Comments by "SeanBZA" (@SeanBZA) on "Scott Manley" channel.

  1. The thing about the photography side was that the ultra fast gas switches were not used to fire the Xenon flash, which, for the technology of the time, was easy to do, using a simple high voltage pulse that ionised the gas in the Xenon flash tube at the cathode end. The big thing was they had to actually only fire the tube for a very brief period, so as to only have this very short burst of very bright light, so that the motion of the aircraft would not blur the image. Thus the need to develop a device that would be able to turn on very fast, and also handle a massive current pulse, so as to dump all the charge in the capacitor bank used to provide energy to light the flash tube, so as to drop the voltage across the flash tube (at this time it would be dropping from the 400V or so initial voltage, to the cut off point of around 60V, where the tube itself would start to slowly cut off due to the arc voltage being below the voltage needed to keep it on, slowly being in the order of tens of microseconds) to close to zero, and thus ensure it has a sharp cut off. Most devices at the time would either not last more than a single use, or would not have the fast response needed. This device was the original gas thyratron, and the need for fast ones meant they made them with a hydrogen gas fill, with early ones filled with neon being both slow, and too low an operate voltage. Hydrogen gave the needed high voltage stand off needed, and because it is light, it also ionised very fast, giving the very rapid current path build up, in the order of nanoseconds from fully off to fully on. This has led to them being now an export controlled device, and to this day an item that is still made, on the original tube lines, by some specialist companies in the USA, as the US military needs them for operational parts, and, because of the hydrogen gas fill being able to penetrate almost all seals with ease, a part that has a very limited shelf life of around 2 years, before you need to either replace or rebuild it. Neither are cheap either. You can test it at lower current, and do all your qualification at this level, as full power operation you only have around 5 uses, before it degrades to the point it is no longer usable. Selling them is ITAR restricted, as heavily as any part can be, because of the one use case, so there have been a few attempts to steal the technology. These days you still find it hard to get the same power delivery with small volume, it really is a part that is perfect in it's application. But you can do it, with modern high power semiconductors from specialist companies, with corresponding exotic semiconductor compounds, and prices that make the gold used to plate them the cheapest cost in production. Incidentally the bridge wires also underwent massive changes, from simple thin wires, to the modern ones, mass produced using semiconductor wafer processes, to make thin film metal alloy strips that are precisely controlled in shape, composition and dimension, so that all of them are as close to atomically identical as possible. The difference in timing between them is in the order of picoseconds, they are that identical.
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  2. Delta, predated the shuttle, survived the shuttle, outflew the shuttle, and worked out overall cheaper than the shuttle.
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  3. Funny enough, I did once jump start a helicopter, which had a battery that had run down due to the DC bus being turned on overnight so the security guards could use the aircraft radio to listen to broadcast FM. Helped that I did my apprenticeship on that model, and knew the entire electrical system, and also the pitfalls that could occur with them running the battery down, and what to look for. Ground power unit and the ground power connection, start the ground power unit and power up the DC bus, and they press start. Low current, the ground support unit is designed to supply 8kA at 28VDC, and this little turbo barely made it to 400A during start, so after a half minute of idle, pulled the cable ( only way, there is no disconnect other than a sense contact on the plug), waited another 5 minutes at idle to see if the battery was not going to go into thermal runaway, it was still cold so gave them a clearance to take off back. As well used another ground support unit to jump an ambulance that had waited 6 hours for the casevac to get there, with lights on, and there had to grab jumper leads to make the link between the connector and the battery. those lights went very bright on 28V instead of 24, and that ammeter needle did not even budge off the zero during the very very vigorous starting. As to the LRV batteries being used to fire the ascent stage probably no issue, the batteries certainly were the same chemistry, they used a similar enough voltage. The major issue was the disconnection, as the LRV batteries would stay behind, and the ascent stage needed power to keep the valving operational, so they designed the systems to get you power from an alternate set of ascent batteries if the main ones failed, but use batteries on the ascent stage. You could not have kept the mass centre stable if you used the LRV battery pack and carried it with, no real space to place it (otherwise they would have had equipment or battery pack there already) and also it would move the mass centre from the engine bell outside the ability of the RCS system to compensate for the eccentricity. Silver Zinc batteries are heavy, and are only used in space applications because they are so reliable and tolerant to abusive temperatures and charge and discharge use, unlike the modern lithium chemistries. Thus you can have a smaller battery pack for the same high current draw, and not have to worry too much about it cycling from -100C to +200C every orbit.
