wumpus

I'd hope that modern reusable rockets could at least improve payload integration beyond shuttle procedures. Customer side isn't going to change, and will only get cheaper with cheaper spacecraft that are considered more expendable (still require considerable testing to avoid damaging the booster). Spacex (or whoever else is launching the thing) will still need to integrate the payload cradle. Hopefully payload cradle integration will be sufficiently routine to become cheaper. Integrating the payload into the payload cradle tends to be a one-off thing, and thus expensive. Maybe for something like starlink they will be able to reduce costs after the first 20 or so birds are up. One thing that might drastically change these costs is "green hypergolics". Personally, while I think Proton levels of hypergolics are a disaster (as well as dropping spent hypergolic tanks on villages), the problems with hypergolics in payloads is one of cost and safety, and "green" isn't an issue. Just seeing something better than "three fours" on the old safety diamond would be an improvement for hypergolics, and should greatly improve payload integration (can you even check CoM when you know you aren't going to load fuel until everything else is done?). Once you have reusable rockets, you still have plenty of launch costs and payload integration costs. According to the infallible wiki, the DC-X crew that makes up the core of Blue Origin performed miracles in reducing launch costs. But as far as I know, DC-X never had to deal with payload integration. Finally, I think this whole thing makes plenty of assumptions that have been handed down from years of Military Industrial Complex procedures and custom everything. One thing Spacex needs (along with BFR) is some kind of standardized payload: I'll at least give them the start of an acronym: SOPWITH (Standard Orbiting Platform With Integrated Technology). Making the thing big and heavy isn't so much a problem (it will only make it uneconomical on anything but BFR and Falcon Heavy), but easily designed, built, and integrated. Put in whatever is in all satellites (full power and cooling systems, possibly with overkill on the computing side [should be reasonably cheap to built highly redundant systems), and have it ready to hang on whatever sensors and antennae are needed (one model might include a "standard dish"). If you've vastly reduced lifting costs, the idea is to make everything else a lifting cost. You probably can't even make integrating your SOPWITH into the rocket too cheap (although I'd assume the payload cradle is built into the chassis), but it should be wildly better than a one-off bird.

How much can you heat a Jupiter before it becomes a star? And does it really count as a star if it requires external heating to maintain criticallity?

I'm curious if you will have any significant load on the rest of your processors. I'd expect that the RAM matters (especially once you start overdoing the mods) and the GPU matters (if the mods hit it hard enough), but getting KSP and/or the mods to use the rest of the threads will be impressive (unless you are planning something like fleets flying in formation). For a long time it was pretty clear that a high power Pentium could likely match even the most expensive CPUs (unless the L3 cache became critical), multithreading changed that, but I didn't think it changed it by all that much.

Hmm, I don't know. Pallet, shipping container, how about orbit container? Granted, assuming you are launching the cage, that "cage" costs at least a buck a gram for Falcon, but might make sense on BFR. I wonder if you could make them "stackable", so you could buy a certain amount of vertical space relatively easily (I'm guessing not, unless you were willing to meet critical center of mass requirements and be willing to pay for ballast). But if you want to really make shipping to space crank up into high gear, this is what you need (try imagining modern shipping without shipping containers). Eat the efficiency loss (presumably with BFR or similar) and do it.

Note that the Soviet rocket program refutes Black Hat Guy's point. The Russian rocket scientists were able to grab a lot of gear (they especially loved grabbing test jigs) if not actual scientists (they had one relatively low level guy). Luckily for us, Boris Chertok was on the team that did the "poaching" and wrote it up in "Rockets and People". Oddly enough, it was probably lack of a proper test jig that did N-1 in. https://history.nasa.gov/printFriendly/series95.html#ebooks

Here's another take on it: https://arstechnica.com/science/2018/04/boeing-slams-the-falcon-heavy-rocket-as-too-small/ The author wasn't all that interested in the story (besides disgust from Boeing jumping in the "Fake News" industry), but does note that the story "for more information" that Boeing linked quoted his website (arstechnica) as the only source.

