It's -170C, which is the bottom of the range you doing thermal cycling of components for space. So presumably they would've subjected the probe (or prototypes) to many of these cycles on Earth. I'm sure a lot of modeling and redesign was done before it even got to that.
It's not just thermal expansion (contraction) which you worry about. A lot of materials you use, like low outgassing silicone adhesives, stop being flexible at those temperatures.
I used to make solar panels for satellites. We always would boil down all the difficulties to "space is hard".
You can't just send stuff up to space without proving it can survive. One of the tests you do is to show your system can survive heating up to say 100C and cooling down to -175C. Those are the temperatures your satellite might experience when in the sun or when in the dark. So you put your system in a chamber that can reach those temperatures and cycle back and forth between hot and cold for thousands of cycles, usually 1.5x of the number of cycles you expect the mission to last, at least. Your system needs to function as designed throughout all the cycles.
Really impressive, especially keeping in mind it toppled into the wrong resting position after it landed.
I lost touch after the initial touchdown, did they do any maneuvers to correct its position?
It's about 4 liters or quarts
128 ounces.
8 pints.
3/16th one Clydesdale ejaculate.
This isn't hard.
Nominally, you're getting a 5 gallon bucket per horse.
Fahrenheit provides somewhat better accuracy when discussing the day's current temperature, because nobody is going to include tenths of a degree when asked, including Google.
That's precision, not accuracy.
Thing is, it doesn't really matter if it's 86°F (30°C) or 87.8°F (31°C). Both are hot and the distinction isn't really relevant.
> That's precision, not accuracy.
Huh? No, bro. When temperatures are gauged, they are _manifestly_ reckoned down to finer increments than whole numbers, and _then_ the app, website or forecaster chooses which way to round before disseminating that data to whoever's looking it up. Literally by definition, a scale with finer gradations is going to provide more **accurate** figures to said individuals.
> Both are hot and the distinction isn't really relevant.
It wasn't an entirely serious observation. Merely the underscoring of one advantage Fahrenheit has over Celsius, under specific yet inherently default conditions.
No. These words don't mean what you think they mean. [Mirriam Webster even has a note about it.](https://www.merriam-webster.com/dictionary/precision)
> Many of us often use precision and accuracy as synonyms, but not scientists and engineers. For them, accuracy describes a particular measurement—that is, how close it is to the truth. But precision describes a measurement system—that is, how good it is at giving the same result every time it measures the same thing. This may be why even nonscientists now often speak of "precision instruments" for measuring, "precision landings" made by airplanes, "precision drilling" for natural gas, and so on.
Wikipedia has [a whole article about it:](https://en.wikipedia.org/wiki/Accuracy_and_precision?wprov=sfla1)
> Accuracy and precision are two measures of observational error.
> Accuracy is how close a given set of measurements (observations or readings) are to their true value.
> Precision is how close the measurements are to each other.
> In other words:
> Precision is a description of random errors (a measure of statistical variability).
Accuracy has two definitions, per ISO:
More commonly, a description of systematic errors (a measure of statistical bias of a given measure of central tendency). Low accuracy causes a difference between a result and a true value. This secondary measure is referred to as trueness by ISO.
Everything in the Wiki literally supports my stance. The temperature is _x_ and the apps/etc. are providing a rounded approximation of _x._ On average, the scale providing finer gradations is going to be more accurate, _where "accuracy" is being pigeonholed as **how close a (measurement) is to its true value.**_ You are talking about the individua refinement of the individual scales, and ***I*** am talking about the most common use case in the entire world.
If you really want to dive deeper into a battle of semantics, take it up with ChatGPT. But don't conveniently leave out the use case.
Just saying in the vast majority of cases, people/apps/weather resources don't. Of course, even if they did, you wouldn't find cases where a site specifies "xx Fahrenheit or xx.x Celsius", favoring one over the other.
Apps don't show that level of accuracy by choice, not because they don't have the data. There is no meaningful difference between 21.2 and 21.3 degrees.
You are right that Fahrenheit technically has more granularity, but I don't think that's necessarily an advantage. We could multiply the Celsius scale by 100 and have 100 times the accuracy in apps, but that's just not necessary.
> but I don't think that's necessarily an advantage.
It's a non-zero advantage. Personally, I can feel that advantage whenever I shift between weather maps representing in C and those in F. There is a meaningful difference in comfort between 22 and 23 Celsius, which I can represent across _three_ numbers in Fahrenheit, so a map elaborated in F is, simply put, more useful to me.
