wumpus

To me, it sounds like the really only "need" a few key technologies: zero boil-off systems. If you can do liquid oxygen, liquid methane should be a piece of cake. Hopefully they can hire (at least as consultants) the guys doing the James Webb telescope (liquid helium is wildly more difficult). You aren't storing your fuel/oxidizer long term without them. ISRU - I'd avoid this if possible (yet the cost of *not* doing would likely end the mission unless cheaper propulsion is possible). ion propulsion* (does not appear to be part of the Musk plan, but should make things wildly easier). Bring your cargo to Mars on the cheap (and slow). At least 60% of the mass in the NASA plan is in unmanned rockets. And of course the mass of the manned rockets is almost entirely fuel which need not be transported by chemical means either (dock with a "fuel tank" (read fully gassed up stage) in an elliptical orbit (for pe-kicking around Earth). Why are you using an Isp of <400 when >4000 is available for 90% of your mass*delta-v? Much of the other tech are small steps (although Elon Musk has shown a love for even smaller steps whenever possible) from existing tech (and too many small steps at once add up to impossible risk). And a lot of this will be reduced (i.e. many of the small steps proven) by sending an unmanned dragon to Mars. I remain convinced that ion propulsion (of anything that doesn't have to be manned) is the way to Mars. This includes as much fuel as possible: using such thrusters to get it to high orbit (and looping around the Moon if necessary, your thrusters want to move in circular orbits and you want any fuel stages to end up in highly elliptical orbits). There remains the problem of avoiding the Van Allen Belts, but that should be possible to plot a course similar to the Apollo missions to avoid them. I'm not at all convinced that upper stages need be reused. Unless they can somehow contain the overall cost of launching a rockets, the costs of the falcon are mostly the booster, followed by launch/logistics cost, followed by upper stage costs. Spending so much time on the vastly harder scheme of re-using an upper stage does not appear to be productive. Reduction of launch costs *should* be wildly easier (see DC-X for examples). And then there's the ISRU. My guess is the first unmanned trip to Mars needs to bring one along, and it has to work if spacex wants to go to Mars. Even with a working ISRU, it will be a huge challenge for the astronauts on Mars to refuel and launch the thing with Houston so far away. Or you could deliver all the fuel you need [very slowly] with ion propulsion and gravity assists. * note that ion propulsion might not be the ideal high Isp means of propulsion. It simply is the one proven via NASA (and other space programs) flight. Also don't be surprised if the Isp goes way down if you have to substitute Ar for Xe due to the impossible masses of Xe required (Ar is more common than CO2, Xe is *rare*). In case you hadn't noticed, that Isp in KSP are pretty close to the real thing, but the thrust is even worse (they would be a lot more popular if you could use them while time accelerating. Since IRL you can't time accelerate anyway, the low thrust is more of an issue with plotting a course and capture (you can't just Hohmann over and burn to capture).

You better believe every contract on the whole manifest is being renegotiated to include such a condition. I'd expect it to be covered *somewhere*, but who ends up with the hot potato is an open question. Of course, since Elon Musk doesn't consider "his customers" to be just those already in the market for satellite launches but those who would buy a much cheaper satellite launch if such were available, he might cover an extra launch where ULA wouldn't (defense contractors provide *exactly* what the contract says, no more and no less).

"Chasing" a launch from North Korea (with the anti-ballistic missile in South Korea*) is likely possible. The big issue is time to launch, and just how expensive (read how much delta-v you require them to burn before go-nogo with the interceptors) any decoys would be be. This wasn't really considered on Reagan's original Star Wars dream as the USSR was simply too big. I wouldn't be too surprised if you could re-purpose an existing ICBM (with quick launch capability required in the cold war) by using a lighter warhead for more delta-v (a stern chase is a slow chase, but that makes it easier to hit in the end). This might be too inexpensive for the DoD and partner/contractors. * maybe in submarines. Since Seoul is within artillery range of N. Korea, this might not be popular among the Koreans. I wouldn't be surprised if the Chinese didn't at least have a bunch of proposals (i.e. they probably aren't ready to build it, just think about it) for building the same (i.e. stop N. Korea from firing an ICBM anywhere) simply to keep China and the rest of the world intact.

Ah! So that is why the satellite is still covered, but the cost of the rocket (and launch) is still in question. I'm guessing the lawyers have been up and down the contract trying to figure out if spacex have completed their obligations or not. Now I rather expect a "flight proven" launch, but a lot depends on the contract and how the satellite launching community [market] feels about such contracts and how closely they should be enforced (and of course if the thing leaves spacex on the hook for the full launch).

