Wikipedia:Reference desk/Archives/Science/2019 May 20

= May 20 =

What would be the first and last function to fail if?
You teleported an unshielded smartphone to low Earth orbit? (of course that's science fiction, do it in a thought experiment physics simulator if you hate teleportation thought experiments so much) What if you teleported a smartphone to a Trojan asteroid of Earth orbit? How damaging is sunlight and solar wind compared to the radiation of the rest of the universe? How many pixels fail per second? When would the screen turn off if it's set to always on? Also I'm wondering when a contemporary smartphone's GPS would stop working well if you could put it in a climate-controlled shield that only lets non-damaging radiations through and hitchhike it on a spaceprobe. Can it work outside the constellation? What velocities does GPS work at? Would it give crummy readings if you could make the receiver move at ~100 km/s relative to the satellites or a thousand or 10K or 0.999c? Sagittarian Milky Way (talk) 16:54, 20 May 2019 (UTC)
 * The cold would do damage before radiation in a number of ways. Shrinking pieces would crack, battery would fail, inner moisture would turn into ice, LCD would freeze and stop reponding to electric signal, the chip would fail...
 * Gem fr (talk) 18:14, 20 May 2019 (UTC)
 * The average temperature of the Earth without the greenhouse effect was about 0F if I recall so the phone average temperature might be bearable in sunlight but however much temperature differential the conduction can't remove will of course still stress the parts. Sagittarian Milky Way (talk) 01:23, 21 May 2019 (UTC)
 * This is wrong. Without atmosphere part of the moon exposed to the sun are close to 400K (this value depends on albedo, which is why astronauts wear white suits, so they do not roast in the sun); plastic parts will not withstand that. In the shade it drops to 3K. Average temperature do not apply to such a small object as a smartphone, it lacks thermal inertia. Gem fr (talk) 09:42, 21 May 2019 (UTC)
 * Could it work for seconds while the sun side hadn't heated up fully yet and vice versa? Sagittarian Milky Way (talk) 12:36, 21 May 2019 (UTC)
 * I dunno. Here are my 2 cents. The energy gain when lit would be in the kW/m² magnitude, a typical smartphone being ~100cm² so it gains ~10 W=~10 J/s. Specific heat capacity would be in 1 J/K/g magnitude, but it will depend a lot on whether the energy spreads on the entire 200 g typical smartphone --in which case it would heat at ~1/20 K/s, and could keep working for tens of minutes--, or first concentrate in a small, directly exposed 2g part -- in which case this would heat at 5K/s and would be destroyed in less than half a minute. Probably somewhere in between, meaning, it could work for some seconds.
 * For freezing, the energy loss would be 1/3 of the aforemantioned gain, so time needed would be x3.
 * but don't take my word for it
 * And check Nimur (talk) answser below. I underestimated soft error from radiation, that wouldnt destroy the smartphone but would cause critical malfunction. The average mean-time for such is not clear from his ref, though, so it all depend on whether they occur in a matter of minutes, or need more time. Gem fr (talk) 21:08, 21 May 2019 (UTC)
 * GPS satellites direct their antenna beams towards Earth surface. An unprepared GPS receiver needs several minutes continuous reception to acquire ephemeris and then can obtain a location in seconds if it receives simultaneously from 4 satellites. NASA report that GPS can be used (with proper equipment) as far out as geosynchronous orbit 36,000 km altitude. Simple domestic GPS receivers that have only two channels that are multiplexed amongst satellites lack processing bandwidth to handle more than about 100 mph speed. DroneB (talk) 20:34, 20 May 2019 (UTC)
 * As I understand it, while GPS may be able to work that far out, many GPS device you're able to buy probably won't. They still enforce the Coordinating Committee for Multilateral Export Controls (in an OR fashion) meaning they won't work above 18km altitude even though as I understand it the COCOM rules are dead and their replacement don't actually have an altitude limit. See e.g. [//community.balloonchallenge.org/t/what-is-the-maximum-altitude-of-typical-gps-module/236] [//space.stackexchange.com/questions/14687/current-situation-with-cocom-regulations-and-gps-receivers-for-balloons-and-cube] [//www.rocketryforum.com/threads/gps-barometer-and-microprocessor.142015/]. P.S. Some people suggest some devices obey COCOM in an AND fashion although I'm confused by this since the COCOM text seems to be clearly OR. Possibly these devices are only complying with the Missile Technology Control Regime speed limit and people are simply confused. I think it's far rarer that people actually encounter the speed limit in practice compared to the altitude limit. So many probably don't actually know if it's obeying COCOM in an OR fashion or it's only obeying a speed limit with no altitude limit. Since MTCR seems to clearly require a speed limit, I would be surprised if devices instead obey COCOM in an OR fashion although then again I wouldn't be that surprised if whoever is in charge of implementing these limits are as confused about what they're supposed to do as random commentators, despite the fact they should have lawyers etc to tell them. Nil Einne (talk) 02:12, 21 May 2019 (UTC)
 * P.P.S. It is obviously possible that one or more governments e.g. the US, still had the COCOM limits in law/regulation despite the treaty establishing them ending so manufacturers did have to obey the limits or risk trouble. Nil Einne (talk) 02:17, 21 May 2019 (UTC)
 * Consumer GPS had a COCOM or other limit of 999mph as of some years back, but at least some of them worked fine at 500+ mph. I remember taking mine (a cheap Garmin) on an airliner just to try it out. 67.164.113.165 (talk) 06:08, 21 May 2019 (UTC)
 * From what I can tell the actual COCOM limit was 1000 knots. The MTCR limit is 600 m s$-1$. I suspect some devices were conservative because they weren't sure of their accuracy at such high speed and didn't think it mattered or because (as per the altitude limite) whoever was in charge of implementing the limit wasn't given proper guidance, but I'm not sure if these was every any legal reason for such a low limit. Nil Einne (talk) 07:29, 22 May 2019 (UTC)


