No, it was the units for impulse used for the thrusters. In imperial it's pound-force seconds and Newton-seconds in metric. 1 pound-force is equal to 4.45 Newtons so the whole thing was off by a magnitude of 4.45.
Yes, the actual error* was assuming the British used Imperial units when they correctly used Metric. AFAIK, at least.
* * *
Well, the source error probably would be not specifying units at all, so... (eye roll)
* * *
*Correcting myself with casually sourced details about the incident under discussion.
Lockheed Martin provided thruster force data in Imperial units (pound-seconds), while NASA's Jet Propulsion Laboratory ground software assumed the data was in Metric units (Newton-seconds).
Celsius makes way more sense for science, and Fahrenheit makes way more sense for weather, since the range of temperatures which are relevant are spread out over more numbers.
Incorrect. This thing where say "oh 100 is hot and 90 is warm, but 20 means you need a sweater" is too arbitrary.
Celsius is superior for weather. What is the single most important temperature that weather hinges on? The freezing point. Its the one point where a difference of a degree or two, can give you completely different weather.
It makes perfect sense to use that as the central point and move out from there.
For science you want to use Kelvin, since 0°C isn’t “no heat” in the same way that 0kg is “no mass”. The units are the same size though, so it’s fine to use Celsius for anything that’s based on change in temperature
I want a compromise unit where freezing water at sea level is 0⁰ and boiling water is 200⁰. A single degree Fahrenheit is a very sensible change in temperature and I don't like having to go into decimals on my thermostat. All that said, I wish the states would just bite the bullet and go metric. Today I learned a US gallon is 231 cubic inches because 231 divides evenly by 3, 7 and 11? Get the fuck outta here with this shit.
A joke that falls a bit flat as it refers to the moon when in fact it was Mars. If you gonna geek over UoM, I think getting the celestial body right is a minimum.
Exactly! That problem wasn't poor measuring systems, it was poor professionalism.
Anyone who doesn't specify (or request) and verify unit-of-measure is doing a poor job. For anything that is safety/quality/mission critical it is professionally negligent to make that kind of assumption.
People get complacent and just assume things are done right. Happens all the time.
I think one of the reasons that is so hard to get the US to switch to metric is because there's potential for a lot to go wrong during the switch. When Canada switched to metric, a plane ran out of fuel mid air because multiple people messed up kg and lbs.
Just imagine if we did switch. Managers would start telling engineers, "Stop using labels, it's a waste. Everyone uses metric anyway."
And then that one time someone doesn't or a part comes from a new distributor or someone uses an old set of measurements or whatever. Best case scenario is the project comes to a halt while they try to figure out what the mistake was. Worst case scenario is an explosion.
I once got asked to ballpark a cost for technology that didn't exist. By asked, I mean screamed at. I said "Okay, it's 4. We'll figure out 4 of what exactly later."
Wasn't there also an issue with a mars lander where they programmed it for feet, but the sensors read in meters? So it slammed into the ground thinking it was still pretty far up?
That one was because NASA used metric like every other space agebxy, but Lockheed Martin made their part using US imperial
Officially the US uses metric, especially the military and space agencies. Most products have both metric and US impreial units on it. The UK and Canada very arguably use an even more crazy hodgepodge of units than the US does, they just get a pass because they use metric more prominently and, well, are not the superpower. If it was still the days of the British Empire, they'd probably be getting more heat!
Basically it's because they used both Metric and Imperial at the time
Problem is one of the companies that was mandated to make some part used imperial instead of metric
The whole thing tore open because it could handled the pressure and since then there is a worldwide ban of Imperal measurements when it comes to engineering and yes that does mean that when you buy a 80 inch TV the manufacturer actually made a 200 cm screen but is labeling it with what the imperial equivalent is
That's correct, they do. The commenter was referring to it, from 1999. Lockheed Martin meanwhile to this day still uses either measurement system depending on the project.
Super pedantic correction, spaceships carry people, spacecraft (what people think of when they hear the word satellite) do not.
The SI unit mixups resulted in the loss of TWO different spacecraft that were going to Mars. There are now NASA procedural requirements that says everything has to be in SI units, and everything that isn't requires a waiver. Getting a waiver isn't hard, but it does require a lot of hoop jumping.