All I've heard are reports that claim that the normal "satellite insurance" doesn't cover anything that doesn't happen during the launch (this wasn't a launch. It wasn't even a countdown for launch). I also have a hard time believing that the satellite was somehow manufactured, transported to KSC, and placed on top of a rocket all without insurance. My guess is that all the various insurance companies are doing their usual game of hot potato and passing the claims around insisting that someone else pay them. While spacex may have a burning need to fire up a few "flight proven" boosters (if only to reduce storage pressure), it will still cost them a bundle in logistics and other costs (largely because nobody has needed to care about such things. [Note that in retrospec, much of the DC-X innovation seemed to center on reducing these costs]. Can anyone guess how expensive it is to launch a Soyuz (or similar) rocket after the rocket is manufactured?

You need about ~4000m/s from LEO to get to Mars, and your escape velocity is ~3000m/s. I'm guessing this means about 4 kicks around ~1k/ms apiece. I'm pretty sure the Mangallayan probe used more, but that last one has to be big. We know that the ~3000m/s flight used in the Apollo missions barely went through the radiation belts at all, so at most two trips. I suspect that the flight and surface of Mars are sufficiently exposed that you don't want any more radiation exposure than strictly necessary, but I'm sure you can handwave it away if you want. I'm not even sure that ~1km/s will even get to the belts (I've tried to figure this out as such tricks could make manned mars vastly more feasible).

I swiped this description of a "safe" turbine failure/explosion from a bit of social media: "Basically, engine designed not to fail. If fails, casing is supposed to contain the bits, if casing fails, fairing is designed to slow down the exploding bits enough to save plain, if fairing fails, bits should be of small enough size and velocity as to cause little to no damage. If that fails, there are no windows or seats in the likely zone of explody bits coming into plane. (Notice the window that is not there, parallel to the N1 rotor) Basically 4 of 5 systems failed, but in whole, they all died protecting the plane as they are designed to die doing." 4/5 bits of swiss cheese were penetrated, and the pilot had to earn his pay landing with only one engine (and a presumably wildly imbalanced plane. I seem to remember Rutan designed the Boomerang for a reason). But no injuries, and after the last "slice of cheese" succeeded, no real danger.

In KSP it is wildly easier to send a rocket into space (presumably something a newbie player can do in a few missions) than building a plane to hop over to the nearby island and land on the runway. IRL such things were done with aircraft by at least 1910ish, while Yuri Gagarin didn't fly until 1961*, and unmanned space flight was closer to 1961 than 1910. The obvious reasons that planes are harder in KSP is that it is a rocket simulation that has planes grafted on after the fact. * sure, he hit orbit which it obviously much harder than "get into space". But he certainly couldn't make it into space much before 1958 or so, which would only give Korolev a short time to build a rocket "merely" capable of going to space.

Well, that's the theory, and while I expect to indeed lose some infinitesimally small mass while biking, I think we should be a little more careful about extending an equation far, far longer than it can ever be verified. There might be other, much smaller bits hanging off that equation that we are yet to find.

This belief is only held by people who haven't looked into rockets at all or haven't really noticed the differences between Kerbin (and KSP jet engines for that matter) and Earth. According to here: http://forum.nasaspaceflight.com/index.php?topic=34464.0 the Falcon 9 separates stages 1 and 2 at mach 6 for recoverable stages and mach 10 for non-attempted landings (no idea what the "coming in hot" separations were). Stage 2 is ~10% of the mass of stage 1, so presumably "only" getting to mach 10 is quite valuable. NASA has built an airbreather that hit mach 9.6 (and I'm guessing it melted down instead of running out of thrust, but don't really know. They didn't try to recover, so it could have melted *after* running out of thrust), so these are hardly "impossible" values. ISPs (effective, presumably ignoring the mass of the air) were well over 1000, and even higher around the mach 6 range Skylon would top out at.