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  4.  @-yttrium-1187  But also equally hard to cool, as only radiation to carry it away, and you need massive thermal shielding to provide thermal barriers.
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  5.  @codymoe4986  Also was a single use vehicle, and definitely was not going to be used again, even if you did manage to find it.
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  6. Also a lot of different propellant types, based on if they are derivatives of ICBM designs, or are made from designs appropriated from other countries. All controlled centrally, but they obviously are all different to see which ones are going to be best at getting reliability. My guess on the dual crater is that this second stage still had a satellite on it that was not disclosed, and it failed to release for a reason, and thus was still attached as it was approaching, and the tumbling just before impact tore the payload apart to make the second crater.
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  7. With all the things about these hypergolics, they are still the least dangerous ones that are in use, the more exotic ones proved to be a little hard to handle, so the ones that merely dissolve you are the ones in use.
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  8. You can see a skirt on the base, so likely it was lowered onto the stand and sat on the skirt. Then they likely used multiple clamps to hold the skirt to the stand. Most likely is that one or more of the clamps either were not tight, or the bolts had been machined undersize, leaving not enough thread engagement, or only a part of the thread was engaged. Then the thrust snapped those, and the others that held tore the skirt loose, which accounts for the damage, as that skirt likely also damaged the engine bells as they rose up past the stand centre, and either bent them or fractured them. Bent ones got hot spots that later on failed, and the cracked ones were losing lots of cooling fuel till the uncooled areas melted away, and caused that engine to shut down because controller saw dropping thrust. Then the remaining engines were slammed to 110% to compensate, and this extra stress meant that one of the dented ones split open, and the parts blown off into the plenum damaged piping and such on others, and also likely destroyed the guidance controls, as it did not recover. Thus the big black cloud of burning fuel and hydraulic fluid, and bits of engine rich exhaust. Controller saw thrust was dropping on those engines, or pressures were dropping and flow rates were running wild, and shut off them, trying to correct attitude with the others by throttling them back and trying to correct with steering the remaining engines, and then it went horizontal. It probably detected a launch abort, and attempted to blow the destruct charges. Of course, seeing as this is a test firing, those likely were not fitted, just had the test bypass units in place, to pass the regular self test cycle.
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  9.  @thetimebinder  Granted not man rated, but better overall safety record than the shuttle anyway.
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  10. Also a part with a very finite life, as it is designed so that it is very close to it's elastic limit in normal operation, so you have a very limited number of cycles before you run the risk of it failing from fatigue. Needs very special care to keep it from having any extra stress from installation, so likely is a bolted on part as well, not welded, especially in an application like this where the margin between operation and failure of the main structure is so small. Whoever is making them probably has a few dozen per batch, and tests half to failure to ensure the rest are going to be within the required range of operation.
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  11.  @Jonascord  Did the same, they burn really fast, he got a single puff out of it before it was down to the filter. With LOX remember not to use shoe polish, it may not be the best thing. Was filling a LOX tank in the bay, and there was a snake in there. Broke it, as it fell out of the gloves when I grabbed it, and on landing on the floor at cryogenic temperature it broke into pieces.