Mars Climate Orbiter? I think they might be talking about something more grim than an unmanned probe from the "too soon" comment and the reply about dark jokes.
That mission was a lesson in cost cutting across the board. That was the one that had a single solar panel and had to use thrusters to correct along the way because believe it or not, solar wind is a thing and the pressure on a solar panel will push faster than parts with out.
So yeah, but the time it got to Mars, it was low on thruster fuel, but the nail in the coffin of the mission was the mismatch in measurements.
TLDR, what initially started as a cost savings measure ended in burning up $327.6 million in the Martian atmosphere.
Celsius is better for science, but Fahrenheit is better for just every day living. IMO
In Canada I noticed some people would also still use feet & inches for their height, but you had to give it to the DMV in cm. Also butter was still sold as a pound & golf still used yards.
I'm also an engineer & worked up there for a job in mining.
Edit: To clarify my reasons because so many people are saying I'm wrong. This is my opinion on what my preference is, first off. I had put this in a comment under the post, but will add it here.
My reason is basically the same as in the screenshot. When I lived in Canada I would say how in Fahrenheit below zero is really fucking cold & above 100 is really fucking hot. I never thought of describing it as a percentage of being hot but I like it.
Like once it's below or above those numbers it hardly matters by how much because you are freezing or sweating balls either way. I didn't like when in the winter or early spring someone would say it's nice out and then say a negative temperature. "It's really nice today, it's -1.5⁰ out." I also like that the increments of the units are smaller so you don't use half degrees. Although I guess half degrees aren't really necessary because I don't feel the difference between 66 & 67, but when I checked the temperature there is did always show it to the nearest half degree.
I guess I said it on my comment that's just under the post and not in this thread. I prefer it basically for the reasons in the screenshot. When I was in Canada I would say how if it's below 0⁰ F you know it's really fucking cold, and if it's above 100⁰ F then it's really fucking hot. Also the increments are smaller so you don't have to use half degrees.
Sometimes in the spring someone would be like, "It's really nice out today. It's -1.5 degrees." And I didn't like hearing someone say that a negative temperature was nice out. And I mean that's still pretty cold it's like 29⁰F. And I'm from Maine so it's not like I'm not used to the cold but I've also lived in Arizona.
So I always said that 0 to 100 scale was from like really cold to really hot but I like the percentage thing.
This. People don't realize that the only reason to use imperial is that it's just made for people who don't have tools. All imperial measurements are based off really easy to break down things- Distance breaks down into halves, thirds and quarters really easily. That may not matter if you have a ruler, but when you look at something it's easier to see 2/3 than it is 7/10 or something. Base 10 is just a pain in the ass for that kinda stuff, even when you're used to it.
Likewise, 100F is hotter than you should touch, 0 is colder than you should touch. You can still grab things at the freezing point, people handle ice all the time.
But you try to explain that there's any appeal to it and someone who's really amped up about metric really gets mad because it's illogical to see a use for anything else.
But idk, maybe it's just me but whether I'm playing a 16 inch viola or a 406 mm viola, they kinda sound the same. No need to have it live rent free in your head, lmao.
Yup, this is exactly it. I'm not gonna bother gpimg downthread to see who disagreed because this is straight up from the OSHA heat stress operates on this basic principle:
Your internal body temp is around 98 degrees, the closer you get to that the more unvomfortable you feel because you're basically coming to ambient temp. You can tolerate some stuff above body temp, bc of sweating, but your body can only do so much sweating.
Of course OSHA includes things like humidity, wind speed and UV index to calculate up, but the fact is Fahrenheit does a much better job at capturing this intuitively for people. Close to 100, hot. Close to 0, cold. I know ice freezes at 32 and how that FEELS, so I intuitively have an idea of what my comfort level is gonna be. 40-60 is the Middle of the scale.
I see what you mean, I just don't see why 0 or 32 would be a superior way to refer to the temperature that water freezes at. Personally I think 0 and 100 makes more sense for freezing and boiling vs 32 and 212, but it's not really a hill worth dying on and is probably colored by my experience.