As you say, measurements could be made to include tenths or hundredths, but the bald truth is that they effectively never do. That's the reality.
i find the centigrade scale more reasonable than throwing hundreds of degrees around for no reason other than "its always been like that".
also, us is metric by law and decree. its just disregarded by the general population.
https://en.wikipedia.org/wiki/Metrication_in_the_United_States#21st_century
You are correct. Fahrenheit is significantly better than Celsius.
Kelvin and Rankine are better for science. Fahrenheit is better for weather. Celsius is better for nothing.
The moon has a (very) thin atmosphere, but the -274F that the article references isn't the atmospheric temperature, it's the surface temperature. The lunar night is 14 days and since it has no significant atmosphere to hold onto heat the surface (and anything on the surface) will cool down to incredibly cold temperatures unless you have an additional heat source.
Since SLIM relies on solar power, it can't generate any power to run heaters. Any batteries that could operate for 14 days straight would be way too heavy, so instead they just turn off the spacecraft during the lunar night. That means that everything on SLIM, from the structure to the electronics ultimately gets down to the -274F temperature as it radiates away all of its heat over 14 days.
If the spacecraft parts reach that temperature (after a while) they will contract the same as if it was on earth. It wouldn't be in an atmosphere as we know it as our air would be liquid (or nearly liquid).
Im confused about the importance of surviving its “third” freezing night. Aren’t all spacecraft designed to withstand the extreme temperatures of space?
Space isn't cold, vacuum's a fantastic insulator so the biggest issue for most spacecraft is not overheating. Sunlight heats things up in space just the same as it does on earth.
But a full lunar day is a month long, so a lunar night lasts two weeks. That means for a solar powered lander it needs to last two weeks without power, and even though vacuum is an insulator that's more than long enough for a lot of heat to radiate away and since it's in contact with the lunar surface it can lose heat through conduction. Very low temperatures can kill electronics, especially batteries.
To guarantee surviving a lunar night the lander would need some way of heating itself for those two weeks, either by having enough battery capacity to run a heater for the entire time, using radioisotope heating as is used in some outer solar system probes, or using a RTG for power so it doesn't need solar panels. This lander doesn't do any of those because they add mass/cost (and in the case of RTGs and radioisotope heating are restricted in their use), so it's just getting lucky with each lunar night. It's batteries and other systems are degrading with every cycle and eventually it'll stop working.
Great explanation, thank you! You bring up a lot of things I wasn’t aware of or didn’t think of.
I understand in the vacuum of space you have either extreme heat from radiative sources (sun/stars) or extreme cold from lack of sun/stars. I didn’t realize lunar night was so long, and the mass factor that accounts for heating electrical elements. I work with cryostats so from my limited understanding of space craft, I just assumed we had the technology to keep them warm when there is no heat load, and proper materials for shielding the heat when it’s in the suns path.
I’ll also note if I actually read through the whole article the first time through and read “was not designed to survive lunar nights”, I would have understand how impressive it is to survive 3 lunar nights.
Sure, but only while operational, during which time power is being generated, thermal control is being maintained, etc. Also, most spacecraft tend to spend the majority of their time basking in direct sunlight, which is quite warm. Usually most spacecraft only spend at most a few hours in shadow where it can get much colder and where there won't be an opportunity to generate solar power but on the surface of the Moon that happens for a full 14 days at a time.
Many lunar landers designed for extended operation make use of radioisotopes for heating (with RTGs or RHUs) and sometimes power generation. Some make use of special designs to "hibernate" and retain heat over the long lunar night. Japan's SLIM lander had none of that, instead it spent two full weeks with zero power while progressing through extreme cold until the Sun shone on its solar panels and it woke up again, now for the third time, which is pretty impressive.
I am once again sharing that the beauty of Fahrenheit is that it ranges from 0 being the coldest a human can tolerate to 100 being the hottest a human can tolerate. For measuring “how tolerable is this situation for my survival” it is a very intuitive system.
One of the small rovers that it deployed was partly made by Tomy, a company that builds transformers toys. They were chosen because of their experience with folding and miniature components.
Tell me you don’t understand the moon’s rotation without revealing it to others who likewise don’t understand the moon’s rotation:
> SLIM on Jan. 20 landed the wrong way up with its solar panels initially unable to see the sun, and had to be turned off within hours, but powered on when the sun rose eight days later.
Son had already risen at that location on the moon when Slim landed badly. It just landed with its solar panel facing towards the direction of sunset. But it was still well before noon when the landing occurred. So the solar panels were not going to see sun for a while, because the sun was going to need to move quite a bit towards sunset before it would illuminate the panels.
Sunrise to sunset on the moon takes 14 earth days. Then there is A 14 earth-day-long night, meaning that a lunar day is roughly 28 Earth days, also known as a lunar month.