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  12. A lot of very bespoke computer designs were around before the microprocessor came along and guided them into a few very rigid areas. Especially those that were made from discrete logic, and where the designers went and made it with instructions they needed, and little more, and where your software and hardware were very tightly bound. Designed for the purpose, and then made to be as compact as possible, with, in that era, as few transistors as possible, because they were both very expensive, and also not as reliable as diodes. So you had a lot of diode logic, with transistors scattered around where absolutely needed, to act as inverters and regenerate the logic levels. Many of those designs were translated into early IC based systems, and they often used EPROM to do complex functions, like a lot of glue logic, and also to store tables used in math, so as to simplify multiplication, giving you the ability to have 2 5 bit numbers be multiplied together, to give an 8 bit output, in a single clock cycle. Used a 2708 1k EPROM, holding the decimal number table, and allowing you to do multiplication in a few cycles through the table per digit.
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  13. I remember being in an aircraft that used that overshoot once, rotated just about the end of it. Hot, altitude and a full load of fuel on board. Flew in ground effect for a while as well, till those 4 jet engines had burned off enough fuel, and gotten up the speed, so we could climb. Trees were companions for a few minutes, as well as the town we went over at a little above treetop and rooftop height.
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  14. Bear was drugged, guess the Air Force had a bear problem, as normally they did these sort of experiments using a full grown pig, as it very much approximates the human body in accidents. Normally after the test the pig has an invite to the BBQ, as guest of honour, after the autopsy.
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  15. Why do you think the Hubble mirror was flawed, focus length was to the original spec of 270km and not infinity.
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  16. Build there so it is convenient to have the workers close by, and also the test engineers can stay at a local hotel, and enjoy the city, not have a 4 hour commute each way every day.
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  17. You also get inadvertent jamming in built up areas, with harmonics of thousands of cheap poorly filtered power supplies and LED lights, all creating a much higher noise floor in the area, so that the initial lock of a GPS takes a long time. I often see that, startup time can be up to 10 minutes, or you have the GPS time out, because it cannot get a lock, yet when the power to the area is cut you get a lock within a minute just from the lower noise floor.
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  18.  @aBoogivogi  The Soviets had somewhat less good results, and have had a good number of failures as well. most memorable was the Kursk, destroyed by a leaking torpedo, a well known issue, that they had ignored as a possible cause for concern, because the torpedo tube was designed to contain the blast with the inner door closed. Too bad it did blow with the inner door not fully closed, because of a poorly designed or made electrical connector, another well known issue, combined with a catalyst in the tube, otherwise known as rust.
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  19. To be fair, a lot of fighter jets are aerodynamically worse than a brick, but fly because even a brick can fly, if you strap a big enough engine to it.
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  20. Not likely much, cut to appeal to the average market, not any with the ability to think beyond Ooh shiny ball.
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  21. Also your mobile phone absolutely depends on GPS, just to provide an accurate clock that allows for the time slots per device to be as tight as possible, allowing for maximum data throughput, but also to provide an accurate clock that allows the base stations to be able to use QAM256 to get as much data through per signal transition, using the GPS clocks to generate a very precise, as in down to single parts per billion accurate, clocks for the base stations, to do this. No GPS, no clocks, and very much degraded phone service, as the towers need to fall back to a very coarse clock provided by a heated crystal, good enough for one part per million, but now resulting in a much reduced data rate per device.