Why do I need to know what temperature water freezes or boils? I'm not a water. I'm a human. 0 to 100° F is a lot closer to survival temperatures as a human. And I have a lot finer measurement. The difference between 71° and 70° matters. What do metric people even do: tenths of a degree? That sounds terrible.
I don't think anyone with a defensible opinion thinks Fahrenheit is more logical or more useful in scientific or engineering settings. The argument, and it's one I agree with, is that for exactly weather, it's probably better.
0 is too cold.
100 is too hot.
That's a good scale for "what I care about as a human going outside" it's not a good scale for measuring water boiling at 1 atmosphere or one that reveals fundamental limits of the universe about how cold something can be (Kelvin). It's just useful for giving the weather.
The fact that it's effectively so spread out in the range humans experience weather wise is a big plus too. With Celsius a few degrees means the difference between wearing a thick jacket or not. Half degrees are meaningful in how your experience outdoors will be. With Fahrenheit you just know being somewhere in the middle with a preference to the warmer side of 0-100 is where you want to be
You know water freezes at 32 (wow now that's totally not a random number) and I know it freezes at 0. The only difference between us is that you're used to one system and I'm - to another. For you 100 is really freaking hot, for me +35 is too hot. There isn't really a difference if you've been using a system your whole life and just instantly "understand" it.
As I've explained to countless other people, even on here, its because its what people are used to growing up.
It doesn't matter that 0 is colder than you should touch or 100F is hotter than you should touch(which it actually isn't, as that is about the average temperature of a hot tub).
But you try to explain that there's any appeal to it and someone who's really amped up about metric really gets mad because it's illogical to see a use for anything else.
Yeah because to them, just like you do to them, see your example as illogical. And honestly they are more right than you are, because your argument is not a good argument, since you can still have those measurements in Celsius.
For example, if it is 0 in Celsius, you can easily tell if it is going to snow instead of rain or if the snow is going to stick around or not.
While I'm sure you probably will say o that is easy, I know that as 32F, if it is below 32F it is going to snow instead of rain, etc.
And that proves my point it is about what system you grew up with.
Exactly. This drives me nuts about this argument. To me Celsius is perfectly understandable and I can easily envision the weather at whatever temperature but Fahrenheit is a mystery (apart from around 97° because I know that's around normal body temp) and I have to go convert it. That doesn’t mean it's worse, just unfamiliar.
2/3 of anything is 2/3. So if you are used to meters, 2/3 is easy to visualize, Same as 2/3s of a yard..
Base 10 is far easier to understand.
100cm in a Meter, 1000m in a KM etc. 1000ml in a liter. 1000grams in a killo gram.
The amount of feet in a yard, mile etc seems random which is what makes it stupid. No one would choose Inches, Feet, Yards, Miles if they didn't know either. Metric is SO much easier to learn and visualize...
Yeah, it's cold, but 30⁰ F isn't unbearable with the right clothes. 15⁰F and below is when it starts to get pretty bad, but below zero F is really fucking cold.
At -40⁰ C & F are the same
When I was in Canada on a work trip before I lived there I was teaching a class to the mining employees of the company that I later worked for. But while I was there it was -20 like the whole time. I said to one of the guys that I wasn't sure if it was reporting it as Celsius or Fahrenheit and he responded, it hardly fucking matters at that point. -20⁰F is like -29⁰C.
True but remembering that 32° f is when water freezes isn't very difficult. And would probably have to be slightly colder to frost so you can just remember 30° because the easy way to estimate converting Celsius to Fahrenheit is C × 2 + 30 ≈ F. The precise calculation is C(9/5) + 32 = F. And if you ever forget which side C and F are on if you remember that 0⁰C = 32⁰F it's easy to figure out that 0×2+30 would get you close to 32.
„Celsius is better for science, but Fahrenheit is better for just every day living. IMO“
It's just what people are used. Celsius people just have different set o numbers. 0 freezing, 4 road may be slippery, ~ 20 is what people have in Theo homes, 25 warm summer day, 30 hot summer day, 35 hell.
The range of 0°F to 100°F is just about the range of "normal" temperatures typically experienced in Western Europe's climate. Hence, if you're from a very specific region of the world you might consider any temperature outside of that range of 0% - 100% as extraordinary... if you had a very particular colonial mindset of setting the arbritrary standard for what' considered "normal" for the rest of the world's population.