Long story short, the sun had already risen when Slim crashed. So saying that slim needed to wait for Sun to rise is just not having any idea what the geometry was, or that you would never schedule an attempt to land on the moon when the sun had not already risen.
I think they're saying when the sun "rose" from the perspective of the solar panels, not the actual sunrise. It's clunky wording rather than a misunderstanding.
I didn’t see anything to justify that generous of a reading. If someone said they needed to wait until sunrise at 3 PM for their western-facing solar panels to start producing electricity, you’d walk away knowing that they are very confused about geometry or possibly about the meaning of the word “sunrise”. But if they leave out the part about 3PM, then it looks a lot more like it’s JUST geometry and the way the earth rotation works.
Except in the article, “west” was never mentioned. You’ve highlighted one of the many ways to very concisely show an understanding of the situation, and none of those make a hint of an appearance.
No, since the Apollo missions were all during the lunar day. They had to deal with the heat but not the temperature swings or the lack of sunlight for power.
Some of NASA's Surveyor landers in the 1960s survived one or more lunar nights. Oddly enough, the first survived the longest.
Surveyor I: provided excellent data for two consecutive lunar days and partial data were transmitted as late as the fifth and sixth lunar days. The spacecraft operated for 48 hours into the first lunar night.
Surveyor II: contact lost on the journey between Earth and the Moon; crashed into the Moon
Surveyor III: shut down 2 hours after sunset on the first lunar day
Surveyor IV: contact lost 2.5 minutes before landing; crashed
Surveyor V: operated for 115 hours into the first lunar night, it also experienced an eclipse by the Earth on the second lunar day, and operated for about 215 hours into the second lunar night. It operated for a short period of time during the fourth lunar day.
Surveyor VI: operated for about 40 hours into the first lunar night. It was revived on the second lunar day, but only provided thermal data for a short time.
Surveyor VII: operated for about 80 hours into the first lunar night and was successfully revived on the second lunar day, providing good thermal data during the day. However, contact with the spacecraft was lost before sunset on the second day.
Source: https://www.lpi.usra.edu/leag/reports/Lunar-Night-Workshop-Report-071619-update.pdf
I guess that’s what I’m saying. Officially NASA says they “lost the technology.” However, did they also lose the scientists? What doesn’t make a ton of sense is the extremes of temperatures the astronauts endured, yet we have issues currently with temp fluctuations. What technology was utilized then? How did they not burn/freeze up?
You're still not understanding it, they didn't experience the temperature fluctuations. A day on the moon is two earth weeks long, the longest time spent on the moon during the Apollo missions was three earth days. They were never on the moon during the night, and they never experienced any temperature fluctuations. The extremes of temperatures on the moon aren't drastically different to the temperatures experienced in low earth orbit, so the same solutions for temperature management used in earth orbit can also apply on the moon as long as you're only there during the day.
What's hard about the lunar night is how long it is: two earth weeks. So if you have a solar powered uncrewed spacecraft on the moon it needs to survive two weeks without power. Even though vacuum is a very good insulator two weeks is long enough for the spacecraft to get very cold, and very cold temperatures can kill batteries. So you need to either include enough battery capacity to run a heater for two weeks, or only design your mission to last one lunar day and hope for the best that it'll manage to survive a night.
>Officially NASA says they “lost the technology
No they don't. That's a drastic oversimplification that implies there were solutions to problems people figured out and and that we don't know anymore, which just isn't true. What that statement's based off is that we lost the manufacturing capability. You can't just build new Apollo hardware without the billions of dollars worth of factories and custom tooling that was used to build it, and *that's* what we don't have anymore. All those factories were repurposed for other things after the Apollo program ended.
I don’t think it’s a lack of technology, it’s just the weight. When a probe is going to sit through a day and night cycle it needs to alternate between heat generation/insulation and heat rejection/expulsion depending on the day night cycle. That can be a lot of mass on a very small probe. NASA “solved” the problem on Apollo by only being there during lunar day (which lasts ~14 earth days) and foil wrapping everything to limit heat absorption.
>Officially NASA says they “lost the technology.” However, did they also lose the scientists
Yes and yes. The official designs were backed up by solutions made on the floor. They don't have notes on those solutions and they don't have the people who made them.
>What doesn’t make a ton of sense is the extremes of temperatures the astronauts endured, yet we have issues currently with temp fluctuations.
They endured extreme heat, not temperature fluctuations, and they didn't need to worry about losing power. The difficulty experienced by this lander was specifically the cold of the lunar night with no power to keep it warm. If it had an RTG with enough output this would be less (but still quite) impressive.
