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February 15

Simple glacier models

Has someone ever made a simple glaciological model that relates insolation, temperature and precipitation (perhaps also wind) with the equilibrium line altitude? Perhaps only for a simple conical mountain. Jo-Jo Eumerus (talk) 15:24, 15 February 2021 (UTC)

• GScholar for "snow line modelling" turns up Multi-decadal mass balance series of three Kyrgyz glaciers..., Barandun et al. 2018. §3.6 seems like a good starting point and has some cites to a "classical temperature-index melt model". Tigraan^{Click here to contact me} 16:58, 15 February 2021 (UTC)

  Thing is, none of that discusses an ELA from a quick check. I should probably specify that I have seasonal freezing level elevation, insolation and precipitation. Jo-Jo Eumerus (talk) 13:48, 16 February 2021 (UTC)

Meteors approaching head-on

Are there any observations of individual meteors, bolides, etc flying head-on (that is, towards the observer on an approaching course in the atmosphere) rather than parallel to the observer? 212.180.235.46 (talk) 22:24, 15 February 2021 (UTC)

There are a gazillion videos of the Chelyabinsk meteor. I'd look there. I doubt you're going to find an exact Hollywood-style "ahh it's coming right for us" video, just because it would be such a freak occurence. --47.152.93.24 (talk) 02:36, 16 February 2021 (UTC)

In the 2001 film adaptation of The Discovery of Heaven, such an event is shown from the subjective viewpoint of a protagonist, but as they were instantly vaporized and could not leave a record, the event as shown through the eyes of an imminently moribund character can equally be described as being from an omniscient point of view.

[Not the previous unsigned commenter] Various textbooks, etc., discussing meteor observation that I have read over the last 50-odd years have mentioned that such 'head-on' meteors are occasionally both observed visually and recorded photographically. Usually they are seen at the radiant point of a meteor shower being observed/photographed: the chances of seeing a non-shower sporadic meteor head on are obviously much more slim, although I might have seen one in late 1985 (within the Square of Pegasus) while looking for Halley's comet at dusk.

A meteor is of course an atmospheric phenomenon usually occurring at an altitude of some 80 miles or so. Only if the meteoroid that causes it were to be unusually large and reach the ground as a meteorite or explode at a low altitude as a bolide could it harm a 'head-on' observer. {The poster formerly known as 87.81.230.195} 2.125.74.203 (talk) 13:26, 16 February 2021 (UTC)

Why is electrolysis more effective at permanent hair removal than laser hair removal is?

Why is electrolysis more effective at permanent hair removal than laser hair removal is? Futurist110 (talk) 22:58, 15 February 2021 (UTC)

Who says it is? ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:02, 15 February 2021 (UTC)

https://www.allclearelectrolysis.com/faqs "Laser is permanent hair reduction while electrolysis is permanent hair removal as approved by FDA." Futurist110 (talk) 23:22, 15 February 2021 (UTC)

Consider the source. Of course a site promoting electrolysis will using wording to promote it. Do you have any neutral sources that say one is better than the other? RudolfRed (talk) 00:35, 16 February 2021 (UTC)

This link talks about the FDA approving laser hair removal for permanent hair reduction, but NOT for permanent hair removal: https://web.archive.org/web/20180725213940/https://www.fda.gov/radiation-emittingproducts/resourcesforyouradiationemittingproducts/ucm252757.htm Futurist110 (talk) 01:03, 16 February 2021 (UTC)

Efficacy of laser treatment actually depends on the type of hair you have and your skin phototype. Electrolysis works by sending a current through a needle to cauterize each hair follicle one by one. Laser treatment works by pulsing beams at wavelengths absorbed by dark hair follicles; the absorbed energy is converted to heat which destroys the follicle. Blond and red chromophores are not targeted effectively by lasers because there is less absorption at the wavelengths needed to zap the follicles. Laser are also not generally appropriate for people with dark skin as they have to use lower laser fluences to protect against burning the more-pigmented epidermis. The best candidate for effective laser treatment has pale skin and dark hair. JoelleJay (talk) 03:03, 16 February 2021 (UTC)

