrust is needed LV-Ns: for when a high TWR is not needed, but you do need decent amounts of thrust Ions: for when a very low TWR is acceptable. All the other engines have very marginal uses if part count is not an issue

"I don't think NTRs have the necessary specific thrust to be useful for SSTOs" Specific thrust? I think you mean specific impulse? Even going with the old NERVA from the 70s... upwards of 800 ISP, TWR of what.. 3:1? (just for the engine?, not the entire proposed nuclear stage) http://en.wikipedia.org/wiki/NERVA#NERVA_rocket_stage_specifications ISP vacuum: 850 M_0 / M_1 = 5.2418 9.8*850 * ln 5.2418 = 13800 That is more than enough to achieve orbit, but its the low sea level ISP and the low TWR that are the problem. Adding SABRE precoolers and running it as a combined thermal rocket/turbojet will take care of the first ~1,000 m/s of dV, get you up where the ISP is better, and a pair of wings should allow you to get around the relatively poor TWR... Maybe develop it into a LANTR (LOX-augmented Nuclear Thermal Rocket.) for takeoff... The NERVA of the late 60's could be significantly improved too. Even the Dumbo reactors would be great. You wouldn't even need half the TWR of timberwind for this to work, no? "This isn't something you can engineer away, either - it's the simple fact that any supercritical amount of uranium is heavy, and the radiation shielding is even moreso." Well, you can engineer a lot of it away... the more enriched the uranium is, the less of it you need to go critical, add berrilium neutron reflectors to make subcritial masses go critical... the radiation is a bit of a problem, but sitting on the launch runway, with the reactors never fired up yet, there'd be no need for radiation shielding. Running it for a few minutes at high altitude would really only require a shadow shield for the occupants, no radioactive particle would be thrown out. However, after repeated use, it would be quite hot... as I mentioned in the first post.

You are aware, that as a Eukaryote, you are more closely related to Archaea than the "common" Eubacteria, no? I'm not talking just infections, I'm talking biosphere contamination. If this Europan life could survive, say in lake Vostok... that would mean significant and permenant changes to Earth's biosphere. The attrition rate of microbes to viruses is tremendous, but if Europan life was a separate origin, and we didn't take any europan viruses back/ they didn't make it to (for example) lake Vostok... Europan life would have a significant advantage in the form of a virus free habitat. Then maybe at the edges of its habitat, it starts evolving for more and more Earth like habitats... who knows what happens. The microbes are the base of our ecosystem, if some alien life manages to outcompete them, we're screwed. If that Europan life is essentially the same as Earth life... well, it will likely come under viral attack, and even if it does manage to outcompete some Earth life, given their similarity it likely won't cause a large ecological disruption.

We wouldn't want to send life there, we wouldn't want to bring that life here. We'd want to study it somewhere else.. perhaps a lunar or martian base. Sample return - to mars or the moon! I would be very interested to see if: 1) it uses nucleic acids as genetic material 2) if said nucleic acid is DNA or RNA 3) if said nucleic acid encoded proteins with a triplet codon 4) if said nucleic acids use the 5 bases we use and no others 5) if said encoded proteins are composed of the same 20-22 amino acids found in earth life 6) if said encoding is by and large the same encoding (ie mapping of a tripled combination to an amino acid) as found in Earth life. If the answer to all of the above is affirmative, we'd have very strong evidence of a single origin. It would also have implications for the biosafety required - though we'd still want to get genomic data and RNA seq to construct phylogentic trees and see how the they fit in with us, and based upon that, proceed. I suspect if 1-6 are all affirmative, they'd basically be just as if we found new species of extremopholes on Earth, and they wouldn't represent a hazard, and they'd be outcompeted on Earth, since they adapted to a very different niche.