I know this is an astronomy class, but do the students really know the difference between suborbital and orbital? Different schools have different levels of rigor. I remember a TA being surprised at the number of students taking Astronomy: where he was an undergraduate, astronomy programs were hard, while geology 101 was called "rocks for jocks" (don't take geology at UofM unless you really want to find oil). You mention the speed of sputnik, that looks like a good place to explain the difference between suborbital (you might be going to space today, but it won't be for long) and orbital (you are going to space today). Both "first spacewalks" by the USA and USSR were much more dangerous than anticipated. The "Neil Armstrong managed to stop it' was more like managing to perform all the "standard procedures" while spinning fast enough to be in danger of losing consciousness and adjusting those things so all possible bases would be covered before he finally lost consciousness (which would mean death, as you needed more pilot action for re-entry). It was one of the reasons he was the first to walk on the Moon (the other was scheduling re-jiggling due to Apollo 1, see: "Carrying the Fire" by Micheal Collins). The whole point of Gemini was that it involved tasks that they thought they would need to do to get to the Moon, but hadn't proven in flight. Once they were ready, they started testing out the Saturn rocket. You mentioned the three main points of Gemini, but these weren't just stunts they did to "beat the Russians" to those milestones. The whole point was to learn the skills they needed to get to the Moon.

Count me in here as well. For hobbyist sized motors (and even to small plane sized), a piston engine will be more efficient, cheaper, and probably even easier to maintain than a turbine. I'd guess that the same purists who insist on a jet engine (when a prop would be more powerful) don't want to go half way, although I think most of the reasons for inefficiency are on the turbine side, not the compressor side. I might be pretty unclear about the point of high-bypass turbofans, but they sound like turboprops with better marketing (and a tiny bit of jet action). People don't complain the way they do when they see an open propeller when the "propeller" looks like a proper jet compressor and has a jet's shroud. I also suspect that that "last little bit of jet action" is a net gain over a turboprop, and so is the shroud around the fans (propellers drive air in many directions).

Except that everything that requires AC and isn't an induction motor requires it because there is a transformer between the the mains and the full-wave-bridge rectifier. Of course, sufficiently old (non-switching) systems absolutely relied on that transformer to get the voltage right, but today it is often a bulky and unneeded relic (and there is the possibility of a half-wave rectifier from the unbearably cheap manufacturers). I'm not expecting outlets to be wired this way, more likely things that are wired directly (such as a central heat pump or lighting. But possibly including things that could have their plugs altered because of just how rarely they are moved such as refrigerators and ranges. Power tools really shouldn't be using brushes. They limit the tool's lifetime and are almost certainly more expensive than transistors. You'd be surprised just how cheap a motor will be brushless. Of course the issue with a transformer in the initial supply matters: DC won't pass it and simply bypassing it will give you the wrong voltage (and you probably need the inductance to make the rest of the power supply work).

There's a lot more than the vehicle and the fuel. Every technician needed to bring the thing from barge to pad and on hand to launch the thing needs to be paid. When Spacex charges $60M to launch a used Falcon, it isn't clear how much is profit. Certainly nearly 90% of the rocket is saved, but there is also certainly a lot of money getting the payload integrated into the first stage, and getting the whole thing into space. With Spacex pushing into launch cadences only previously dreamed of by Shuttle propaganda, they might see just how low these costs can go (low, but certainly much higher than fuel costs).

Pegasus claimed a "base price" of $6M (in 1990s dollars), but I think that was missing critical support options and NASA has paid 10 times that price. Falcon (and Merlin) were originally designed to land via parachutes, and had to be tweaked to hoverslam (no idea if the early Merlins could throttle). If you are designing from a nearly clean sheet of paper, I'd expect you would make the engines capable of hovering. From a controls perspective, I suspect that a hoverslam is easier on land (thanks to your control fins never stalling) but harder at sea (thanks to the issues of a moving boat/barge).