February 16

Milk questions

I am working on my science project. I have ten properties of milk. There are two properties that I want to include, but I can't find information on them. First, can you make milk not curdle? Is there something you can put in milk that keeps the curdles from clumping up? I wrote about how proteins coalesce into curds, but it seems like there should be something that makes them too slippery to stick together. The other question is about chocolate milk. If I make it, the chocolate will settle at the bottom after a bit. But, the stuff at the store stays mixed. Why is that? Does the chocolate stick to the milk somehow? — Preceding unsigned comment added by 97.82.165.112 (talk) 13:09, 16 February 2021 (UTC)

On the second part, there are two processes involved in keeping things mixed. There is a physical process, called Homogenization, which involves mechanically making one of the liquid particles so small and well dispersed that individually, they don't have the activation energy to reform clumps, so they stay in Suspension. There is also a chemical process called emulsification, which involves the presence of substances called surfactants that act as a way to keep two immiscible liquids mixed together. This can include ingredients like lecithin or polysorbate or things like that, which are often added to pre-made chocolate milk to keep it from separating. --Jayron32 14:07, 16 February 2021 (UTC)

The Science of Chocolate Milk (And How to Prevent Sedimentation). We also have an article called Chocolate milk with lots of links in the "References" section at the bottom. Alansplodge (talk) 15:15, 16 February 2021 (UTC)

Googling prevent milk curdling and prevent chocolate milk separating suggest various methods, both chemical and physical. Be creative in inventing more search terms! Cheers! 85.76.75.69 (talk) 16:01, 16 February 2021 (UTC)

[1] has some good leads on particular chemicals used. Rmhermen (talk) 00:15, 19 February 2021 (UTC)

Transgender hormone therapy stats

Neither reading our articles on this topic nor the web seems to help me to find numbers or statistics of gender-affirming hormone use in transgender individuals, in the U. S., ideally for F-T-M and M-T-F separately. There are obviously studies that provide numbers about gender-affirming surgery, but when it comes to hormone therapy, I only found the statement that the occurrence has been increasing, but no exact data. Can somebody help me out? (Please, ping me.) --Stilfehler (talk) 18:00, 16 February 2021 (UTC)

Found an answer here. --Stilfehler (talk) 19:35, 16 February 2021 (UTC)

February 17

IQ and narrow-sense heritability question

If the average IQ of a couple is 110 and the group that this couple come from has an average IQ of 80, and IQ has a narrow-sense heritability of 0.6, are this couple's children going to have an average IQ of 92 or 98? I'm obviously taking regression towards the mean into account here. Futurist110 (talk) 07:01, 17 February 2021 (UTC)

