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Just done a couple of back to back checks using one of my probe setups. Ground to 100km orbit required 4604m/s delta, transfer to jool requires 1926m/s Ground to 605km orbit required 5137m/s delta, transfer to jool requires 1918m/s It's more efficient from the lower orbit (by 525m/s). Orbital altitude makes practically no difference to the required delta for the interplanetary burn. However the 101 so days until my transfer window would be best spent at the highest possible time acceleration. I tend to park my interplanetary stuff at 1250km to cut down on actual waiting time, I'm too disorganised to do the time accel whilst landed.

Depending how good the materials technology gets another option may be to have a rigid lift envelope filled with a vacuum.

It's not a crazy idea at all, so no need to get all bashful. As others have said the whole capturing / separation of hydrogen "on the wing" could be problematic (i.e. heavy and / or complex). Maybe a non-combustion engine? There's some pre-existing tech that might be able to be adapted to purpose if someone were so inclined to tweak it a bit for different atmospheric composition. It's from the pre-ICBM days and was conceived to power long-range strategic bombers. https://en.wikipedia.org/wiki/Aircraft_Reactor_Experiment https://en.wikipedia.org/wiki/General_Electric_X-39#The_nuclear-powered_X39 https://en.wikipedia.org/wiki/General_Electric_J87 The last link is interesting, suggesting they were near running a pair of 34k lb thrust turbojets without using combustion. (it sometimes surprises me how much awesome tech was developed then abandoned)

Must.... build.... fireball XL5....

That was pretty much how it worked yes, hybrid afterburning turbojet / ramjet. The line between high-bypass turbojet and a turbofan can be a little blurry

It got to 10,461 km/h (2905 m/s) after a 10 second burn of it's own engine - after being boosted to hypersonic velocities by a solid rocket booster that weighed several times more than the test vehicle. Impressively fast for sure. But strapping huge SRB's to an SSTO is cheating And it's still too slow

At the moment - no, it's not possible. Turbofan engines (with afterburners) have only been able to reach around mach 3.3 (on the Sr-71 blackbird) which translates to somewhat less than 1000 m/s. Scramjet engines may be able to get to near the 2km/s mark. There is no existing (or proposed) air-breathing engine that'd get you to the 7.66 km/s velocity of something like the International Space Station.

Action groups and a couple of sets of the radial mounted engines (to produce offset thrust on the orbiter) did the trick for me when I tried. I've only done it small-scale though. On this one there's an engineless central underslung fuel tank (mimicing the shuttle external fuel tank) and a pair of liquid boosters (replacing the shuttle-style SRBs) - mechjeb was handling the basic ascent whilst I was dancing through action groups stopping it flipping. That little semicircle of radial engines at the back of the orbiter was what was used (in groups) for stability during launch and ascent. edit - balancing them for CoM / CoT throughout the whole takeoff is almost (if not completely) impossible. CoM & CoT change too much during flight to compensate for using engine gimballing alone.

That'll have added a couple of tonnes of mass to your vessel, decreasing it's total deltav unless you added more fuel to compensate. Do you mean here you're flying from Kerbin, outside it's SOI to a solar orbit, then aiming for Moho? Your Moho intercept burn should be occurring in Kerbin orbit, taking about 1750m/s of deltav to make an intercept (checking my savegame the next launch window for that deltav to Moho is about 20 days away). More fuel would be required for orbital burn, reentry etc so a 5000 m/s total deltav budget for the trip isn't particularly unrealistic. LV-N's (or addon parts with a similar ISP) are good for that kind of thing if you don't mind the low thrust to weight ratio

Probably couldn't do it with the ISS as a whole but maybe doable using whatever resupply vessel is attached to it at the time? The way I see if if you can't manoeuver something to the drifing astronaut before the life support expires (about 8.5 hours max) then all you can do is wave goodbye and notify next of kin. Personally I'd use a self-propelled "rescue buoy" by forcing all EVA capable craft to carry what amounts to an RCS propelled low speed wire-guided missile / torpedo - that trails a high-strength monofilament line attached to a winch. Simple (70s tech), effective and reuseable. But I'm not NASA

Generally true - there's precedent for getting around that though. The ol' Orion design used reaction mass attached to a nuke to provide propulsive force. The idea was the nuke went off and threw a mass of (presumably vapourised / plasma) tungsten at a pusher plate to push the ship away from the detonation point.