Given how awesome the sabre engine is... and given how awesome a nuclear thermal rocket could be... and given that nuclear jet engines have been made... How feasible would it be to combine them into a single, nuclear SSTO? Given the stats that project Timberwind was hoping for (30:1 TWR, 1000 s ISP), I suspect that alone would be good enough for an SSTO. http://www.astronautix.com/engines/timnd250.htm Of course, hydrogen is rather expensive and hard to store... it sure would be nice to use the atmosphere as re-mass as much as possible http://en.wikipedia.org/wiki/Project_Pluto I wonder if the pre-cooler technology of the SABRE engine could be made to work with a thermal-nuclear rocket core, to get an even higher payload fraction. Ie: Pump NH3 through the reactor during liftoff (more thrust, at expense of lower ISP, more mass efficient tankage, easier storage), accelerate to ramjet speeds, stop the flow of NH3, instead use liquified air as the saber precoolers are supposed to do, when air tapers off, pump H2 through it the rest of the way to orbit. The reactor wouldn't run that much for each trip, but would eventually get quite hot... reprocess the fuel rods? Once in orbit, transfer the reactor to a waiting tug for interplanetary or lunar missions (so the "tugs" are all running on old, "hot" reactors, the SSTOs are all running on newish, not-yet-that-hot reactors). Would such a craft be feasible with near-future technology? I've previously been really enthusiastic about fusion technology (Dense plasma foci, Polywell reactors, etc, NOT ICF or toruses like ITER)... but the more I think about it... the power density one can get with plain old fission is enourmous.. some of these compact reactor designs are putting out several gigawatts of power. Even under "ideal" or "optimistic" projections of power output for fusion ractors (like say... 1 gigawat reactor with a 3m diameter core) would be far worse, and would struggle to acheive orbit (either too little thrust, or increasing thrust lowers ISP too much, or chemical power would need to be used, like a LOX Augmented Nuclear Thermal Rocket - where the nuclear we're refering to is Fusion reactions). If you want to go interstellar with long burn times, out to significant fractions of the speed of light, fusion is what you want... But it seems fission is the way for getting to and from orbit... its a shame we can only launch from 1 inhabited planet where the dangers of flighing fission reactors around is so great.

If using "solar" as a name, as in "the solar system", there is only 1. If using "solar" as an adjactive, as in a solar system, as in a system of things revolving around a start that is thus a sun (latin for sun = sol) to them, then its fine.

Drawbacks: poor TWR, high weight.... Other engines in the game probably use LH2, given the ISPs appraochign 400... should we nerf them too? http://en.wikipedia.org/wiki/Project_Timberwind Sadly, this is unsourced, and I think the numbers are switched on the diameters... Vacuum specific impulse: 1000 s Thrust to Weight Ratio: 30 Note, that LH2 doesn't need to be used, you could use a heavier gas (it gets you more thrust too!, just less ISP) http://www.projectrho.com/public_html/rocket/enginelist.php#id--Nuclear_Thermal--Solid_Core Going to a closed cycle gas core would get ISPs >1,500 s One could then easily go with CH4 or NH3, and still get the ISP desired (and a pretty awesome TWR)

Umm, while I hate the "earth-like" hype, there is no problem with what they said. Just as there is a distinction betwee "a moon" and "the moon" (ie Earth's moon), there is a distinction between "the solar system" and "a solar system" The moon is called "the moon", but we can talk of other moons around other planets, like titan is "a" moon of Saturn. The same thing is true for "the sun", and "a sun" (basically refering to the star at which a specified planet revolves around). So an extra solar planet would have "a" sun, and it would be "a" solar system, just not "the" solar system. http://en.wikipedia.org/wiki/Exoplanet Note they specify "Earth's sun", because to other worlds, another star may be a sun. Most times, planetary system may substitute - but we can also talk of solar systems that lack planets - perhaps still surrondeded by an accretion disk/in the process of planetary formation/ only surrounded by debris/asteroid/comet belts.

It depends on the position that the occupants are in... 3.5 G is a lot worse if you are standing up instead of laying down (assuming the 3.5 G is in the "down" direction). Having personally experienced 6.3 G, and started to have vision problems then (upright seated position, the G's forcing blood from my head to my feet), I'd say, no, 3.5 G is not so bad. I wouldn't want to live in it though, but a few minutes... no problem

Hello all I've found it pretty easy to add new parts, and change waht techs unlock them, but how do I add new technologies... like say I want to add something to extend the tech tree, like a tech that requires metamaterials and specialized electrics, and costs 1000 science points... how would I do that?