off-topic

How is "the group that this couple come from has an average IQ of 80" relevant to the IQ of their children?--Shantavira|feed me 09:26, 17 February 2021 (UTC) See Heritability of IQ. It has a well studied and well established genetic component. Therefore genetic background is relevant. Fgf10 (talk) 12:06, 17 February 2021 (UTC) First you need to show that IQ represents anything more than the ability to do well on an IQ test. --Khajidha (talk) 11:26, 17 February 2021 (UTC) Why? The question is about IQ. How representative IQ performance is of intelligence and how you define intelligence are different (important) questions. Fgf10 (talk) 12:06, 17 February 2021 (UTC) The only thing an IQ test measures is someone's ability to do well on an IQ test. ←Baseball Bugs What's up, Doc? carrots→ 12:17, 17 February 2021 (UTC) https://twitter.com/stevestuwill/status/1076000663824461824?lang=en Futurist110 (talk) 23:10, 17 February 2021 (UTC) I wouldn't say only. It also measures things like your stress level, your level of childhood nutrition, how much sleep you had the night before you took the test, whether or not you've experienced trauma, your socioeconomic status, and a whole slew of other things that affect the performance on the test (which are ultimately, of course, unrelated to the very thing that the IQ test is supposed to tell you about a person). --Jayron32 13:39, 17 February 2021 (UTC) Do IQ tests nowadays ask questions about those kinds of things? ←Baseball Bugs What's up, Doc? carrots→ 15:41, 17 February 2021 (UTC) No, but all of those things can affect how you answer the IQ test questions on a given day, and have nothing to do with a person's inherent intellectual ability. --Jayron32 16:53, 17 February 2021 (UTC) Yes, things like that will affect your score, as they will with most psychometric tests. But how important are they quantitatively in practice? Regarding "how much sleep you got", for instance, we can easily test people on two or more occasions and get data about this rather than opinion. According to our article the standard deviations are as low as 3 points (cf. population mean = 100, population standard deviation = 15). It is not so easy to measure the effect of things like socioeconomic status, but far from impossible to make an estimate based on statistical analysis. So it seems to me a bit silly to denigrate IQ just because the scores are influenced by factors that you might want to factor out (others might not want to factor them out; it depends on their questions). It is quite another issue how much IQ is useful for estimating "inherent intellectual ability", but it was you that brought that up, not the questioner. One can have different opinions about that issue yet still find IQ a valid psychometric measure. Jmchutchinson (talk) 17:51, 17 February 2021 (UTC) I think the main disagreement is over the third to last word in your statement. --Jayron32 18:46, 17 February 2021 (UTC) (ec)Sure, they can affect one's performance on the test, but they aren't measured by the test. In fact, some folks perform better under stress. ←Baseball Bugs What's up, Doc? carrots→ 17:54, 17 February 2021 (UTC) You might get better answers if you ask the same question about height (for instance), where environmental influences are less important and the research is less controversial. TigraanClick here to contact me 14:00, 17 February 2021 (UTC) Environmental influences are not clearly less for height. Heritability of IQ in adults is about 0.8, very similar to that of height. You are correct though that IQ research often triggers a distracting knee-jerk response, as several responses have already demonstrated. One might justifiably object to some of the ways IQ has been interpreted, but it is a well defined and reproducible measure, so there is no reason why one cannot measure its heritability within a population. Ironically, that research actually provides some data about claims of environmental influences! Jmchutchinson (talk) 15:11, 17 February 2021 (UTC) Since you were not triggered by my question here, can you please try answering it? Futurist110 (talk) 20:43, 17 February 2021 (UTC) There's a melange of issues here that everyone seems to confuse though. The issue is whether a single score given by a single test is a reliable measure of something useful, which is a distinct and entirely unrelated question as to whether intellect (or more properly intellectual potential, since many factors can affect your intellect at any given moment) is a heritable trait. The connection between the former and the latter is tenuous at best. --Jayron32 16:56, 17 February 2021 (UTC) A big thing I think is being missed here, as well, is that heritability of a trait does not explicitly mean that the trait is genetic. For example, a test for heritability of monetary wealth will show that it is a heritable trait, since comparing the Walton family through 3 generations to almost any other family will show that wealth is heritable. Spoken language is another trait that tests positive as a heritable trait; you are far more likely to speak the language that your parents spoke than any other, which means that you likely speak the same language as at least one set of grandparents, one set of great grandparents, etc. Probably more than that, since people are more likely to have relationships with and children with people who also speak the same language. Is the fact that I speak English and not Romansh a genetic trait? Of course not. It is, however, a heritable trait. This also applies in many other areas that we tend to think of as "genetic," rightly or wrongly. Certainly genetics has a role in height, for example, but if you are born into a family in poverty, there's a good chance that your grew up malnourished and with stunted growth. There's also a good chance that you spend your whole life in poverty, since lack social mobility and wealth inequality are big problems globally. So, chances are that your parents were malnourished and had stunted growth, and that your children will be malnourished and have a stunted growth. Even though you may have genes that suggest you will be tall, the heritable trait of poverty has meant you have heritable stunted growth. Barring epigenetic effects, if one of your descendent got out of poverty, they