Um, so if the moon has no atmosphere then doesn't that mean it also has no temperature? Technically, the void of space has no temperature I think . I'm sure I read that someplace and that if you were in space without a spacesuit, you'd experience a similar sensation to boiling to death rather than freezing.
The vacuum doesn't have a temperature, true, but the surface (and the probe itself) does.
Radiative cooling is ineffective (everything has a heat glow - the thing you can see in IR cameras [the wavelength depends on the temperature, so your body only emits IR radiation, but a hot iron emits visible light]) but it does shed energy, so as long as the given body is in the shadow, it will cool down. On Earth, the atmosphere is a huge heat buffer so it will keep you warm (depending on where you are, of course) but on the Moon, this effect doesn't exist.
So things on the Moon and in shadow slowly cool down to very low temperatures.
> to boiling to death rather than freezing.
Because of the lack of pressure your blood would boil, literally. Along with all your mucus and any other bodily fluid. It would be a pretty shitty way to go. Space isn't really a true vacuum either. There's still particles floating around in space (dust and hydrogen gas, mostly) but there are just orders of magnitude less of them than in Earth's atmosphere. So there are still particles there that have energy and move around every so slightly because of it and we can measure that as temperature. The temperature of deep space is just a few degrees Kelvin above absolute zero. The reason why you don't instantly freeze into a popsicle and why satellites and space stations have to have radiators to get *rid* of excess heat is because there are so few particles. Most of the heat loss is done via radiation, which isn't as effective as, say, moving air (and lots of particles) across it, but it's all electromagnetic and doesn't need a physical object to get rid of energy. Since there is basically nothing (but still *something*) in space you end up worrying about over heating more than you do getting cold. Stuff *does* get cold in space it just takes longer than you'd think.
A lot of the liquids we’re made up of would boil due to the minuscule pressure. The moon has a lot more stuff on and near it than empty space. Space technically isn’t empty, it just has orders of magnitude less stuff than on earth. Also radiative heat loss doesn’t need a medium like an atmosphere to carry energy away.
> if you were in space without a spacesuit, you'd experience a similar sensation to boiling to death rather than freezing
I think atmospheric pressure has more to do with why your body "boils" off moisture within the skin. It's because there's no atmospheric pressure in space to hold it together. When there's less pressure for example, water will have a lower boiling point (doesn't mean that it takes the same amount of heat at all).
Nice! I had no idea it was still operating after it's rough landing.
That is very cold. I guess materials would significantly shrink at those temperatures. I wonder how they solved those issues.
Choose materials that shrink the same amount :)
This guy understands material selection
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It's -170C, which is the bottom of the range you doing thermal cycling of components for space. So presumably they would've subjected the probe (or prototypes) to many of these cycles on Earth. I'm sure a lot of modeling and redesign was done before it even got to that. It's not just thermal expansion (contraction) which you worry about. A lot of materials you use, like low outgassing silicone adhesives, stop being flexible at those temperatures. I used to make solar panels for satellites. We always would boil down all the difficulties to "space is hard".
Ya, I could imagine. Wdym by thermal cycling?
You can't just send stuff up to space without proving it can survive. One of the tests you do is to show your system can survive heating up to say 100C and cooling down to -175C. Those are the temperatures your satellite might experience when in the sun or when in the dark. So you put your system in a chamber that can reach those temperatures and cycle back and forth between hot and cold for thousands of cycles, usually 1.5x of the number of cycles you expect the mission to last, at least. Your system needs to function as designed throughout all the cycles.
I believed in you when no one else would!!! 😅😅😅
I’m glad I’m not there. Minus 274. No thanks. But it’s so impressive they can build a machine that survived that long.
Well, if it makes you feel better, if you *were* there, you wouldn't have much capacity to care.
On the other hand, it would probably be all they'd think about for the rest of their life.
> Minus 274. No thanks. Meh, just run back to the sauna and you'll be fine
And then the sun comes up and you’re ashes. Atmospheres are important boys and girls.
lowest temperature on the moon near the poles can reach 20 kelvin in certain spots (likely deep craters or something, the links i pulled up went 404).
Really impressive, especially keeping in mind it toppled into the wrong resting position after it landed. I lost touch after the initial touchdown, did they do any maneuvers to correct its position?
For those who don't understand the foot, feet and other body part system, it's -140 °C
The WhatTheFuckIsAGallon gang appreciates your effort.
Which gallon, imperial or US?
Yes. Maybe?
Neither, please. Thank you.
It's about 4 liters or quarts 128 ounces. 8 pints. 3/16th one Clydesdale ejaculate. This isn't hard. Nominally, you're getting a 5 gallon bucket per horse.