They can be sued for negligence. What the protections are, are to prevent them from being sued every time someone who takes their vaccines (ideally, everyone) gets sick or has some medical problem. Otherwise, everyone with an autistic kid, or a stupid kid, or a kid with some other disability, would be having lawyers line up to sue the companies, likely trying for an out of court settlement. They can still be sued if their product is proven to be defective, or the lie, or were negligent, etc. They can't be sued just because they made a vaccine and you think it might have some link to something else based upon timing. There is A LOT of testing So are your roads, and your military, and your police... but your vaccines... Obamacare just fines you if you don't pay a private corporation to cover you I can't say, but perhaps there were shortages because everyone was going for them, causing the shortage? Perhaps there is some lag effect - if it was suppressed the years before, it won't come on as strong this year? I don't know. The *biggest* problem, is that the companies, at least in the US, stopped selling the old vaccines that were really cheap - the patents had expired. So they make a new vaccine (using newer genetic engineering techniques to produce just the antigen, rather than killed virus or weakened virus), patent that, then sell it for a couple hundred per dose, when the old one could be sold for a few dollars per dose. Then they lobby to get this new, expensive vaccine put on some list of required vaccinations for school (or something like that, I'm not sure/ I forget what they did to cut out the generic on the vaccines with expired patents, maybe they just have the doctors/health care places push the old drug, or ban the import, and then engage in anti-competitive action and all companies selling in the US agree to stop selling the cheap ones). Now, a marginally safer/better vaccine is making the cost of vaccination increase 100 fold. Personally, If I had a choice, and cost wasn't an issue, I'd go with the new one... but the old ones were just fine, and should still be available. The only reason the new ones are expensive, is because they are patented and the companies wish to make profits. The old ones... with expired patents, their profit margin is so low that they don't really even want to make them. Its a problem of new and patented = expensive, but you can't turn to the old and expired patent... except in other countries... but they won't sell the cheap ones in the US Capitalism fails again when monopolies and collusion/anti-competitve practices or simply pure greed takes root.

All real life rockets have way better TWR than what you see in KSP. All RL fuel tanks weigh much less (when empty, compared to full) than in KSP. Many RL liquid fuel engines have ISPs better than 400, while KSP's top out at 390 However, RL is 10-11x "bigger". If we were to scale things correctly, then 1 Kerbal meter = 10 Real meters. An exhaust velocity of 8000 m/s would only be an exhaust velocity of 800 Kerbal meters/second, and would have an in game ISP of 80, not 800. 1 earth gravity would only be .98 kerbal m/s^2... thrusts would have to be adjusted downwards. In real life, we make rocket stages with a 17:1 empty:full ratio for *everything*, engines and fuel tanks, and all other systems, in KSP, its impossible to get better than 9:1 (and if you want a TWR over at least 1:1, it gets even worse) Lets look at the shuttle external tank + space shuttle main engines, and the tsiolkovsky rocket equation, vs some KSP contraption that is a Mk1-2 command pod, 2 orange tanks, and a poodle engine getting 390 ISP. Shuttle orbiter weight: 68.58 tons Tank empty weight: 58.5 tons Tank full weight: 760 tons. So M_0 = 68.58+58.5+760 = 887 tons M_1 = 68.58+ 58.5 = 127.08 M_0 / M_1= 6.98 ISP: 455 9.8 * 455 * ln 6.97 = 8664 m/s KSP equivalent: pod: 4 tons Engine: 2 tons Fuel tank weight: 4 tons empty, 36 tons full. M_0= 78 tons M_1= 14 tons M_0/M_1= 5.57 9.8*390* ln 5.57 = 6565 m/s RL example gets almost 32% more dV Nerva engines are very real, and were tested in flight configuration, they are flight ready, but they haven't actually been used. * A failed rocket launch with an obliterated nuclear reactor is feared by the public: note that until you switch such a reactor on for the first time, its not veyr radioactive, no more so than the RTGs we already send up * Its heavy, much like the KSP nuke, this means that its not mass efficient to use one if all you want to do is go to low orbit. Planned missions to mars were all initially assuming the use of NERVA engines. However, missions to mars were never undertaken because of the cost of such a project, so NERVA engines became rather unneccesary. They did look into using it as a 3rd stage on the saturn V, but they just stopped the saturn Vs all together http://en.wikipedia.org/wiki/Saturn_C-5N I'd love to see something like project prometheus with a biomodal nuclear reactor. Nuclear thermal for an ejection purn, switching to some form of ion drive for a braichistichone followup, making the travel time shorter. Possibly even make a trimodal one where the nuke helps provide thrust during liftoff to orbit http://www.projectrho.com/public_html/rocket/enginelist.php#ntrsolidcore