Here is a thread of cheap non-recoverable rocket design (you might want the older thread, as it was specific to stock rockets): To go recoverable in stock KSP is quite possible, but difficult. Typically I like to a few kicker SBRs (never recovered) as a "half stage" to make things easier (kickers are cheap enough to not bother recovering anyway). The next stage has to at least get to a suborbital trajectory, and when I was recovering them I typically took them all the way to orbit. The reason they went to orbit is that you need to be controlling them after they go below 22km, and that means your payload has to be orbiting by that time. It takes longer to land the booster than it did to launch all the stages. It takes even longer to design a rocket that meets all the extra criteria (and hopefully costs less after everything is recovered). Unless your goals in KSP are to emulate Elon Musk or at least show NASA how the shuttle "should have been made", I wouldn't recommend trying to recover your boosters (I've quit for months due to burnout caused by this very choice). If you really want a "cheap reusable spacecraft", I highly recommend a NERV (LV-N nuclear engine) powered ferry to move kerbals from Kerbin to Mun and Minmus. WARNING: docking is one of the more difficult tasks in KSP and you won't have mods to help you. Expect to study a few guides and start with the rescue missions (don't forget to kick Jeb out of the capsule). NERVs are expensive, heavy, and super efficient so just having one up there to move your landers/probes/whatever back and forth is ideal.

The Linux edition can use mods, I'd assume the mac can as well. Using the charger shouldn't be an issue, and go for the laptop cooler (it should help with the computer's lifespan). To be honest, I'm not sure that having all my progress reset on occasion would be easier to deal with than giving up mods, mouse, and keyboard. All of them are showstoppers and not an issue with the mac (if there are, you can presumably install linux via boot camp and use that). Without a specific model it is hard to tell, but I suspect your mac can run KSP "better" than a PS4 (the GPU isn't nearly as good, but expect it to handle lots of parts better due to a vastly more powerful CPU). Get the HDMI cable (and preferably laptop cooler) and go for it.

It sounds nearly ideal*. It also is *way* too complex to be sold alongside the scam entries listed here. While pretty much any modern car can have the "ignition setting and fuel balance" changed (by either flashing or replacing the ECU), the whole engine is a big deal (although that miller cycle is just waiting to destroy the turbo with the wrong value opening at the wrong time). Also include chips that *don't* flash or replace the ECU in the list of scams: these "chips" do almost nothing and if you are unlucky try to change things by interfering with the engine's signals. https://www.youtube.com/watch?v=VGtImIP6j3A (note that these aren't the most accurate guys around, their love of black intercoolers has been debunked, but this is a pretty straightforward scam). * About the only thing "left on the table" are things in a hybrid (and the possibility of using something like a turbo to run a generator to charge the battery). Unfortunately, all these things add weight (not to mention cost) that the infinity engine doesn't need. Expect an amazing combination of power and efficiency, as well as some rather strained engineers making sure the controls work *every* time over hundreds of thousands of kilometers (as much as it impresses me, there's no way I'd buy one the first year it's available).

Just try to do carbon dating without taking into account the bikini atoll (and similar) tests. The changes are measurable already, and piling up. I imagine this type of thing will significantly change the way we look at nuclear power. Until global warming smacked us with the obvious, "the solution to pollution is diffusion" was considered absolute. Now we've realized that the Earth's entire atmosphere isn't big enough for some pollutants. Nuclear power allows the pollutants to be concentrated and sequestered (and potentially moved off-planet, but I suspect that sooner or later someone will want the stuff). I suspect there are other cases were pollutants can be concentrated instead of diffused, but that is the obvious one.

According to physics, when you pedal a bicycle you are converting mass into energy. The equation is absolute, energy *is* mass time c**2. The reason we tend to limit it to nuclear is that such things can be measured (or at least computed. We know the masses for the isotopes in the nuclear reaction, and they only add up if you include all the energy). The change in mass of ATP when you bicycle is too small to measure. The reverse (converting energy into matter) is considerably harder, as you need enough energy for at least an electron (or whatever bit of matter you are creating). This is a huge amount of energy and it has to be concentrated enough to form a particle. If you want something the mass of a Higgs Boson, nothing less than the LHC will provide the energy you need to create it. If you want something significantly more massive, you will need to build a bigger collider. There is also no known way to choose what you get (this is why it seemed to take awhile to confirm the Higgs Boson: they had to go through everything it was making to find the things). If you want to make a "Star Trek replicator" your best bet is to start with a 3d printer* (and replace the printstock with a selection of all possible atoms. Creating the right molecular bonds in all the right places will be even more fun), although I've heard the "official" explanation is energy-mass conversions (which simply assume that the 25th century will have a better grasp of such physics, as well as an anti-matter power source. Right now such things are pure magic). * I'd expect something closer to how we create chips: only instead of coating each layer with the proper atom and removing the ones we don't want (an option) charge the locations we want them and build up a layer of the right atom (then more magic happens as you convince the right chemical bonds to form, possibly in temporary conditions until all the atoms are in place). Don't expect it anytime soon, but it should be *slightly* easier than warp drives and transporter beams. Creating "tea: earl gray, hot" from energy is closer to the warp drives and transporter beam tech.