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  22. Probably will need around 5 times the delta V to deorbit, though of course that is also something you can do with just using a large ion engine, and a lot of fuel for it, with power being provided by the on board satellite arrays, as you would need minimal power to charge batteries as they only will have to provide orientation and 45 minutes of low draw during the night passes, and will not really need to power much in the environmental system with no people on board, do you can simply shut down and drain a lot of the systems to safe them, then keep the bare minimum like attitude control, computer systems and circulation to even out temperature. You can close all the airlocks as well, and that will reduce the need further for power. Just your booster bus will need some redundancy power wise and control wise, probably like the shuttle, 5 general purpose computers to run it, and likely some solar panels to augment power, and also a lot of RCS fuel for attitude control. Easy to do if you have 2 of them one each end, and thus taking turns in providing thrust in orbit to raise it, and slowly over say a year getting up to a relatively open orbit. To get past LEO will take about as much ion engine fuel though as what you can fit into a Falcon 9 heavy payload fairing, as a single large cryogenic tank, so you probably will want to make the tank emulate the fairing and take it to orbit, it will save weight using the fairings as structural and insulation instead of discarding them. Would say 4 F9 heavy launches will get the lot up there, with 2 separate orbit lifter units and tanks, and then probably a final set of spacewalks to provide connection to them so they can share fuel and power
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  23.  @flymypg  Antonov had that yesterday, probably seized compressor bearing and the fan decided to take a holiday, wiping out the AC electrical buses and the instrumentation and hydraulics, so the pilots had to do a really heavy landing with no brakes or spoilers. Tough aircraft frame though, it did not fail until after it had left the runway end and was ploughing the frozen field.
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  24.  @big0bad0brad  As you have to service them every 6 months, it is not an issue, you would replace them and refurbish them every second cycle, long before they are possibly going to fail. Remember you are talking about radioactive things, and you do not just put them in a box and store for the next decade or three, like conventional explosives. You have to keep them in a 6 month maintenance cycle or they simply do not work. Anyway your ignition package is likely to need replacing regularly, simply because it lives in a very radioactive environment, and you are going to swap out the explosive pack in that 6 month cycle, because there will be degradation from the neutron bombardment that makes for all sorts of unstable new compounds in it.
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  25. Simplest would be to use those airlocks throughout the station, and simply take modules out of service, and use a Progress to control the deorbit of the module or pair of modules, so that you gradually get a smaller station that is easier to control for the last unmanned missions to go up and automatically dock, so they can then have a full fuel load for control.
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  26. turpentine trees are really flammable, in that the green leaves will burn very easily. We used to use turpentine tree branches and green leaves as firelighters, taking the thin fresh growth green branches and leaves, and using a layer of them, along with old newspaper, to light the charcoal of the fire.
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  27. Lithobraking was done, due to them forgetting to make sure the software would work in simulation.
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  28.  @big0bad0brad  Because the internal pressure is critical, you would have to have an external chamber with gas at the right low pressure to have any hope to keep it correct, and that container would also leak hydrogen even faster.
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  29. The plans are available, along with the patents. The big problem is not making one, but living to finish assembling it, as the least of the worries you have is radiation, the metals involved are all by themselves a pretty toxic group, and the radiation they give off is rather hard to conceal.
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  30.  @Keldor314  Yes multipath reflections and diffraction off of the sharp edges of the mountain peak, which means the signal appears to be shifted in time with the reflection off the other side, and also takes longer with the diffraction, so the GPS receiver calculated position is wrong, but to the GPS it is still a valid position on the internal map it has of the area.
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  31.  @dylanwinn3  Volunteers out of the prisons, who were offered free passes of remaining sentence if they did so. None were told it would likely be fatal for them, and they were run through till they could not go any more. Plenty are no longer mentioned in any records. Luna team would have been better off result wise if they had pulled old fighter plane tech out of the stores, and used the tube based avionics there instead, with the simple magnetic amplifiers and hollow state electronics, which would survive the high radiation a lot longer before failing. Yes you need to bring along 400Hz generators for power, but those are common enough, at at worst you could simply grab one of the helicopters, and run it as a power supply.
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  32.  @GrogAdHoc  Load paper tape, enter 5 command bootloader on the front panel switches, then press start on the tape reader, and wait for the terminal to give a ready prompt. Then you can load the actual operating system into memory from the mass storage device. Then you can start the GUI and use it.