 * How about we avoid speculation, and point our OP to a real resource?
 * Radiation Effects on Integrated Circuits and Systems for Space Applications, with a new second-edition published this year, is written by Raoul Velazco, research director at the TIMA Lab in Grenoble. He's a world expert on a subject near to my own personal interests: the infamous single-event upset.
 * In 2011, several iPhones and other consumer telephones flew on STS-135. Here's the NASA "What's Going Up" article.  Some technical details are published by the experiment investigators, Odyssey Space Research, and summarized in this press release.  Here's the NASA Blog article, too: SpaceLab for iOS.  Among the research, the LFI (Lifecycle Flight Instrumentation) characterized the effects of radiation on the device.
 * To excite and inspire the community at large, Apollo astronaut Buzz Aldrin gave a presentation at Apple's World Wide Developer Conference in 2011 to show off some ideas for consumer-electronics and promote enthusiasm for spaceflight.
 * Here's another NASA article, Socializing Science with Smartphones in Space. They also point to a following experiment, SPHERES, in which a team of MIT student-researchers planned to emplace the smart-phone powered Nanoracks satellite outside the space station - that is to say, a smart-phone, outside, in low earth orbit.
 * Perhaps to the surprise of everyone commenting in the thread - but sort of expected by anyone with a little background in this area - the first thing to fail was the application software. The hardware itself was qualified for spaceflight.
 * If I may take a moment to grump out at this late stage of the morning, the real metaphorical take-away here is that as of this decade, the limiting factor in spaceflight is software-quality.
 * Interested future engineers should spend more time learning fundamentals of math, science, and engineering, and then spend a lot more time engaged in formal education relating to software engineering and computer science, so that our next generation can have exponential improvement in software quality.
 * Some people say that "everyone can code." The truth of the matter is, very few people can code, and even fewer people are good enough at math and science and logical thinking to code well enough for a mission-critical space-flight application.
 * Nimur (talk) 16:30, 21 May 2019 (UTC)


 * Another possible failure mode would be that the battery would be ejected. That is, if air inside the cell phone is at 15 PSI, and the battery and cover is maybe 2x3 inches, or 6 square inches, that would be about 90 lbs of instantaneous force first on the cover, and, once it blows off, on the battery. Whether this actually happens depends on the specifics of the cover design, though, and how well sealed the rest of the phone is. Ironically, a waterproof model might be more prone to this than one with gaps, like the ill-fated Galaxy Fold. SinisterLefty (talk) 22:12, 27 May 2019 (UTC)