I should hope the "power source" is a carefully controlled power supply. The AC you get from the outlet is pretty hairy and optimized for electric motors and not scientific experiments. Not sure what an "off the shelf microwave" expects, but obviously you keep following the power in and power out (and tightening the controls on all of them) until you understand what is going on. Also not that whether an emdrive works or not, we can "create" arbitrary amounts of reaction mass by "merely" accelerating some "seed reaction mass" very fast. Use a cyclotron as an engine and you can make your Isp arbitrarily large (just don't ask about the power efficiency, hopefully the EmDrive can do better).

Mucking with the intake: typically only changes performance (power and efficiency) when floored. Otherwise you intake losses are dominated by the throttle (includes air filters). Note that mucking around with the exhaust *should* increase efficiency all the time, but don't expect much (and this doesn't include things like headers used for more power). Fuel additives: Tetra-ethyl lead *does* work, is typically illegal, and will destroy a catalytic converter. It also requires tuning and/or significant engine modification* for any effect to happen (it basically increases the octane rating of your car). The ones that work (and do the same thing) do so by replacing gasoline with a "better" fuel (see E85) and also require the same tuning and are obviously going to be more expensive than gas (unless your gas taxes are sufficiently high and "paint thinner" is actually cheaper). There are a bunch of "low hanging fruit" out there that either engineers or manufacturing managers don't bother to include in a car. A few of them simply require owners to perform more maintenance then the public will do (oil catch cans, methanol injectors) and others simply cause more warranty issues than they want (i.e. you should understand that the cost for adding the part may well be much, much higher than the part itself). But all of them only add a few percent (if that) changes in performance (and all the insanely aggressive tricks, such as including steam turbines to scavenge exhaust heat) seem to give about ~20% improvement in mileage). Anything more than that is a scam. * read "changing the compression ratio", especially on non-turbocharged cars. I knew a hot-rodder who liked to do that in the 1970s, but I suspect that changing a modern combustion chamber isn't going to help (although getting there by increasing the stroke isn't an issue). If you have to ask what it is, don't even think about trying it yourself.

There's also the square/cube effect for air resistance. A SaturnV-sized rocket will burn a smaller ratio of its fuel to over air resistance than a Falcon9 sized one. But Isp is the big thing that matters.

First, I can't imagine a 10g "probe" sending back signals across a few light years. You might want to redefine it as "message in a bottle" or "message in a bottle flying past the subject at a significant fraction of c". Second, why a laser? You have an unlimited source of light (at levels significantly above "brightest Earth Sunlight") in nearly all space. Just make a bigger sail and fly that way. Better suggestion, fly toward Jupiter then sling around as close to the Sun as your vessel can handle and spread your sail there. Of course, you could always use the laser as well, but expect enough heat issues already with just the solar sail.

I would assume that a few of them have a version without the boosters that are strapped onto jets and simply released at > mach .8. I know the US (Navy?) had an air-air ramjet missile that downed another aircraft during the Viet Nam war, I'd be surprised if they bothered with a booster for that (although what do I know, in all that turning do you really expect the pilot to care if his relative air velocity is >mach .8? All he cares about is his velocity relative to his enemy). Subsonic ramjets sound pretty silly. First, efficiency increases with speed in ramjets (although I'm not sure if it increases fast enough to overcome the drag). Second they are so inefficient you typically want to replace them with normal aircraft engines, so they are exclusively used on [obviously single use] missiles (I think Kelly Johnson once designed one into a target practice drone, obviously also single use). Running subsonic seems like a means to make it easier for enemy anti-aircraft (perhaps you are using many cheap bombs with a goal of using up anti-aircraft missiles). I suppose if your pilots/anti-aircraft need to practice against subsonic aircraft, you might make a targeting drone run that speed (or more likely pull a glider at high altitude and let it maintain mach .8 by controlling the descent).

Mercury isn't tidally locked (in a way that would prevent a magnetic field around Proxima Centauri). We know any atmosphere will be eventually lost from Mars. Proxima Centauri (the star) will last a trillion or so years, meaning it would be a good place for a "long term human/Earth life survival cache". Not so much if they are huddled on the shady side of a mountain range next to the terminator.