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  33.  @NicholasRehm  Not likely, just that the computer systems are probably only going to be Intel 386 based at best for the core of the ISS, as those are currently the only, aside from some Motorola and MIPS parts, of around equal speed and complexity, parts with space grade reliability available, Laptops and other stuff they handle by having multiple devices, so a radiation induced failure is not terminal, and they do repair a lot of them by swapping parts around common devices. Remember most of the control software is either running on redundant hardware with error correction, and no method to update it, or is running older versions of operating systems that are different enough that your common malware will not run on them. However nothing stopping somebody from doing a Stuxnet style attack, though that requires intimate knowledge of the systems and how they are connected.
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  34. Not really, the field would very likely also affect operation of the craft itself, so much simpler is simply to have light mass shielding, or something that you need to take with do it as well. Most likely thing is that there will be a water tank that is also a shelter, with the water acting as shield, and also the required food rations can do the shielding as well. Probably there will be a thermal shield used on the spacecraft that does triple duty, acting as sun shield, and also as a micrometeorite shield by having multiple thin metallised mylar layers, and acting as a radiation shield by allowing the high energy particles to impact it, and the inner layers handling secondary emission, then the spacecraft hull itself acting as a barrier, with the rations packed so as to absorb it's secondary emissions. The dried waste would also be packed back into the same spot, so the shield gradually changes from food to poo as they travel along.
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  35. No, low background steel is still a problem, unless you go to the expense of taking iron ore and using a brand new blast furnace to refine it, and not do like most common operators do and add scrap steel to the furnace as extra charge. Thus you still need to get the old steel, and vacuum melt it to keep the contaminants out, then cast it into a mould and machine it. Still enough residual radiation from that old atmospheric testing, plus the releases from the assorted nuclear accidents, that you will want a old steel shield, especially if you are looking for very low levels of radiation, and need to have as low a background as well.
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  36. All those reactions use cheap catalysts, like pure iron, or iron oxide. However they also need those catalysts to be ultra pure, so the iron used to make them has to be specially refined, to remove all of the other metal contaminants that normally are added to improve strength and ductility, as they can also act as catalysts and make unwanted side reactions.
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  37.  @AnonymousFreakYT  Less room than that, imagine living for 2 weeks in just the front seats of the original Mini. Wearing boots and a crash helmet, along with full motorcycle gear, including gloves.
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  38. Do not forget the provenance of that film the Soviet luna orbiters used, being actually US made film that they "got" from the USA by a rather unusual method.
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  39. Yes, but there is a big chunk in the middle of the throttle range that is not good to stay in long, you transit fast, because there you will have instability.
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  40. Biggest impovement was the patch antenna, which placed most of the receiver filtering at baseband into a single precise ceramic puck, that not only was the antenna with a wide acceptance angle, but also the front tuned circuits and selectivity, and with it being a very high Q filter to reject out of band noise as well. Got rid of half a rack of cavity filters and amplifiers, that you needed to keep at a constant temperature, and also a good chunk of power needed for all the amplifiers and temperature control.
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  41. Have to be better than a space suit, that only has to withstand direct sunlight and vacuum for a while. The suits need to survive conditions like that in the Jovian upper atmosphere. Jupiter's colours come from having an atmosphere mostly made from all sorts of nasty nitrogen and hydrogen compounds.
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  42. Well, it would devolve to VFR from 1924, when pretty much the instrumentation was the pilot and his eyes. Would suggest a good upgrade would be to add in a standby compass, standby altimeter and a standby airspeed indicator, as a minimum flight instrument list, that will help in case the ancient Garmin decides to brain fart, as they are well known to do with some combinations of a complex map and some locations. All 3 can be bought used, and simply sent in for a certification, and then the standby compass will just need to be swung with the aircraft in flight ready configuration, to adjust the 8 cardinal point compensation screws. Memories of 3 hours in the swamp, in the compass bay, acting as the intercom link between my instructor melting in the rear, and the 2 pilots and flight engineer melting in the cockpit. After the 10 full circles to get the newly repaired fluxgate sensor aligned perfectly, the others decided to drive back on the tow tractor, while I elected to stay on board, and fly back with the 3 in front. They still had 3 hours of fuel left, but only needed an extra hour to complete flight hours for the month, so they did a little trip out to sea, and there I got to see them doing an aerobatics show with the 16 ton helicopter, doing all the daring moves, that are limited to 0G to +3G, that are permitted with a helicopter when you want to avoid chopping your own tail off, or having the main rotors separate. Sitting in the door, hand through the strap, and looking up at the ocean above me, and the sky past my feet, as they did a few barrel rolls around 1km offshore, with the closest place to swim to being the offshore oil platform. 2 very happy and now cool pilots.
