NERVAfan

I really like Northstar's idea... it would provide away to connect what I'm doing here to what I'm doing over there and really build up a space program where some stuff is dependent on other stuff rather than have each mission be an island*, but I'm afraid it's a bit more complex than what Squad would want for the core game... *in real life, we don't have the mining yet, but the rovers on Mars use the orbiters for data relay, and the ISS actually has to be resupplied unlike KSP craft/stations, EDIT: and now they're trying to use Hubble to find post-Pluto KBO destinations for New Horizons, etc.

I imagine treating planets as movable objects would mean some performance hit as if they were extra "ships" ... not that I know anything about programming... for very little benefit. It would be kind of cool to think about, but you couldn't really do anything with it - probably not even with nyrath's Orion mod. Gilly is the smallest celestial body (except ARM-pack asteroids which are already movable); according to the wiki its mass is 1.2420512×10^17 kg. F = ma so to apply an acceleration of a millimeter per second (which might get lost in game noise) you'd need ... 1.24 x 10^17 kg * 10 ^-3 m/s = 1.24 x 10^14 N. Game measures thrust in kiloNewtons so that's 1.24 x 10^11... a Mainsail is 1500 (1.5 x 10^3). So that's ... a bit under 100 million Mainsails. The new KS-25x4 engine cluster is 3200, so you can cut that about in half... Yeah, not practical.

I agree that the reaction wheel masses need to change, but I think it would be better to increase the mass of the 2.5m one -- the LV-T45 engine weighs .25 ton more than the LV-T30, and has 15 less thrust, for the sole benefit of thrust vectoring... if the 1.25m reaction wheel was less than .25 tons, the LV-T45 would be (as far as I can tell) completely pointless (I already pretty much don't use it). Alternately, they could just give the LV-T45 better thrust and decrease the reaction wheel mass. But they're pretty powerful...

That's pretty accurate. Just because the Poodle, Skipper and Mainsail line are older doesn't inherently mean they are the better balance point. Compared to the 1.25m engines ... the Mainsail at least has good TWR, but the Skipper has slightly worse TWR than the LV-T30 and 20 sec less ISP both atmospheric and vacuum.... yeah, it has thrust vectoring, but that doens't mean much as command pod torque means you don't really need thrust vectoring on smaller rockets, so its lack on the LV-T30 doesn't hurt that much for many applications (I find myself hardly ever using LV-T45s). And the Poodle is just plain worse than a group of LV-909s. I think it could help to increase the mass of the Advanced Engine and 4xKS-25 cluster (I think that'd be better than reducing the thrust) but the Skipper/Mainsail Isps should go up ... I'd suggest 320/370 (like the LV-T30/T45) or 280/380 (like the Advanced Engine) for the Skipper, and 300/350 (current Skipper) or 320/360 (4xKS-25) for the Mainsail.

I'd like to see some kind of resource gathering, but I really would like to see what contracts provide in terms of "goals" before suggesting a particular way to implement it. I do think it would be good if it encouraged a real connection between the different things you're doing in different places. I think it would be nice if, say, Minmus had one thing and Mun had another, and to supply a base in either place without shipments from Kerbin, you needed both. (Or if you had to find them on two different places on Mun - say polar craters vs rock outcroppings elsewhere -- or whatever). OTOH, that would be really hard to do in the existing game when there's only one kind of fuel and oxidizer (barring ion engines) and no life support resources, so again, I think what form it should take will be dependent on future developments (will there be stock life support?) If that doesn't turn out to be feasible, though, I'd have no objection to just putting Kethane into the stock game wholesale.

This is true, but I actually think the Mainsail and Skipper need to get better Isp. I know they're the "standard" since they've been around longer, but their Isp is much worse than the equivalent 1.25m engines, and I don't see why bigger engines should be less efficient. The LV-T30/LV-T45 are 1atm 320/vac 370; while the Mainsail is 280/330 and the Skipper is 300/350. I can see the Mainsail being less efficient since it has very high TWR (150% the mass of the Skipper - 6 tons vs 4 tons - but 230% the thrust - 1500 kN vs 650 kN) but the Skipper falls in between the LV-T30 and LV-T45 in TWR. So I'd suggest: Mainsail: Isp 300/350 Skipper: Isp 320/370 and maybe drop the cluster (S3 KS-25x4) to 300/350 or 300/360 rather than the current 320/360, but I'm not sure it's necessary -- I don't really think the bigger engines being better is a problem, since the smaller ones will still have a role for smaller rockets. It might make sense to increase the mass of the new engines though. Their TWRs are pretty incredible.

Also, in RL an all-in-one setup would require spending fuel to land the heat shield on the moon and lift it back off, but in KSP we don't need those. Furthermore, the delta v requirements are a lot less in KSP. EDIT: All mine are direct returns. I started out with something almost exactly like the one Tank Buddy posted above, but I had issues with it tipping over, and now I use a wider lander made with two radially attached FL-T200s with 48-7S engines, and put two landing legs on each tank. The two side tanks/engines are attached with radial decouplers and get jettisoned on the way home.