would no longer have stunted growth and would grow tall, but that doesn't change that stunted growth was a heritable trait for several generations. I'm bringing this up because it is a very common issue with the IQ test. People assume that heritability of IQ within a family explicitly points to IQ being genetic, but it may not. Sometimes, its that tests are written in a way that uses colloquial language that some in a population understand, and others do not. Sometimes it points to things like what type of problem solving was emphasized during primary schooling, or even access to primary schooling. Sometimes it merely represents literacy rate. There are so many factors that go into how well one performs on these tests that, to assign it a genetic component is not at all straightforward. Heritable, sure, but not necessarily genetic. That's not even getting into the issue on how well IQ tests actually measure intelligence at all (spoiler: they probably don't do that very well, as @Baseball Bugs: pointed out. --OuroborosCobra (talk) 21:32, 17 February 2021 (UTC) I think this last contribution is fundamentally wrong in a technical sense. You are right that we usually inherit far more than just genes from our parents, so that these epigenetic effects may superficially mimic genetic inheritance. But heritability is specifically defined to measure only the genetic component of inheritance. That makes heritability more of a challenge to measure in humans, but there are some tricks involving adoptions, or comparing similarities between twins and siblings, etc. There is some information on methods in our article. Geneticists are very, very aware of the confounding of genetics and environment! How accurately they have managed to isolate the genetic component in the specific case of IQ, I don't really know, but you can't so simply explain away high heritabilities of IQ as due to epigenetic inheritance of home environment or socioeconomic status. Jmchutchinson (talk) 07:39, 18 February 2021 (UTC) I think you're missing the point, or rather my point (can't speak to others), which is that IQ is basically modern-day phrenology. Proving that a person can inherit the pattern of bumps on their head from their parents doesn't make phrenology valid. That IQ is heritable doesn't mean that IQ is useful or valid for anything. --Jayron32 17:48, 18 February 2021 (UTC) Right. Even if we want to use the strict definition that "heritable means inherited to a statistically significantly through genes," then I guess the issue is proving that IQ is heritable at all, which isn't a given or an assumption that can be made. Testing for heritable traits is not a simple task, and the more complicated/less understood the trait, the more difficult it is to test. IQ and the idea of intelligence in general is not a trivial trait to describe in the way that eye color or even height can be and, as I showed in my earlier comment, shortness can be mistaken as a genetically inherited trait when it is actually inherited malnutrition due to poverty within successive generations. Yes, a twin study could figure that out, but that means conducting an experiment (or being lucky enough to find identical twins separated at birth) where one is raised in poverty and the other is raised in abundance. This is not easily done on a complicated trait like IQ that, let's be honest, doesn't even have a great definition of itself. Building off your phrenology example artificial cranial reshaping was a not uncommon practice among certain mesoamerican communities, and since children with elongated skulls tended to have parents with the same, it was easy to assume some genetic link and possibly even link that to other traits that may not even exist (I think Stargate SG-1 had these connected with psyonic powers, or maybe that was Indiana Jones). Just as with phrenology, there was no genetic link to these shapes, and certainly no link to anything else, like psyonic powers. --OuroborosCobra (talk) 20:07, 18 February 2021 (UTC) Jayron is interested in one aspect of validity, whether IQ measures anything useful and in particular something people want to call "general intelligence". My impression is that nowadays psychologists tend to deal with a multidimensional suite of measurable and specific intellectual abilities, not general intelligence. Their working assumption would be that IQ score reflects just some of these abilities. People obviously do differ in their various intellectual abilities and I don't know how you would intend to start investigating this phenomenon without obtaining data from performance tests, of which the IQ test (or refinements of it) is one example. A test of memory would be an analagous one that perhaps you find more palatable. What IQ does relate to is an empirical question; there are some pointers to the results in part of our IQ article. Your apparent opinion that it relates to nothing useful seems to me not to be based on empirical data. OuroborosCobra, I think you are seriously underestimating the sophistication of geneticists in measuring the heritability of IQ, and other human traits. Twins separated at birth are just one source of data, which indeed are now a sparse resource. Another is the difference in similarities between monozygotic and dizygotic twins, or between full sibs and half sibs; these would normally share most aspects of their environment. Really, "proving that IQ is heritable at all" is not the issue. Everybody is surprised with how heritable IQ has been proved to be in multiple rigorously performed studies. Most of us find it uncomfortable to learn how little normal environmental variation affects adult IQ, which does not mean that extreme environments cannot affect it considerably. Again, I recommend looking at the empirical data, not relying on your intuition. Jmchutchinson (talk) 22:46, 18 February 2021 (UTC) I think it is utterly impossible to suggest geneticists could measure the heritability of IQ if we don't even have a good idea of whether IQ is a measure of anything useful. If it isn't even a measure of anything beyond "I was capable of taking this test," then we have a problem if geneticists are saying that they've found a genetic link to the ability to pass this one specific test. --OuroborosCobra (talk) 22:57, 18 February 2021 (UTC)