So, now that SP+ is going to be stock, I've downloaded it, and the cargobay is the most interesting item for me... but placing things in there seems a bit... tricky... It doesn't seem to have any decouple ability... if I place something in there, its basically just attached like any other part that attaches radially, no? I've been able to put a decoupler pretty close to the centerline... but...its hard to get the symmetry right. Does anyone have any tricks for placing things inside the bay?

*X*Question: Why are you using ASAS units instead of inline reaction wheels? those are heavier and provide the same torque.*X* Nevermind, I see now that ASAS units are now .02 lighter, and produce almost double the torque.... I guess that changed in .24 The previous ASAS was inferior in every way to the Inline wheel, and was said to be kept in just so old designs weren't broken (back when you needed the ASAS module to get SAS to function) Also, I question the use of SRBs beyond the first stage lifting from Kerbin. I can't really tell from the picture... Are you landing a truss structure with those flat tanks with aerospikes on them to soften the landing, and then the ascent vehicle leaves behind the girders and such? From what I think is your ascent vehicle, I wonder if the TWR is enough. Also, couldn't you save weight on your lander by getting rid of the "soft landing" aerospikes, and instead run fuel lines to the engines of your ascent vehicle?

Use the [ and ] keys to select different ships within 2.5km, or go to map view and click on the vessel you wish to control, and select switch to.

His mind will be blown when he visits the north pole of Kerbin and searches for long enough... And then blown again when he investigates the Mun thoroughly enough And blown again if he finds... "it" on bop, and what "they" built on Vall RIP magic boulder

Set your munar PE to about 8-10km, burn retrograde to circularize your orbit... you should now have a velocity of ~550 m/s, instead of whatever you were coming in at. Next, burn retrograde some more when you feel like it (you're in a stable orbit after all, you can wait), until you see your trajectory intersecting where you want to land (somewhere flat!) Next, put a maneuver node before where your trajectory intersects the terrain, and pull the retrograde marker all the way back. Look at your burn time estimation (I often have to give a momentary burst of throttle to get it to display right for some reason...), take whatever time it says the burn will take and start burning when you have 2/3 to 1/2 of that time until you reach your maneuver node. Suppose it reads 1 minute... start burning 30-40 seconds before you reach that node. This should put you nearly stopped over your landing area with a bit of altitude, now just come straight down like its a 3d version of that old moonlander arcade/Dos game. All this supposes, of course, that you've built a rocket with enough dV to do this.

Umm, its KerbIN orbit, and the KERBol system. If we don't then you can't disregard the difference in full/empty ratios of fuel tanks, and the low TWRs of engines, etc. KSP ships are HEAVY when empty, relatively speaking - to balance out the reduced scale and thus reduced dV - although this solution is far from perfect. Well, we don't even need to do a manned mission.. a robotic sample return would be amazing. All of our missions there have been 1 way *on to the OP's topic* Duna has the following challenges: * Requires using a good transfer window (or a whole lot of dV!) * More gravity than the Mun making the final stages of a landing harder (somewhat offset by parachutes though) * Aerobraking required to get it done in similar dV, or a higher dV budget needed * Ascent stage of a craft requires much more dV than the Mun * Ike has a strong tendancy to muck up your approach * parachutes don't semi deploy until you are very low. For standard chutes, this can be as low as 800 meters- coupled with a fixed deployment altitude, this can mean you are still going very fast when they deploy, and you may just rip your craft apart with them. * because of the issues with the atmosphere, landing site selection and maneuvering becomes even more important IMO, it doesn't even have to be harder challenges, just as long as its a different set of challenges. Its likely to be the first body with an atmosphere that you will visit (or at least return from). Its likely to be the first body you need to have knowledge of transfer windows to get to. Dealing with Ike may prepare you for a visit to the jool system. From a gameplay perspective, I think it is in a good place.