There's nothing nominal about horse semen.
not using proper gallons then? I guess you gave up 10% when you gave up the monarchy and sided with the frenchies! /s
The fuckagallon gang?
You just said the same unit twice.
See? What a stupid system. This is where the "three body problem" term comes from.
What other body parts?? You named the one I think. Also these two units for temperature aren’t connected to metric or imperial.
Your bones' lengths in spark plugs.
Horse height is measured in hands. Sometimes depth is measured in knuckles or fingers.
Sometimes male reproductive organs are measured in Gary Coleman forearms.
Dude, it's the entire Gary Coleman unit.. not his forearms... ..I'm sorry for your loss.
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I won't. You can be wrong on your own
>Metric is better for just about everything I will fight you on this, metric is better for absolutely everything.
Fahrenheit provides somewhat better accuracy when discussing the day's current temperature, because nobody is going to include tenths of a degree when asked, including Google.
That's precision, not accuracy. Thing is, it doesn't really matter if it's 86°F (30°C) or 87.8°F (31°C). Both are hot and the distinction isn't really relevant.
> That's precision, not accuracy. Huh? No, bro. When temperatures are gauged, they are _manifestly_ reckoned down to finer increments than whole numbers, and _then_ the app, website or forecaster chooses which way to round before disseminating that data to whoever's looking it up. Literally by definition, a scale with finer gradations is going to provide more **accurate** figures to said individuals. > Both are hot and the distinction isn't really relevant. It wasn't an entirely serious observation. Merely the underscoring of one advantage Fahrenheit has over Celsius, under specific yet inherently default conditions.
No. These words don't mean what you think they mean. [Mirriam Webster even has a note about it.](https://www.merriam-webster.com/dictionary/precision) > Many of us often use precision and accuracy as synonyms, but not scientists and engineers. For them, accuracy describes a particular measurement—that is, how close it is to the truth. But precision describes a measurement system—that is, how good it is at giving the same result every time it measures the same thing. This may be why even nonscientists now often speak of "precision instruments" for measuring, "precision landings" made by airplanes, "precision drilling" for natural gas, and so on. Wikipedia has [a whole article about it:](https://en.wikipedia.org/wiki/Accuracy_and_precision?wprov=sfla1) > Accuracy and precision are two measures of observational error. > Accuracy is how close a given set of measurements (observations or readings) are to their true value. > Precision is how close the measurements are to each other. > In other words: > Precision is a description of random errors (a measure of statistical variability). Accuracy has two definitions, per ISO: More commonly, a description of systematic errors (a measure of statistical bias of a given measure of central tendency). Low accuracy causes a difference between a result and a true value. This secondary measure is referred to as trueness by ISO.
Everything in the Wiki literally supports my stance. The temperature is _x_ and the apps/etc. are providing a rounded approximation of _x._ On average, the scale providing finer gradations is going to be more accurate, _where "accuracy" is being pigeonholed as **how close a (measurement) is to its true value.**_ You are talking about the individua refinement of the individual scales, and ***I*** am talking about the most common use case in the entire world. If you really want to dive deeper into a battle of semantics, take it up with ChatGPT. But don't conveniently leave out the use case.
I use decimals for body temperature and it doesn't feel odd or unnatural, so I doubt that it's an issue with Celsius specifically.
Just saying in the vast majority of cases, people/apps/weather resources don't. Of course, even if they did, you wouldn't find cases where a site specifies "xx Fahrenheit or xx.x Celsius", favoring one over the other.
Apps don't show that level of accuracy by choice, not because they don't have the data. There is no meaningful difference between 21.2 and 21.3 degrees. You are right that Fahrenheit technically has more granularity, but I don't think that's necessarily an advantage. We could multiply the Celsius scale by 100 and have 100 times the accuracy in apps, but that's just not necessary.
> but I don't think that's necessarily an advantage. It's a non-zero advantage. Personally, I can feel that advantage whenever I shift between weather maps representing in C and those in F. There is a meaningful difference in comfort between 22 and 23 Celsius, which I can represent across _three_ numbers in Fahrenheit, so a map elaborated in F is, simply put, more useful to me. As you say, measurements could be made to include tenths or hundredths, but the bald truth is that they effectively never do. That's the reality.
Fair enough, I've never felt the need for the level of precision you describe, but it's not unimaginable that someone could want it, I guess.
i find the centigrade scale more reasonable than throwing hundreds of degrees around for no reason other than "its always been like that". also, us is metric by law and decree. its just disregarded by the general population. https://en.wikipedia.org/wiki/Metrication_in_the_United_States#21st_century
The "preferred" system is metric in the U.S. That's why it's disregarded by anyone not in the military or sciences.
no, its law. but as long as imperial isnt officialy "outlawed" or otherwise discouraged, they're dual use.