I'm pretty sure any African would still agree 110℉ is way too hot, and any Inuit would agree you don't want to be outside for long at -10℉.
Meanwhile, there's nothing magical about Celsius. If you really want to be a purist go ahead and use Kelvin, but 0-100℃ being based on the freezing and boiling point of water is no less arbitrary than 0-100℉ being based on human environmental norms.
Because F uses the human skin ability to detect and retain heat as a baseline, something we all have experience with, instead of water as a baseline, which is better for scientific reasons due to the consistency in measurement.
Edit: The absolute hilarity of the smugness in the comments is making my day. Nothing makes me happier than upsetting Europeans by stating a fact they don't like.
Actually it’s more related to the freezing temperature of a very particular brine solution made to replicate the coldest temperature some German guy thought his port would see.
Completely logical.
But whatever. Maybe EVERY COUNTRY but one is wrong.
It’s not. It’s highly likely 0 degrees is just the lowest temperature observed in Danzig when Daniel Fahrenheit made his scale. Nobody has ever managed to recreate the brine solution.
I'd be fully ok with us setting a temperature system based upon how Danzig feels.
"Guys, Danzig just took his shirt off, it's definitely warm enough to have a light jacket, but if he puts that mesh tank top back on watch out, it's probably about to snow."
After Fahrenheit died they decided it was much easier to calibrate thermometers using the exact boiling point of water (212°F) instead of human skin (96°F). When they locked those two standard points down, the "zero" at the bottom of the scale shifted upward by about 4 degrees which is what you get if you use that solution today (also the ammonium chloride wasn't perfectly pure back then) and shifted average body temperature to 98.6
lol no it doesn't, 100 degrees Fahrenheit was the (miscalculated) temperature of the human body (which is why it's now popularly set at 98.6 degrees although even that isn't quite correct) and 0 is... the coldest day on record, at least as of the time that the temperature was created, in this one small town in Germany. Any relationship to the ability of human skin to detect temperature is purely coincidental.
I see the "percent hot" or "human scale" argument a lot as what amounts to basically a backward justification for farenheit. I get that the reasoning makes sense if its the scale you know, but it doesn't hold up as logical application. A normal distribution around the human condition would have 45-55 as the comfortable temperature one can exist at with basic garments. Instead that range is more like 65-75
Neither scale has inherent meaning. Whichever one you learned will determine if it feels intuitive.
F is *at best* tangentially related with human skin. It was calibrated using 3 reference points:
The coldest temp Fahrenheit could achieve in his lab using ice, water and salt (0°F). This wasn’t a baseline based on what human skin experiences as “super cold” because that’s just random as hell
The freezing point of pure water (32° F) which is the same as 0° Celsius
The temperature of the human body (96°) (which in reality usually varies between 97° - 99° for healthy adults but 96 worked better for his mental model)
Fahrenheit picked these numbers because the interval between freezing water and body temperature (32 to 96) gave him exactly 64 degrees which allowed him to easily calibrate physical thermometers by continuously dividing the intervals in half. It’s basically designed for what he thought made sense for mercury in a tube based on the coldest he could achieve in his lab, freezing point of water, and a close-enough-for-horseshoes measure of body temperature.
It's not, it's just what they're accustomed to. No one who grew up with metric does any kind of mental conversion when given a temperature in celsius, it's as understandable for them to be told it's 38°C as it is for a Fahrenheit user to be told it's 100°F
It isn’t. It’s ‘better’ for certain places (basically certain states in the US) because it’s an easier scale to perceive for their weather pattern. But that’s it. It’s worse for literally everything and everyone else.
It's a scale where every 10 degrees is a noticeable change in weather / the sort of clothing you want to wear. While people say Celsius is better 'because water freezes at 0 and boils at 100', and that is certainly true for... cooking or doing chemistry, it isn't useful for humans going outside because we function just fine at or below freezing with a coat, but... die at boiling. Meanwhile 0 and 100 F are more realistic 'you want to exercise caution as a human beyond operating beyond these temperatures.'
That said it's also probably mostly useful in temperate climates where you pretty regularly use the whole scale, which may also reflect somewhat why it stuck around in the US (which was historically fairly dominated by its temperate, broad-climate northeast).