So 98 comes from

$R=h^{2}S$

How did you get 92? Rmhermen (talk) 00:01, 19 February 2021 (UTC)

Why don't we develop two visions if we have two eyes?

I always wonder Why don't we develop two visions if we have two eyes? From Wikipedia, I can only tell eyes contains rod cells and cone cells. Rizosome (talk) 15:05, 17 February 2021 (UTC)

Some people have two eyes and see two images. In non-pathological cases, the brain (more precisely the thalamus) does some post-processing and blends both inputs. Binocular vision has more on the process and it's advantages. Bumptump (talk) 16:01, 17 February 2021 (UTC)

It depends on how well your brain works. Each eye does produce a different image. You can check this yourself where you alternate closing one eye and then the other, and you can confirm that you do receive different images from each eye. A classic test of this is to use parallax. Hold a finger up in front of your face and close one eye. Align the finger so it blocks a distant object. Swap your eyes, so you close the open one and open the closed one. The formerly obscured object will be visible, and it will appear that your finger has "jumped" to the other side. The reason why you don't see two images when both eyes are open is that the Visual processing in your brain automatically stitches the two images together into a single image. As Bumptump notes above, there are people whose brains don't do this correctly, and they have a condition known as diplopia or "double vision". --Jayron32 16:51, 17 February 2021 (UTC)

Go to blind spot (vision) for another fun way to see how your brain processes what it gets from the eyes and fills things in without you being conscious of it. --47.152.93.24 (talk) 04:15, 18 February 2021 (UTC)

Something like that happens with a helmet-mounted display where pilots learn to see one system (e.g. avionics) through one eye, and another system (e.g. weapons) through the other. Might take some serious re-training of your brain, but appears to be doable. 85.76.75.69 (talk) 19:23, 17 February 2021 (UTC)

As a personal anecdote, back when I worked in VR, our pre-oculus headsets actually took two separate VGA inputs, for testing I would sometimes exploit that to display the simulation to one eye with the my debugger going to the other eye. At first I would close one eye, but I got to the point where I could look at both at once. ApLundell (talk) 21:25, 18 February 2021 (UTC)

Generally speaking, predators have binocular vision while prey tends to have mostly monocular vision. Binocular vision helps the predator focus more accurately on their prey. Prey needs to see 360 degrees around to watch for predators. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:15, 17 February 2021 (UTC)

As an actual data point, after some face surgery my right eyeball was moved slightly, vertically. It took several days before my vision re-synched. Greglocock (talk) 20:34, 17 February 2021 (UTC)

See Ocular dominance. Most people's brains rely mainly on the image from only one eye. Alansplodge (talk) 13:00, 18 February 2021 (UTC)

February 18

Satanic landing gear???

So here I am looking at a schematic for the main landing gear of the Mirage F1 fighter, and two of the parts labels are puzzling to say the least -- one says "Diabolo balance", and the other says "Diabolo pivoting mechanism". My question is, what exactly is it??? 2601:646:8A01:B180:847D:B967:D877:9361 (talk) 02:59, 18 February 2021 (UTC)

My guess would be that it is in reference to the juggling/circus prop of the same name. Many terms in aviation do that, where they refer to something else similar in some way. Canards, for example, the foreplanes ahead of the main wings on some aircraft, is the French word for "duck" because one of the first aircraft equipped with them looked to observers similar in appearance to a duck in flight. --OuroborosCobra (talk) 05:05, 18 February 2021 (UTC)

Searching the web for "diabolo landing gear" suggests it means two wheels mounted side by side on a common axle, e.g. here. The word is used for various objects that are thin in the middle and surrounded by two wider disks. 85.76.75.69 (talk) 09:34, 18 February 2021 (UTC)

That's a devil of a good answer. Richard Avery (talk) 11:15, 18 February 2021 (UTC)

This French-English technical dictionary says that diabolo translates to English as "twin-wheeled" but can also mean bobbin, dolly or a waisted slug. This English language article says: "Bogie landing gear has 4 wheels, while the Diabolo has 2 wheels". Alansplodge (talk) 12:50, 18 February 2021 (UTC)