Y'know, depending on how much we want it to miss by, 30 years is plenty of notice to nudge something like that off course enough to avoid collision. 1mm/s of lateral velocity applied now would be sufficient for it to clear us by nearly 1000km. It'd still be brown trousers time, but maybe not the end of everything. Tidal effects would be interesting to say the least. (warning my maths may be off, I'll recheck it tomorrow whilst more awake) Depending on rock density aren't we only taking an energy requirement in the 2x10^16 to 1x10^17 Joule range to put 1mm/s of velocity on deathrock? The lower boundary translates to the output of a 5Mt nuclear warhead and a fairly light asteroid, the upper boundary a 25Mt (for an asteroid denser than iron). Hitting deathrock directly with a nuke probably woudn't do much, but a handfull of massively overpowered orion-style nuclear shaped charges alongside it to nudge it sideways may be enough to do it. How close would be "better" than a direct hit? Deathrock radius: 125,000m Deathrock volume: 8.1812 x 10^15 m3 Density (light rock): 2700kg/m3 Deathrock mass: 2.209 x 10^19 kg Required deltav = 0.001 m/s Required energy to achieve 0.001 m/s = 2.209 x 10^16 joules (is this part right?) nucear detonation: 1Mt equivalent of TNT = 4.184 x 10^15 J nuclear detonation Mt required = 22.09/4.184 = 5.27 Mt TNT equivalent

It can be enough, yes. Water starts to thermally decompose at about 2000c but you want it a thousand degrees hotter for there to be a good percentage of the water converted to baser components. As daft as it sounds this is why the fire extinguishers used around molten metals (or worse, burning metals) don't contain any water. I wonder what the nozzle could be made out of? Would graphite work at those sort of temps if there's a bit of excess oxygen floating around?

For the record - Innswerants isn't completely inactive. His blog has some recent updates explaining the delay (and the update to the MapSat licence). Health issues are more important than a mod for a game. Anyone who believes their sense of self-entitlement is more important than Innserwerants' health and well being can join the queue to go eva sans spacesuit.

It'd be awesome to see it brought in as stock. If only so they could assign a science value to it Surprisingly, as long as you remember to delete the hilo.dat file that comes with the x4r1 release there's nothing functionally wrong with the mapset. Have been running my traditional "new version, get mapping" theme since the .22 release lol. If you want to add the parts to the career tech tree that's a fairly trivial .cfg edit. The downside is that the scans don't have any science value (and now I feel the need for a large-format printout of one of the satellite maps as a wall picture)

Of course you'd have to make modifications to the setup as a whole - the question "could a modified Apollo spacecraft have been used for a manned mission to Phobos" implies some deviation from the original configuration. We are after all not talking about a simple jaunt to our own moon. The mods are likely fewer than you'd think though. One of the uses slated for the NERVA was was part of the Saturn-launcher-based RIFT programme - NERVA upper stages placed in LEO to act as tugboats for moving things to higher orbits, or used to lift 170-odd tonnes at a time to LEO. The proposed vehicle was a Saturn S-IC first stage, S-II second stage, S-N (Saturn, Nuclear) final stage. That's two stages of off-the-shelf technology and a bit more work on one near completion. Even Von Braun had them lined up to be the engine that'd take humanity to Mars. Apollo based craft? Maybe not (if only because you don't lock people in a container that small for an interplanetary flight). But sharing the Saturn-based launch vehicle and using other NASA tech that was tested and available in the '70s? Certainly.