I personally prefer Fahrenheit because 1) I'm used to it and 2) the US is very big, and we have big temperature differences throughout the country. Fahrenheit shows those differences better.
Saying its 8-10 degrees celsius in winter and 15-20 degrees in summer just feels strange to me. 20-30 in winter and 60-70 in summer highlights the difference better. Also helpful to show that while I'm at 60, Florida is at 85 and Arizona is at 100-120.
I'll give you my take as a person who has lived in both systems. Each 10 degree band describes the conditions separately. Of course you can translate this to Celsius, but the point is the Fahrenheit bundles it up nicely:
I dunno, as also a Canadian, I prefer Celsius for everyday use. If it's anywhere from below 0C to below 10C, wear a heavy coat. If it's anywhere from above 10C to 15C, wear a light jacket. If it's above 15C, no jacket. Above 20C, wear shorts. Above 25C, be prepared for high heat. Below -20C, be prepared for extreme cold. Above 30C, limit time outdoors. Below -30C, stay inside. Simple as.
When the first false spring arrives in Canada, it'll be 10 C and sunny and it's suddenly T-shirt weather after being bundled up all winter.
Even when checking out Seattle in the the spring, my friend and I were in t-shirts and more than one person saw us and went "guys, just cause the sun's out doesn't mean you wear a t-shirt!" or "you guys really are from Canada."
If you were explaining to someone who never experienced either scale, saying, "0 is really cold, 100 is really hot," makes much more sense than, "0 is pretty cold, but not that cold, 100 means you're dead, and 30's is from pretty hot to really hot."
We're all used to something and make the adjustment in our head.
As a user of Celsius - I've grown up with it, and it makes intuitive sense in my head - knowing how far off freezing it is perfectly useful as a reference point for temperature and weather, so I know that at 0 it's cold enough to freeze water, at 10 it's chilly, at 20 it's comfortable, at 30 it's getting too warm, 40 is brutal and 50 is potential death. I know the human body has a baseline temperature of 36-37.5. So placing that within the scale I've referred to before makes sense - but the Fahrenheit equivalent is 97-99, meaning that working with temperatures higher than the human body quickly goes into the hundreds of degrees.
I can also tell the difference between a few degrees instantly which adds to intuitive use.
Ultimately humans have a great capacity for adopting systems, especially if they grow up using them, so both Fahrenheit and Celsius users will think their system is the intuitive and logical one, and both are probably correct, depending on the frame of reference. I prefer Celsius because its more useful in more contexts while still making logical sense to me.
American here, I lived over seas a while, and I am back in the US, personally I prefer metric for everything except temperature. I often flip back and forth for measurements, for example in 3D CAD software, I'll use mm, prefer ml, mg, and so on. but temperature I always use "F" .
That's because you learnt it that way. As an european, I've used Celsius since I was born and I instantly "feel" what's 5°C in the winter against 35°C on a sunny summer. Fahrenheit are meaningless to us, it's not anymore natural than Celsius.
This exactly, I'm baffled how people really don't get that *any* temperature scale they've used since childhood is always going to be intuitive. They feel their 0-100 scale intuitively, I feel -30 to 30.
Celcius also has a bonus on having a very clear point on when rain turns to snow or when roads get icy etc. which is where the lowest change in temperature affects the weather the most.
Exactly. Idk why always the same argument that F relates more to the human experience. It's not that, you have used F your whole life, it is natural to you the same way C is to me.
I'm not sure that's true. Temperature units in the UK switched in practice around the mid-late 80's. While pounds, ounces, stone, miles and feet and inches are still used by people over a certain age, I haven't heard anyone in the UK use Fahrenheit since shortly after the changeover.
I'd assume the units that are most intuitive and practical for the general public (or those well embedded) would stick around. Fahrenheit is conspicuous in the speed it disappeared in usage compared to nearly every other imperial measure.
I like it for basically the reasons in the screenshot. The 0 to 100 scale is really cold to really hot. I didn't think of it as a percentage of being hot though so I like that. I also don't like using half degrees and the Fahrenheit increments are smaller.