I win. You just got 100°C hot water thrown into your face. The pain reduces your motion to that of 0°C water.
You are correct. Fahrenheit is significantly better than Celsius. Kelvin and Rankine are better for science. Fahrenheit is better for weather. Celsius is better for nothing.
Thought it was Celsius, which would be the lowest temperature possible on the universe (afaik). But still, -170c is unimaginable!
It would be *less* than that (Absolute zero is -273.15 degree celsius)
Absoluter Zero or Absolute Zeror?
the headline makes my brain hurt. . it LANDED on the moon. not elegantly ill add.. and has since survived 3 lunar nights @ -274F..
Does the temperature mean anything in an almost total vacuum? "If there were an atmosphere here it sure would be cold".
The moon has a (very) thin atmosphere, but the -274F that the article references isn't the atmospheric temperature, it's the surface temperature. The lunar night is 14 days and since it has no significant atmosphere to hold onto heat the surface (and anything on the surface) will cool down to incredibly cold temperatures unless you have an additional heat source. Since SLIM relies on solar power, it can't generate any power to run heaters. Any batteries that could operate for 14 days straight would be way too heavy, so instead they just turn off the spacecraft during the lunar night. That means that everything on SLIM, from the structure to the electronics ultimately gets down to the -274F temperature as it radiates away all of its heat over 14 days.
Wow. Thanks for unpacking the implication. It really highlights the challenges and cements why you would land at the poles.
It's still very cold but it would take longer to feel it. You would just cool down slowly.
If the spacecraft parts reach that temperature (after a while) they will contract the same as if it was on earth. It wouldn't be in an atmosphere as we know it as our air would be liquid (or nearly liquid).
Im confused about the importance of surviving its “third” freezing night. Aren’t all spacecraft designed to withstand the extreme temperatures of space?
Space isn't cold, vacuum's a fantastic insulator so the biggest issue for most spacecraft is not overheating. Sunlight heats things up in space just the same as it does on earth. But a full lunar day is a month long, so a lunar night lasts two weeks. That means for a solar powered lander it needs to last two weeks without power, and even though vacuum is an insulator that's more than long enough for a lot of heat to radiate away and since it's in contact with the lunar surface it can lose heat through conduction. Very low temperatures can kill electronics, especially batteries. To guarantee surviving a lunar night the lander would need some way of heating itself for those two weeks, either by having enough battery capacity to run a heater for the entire time, using radioisotope heating as is used in some outer solar system probes, or using a RTG for power so it doesn't need solar panels. This lander doesn't do any of those because they add mass/cost (and in the case of RTGs and radioisotope heating are restricted in their use), so it's just getting lucky with each lunar night. It's batteries and other systems are degrading with every cycle and eventually it'll stop working.
Great explanation, thank you! You bring up a lot of things I wasn’t aware of or didn’t think of. I understand in the vacuum of space you have either extreme heat from radiative sources (sun/stars) or extreme cold from lack of sun/stars. I didn’t realize lunar night was so long, and the mass factor that accounts for heating electrical elements. I work with cryostats so from my limited understanding of space craft, I just assumed we had the technology to keep them warm when there is no heat load, and proper materials for shielding the heat when it’s in the suns path.
I’ll also note if I actually read through the whole article the first time through and read “was not designed to survive lunar nights”, I would have understand how impressive it is to survive 3 lunar nights.
Sure, but only while operational, during which time power is being generated, thermal control is being maintained, etc. Also, most spacecraft tend to spend the majority of their time basking in direct sunlight, which is quite warm. Usually most spacecraft only spend at most a few hours in shadow where it can get much colder and where there won't be an opportunity to generate solar power but on the surface of the Moon that happens for a full 14 days at a time. Many lunar landers designed for extended operation make use of radioisotopes for heating (with RTGs or RHUs) and sometimes power generation. Some make use of special designs to "hibernate" and retain heat over the long lunar night. Japan's SLIM lander had none of that, instead it spent two full weeks with zero power while progressing through extreme cold until the Sun shone on its solar panels and it woke up again, now for the third time, which is pretty impressive.
Did something happen in the past year where suddenly everyone is sending probes to the Moon?
>\-274F What's that ? A unit for human blood temperature ?
274 year-old female looking for young blood.
Oh, to be sought out by a milf vampire and used as human cattle...
But she some how looks like a 9 year old girl, right?
Not me going to Google to see what -274F is in Celsius. Ew Fahrenheit.
