p1t1o

I dont think they can be re-started, but the last stage has RCS for attitude control and a little extra dV (it uses this to place multiple warheads onto different targets). **edit** Unless I am missing something...and I might be! ..... It sounds like you are describing a standard Hohman transfer - what I am alluding to is first burning to raise your (solar) Ap waaaaay above what you need it to be, then when you reach this new, higher Ap, you can alter your Pe for super-cheap. The savings on changing the Pe will offset the extra burn to initially raise the Ap. I think this even holds when you want to re-circularise as well, but in this case we are plunging into the sun

My money is on: instrument sensitivity has been rising steadily, now we are getting tiny readings from nowhere that we couldnt detect before - is it from tiny environmental factors or newly discovered, ground-breaking physics? I'll let you try out Occams razor on that one.

dV values do not seem to be published, it would seem prudent for exact figures to be classified. But it can be estimated from data that is published, and also from observing their performance. Some good science here: https://www.armscontrol.ru/course/articles/primer.pdf As a rough guide, many ICBMs are capable of putting something into low orbit, which gives you an idea of their dV capabilities. It aslo obviously depends heavily on the payload, which is not necessarily fixed per missile. Is it not true that you can do it with significantly less dV than this if you do...what is it called?...a bi-elliptic transfer? Raise solar apoapsis first, then when you reach apoapsis, burn to lower periapsis into the sun?

@kerbiloid You've got a TV series brewing right there!

I did some googling to try and find some pictures, bad news is I couldnt find the specific one I was looking for, pretty sure it was in the 90s. Weird news is, there are tons and tons of similar examples! Heres one that shows that the roof is still there but no longer attached, similar to my story, but if you google variations of "deoderant can blows roof off house" you get records of lots of different events! http://www.worcesternews.co.uk/news/11849037.Exploding_aerosols_almost_blow_roof_off_Worcestershire_house/# Keep your pressurised containers in safe places folks!

I heard a similar anecdote about an SR-71 pilot requesting "Clearance to Flight Level 60" (60,000feet) and the reply came back something along the lines of "Sure, but I dont think you'll make it that high!", the response: "Sorry Control, we are requesting clearance down to FL 60"

I did hear a story once where a can of deoderant was left on top of a HiFi - the HiFi caught fire due to an electrical fault and cooked off the deoderant causing a classic BLEVE - Boiling Liquid Expanding Vapour Explosion, which lifted the roof off the house. It didn't "blow the roof off" but the entire roof of the house seperated from the walls, shifted several inches and fell back down. There was footage of the aftermath and the story feels legit. Gas explosions can be deceptively powerful, the expansion ratio is nowhere near as much as a high explosive, but you often start with a far larger volume, and the pressure impulse is longer, generating more work for a given overpressure. Perhaps the alkali metal stories are often overblown, but I can easily imagine a situation where an ill-advised exposure to water caused a dangerous build up of hydrogen.

If the cable goes along the bottom of the ocean you can take 1000bar off that, much easier now!

Thats all fine, Im fine with superconductivity, but why would anyone assume "it could be metastable"? Actually, no Now I feel UNDER PRESSURE to come up with an intended one... **edit** Did some searching around, almost all mentions of metastability were in the form of "...if it turns out to be metastable..." but there is one reference, to a 1972 paper from a Soviet physics journal which apparently has some calculations which predict metastability: http://jetp.ac.ru/cgi-bin/dn/e_035_04_0783.pdf This is an old paper, have the physics been updated since? Can anyone judge its quality or validity in present-day physics? Its a little above my pay-grade this one. ITs also not clear whether or not "metastability" would actually mean that it would remain at its metallic density and retain its physical properties all the way down to 1atm, or whether it simply means "a bit more stable but still requiring colossal pressures". *edit* Found more science, maths a bit too intense for me here, not my area: http://www.jetp.ac.ru/cgi-bin/dn/e_034_06_1300.pdf

Heard this in like my first week at uni studying chemistry; There was a chemist who worked with Fluorine gas. One day, he wondered what would happen if he stuck his thumb into a stream of fluorine gas, so (in a fume cupboard of course) he do just so. His thumb turned white but apart from that nothing much happened, but it wouldnt go back to normal so he just kinda left it and hoped it would fix itself. He never did get to find out because 2 weeks later he was blown up in a fluorine explosion. Moral of the story: just dont work with fluorine for any reason, simples.