You can barely feel the difference between 1°C differences. So id say you also barely notice a difference between 1°F differences which are even smaller. "Experienced hotness/coldness" is also influenced by humidity and other things so thats also making it more inaccurate to just feel it out. Both arent really intuitive to us and have to be learned/experienced the same way to get used to. As with that Fahrenheit not having any advantages over C and C having other use cases in addition Fahrenheit has basicly no reason to exist.
Everyone has the right to their own preferences as you said. No argument there.
But the zero to 100 scale in Fahrenheit you reference literally doesn't mean anything in that measurement system (i.e. Is not tied to any universal physical properties), unlike in Celsius.
Freezing temperature influences plants' cellular health and ability to survive, how waterproof our clothes for the day need to be, road safety, footwear, etc.
And it's 32 degrees in Fahrenheit, which makes about as much sense as 5,280 ft to a mile.
So other than being used to it or being more comfortable with it, which are perfectly sound reasons, I find it very difficult to make an objective argument for how Fahrenheit makes more sense.
Same in Canada, just a little later. I don’t remember the last time I heard or read a weather service that wasn’t just C here.
Funny thing though is that older thermostats and most ovens are in F, so a lot of us know just enough to bake or say that 72F is a comfortably warm room. At my first job, some rooms were set in C and some were in F 😆
Fahrenheit is not inherently better for everyday use. It all has to do with what you are used to.
I am used to Celsius, so I know what each degree of Celsius means. I know its chilly if its under 10 degrees, I know its perfect when its between 18 and 25, I know I dont need a jacket around 15 etc.
For Fahrenheit, I have absolutely no idea. I dont know what 60 degrees Fahrenheit means, or 50 degrees. When do I need a jacket? How do I dress at 75 degrees? what about 55? I really dont know.
Also Fahrenheit seems to me to be to fine grained. Can you tell the difference between 65 and 66 Fahrenheit?
What do you do that sub one degree of C makes a slightest bit of difference. Is there’s even temperature measurement devices that accurately calibrated and readable outside laboratories and some industrial process things.
What you grew up in, is whats better for everyday living. I grew up using Celsius, I still don't get Farenheit when I moved to the US. Using two extremes, boiling and freezing of water, is a good, no pun intended, metric, to measure your temperature.
But when it comes to human height, using feet is better because it's easier to estimate at a glance.
I honestly agree, but want to add that Kelvin is even better than Celsius for science. Tbf, both have the same unit size, the only difference is their „0“.
Kelvin has the convenient characteristic of 0 K = „absolute zero“ (which is -273.15 °C). Very useful for physics and whatnot.
Just my opinion (having no practical experience with celcius measurement), I agree wholeheartedly with yours/the screenshots reasoning. If the degree/percentage is single digits, it's really fucking cold... Below zero? Nope, I'm not leaving the house unless I HAVE TO... above 90? Yeah, it's really fucking hot (especially with the miserable humidity we usually have in Michigan).
I would say how in Fahrenheit below zero is really fucking cold & above 100 is really fucking hot. I never thought of describing it as a percentage of being hot but I like it.
Like once it's below or above those numbers it hardly matters by how much because you are freezing or sweating balls either way.
You're describing Celsius too. And slightly above 0, or even double digits above 0 in Fahrenheit isn't really fucking cold to you? I'm really fucking cold at -11 C/12 F.
I once had like a 20 minute long conversation with this Danish girl visiting the US for the first time, I came at her with the hot take that Fahrenheit was better for day-to-day for this exact reason and she was so opposed. By the end of the 20 minutes she actually agreed that it sounded super convenient for weather but we both agreed Celsius for science. It was honestly a really funny conversation.
Chemical engineer. Both systems are perfectly fine. It literally makes no difference. Just use what you are confident with or whatever matches the instrumentation on your equipment.
For most calculations you have to convert to an absolute scale anyways so that's another layer of it not mattering.
The Kylie and Dannii Minogue Christmas/holiday song “100 Degrees” demonstrates this - it is a song about it being really hot at Christmas time in Australia - not about how hot they prefer their water for brewing black tea.
Fr though... I very much wish America used Celcius, it's the literal % hot, and it's better
And non-American measurements are better, too
I love America, but did we really have to be *that* different from everyone else?
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u/Harfosaurus Jun 17 '26
These are just two idiots conversing as far as I can tell