Thanks! So the name refers to the dually wheels having a resemblance to the toy, whose own name was in turn derived from its seemingly supernatural properties -- is that correct? 2601:646:8A01:B180:800E:797F:14C2:9143 (talk) 07:59, 19 February 2021 (UTC)

The toy was used in a game that was a fad in the first half of the 19th century, known in French as le jeu du diable ("the devil's game"), in which le diable was the term for the object being spun, and in English as "Devil on Two Sticks". It got a boost in the early 20th century in a technically improved embodiment, developed and patented by Belgian automative engineer Gustave Philippart. The idea for the name diabolo came from English cricketer C. B. Fry, who tried to turn the game into one with rules resembling tennis. According to his account, his inspiration was an ancient Greek verb meaning "to throw across". (The account has Diabellein; the verb is actually Diaballein.) Philippart registered that name as a trademark, which however was struck after he lost an infringement suit, with the judge ruling that this was not an "invented word", but (by its similarity to the word diabolical) a word referring to the devil, and thereby to the object used in the game known as "Devil on Two Sticks". Whether Fry was truly not (also) inspired by the sense of Ancient Greek diabolos as translating Biblical Hebrew Satan, I cannot tell.  --Lambiam 10:05, 19 February 2021 (UTC)

Medical topic: Technical name for this exercise.

Sit ups with straight legs with head touching to the kneecap. Hand placing backside of the head. I want technical name for this exercise. Rizosome (talk) 13:30, 18 February 2021 (UTC)

Sit-ups or Crunch (exercise), depending on the details, perhaps? Mike Turnbull (talk) 13:40, 18 February 2021 (UTC)

People don't typically "sit up" all the way like that. The position you describe is common enough in yoga, where it's called (appropriately enough) head to knee or seated head to knee to distinguish it from the standing version. Having one leg crooked inwards is called a "bound angle", but I haven't found a more unique name for the overall pose with both both legs flat and straight out together. Matt Deres (talk) 14:17, 18 February 2021 (UTC)

@Rizosome:, I'm again asking, is there a goal or point to these random questions? This question certainly isn't about rocketry, and neither was your question about binocular vision. You didn't respond to any of the answers you were given for that question, either. --OuroborosCobra (talk) 16:56, 19 February 2021 (UTC)

February 19

Chinese first satellite (Dong Fang Hong I)

Dong Fang Hong I - Chinese first satellite (1970), Space technology exhibition in Hohhot, Inner Mongolia, China

Dongfanghong I broadcasting "East is Red" and telemetry data

I have a question about the first Chinese satellite launched in 1970. What exactly is the 'telemetry data' we hear in this recording?

And also, what was the music player installed? Was it a record player? Tape player? Someone trapped inside playing the keyboard?

Please give me an easy ,dumbed down answer as I know nothing about this. Thank you. --Rankaper Pace (talk) 06:07, 19 February 2021 (UTC)

From an article on the website of Xinhua News Agency:

Among the various technical problems, the most impressive one researchers had handled was to make it play in orbit "Dongfanghong," the folk song lauding Chairman Mao, and allow all the Chinese people to hear it through the radio.

According to CAST [China Academy of Space Technology --L.

], researchers made a special musical device to simulate the song with electronic music, designing it to play the first eight sections of the music in 40 seconds and transmit the telemetry signals in the following 20 seconds.

— China recollects first satellite stories after entering space for 50 years

The telemetry data was essentially digital data, which had to be transmitted through an analog channel, for which the standard approach is modulation-demodulation. The digital data is converted into a wave signal of a sequence of segments at different frequencies, to be transmitted by radio. The same wave signal as an analog audio signal will sound as a sequence of whistled tones if the frequencies are within the human hearing range. Telemetry data in the recording can be heard from 44 seconds to 54 seconds, again from 1:43 to 1:53, and finally from 2:42 to 2:52. By artificially supplying a suitably chosen data stream to the modulator, you can create a musical melody. It is kind of like pumping out a very primitive MIDI file. The article does not explain this, but almost certainly the "special device" was a piece of electronic equipment to produce a data stream that, after modulation and interpreted as an audio signal, sang the praise of Chairman Mao. I do not know if it has been made public what the telemetry data represented, but since this was ten seconds per minute at a low baud rate, it cannot have been much.  --Lambiam 09:23, 19 February 2021 (UTC)

February 21

Where exactly parachute will land during Mars 2020?