I've heard several people say "It could be metastable, we're not sure yet." Is there any reason to expect it to be? My gut says that its going to need not a subtle reason, but an extremely compelling one. Who in their right mind would expect something compressed to 5million bar to be stable at 1 bar? I know that metastability is a thing but 5 million bar is one hell of a jump, I feel like its only talked about because it sounds cool.

@magnemoe @cantab @wumpus Relevant: https://en.wikipedia.org/wiki/Republic_XF-84H "Thunderscreech" "The XF-84H was quite possibly the loudest aircraft ever built (rivaled only by the Russian Tupolev Tu-95 "Bear" bomber[16]), earning the nickname "Thunderscreech" as well as the "Mighty Ear Banger".[17] On the ground "run ups", the prototypes could reportedly be heard 25 miles (40 km) away.[18] Unlike standard propellers that turn at subsonic speeds, the outer 24–30 inches (61–76 cm) of the blades on the XF-84H's propeller traveled faster than the speed of sound even at idle thrust, producing a continuous visible sonic boom that radiated laterally from the propellers for hundreds of yards. The shock wave was actually powerful enough to knock a man down; an unfortunate crew chief who was inside a nearby C-47 was severely incapacitated during a 30-minute ground run.[18] Coupled with the already considerable noise from the subsonic aspect of the propeller and the dual turbines, the aircraft was notorious for inducing severe nausea and headaches among ground crews.[11] In one report, a Republic engineer suffered a seizure after close range exposure to the shock waves emanating from a powered-up XF-84H."

Its hard to answer quantitatively questions that have magical premises such as "apart from those imposed by the properties of the materials it could be made of" as we are now operating with a massless engine capable of surviving many many thousands of degrees with no change in structural properties. With this material, you could make some really fancy stuff... But considering an air-breather for the moment: Thermodynamics starts to set a hard ceiling. Essentially, the faster your regime, the hotter the air entering the combustion process - simply by being compressed by the passage of the craft, apart from any required compression within the engine. The hotter the air incoming, the more energy you have to dump into it in order to get a decent expansion and extract work, and as you get faster, chemical combustion stops being able to provide enough energy to raise the temperature of incoming air very much. At this point we are in or near the regime where we are talking about temperatures that will ionise atoms and split molecules apart, so even getting combustion to *work* gets harder. There are also issues involved with the fact that your aircraft will now be travelling around as fast as molecules in a reaction, which makes sustaining combustion even harder, possibly can be tackled with fancy engineering, though anything that adds even a hair of drag is going to be dragging that ceiling down. This is where SABRE engines generate a significant part of their benefit - even though they (nor any other engine) do not operate anywhere near these limiting conditions - by cooling incoming air you are increasing the amount of work that can be done by the engine for a given core temperature. (SABRE also gets benefit from not having to operate at limit-conditions, so lighter metals can be used in construction, significantly benefiting its TWR.) So even if you had a perfectly heat-resistant scramjet (which also needs to be lightweight and assuming you have solved the supersonic combustion problem itself) you will still hit a limit set by the amount of energy that can be stored in chemical bonds. You might find some new exotic fuel that gives you a few more joules per oxygen molecule burned, but it will only be incremental benefits.