NASA had at least two launch sites and the VAB has the room to build four rockets (don't think it has ever been used to full capacity, and half the bays go to pads that don't exist). Gemini (and similar Soviet missions) required two rapid launches (although one was typically, but not always, unmanned). This was a relatively proven technology by the time Saturn V was being designed. For Earth rendezvous I'm guessing it made more sense to fire a J-2 [hyrdrolox] to the Moon (after one or two extremely low orbits) than to wait for the second rocket and spend hours docking and then firing a hypergolic rocket to the Moon. Also it isn't clear how to break the payload up into roughly even bits: the only obvious item to lose is the lander. Lunar rendezvous sounds just too dangerous (but both rockets could get to the Moon by hydrolox). I know there is at least one NASA official that kept insisting that direct landing was the way to go long after the missions were a success. I'd hate to have to perform an Apollo 13 style rescue with not only a crippled SM, but have the LM in another rocket (that can't get back on it's own, and only one astronaut aboard).

The shuttle was tested manned, and deliberately designed as such [can't fly unmanned] to prevent Congress from eliminating the manned space program while still using the shuttle to launch satellites (presumably something only Congress would think sane*). I can't imagine them kludging the SLS in the same way. The LEM was basically untestable. * continuing to pay shuttle costs. There might exist sane people not willing to pay for manned space travel.

I'd be curious if anyone is wiring houses to use DC power (probably 115VDC), at least in some circuits. Solar generates DC, and other forms of available power (wind, water, etc) are unlikely to produce proper 115V@60Hz (or your local power requirements). You can efficiently split a portion of power into a DC load (think a shunt regulator, only instead of wasting the power feed it into your inverter and/or batteries). DC should work fine for most LEDs (be careful), plenty of computer power supplies (check first before buying), and presumably ovens/ranges (may require checking/hacking for the controls). One catch is that the amount of power needed for lighting has drastically fallen (switch to compact fluorescents) and fallen again (to LEDs) and is likely an afterthought. Any decision would likely depend on using DC for the air conditioning (anyone planning this far ahead is probably using a ground-based system, so only those need be concerned) and possibly refrigeration. A quick read through the UL and NEC codes implied this was legal (carefully mark what is what), but I don't have access to them and aren't exactly familiar with them (I had a short job testing things to UL specs). I'm expecting USB to continue to become a major electric outlet, but even if they allow >20V (depending on the code you can get up to 30-40 volts before the "real" regulatory problems kick in) you will always have the original AC vs. DC problem that the lower the voltage the greater the loss is over the wires (although this would be another case where changing from an AC-DC supply to a DC-DC converter should work better: much less strain on the capacitors).

DocMoriarty, You probably can't access 1.0.0,1.0.1, and 1.0.2 but they were not only some of the worst KSP releases I have ever seen, but they were also certainly the highest profile releases Squad has ever made. Squad has taken the "move fast and brake things" mantra a bit too far, and it long predates Take 2. Also the numbers of bugs produced per new line of code is largely a function of size and age (especially coder turnover), I'd expect quality to inevitably decline as long as new features are added. If a release is particularly bad (such as the initial "Making History" release), I'd expect a number of point releases until Squad is confident in the code.

There were two contests for low cost launchers without recovery. Here's a link to the second: The winner appears to be a nearly single-stage Rhino with a pair of asparagused twin-boars. 646 funds/ton. Maybe there was a set of SRBs in there I didn't see them and the files are no longer available (the video is). Getting under 1000 funds/ton isn't that hard (in general, finding an ideal launch for a specific payload is another story). One strategy I used was TTSO, with both stages eventually making orbit (the first stage could easily make orbit without the load of the second). Of course, this was quite hectic without mods (you have to avoid losing the stage due to exiting the physics bubble) and takes at least four times as long as a normal launch. It mostly burned me out of KSP before making it to other planets (I got better). Human time is more important than game funds: use SRBs unless low cost really makes you happy enough to take that much longer to get to orbit.

LEM (dry) : 5.4 tons (US) https://www.hq.nasa.gov/alsj/LM04_Lunar_Module_ppLV1-17.pdf Apollo capsule: 6.1 tons (US), 5.4 tons (metric) source: infallible wiki Dragon2 (dry): 7.0 tons (US), 6.4 tons (metric) : note this is *not* built for the >3000 m/s needed for a lunar landing. ibid wiki Might be possible. I'd still want the return engine in orbit. I also suspect that using a Dragon2 would involve more mass than LEM+CSM(capsule). You aren't building anything with a heat shield lighter than a LEM. Those things were quite flimsy. The real question is whether it is worth taking both spacecraft ~4000 m/s to the moon, another ~4000m/s down and back vs. a heavier system the whole ~8000m/s. Losing the orbital module likely means a lot more mass. Ideally I'd want the return module on the surface and passing all self-tests before launching anybody to the Moon. From what I've read, the return engine was the weakest link expected in the whole system (it was transported the most delta-v, so was lightened the most). Breaking a system into manned and unmanned would change the lunar mission drastically.