I just looked up the stats on keyhole (it might not have been block 3 keyhole and have a considerably less mass, but that is the alleged driver of downward capacity). Ask congress why the shuttle had to do everything. If you have a contract to do all that, which is exactly what NASA got from Congress, a shuttle starts to look like a great way to go. Get anything different about the contract and everything changes.

"The thing is, you never get complex technology right in the first version. Ever.So the only way to get a good product is to start iterating, and learn from your mistakes, and continually improve. If you don't do it yourself, you'll have to rely on somebody else who does it" - Linus Torvolds 8/28/2016 (yesterday, as I write this). Of course, with a 20 year design cycle, NASA can't "continually improve" (the above quote was about CPU design). I'm wondering how many KSP players can design a shuttle replacement that can hit *all* the design parameters of the shuttle with some "better" craft, even in hindsight. Return 20 tons from orbit Hit a polar orbit from Vandenberg reusable (I'd assume that most ignore this bit) Ignoring the reusable requirement (which was likely pushed as hard by Congress as anything else), you might pull off a Saturn V (VI? Saturn 1b/c?) that could do all of the above. You would still have to build a launchpad and VAB (maybe only 1/4 the size, that thing could assemble 4 Saturn Vs. But a 1/4 square foot VAB is going to cost big money) in Vandenberg as you are unlikely to be able to ship a completed Saturn V through the Panama canal upright. The original designs (which appeared to have inspired the overall design of the Falcon) appear to make sense, but the downward cargo area pretty much sets the size of the shuttle in stone. Since you are already committed to orbiting that much mass, simply including an extremely large fuel tank is going to be the "cheap and cheerful" means to orbit. In hindsight, my guess is that hydrogen remains the wrong choice of fuel for reusable engines, but ditching them would be an issue. We know an early engine (I'm thinking an F-1, but google won't confirm) was dunked in seawater and used again. Of course, that was a single test but apparently never followed up on. I'd assume that switching from hydrox to kerlox might possibly allow better reuse, but likely require some means of landing a first kerlox stage (presumably piloted gliding landing, the shuttle SRBs* went *deep* in ways that the F-1 dunk test never experienced [think much higher pressure]). Early shuttle concepts used this, but you still wouldn't get to shrink the size of the shuttle (and all the tile issues it had) and are piling on development costs merely in the hopes that refurbishing kerlox engines (sooty) would be easier than hydrox engines (enbrittled). I suppose that methane was considered at some point, but ignored with all the experience NASA had with kerlox and hydrox. I just can't see NASA committing to an extra manned stage to avoid hydrogen issues in refurbishing the engine. Note that Merlin's fabled "reusable kerlox rockets" have a listed life expectancy (without refurbishing) of 10 flights (and spacex hasn't yet demonstrated a 90% chance of landing) and Discovery flew 39 (granted, the engines were nearly rebuilt every time). * shuttle SRBs hit the water at 82 kmh (according to wiki, that seems slow) and came back to the surface due to filling the center with air on the way down (and at high enough pressure to push water back out on the way up). Expect some seals to break and brine where it never should be.

And to a large extent, the prices (for single use anyway) go the other way (except for propellers).

You seem to get about 30 years of "free" airplane science with KSP. The hard bits of getting into the air: You need an engine with a strong power to weight ratio (nothing like a rocket, but more car-like). KSP starts with jet engines. You need a strong airframe. Check out aircraft 1903-1920: Lots of braces and framing on wings. Eventually aluminum and real engineering took care of that, and is handed to you with easy LEGO style parts. Sure the parts might not be stiff enough, but that is a huge job for aircraft designers. You need some clue about aerodynamics. This was hard in 1903 and still not easy. It is also typically counterintuitive so new players often don't even know the basics about CoL behind CoM. You need to fly the thing. Ok, flying is easy (for more tolerant values of "flying level") but you still need to land (although at level 0 and maybe 1 you might want that perfectly flat grassy plain next to the runway). Also there are more controls to worry about and they aren't great with a keyboard, while a rocket should ideally be flown with just a spacebar (real rockets don't throttle, and any adjustments to your gravity turn are going to be inefficient). But yes, once you abstract away things like turbopumps and light materials (important for aircraft as well), you reduce rocket science down to the bare bones. From the sound of it, spacex might be going to a *cheaper* material with the carbon fiber, I remember something about lithium being in their aluminum alloy which can't be cheap.