I agree it shouldn't be that super difficult. I'm not sure if that actually IS unrealistic though because KSP orbital speeds are much lower than RL ones... that Munar or even Minmus return is going to be far less velocity and thus far less heat than a LEO return in RL. Eh, I actually disagree about this one... but just "lower thrust" is not the answer. The thing is that in RL ion engines are not used in the same way as chemical rockets ... it's not a "burn and coast" profile but a "burn most of the mission time" profile (I think something like 70% of the time for Dawn?) That's why they aren't "believable" to me... they don't function in the same way at all. They'd need a thrust-during-timewarp feature. EDIT: That's why they should be able to function at 10,000x warp (but have like 1 N thrust*). That way the burn actually takes 25% less real (player's) time than a current 2 kN engine at 4x warp... but you can thrust for weeks or months of in-game time and make it actually act like an ion engine. *That's still more than 10x Dawn's, IIRC

If this Popular Science article is to be trusted... http://www.popsci.com/science/article/2013-07/if-sun-went-out-how-long-could-life-earth-survive ... without the Sun, the average surface temperature would drop to 0 F "within a week" and -100 F "in a year", "most plants would die in a few weeks", " Large trees, however, could survive for several decades, thanks to slow metabolism and substantial sugar stores". That last claim sounds rather implausible to me... trees surviving for decades at colder-than-a-South-Pole-winter temperatures???? Of course, that assumes an instant disappearance of the Sun. If the Earth was launched onto an escape trajectory, it wouldn't freeze over or kill plants within a few weeks... it would take longer than that to get to a distance where the sunlight was too weak to be survivable. The oceans, according to that article, would stay liquid (under a frozen surface) for hundreds of thousands of years. Maybe this could be used?

Yeah. For pollen, it's pretty high altitude, given that there isn't anything to pollinate above 300-400 feet (the tallest trees) at best, and more like 100 feet or less most places.

The size does seem small. But Biosphere 2 was poorly designed and horribly in-efficient in terms of supporting people... it tried to replicate a whole bunch of ecosystems rather than work like a farm. It's not really indicative of the limits of what can be done in a closed system, or even close...

Actually, you don't need NEARLY as much as the Sahara desert. Solar constant at Earth is ~1350 watts/square meter. Take off half for night, half for atmospheric absorption and the occasional cloudy day... that's about 340 watts/square meter... say 300. If the solar panels are 15% efficient, that's 45 watts per square meter... 45 megawatts per square kilometer... 45 terawatts for a million square kilometers. World use is more like 15 terawatts... and the Sahara is nearly 10 million sq km, comparable to the entire US. So it's (ideally) something like 333,000 sq km, more like 1/30 of the Sahara or about half of Texas. The more significant problem is that it would be incredibly difficult to build and maintain 333,000 sq km of solar panels, and the places they could be put with relatively little environmental harm (like the Sahara desert) are not very close to large populations. (And the Sahara is not equatorial. It's more like 30 north latitude.) What about polywells (electrostatic confinement)? I think there's a group working on them funded by the US Navy. They're supposed to be workable on a small scale (if they work at all), like a few meters wide. Also, I believe Lockheed Martin Skunk Works is working on some fusion thing... supposed to have a prototype by 2017...

I agree with this entirely. EDIT: Also, using a generic "life support" resource avoids the whole issue of whether Kerbals would have the exact same life-support needs as humans...

I understand that "mass based drag" is there as a simplification... but why does the formula make the drag so high? According to the wiki each ton of mass is treated as 8 square meters of frontal area... I don't see how you could even make a rocket that wide. The FL-T100 tanks are 0.5625 tons and 1.25 meters diameter... that's pi*0.625 squared or about 1.23 square meters. So even a rocket made totally of FL-T100 tanks, one tank high and many tanks wide (and with no engines, capsules etc. in-line to add mass without increasing area) would have about 2.2 square meters per ton, not 8.

I totally agree (as someone who plays KSP on a lower-end Walmart laptop). In fact, this is the only game I play that's newer than 2008 (and in fact most of my favorite games are much older - Carnivores, Diablo, Diablo II all from the late 90s-2000 era). EDIT: But I don't build really big ships, either. I try to stay under 100 parts on pretty much everything, and the SLS parts have let me reduce that even further (I may have to change that when I finally get around to big manned missions to Duna, Jool, Eve etc)

Yeah, a Kerbal on EVA weighs 90 kg. Assuming half of this is the spacesuit, the Kerbal would be 45 kg... which would still make it denser than a human of the same height. But not incredibly super-dense, more like rocks or metal. Much less dense than Kerbin itself, which is denser than osmium (but still nowhere near neutron star matter or even white dwarf matter densities)

Will this mod allow for "Interplanetary Transport Network" trajectories / weak stability boundary /low energy transfers, and if so, is that a result of a basic N-body model or does it need more flourishes? Ah, OK, thanks.

Right. You don't really need it for Kerbin orbit and Mun stuff, but for fancier things...

That's big... 2000+ tons at the launchpad, wow.

Interesting. It just overflows?