Holy double-necro (originally 2012, necroed in 2015, and again in 2018) Jeb! Last go around (2015), somebody mentioned "simple rockets". That seems closer to Harvester's original idea (although the direction KSP eventually took was far superior) and is 2d and on mobile.

I doubt that an orbital person would be required for a modern lunar rendezvous. The direct approach still requires taking 680m/s of fuel to the surface that isn't otherwise needed. While it might be worthwhile to take a single habitable module (heat shield and all) all the way down to the surface and back, you still probably want to leave the last stage of return engines in orbit. The other catch is that whether or not you are "upgrading a Saturn V" or not, you are making a new rocket. Nobody has had the capability to build or launch a Saturn V since the mid 1970s. Tweaking a Saturn V is an interesting game in realism overhaul (or possibly Making History), but any real design would have to start from scratch and would likely be based on SLS, BFR, or New Armstrong (or possibly an extremely upgraded Soyuz or Falcon Heavy).

Assuming that it is roughly (if not moreso) to transmit three phase (delta) than single phase, I suspect that it isn't that hard to get three phase in [USA] farming areas. The [one] appropriate google hit insists that it is common in grain drying bins and irrigation and wells. http://www.electriciantalk.com/f2/3-phase-residential-service-17395/

That's more or less how I'd want to build the SLS: F1s for stage 1 and RS-25s for stage 2. If I need solid boosters I'd use SR-118 (Peacekeeper stage 1: made by Thiokol (a political requirement) with 200 tons of thrust moving 50 tons of booster (1 minute burn)) boosters for non-crewed launch (and higher mass). It should hit all the political notes and use up RS-25s more slowly (not that I expect enough launches to use up the supply of RS-25s).

Depending on the kid, consider https://xkcd.com/1720/ unfortunately there doesn't appear to be a poster in the store, although Kinko's could presumably supply if you don't have access to an engineering printer - (think twice before printing the black poster somewhere you have to answer to ink consumption). When looking up the various xkcd posters, I also found : https://xkcd.com/482/ (not sure how tall the kid is expected to get, nor how a 4-year old is supposed to deal with logarithmic charts).

It was an entire year's setback on a program with only 3 years left on the deadline, so obviously it was pretty severe (of course, so were the flaws in Apollo). But compare that to the Columbia disaster which lead to a 15 year and counting hiatus of all manned flights by the USA.

To be honest, I suspect the contractor that made it had to scale down an existing coal strip miner (or the big ones started right after that. I'm just a little to young to know which came first).

Bringing the third astronaut along wouldn't make much sense as I'd assume that his job can be completely automated. The real gains would likely involve a crewless "cargo run" flight that could land supplies in orbit and on the Moon: I'm sure it was considered but was proven a bad idea by Apollo 11 (the landing computer was aimed at a bunch of boulders). 50 years of technology at least improved landers. The lander already was extremely light and flimsy. I'm not sure a carbon fiber skeleton would make much of a difference. I'd guess the dry weight of any pressurized fuel tank could be improved by modern materials, but that is about it. Don't look for much improvement in engines, and the mass ratios were already pretty good (all modern tech can do is "add [tiny bits of] lightness" and automation. Which is one of the main reasons nobody has been on the Moon since 1972. I'd like to add boosters to the thing from the Peacekeeper missile/Minotaur rocket (probably only for a crewless cargo run), but instead of making it lighter I'm sure any principle investigator (or whoever NASA puts in charge of a mission) would simply add fuel and mass to the payload. There's also the difference in crew safety. In 1967 Apollo killed an entire crew and NASA just did a full check for safety and kept going. I'd expect any modern Apollo to require considerably more safety, and I don't assume that can be done without a hefty cost in mass (forget about the booster in crewed flight).