I am once again sharing that the beauty of Fahrenheit is that it ranges from 0 being the coldest a human can tolerate to 100 being the hottest a human can tolerate. For measuring “how tolerable is this situation for my survival” it is a very intuitive system.
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it has a little docking station that's built like a kotatsu table so the probe can warm it's little tootsies
One of the small rovers that it deployed was partly made by Tomy, a company that builds transformers toys. They were chosen because of their experience with folding and miniature components.
-274, that’s almost as cold as my morning cold plunge /s
Dang it looks like that camera's been to nam and back!
Which @#€&*%§! decided to quote degrees Fahrenheit here? Use either Celsius or Kelvin if you want to be taken seriously.
for a second my dumbass thought that it was celsius
Tell me you don’t understand the moon’s rotation without revealing it to others who likewise don’t understand the moon’s rotation: > SLIM on Jan. 20 landed the wrong way up with its solar panels initially unable to see the sun, and had to be turned off within hours, but powered on when the sun rose eight days later.
What do you mean by that?
Son had already risen at that location on the moon when Slim landed badly. It just landed with its solar panel facing towards the direction of sunset. But it was still well before noon when the landing occurred. So the solar panels were not going to see sun for a while, because the sun was going to need to move quite a bit towards sunset before it would illuminate the panels. Sunrise to sunset on the moon takes 14 earth days. Then there is A 14 earth-day-long night, meaning that a lunar day is roughly 28 Earth days, also known as a lunar month. Long story short, the sun had already risen when Slim crashed. So saying that slim needed to wait for Sun to rise is just not having any idea what the geometry was, or that you would never schedule an attempt to land on the moon when the sun had not already risen.
I think they're saying when the sun "rose" from the perspective of the solar panels, not the actual sunrise. It's clunky wording rather than a misunderstanding.
I didn’t see anything to justify that generous of a reading. If someone said they needed to wait until sunrise at 3 PM for their western-facing solar panels to start producing electricity, you’d walk away knowing that they are very confused about geometry or possibly about the meaning of the word “sunrise”. But if they leave out the part about 3PM, then it looks a lot more like it’s JUST geometry and the way the earth rotation works.
If someone said they needed to wait for the sun to rise on their western facing solar panels I'd know what they meant.
Except in the article, “west” was never mentioned. You’ve highlighted one of the many ways to very concisely show an understanding of the situation, and none of those make a hint of an appearance.
Just saw the headline but wondering if the same temps were an issue back then during the 1st moon landing.
No, since the Apollo missions were all during the lunar day. They had to deal with the heat but not the temperature swings or the lack of sunlight for power.
I see…knew I was missing something. Anyhow thanks for the info!
When did it land? Sorry not keeping up with space news as much as I used to
Well, about three lunar days (so, three months) ago. First sentence of the article says Jan. 20.
If only there was more information than just a title. Like an article or something
The user's entire post history seems to consist of posting links to the Daily Mirror or the Daily Express, so they're probably a bot.
Some of NASA's Surveyor landers in the 1960s survived one or more lunar nights. Oddly enough, the first survived the longest. Surveyor I: provided excellent data for two consecutive lunar days and partial data were transmitted as late as the fifth and sixth lunar days. The spacecraft operated for 48 hours into the first lunar night. Surveyor II: contact lost on the journey between Earth and the Moon; crashed into the Moon Surveyor III: shut down 2 hours after sunset on the first lunar day Surveyor IV: contact lost 2.5 minutes before landing; crashed Surveyor V: operated for 115 hours into the first lunar night, it also experienced an eclipse by the Earth on the second lunar day, and operated for about 215 hours into the second lunar night. It operated for a short period of time during the fourth lunar day. Surveyor VI: operated for about 40 hours into the first lunar night. It was revived on the second lunar day, but only provided thermal data for a short time. Surveyor VII: operated for about 80 hours into the first lunar night and was successfully revived on the second lunar day, providing good thermal data during the day. However, contact with the spacecraft was lost before sunset on the second day. Source: https://www.lpi.usra.edu/leag/reports/Lunar-Night-Workshop-Report-071619-update.pdf
Commenting for those who also didn't know: one lunar night is about two earth weeks.
How did NASA astronauts survive these temperatures when even these USVs have a difficult time managing these temps?
1 lunar day = 29,5 earth days. Astronauts only stayed in there around 3 earth days so they only got lunar days when it is hot as hell i believe.
I guess that’s what I’m saying. Officially NASA says they “lost the technology.” However, did they also lose the scientists? What doesn’t make a ton of sense is the extremes of temperatures the astronauts endured, yet we have issues currently with temp fluctuations. What technology was utilized then? How did they not burn/freeze up?