In the game, actually it is, since the planets are on rails. Even if you modded an engine to have a trillion kN thrust and 100,000,000 seconds specific impulse, it still wouldn't do anything.

IMO because they think people will be more interested in Mars because "we've done the Moon*", and their plan requires public interest for its funding. *Yes, I know that's a silly way to look at it... I don't think that is quite fair. The only places on the Moon with water ice have no sunlight; on Mars, there's at least the possibility of getting solar power and water in the same place (though I don't know if there is near-surface ice in the low-latitude regions that are much better for solar power). Also, Mars has a CO2 atmosphere which can be turned into oxygen via photosynthesis (algae tanks, greenhouses, whatever), or into methane (for fuel) and water by the Sabatier reaction (which does require a store of hydrogen, but that's only a very small fraction of the mass. There's real potential for doing stuff with the Lunar polar volatiles in the permanently-shaded craters, but it is more limited than Mars.

Not on humans, no. There ARE studies on the development of rat fetuses in microgravity though... I linked to two of them, and quoted from them, on the last page. Partial gravity, yeah, no one's really studied much if at all AFAIK. Centrifuge experiments would be a good idea... or maybe just land a bunch of rats on the Moon or Mars with regular food and water dispensers... OTOH. Mars One is planning a colony, which does kind of imply reproduction. Now if you assume beforehand that it won't work out, then yes, it looks like a really bad idea. But assuming the colony will survive and prosper I'm not sure why it's such a bad idea. (Now, I don't think Mars One will ever raise the money to actually colonize Mars, or even a tenth of it... but the same thing sort of applies to anybody's efforts to colonize Mars, whether it's them or somebody else after SpaceX builds its "Mars Colonial Transporter".) EDIT: Well development certainly has been done in microgravity. Now maybe miscarriage rates were higher, but the abstracts of these fetal studies seem fairly optimistic. None of these experiments seem to be a "full cycle" though. Here's another... though this sounds like it might be a different paper about the same research, it also mentions Wistar rats and 0 to 2 G conditions... http://www.ncbi.nlm.nih.gov/pubmed/16237823 "In embryological experiments it was demonstrated that during space flight it is possible not only to maintain physiological functions of an adult organism, but to form functions of a developing fetus. The animals that spent the portion of their prenatal development in space flight were capable to go through the entire cycle of postnatal development, up to sexual maturity and reproduction. In ground based centrifuge experiments with 2G it was demonstrated the possibility of realizing, under hypergravity, of all the main stages of prenatal and early postnatal development of rats: fertilization, embryon implantation, fetal development, birth and lactation of progeny. Exposure of rats to microgravity did not reduce their life span post flight."

Is there any reason to think it would be true in Martian gravity? Your legs are going to push as hard on Mars as they do on Earth -- you'll walk/jump with bigger bounds, but the stresses from striking the ground should be the same if you make the same muscle movements (barring minor differences due to air resistance for a jump). I don't think Mars gravity will be anything like zero-gravity in terms of effects. EDIT: especially if you used weights...

We do? I'm pretty sure rats have given birth in microgravity and it's never been tried with people (or primates IIRC) ... I'm also not aware of anyone doing a "full cycle" from adult rats through natural reproduction, pregnancy, birth, development to adulthood again so... I can see "unwise" (since it seems like there might be a higher risk of miscarriage... if we can extrapolate results from in-vitro fertilization and simulated microgravity via a clinostat to natural reproduction and real microgravity) but I don't think "can't be done" is accurate. Do you have a source that suggests otherwise? http://www.ncbi.nlm.nih.gov/pubmed/2654469 "The flight experiment on female rats has shown that fetuses can grow and develop when the maternal organisms is exposed to microgravity. The data concerning the effect of microgravity on the reproductive function of mammalian males are limited and controversial. Analyzing them, it can be noted that the changes seen are small and reversible and that cells involved in spermatogenesis show greater resistance to space flight factors than other continuously renovating cell populations" http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006753 " Fertilization occurred normally in vitro under µG. However, although we obtained 75 healthy offspring from µG-fertilized and -cultured embryos after transfer to recipient females, the birth rate was lower than among the 1G controls. Immunostaining demonstrated that in vitro culture under µG caused slower development and fewer trophectoderm cells than in 1G controls but did not affect polarization of the blastocyst. These results suggest for the first time that fertilization can occur normally under µG environment in a mammal, but normal preimplantation embryo development might require 1G." [My comment: "Might require" seems an overstatement, since they DID get pups in simulated microgravity... "healthier", sure, but... This is a spinning experiment though, should be tried in actual microgravity... also with natural reproduction rather than in-vitro fertilization] http://www.ncbi.nlm.nih.gov/pubmed/11496419 "It was found out that the compensatory and adaptive potentials of mammalians (Wistar rats) in microgravity are sufficient to let proceed pregnancy, and activate anabolic processes associated with fetus growth and water-salt homeostasis maintenance. In a number of aspects effects of microgravity on the mother-fetus systems appear to be less significant than of various factors on Earth" EDIT: I'd be very surprised if Mars gravity proved to be unworkable for humans if you took precautions (like exercise, maybe weights.)