It was likely doable in the 70's. By the time NASA closed down the NERVA research in '72 they had an engine with 75,000lb of thrust and an ISP exceeding that of a kerbal NERVA. I've always understood that the whole reason they cancelled the NERVA itself was specifically to prevent the ensuing space-race to mars that unveiling tech like that would have caused. The US simply couldn't afford it.

Y'know there's no technological reason they can't do that already. Feed oxygenated blood containing nutrients into the carotid artery, return from the jugular vein & seal the stump of the neck (as they do for any amputation) to prevent you crudding up the jar with leaked blood. Basically a cardiopulmonary bypass without the hassle of having to keep a full body alive. I suspect there may be ethical issues stopping them actually doing it Of all people Sony are the ones that've been showing off glucose / oxygen biobatteries. '07 they could run an MP3 player and in '10 they used a more advanced version to power a small remote controlled car. Running something like an microprocessor is well within that kind of power output.

I assume by 134a you mean the R134a that's commonly used in car air conditioning systems. refrigerators etc? You do not want to expose that particular substance to any significant temperature. I've always been both amazed and horrified that it was ever OK'd for use by the public for any purpose at all. It thermally decomposes (at a distressingly low temperature) to a mix of hydrogen fluoride and carbonyl fluoride gases. The former is corrosive enough to be used in etching glass, the latter is functionally a fluorine based version of the trench warfare agent phosgene. If it came to a choice of being in the same room as heated R134a or swimming to the bottom of a nuclear reactors spent fuel pool - I'd be reaching for my swim goggles. It'd be less immediately lethal.

Several hundred watts isn't sufficient to run an electric vehicle sadly. Even something as lowly as the electric side of a petrol / electric hybrid is up in the dozens of kilowatts, with some pure electric vehicles up in the hundreds of kilowatts. There's also the issue of giving every idiot on the planet access to radiological materials. Hydrogen fuel cells / hydrogen combustion engines are a much better bet. Zero recharge time (just a tank refill), fuel is made from water and unlike RTG's they'll maintain their full power output for as long as fuel is available. Ironically the tech exists to do this right now but environmentalists object strongly to the precursor work required for emissions-free power generation.

Thermonuclear shaped charge torpedo. Copy the project orion propulsive charges (https://upload.wikimedia.org/wikipedia/commons/c/ce/Orion_pulse_unit.png), adding a guidance system and propulsion. The bombs weigh less than a tonne and pack a 0.14kt yield. Not a huge amount in itself (though a bit of EMP and nuclear fireball is always a bonus). On that diagram the propellant is tungsten and the velocity of the tungsten plasma when the nuclear charge goes off is about 25 km/s. You really don't want to be in the way of that tungsten

An awesome idea. So many uses buzzing through my head right now

Can you post up your system specs and maybe a list of any plugins you're running? I'd expect it to get better in future updates. Remember that KSP is alpha software not a 100% polished & optimised finished game. The game engine (unity) is also under continuous development, I'd imagine that if they added features Squad could use to get us more FPS then the Squad would be on it like a shot

Offset center of mass can be worked around - I've been using a couple of action groups of Rockomax 24-77's to handle the center of mass shifts on a shuttle-style launcher (all the major weight changes during launch being on the SRB / liquid tank assembly slung below the orbiter). Works nicely as long as I don't accidentally activate or deactivate the wrong group. Whats your delta v requirement for the launcher? Does it have to get to another planet or just haul the lander up to orbit so it can be picked up a long-distance-optimised transporter? If it's just to orbit then it's doable with one mainsail (on an orange tank - this is the asparagus core) and four skippers (1st drop pair orange tank + x200-16, 2nd drop pair orange + x200-32). edit - added pic http://i110.photobucket.com/albums/n92/tychocaine/screenshot10_zps6b3a12e1.png

I'm assuming you're on Mechjeb 1.9.8, as the only part included in Mechjeb2 is the control unit itself. iirc that 1.9.8 stock ship is to build the mechjeb module displayed in the screenshot in the first post of this thread (the eye and the yellow bits around it). Been a while since that mechjeb version has been updated though (was released for KSP version 0.19) so don't be surprised if not all functions work.