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  43.  @5Andysalive  The saying was in Apollo you were in a space craft, but in Gemini you wore a space craft.
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  44. All the Helium you have on the surface of the earth is also not primordial, it came about as the result of alpha particles grabbing 2 electrons to become stable.
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  45. More like the last part frame was corrupted by the digital signal processor and transmitter becoming fine gravel mid frame, with likely the last image still busy being DCT transformed in RAM by the image processor. Probably you have a part bit sequence that was received, but, because it was rejected due to failing the CRC check (for some reason) as the final part of the last scan line. The lines and such yes are probably partly due to varying composition, of what is basically a cloud of pebbles, dust, and well chilled assorted ices, suddenly being shocked, but I would say a good part is also composed of bits of spacecraft that has pressurised liquids and propellants reacting for a brief moment as they were scrambled and mixed together, along with batteries that briefly were free to express all energy as well.
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  46.  @solarcheese  Well, the main issue I can see is that you would first have to find the remains of the barrel, because it would probably impact the ground at around Mach 10, and, assuming it survived more or less intact, that is more than enough impact energy to bury it at least 50m into solid granite. More likely though the barrel, assuming you used a standard steel 44 gallon one, would ablate through at around 100km altitude, leading to the oil leaking out, and then the remains of the barrel being torn apart by aerodynamic forces around 60km up as it hits atmosphere thick enough to register on regular gauges.
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  47.  @PsRohrbaugh  Plus possession of such a jammer, or at least using one near an airport, will have a few government agencies find you, and have a very long and pointed talk to you. Ask the truck driver who did that near a US airport, because he wanted to jam the GPS tracker on his truck, so he could have some off time on the clock.
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  48. No problem about the light, your smile was light enough Scott.
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  49. No need to actually look for a new processor, simply use one of the more modern Space rated products that are still available in large volumes. Intel still does supply the 386SX and DX in space rated packages, using a SOS technology, which is a more modern and faster part. Yes likely just a few thousand fully tested dies in CA storage, ready to be packed and tested to order, but still a part likely to be around for the next 50 years. Buying an original Mostek or Rockwell part is still there, not robbing old equipment, you just pay Rochester Electronics to take a wafer and pack it, then test the result and get the qualification, they specialise in old silicon, buying up old wafer stock and storing them essentially forever. You need it you pay the price they ask, and smile. With gritted teeth, they price just below replacing the whole lot entirely, but still cheaper. However the 6502 is, thanks to it being out of copyright, one of the more prolific processors around, available as an IP core for pretty much all FPGA and ASIC families, as it is simple, very small and very functional. You have one in every hard drive, used to load the firmware into the ASIC and FPGA units that do the actual work, and it also then is a slow processor, but tiny one, that does housekeeping and monitoring of the hard drive, so that the drive can retract heads and shut down gracefully when power is removed. With only 64k of memory you can make half the fixed ROM, for bootloading the rest, and the rest RAM to handle memory, with a little bit of IO somewhere to feed data out to the rest of the array. Simple to implement in silicon, free assemblers and compilers, and no money to pay for a per unit license, it is very common to have it embedded all over in equipment as a processor doing something.
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  50. No, that was Thiokol boosters. The USSR was constrained by needing to fit onto existing proven hardware that had limits as to dimensions and mass capability. they needed to have it work due to both material restraints and also engineering personnel restraints, so reuse of existing stuff and simply using more duplicates was the solution.
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