"Crayon Ice"? lol autocorrect? With regard to freeze-drying - freezing biological material is hard enough on living tissue as it is, combine that with dehydration and you just multiply the damage. Dehydration is far far more destructive on its own than freezing. Compare a defrosted steak to a piece of beef jerky - which one more closely resembles fresh meat? Which process [drying or freezing] is more easily reversed? CAN you even "un-jerk" beef? Clue: nope. If you did attempt to re-hydrate beef jerky, what you would get would more closely resemble *cooked* beef. If there are going to be advances in the cryonic preservation of living tissue, it will NOT be through freeze-drying. Much of the chemistry of [what we call] life is dependent on being in water solution, and many components will be chemically changed by removing the water present, and many of those will not simply "re-hydrate" if water is re-introduced, but will remain changed. That is not to say that freezing does not cause damage, but removing water as well increases it by an easy order of magnitude.

It no what new dog apex?

Thats just a recipe for negative yelp reviews. "Arrived on time but my body, house, family and city were vaporised. 3/5"

This isn't even that new an idea, there is even real-life precedent! https://en.wikipedia.org/wiki/Rocket_mail It was short-lived but a ballistic, global delivery system was under discussion. *** This is one of my favorite threads of all time.

Its an extremely wide and deep-seated misconception that for someone to be clever, they must be clever in all things, and if they make a mistake in any area, that forever must taint their "cleverness" as well. Humans are not digital computers, are not even naturally rational, thus being clever in a rational field sometime leads to strange things.

China have developed ballistic missiles capable of hitting a moving target the size of a ship, utilising GPS updates and terminal guidance (most likely radar but possibly teamed with IR), with modifications, it should be capable of hitting a house under non-combat conditions, launching from a satellite already in orbit would seem to remove some sources of inaccuracy too. You may want to ask customers to install a radar reflector on their roof, or even an active transponder. The biggest problem I forsee is not triggering any nuclear launch warnings, considering this would be almost indistinguishable from a warhead. Given that this projectile will likely have to be actively guided, it may be able to outmaneuver some ABM systems though. However, the pizza will have to be protected somehow from the 100-odd G's experienced during evasive actions. Be careful of political fallout. With a large enough constellation you should be able to keep the delivery times below 30mins though.

99%? 50%? Really? The second part is a fair point

Honestly the Kerbals have it great. Imagine if humans were only 3 feet tall. Less mass straight off the bat, combined with less mass required for habitation space, supplies, waste storage and management, less power required (for waste processing, light/heat and other environmental factors etc) less radiation shielding needed, hell, a smaller body intercepts less radiation anyway. All things which are problems gets smaller. Its possible that we may be able to reduce the size of humans by simple selective breeding without any fancy genetic tinkering.

THe "atmospheric sound enhancement" mod added a "sortof" sonic boom effect. The only problem I had with the mod was that it made sounds more "realistic" ie: once you were out of the atmosphere, there was hardly any sound at all, so it was a little boring.

I'll +1 both of these

Good point, looks as if optics might play a more significant role than I had assumed at first. Looks like you've done the rounds on the forums a few times so you might have already heard of it, but the ubiquitous http://www.projectrho.com/public_html/rocket/ website might be of interest to you - it is specifically aimed at sci-fi writers with a mind to scientific accuracy, and I believe it has a page entirely dedicated to detection and sensors (although possibly tailored more towards ship-to-ship operations).

Did a little light reading myself. It seems the frequency, and possibly other factors such as beam shaping and other involved stuff, could have a significant effect. The best example I could find was the Goldstone Solar System Radar (https://en.wikipedia.org/wiki/Goldstone_Solar_System_Radar) and whilst it does have a 70m dish, it operates at only 500kW and has been used to extensively characterise various bodies in the solar system. So whilst I am sure that one could get a (relatively) sensible sized dish to be of use, the best bet will still be some kind of synthetic aperture using smaller, seperated antenna. I wonder, in fact, if the best bet might not be to "seed" the system with numerous probes, each one with an antenna and several optical instruments, and a single powerful emitter on the incoming vessel (This single emitter could itself be a synthetic antenna with a baseline of many kilometres if desired).