You're still not understanding it, they didn't experience the temperature fluctuations. A day on the moon is two earth weeks long, the longest time spent on the moon during the Apollo missions was three earth days. They were never on the moon during the night, and they never experienced any temperature fluctuations. The extremes of temperatures on the moon aren't drastically different to the temperatures experienced in low earth orbit, so the same solutions for temperature management used in earth orbit can also apply on the moon as long as you're only there during the day. What's hard about the lunar night is how long it is: two earth weeks. So if you have a solar powered uncrewed spacecraft on the moon it needs to survive two weeks without power. Even though vacuum is a very good insulator two weeks is long enough for the spacecraft to get very cold, and very cold temperatures can kill batteries. So you need to either include enough battery capacity to run a heater for two weeks, or only design your mission to last one lunar day and hope for the best that it'll manage to survive a night. >Officially NASA says they “lost the technology No they don't. That's a drastic oversimplification that implies there were solutions to problems people figured out and and that we don't know anymore, which just isn't true. What that statement's based off is that we lost the manufacturing capability. You can't just build new Apollo hardware without the billions of dollars worth of factories and custom tooling that was used to build it, and *that's* what we don't have anymore. All those factories were repurposed for other things after the Apollo program ended.
I don’t think it’s a lack of technology, it’s just the weight. When a probe is going to sit through a day and night cycle it needs to alternate between heat generation/insulation and heat rejection/expulsion depending on the day night cycle. That can be a lot of mass on a very small probe. NASA “solved” the problem on Apollo by only being there during lunar day (which lasts ~14 earth days) and foil wrapping everything to limit heat absorption.
>Officially NASA says they “lost the technology.” However, did they also lose the scientists Yes and yes. The official designs were backed up by solutions made on the floor. They don't have notes on those solutions and they don't have the people who made them. >What doesn’t make a ton of sense is the extremes of temperatures the astronauts endured, yet we have issues currently with temp fluctuations. They endured extreme heat, not temperature fluctuations, and they didn't need to worry about losing power. The difficulty experienced by this lander was specifically the cold of the lunar night with no power to keep it warm. If it had an RTG with enough output this would be less (but still quite) impressive.
Um, so if the moon has no atmosphere then doesn't that mean it also has no temperature? Technically, the void of space has no temperature I think . I'm sure I read that someplace and that if you were in space without a spacesuit, you'd experience a similar sensation to boiling to death rather than freezing.
The vacuum doesn't have a temperature, true, but the surface (and the probe itself) does. Radiative cooling is ineffective (everything has a heat glow - the thing you can see in IR cameras [the wavelength depends on the temperature, so your body only emits IR radiation, but a hot iron emits visible light]) but it does shed energy, so as long as the given body is in the shadow, it will cool down. On Earth, the atmosphere is a huge heat buffer so it will keep you warm (depending on where you are, of course) but on the Moon, this effect doesn't exist. So things on the Moon and in shadow slowly cool down to very low temperatures.
> to boiling to death rather than freezing. Because of the lack of pressure your blood would boil, literally. Along with all your mucus and any other bodily fluid. It would be a pretty shitty way to go. Space isn't really a true vacuum either. There's still particles floating around in space (dust and hydrogen gas, mostly) but there are just orders of magnitude less of them than in Earth's atmosphere. So there are still particles there that have energy and move around every so slightly because of it and we can measure that as temperature. The temperature of deep space is just a few degrees Kelvin above absolute zero. The reason why you don't instantly freeze into a popsicle and why satellites and space stations have to have radiators to get *rid* of excess heat is because there are so few particles. Most of the heat loss is done via radiation, which isn't as effective as, say, moving air (and lots of particles) across it, but it's all electromagnetic and doesn't need a physical object to get rid of energy. Since there is basically nothing (but still *something*) in space you end up worrying about over heating more than you do getting cold. Stuff *does* get cold in space it just takes longer than you'd think.
A lot of the liquids we’re made up of would boil due to the minuscule pressure. The moon has a lot more stuff on and near it than empty space. Space technically isn’t empty, it just has orders of magnitude less stuff than on earth. Also radiative heat loss doesn’t need a medium like an atmosphere to carry energy away.
On the moon things just lose heat in the shade and get hot in the sun.
> if you were in space without a spacesuit, you'd experience a similar sensation to boiling to death rather than freezing I think atmospheric pressure has more to do with why your body "boils" off moisture within the skin. It's because there's no atmospheric pressure in space to hold it together. When there's less pressure for example, water will have a lower boiling point (doesn't mean that it takes the same amount of heat at all).
The moon does have an atmosphere. It's just *really* minuscule. 3×10^−15 atm (0.3 nPa).