MSL's debris field, imaged 12 days after landing. -- ToE 19:17, 21 February 2021 (UTC)

@OuroborosCobra: I find this JPL page discussing about parachute, but they didnt explain where exactly parachute will end on Mars during Mars 2020 ? Will it burn in atmosphere? Rizosome (talk) 11:18, 21 February 2021 (UTC)

It certainly won't have burned, since it didn't do so while being dragged by the Entry, Descent, and Landing System, and once released would have have slowed to a low terminal velocity. Where it landed (presumably still attached to the back shell portion of the aeroshell) will depend largely on the winds it encountered while independently drifting down.

Related Mars 2020 questions are where the heat shield and sky crane landed: doubtless one or another of the eight active space probes currently orbiting Mars will photograph all these various components in the coming days.{The poster formerly known as 87.81.230.195} 2.125.75.168 (talk) 12:45, 21 February 2021 (UTC)

Yes, 12 days after Curiosity landed, the Mars Reconnaissance Orbiter imaged the area using its HiRISE camera, producing the image above, showing the rover, the heat shield, the crashed descent stage, and the backshell with parachute. The parachute and backshell were about 615 meters away from the rover. See the description field of that image's page for more details. -- ToE 19:17, 21 February 2021 (UTC)

Thank you for the image. @ToE: Rizosome (talk) 06:46, 22 February 2021 (UTC)

February 22

50 cal gun and air

I posted this on the Humanities desk! My bad. The other day, I was watching a Youtube vid (I could not find the link) of someone taking multiple shots with a 50 cal gun. The host showed how the air around the gun got cold enough to see one's breath. What is the science behind this? 70.26.18.103 (talk) 01:45, 22 February 2021 (UTC)

"50 cal gun" only tells us its ammunition size: it could be a Handgun, a Light or Heavy machine gun, or conceivably even a pistol, rifle or other type of Air or Gas gun. Without more detail, I doubt if anyone can begin to offer an explanation: I myself can point to a possible cause if it were an air or gas gun. {The poster formerly known as 87.81.230.195} 2.125.75.168 (talk) 02:12, 22 February 2021 (UTC)

Blood vessels regenerating

What is the maximum length of a blood vessel being removed and then fully regenerating? 10 centimeters? More than that? Futurist110 (talk) 06:59, 22 February 2021 (UTC)

RBMK reactor

A few questions about that clunker called the RBMK:

(1) Did the 32 short lower control rods have graphite tips like the ones inserted from above?

(2) Were these 32 rods under the control of the RCPS and/or EPS systems, and were they automatically inserted by pressing AZ-5?

(3) Were there any safety valves and/or pressure relief valves on the steam drums and/or on the steam lines to the turbines (I wouldn't be too surprised if there weren't any), and if so, where did they discharge -- into the condensers, or into some kind of surge tank, or simply into the turbine hall to the peril of anyone who happens to be nearby at the time?

(4) Why use the graphite tips at all -- was this some kind of tweak to correct an early design flaw (in the process introducing another, arguably worse one)?

(5) Considering how unstable this clunker was, and how laggy the controls were, had there ever been problems with these things introducing current/voltage oscillations into parts of the Soviet power grid (for example, did the lights in places which were heavily dependent on nuclear power, such as Pripyat, flicker more than normal)? And

(6) the million-dollar question: if they had known the finer points of operating this reactor (a partially moot point since if they had, they wouldn't have run the test as they did), could they have averted the Chernobyl disaster if, as soon as the reactivity started increasing, they kicked the main coolant pumps to maximum RPM before (or instead of) pressing AZ-5? 2601:646:8A01:B180:8C91:5C9F:935B:96B1 (talk) 08:12, 22 February 2021 (UTC)

^{[I have reformatted your post slightly to make it easier for others to read and respond to. {The poster formerly known as 87.81.230.195} 2.125.75.168 (talk) 14:11, 22 February 2021 (UTC)]}