13 ms·

Why satellites are manufactured in clean rooms

126 points by ricw 5y ago

sillysaurusx 5y ago
> Once launched into space, satellites can no longer be serviced and contaminations increase the probability of malfunctions occurring during the planned lifetime. Even a single dust particle can interrupt a circuit. How does a single dust particle interrupt a circuit? (I know nothing about this; it's interesting.)
- rtkwe 5y ago
  If it's conductive at all it could bridge contacts on a circuit board.
  - userbinator 5y ago
    Due to https://en.wikipedia.org/wiki/Whisker_(metallurgy) https://en.wikipedia.org/wiki/Whisker_(metallurgy) I believe leaded solder is still the norm for aerospace applications.
    - pipe2devnull 5y ago
      It is, also in my experience boards get a conformal coating to minimize baby risk of FOD being an issue with the electronics.
      - rtkwe 5y ago
        Yeah they do a lot of individual things to bullet proof satellites because you can't repair them and they cost millions (generally, cheaper satellites are starting to be used more and more).
      - marsokod 5y ago
        They do, but for small scale projects like satellites we tend to push con-coat until we have a good confidence the unit is working. Removing conformal coating to replace a failed component or change a resistor can be quite tricky, especially for epoxy based coatings. So there is a long time without any coating (up to spacecraft assembly).
- bArray 5y ago
  I'm assuming it's the connectors and/or soldering. Given the pressure difference I imagine you could see a connector blow off or solder joints explode. I still imagine it's insanely overkill, but when you're paying millions of dollars to send something into orbit, you probably want to make sure it works well first time. With regards to malfunctions, I imagine this risk would actually be better mitigated with (fail-safe) circuit redundancy. After all, radiation is going to be causing bit flips and all sorts of weirdness.
  - edrxty 5y ago
    Space is only ~14 psi of pressure differential from sea level, far less than in your car tires. Nothing is exploding. The issue is mostly off gassing contamination of critical surfaces like optics and sensitive circuit boards.
  - giantrobot 5y ago
    Added circuitry is not free. Every gram or redundancy is one less gram of mission payload. Added circuitry is also increasing the number of failure modes. That's not to say redundancy is bad or should never be considered but it needs to be weighed (literally and figuratively) against every other part of the mission. Optimizing for mass and mission capability means manufacturing will get more expensive.
- dkdk8283 5y ago
  Material science is hard. Conductive contamination will destroy circuits in unpredictable ways. This also makes debugging and future iteration difficult as the satellite cannot be inspected. https://www.ibm.com/docs/en/power9/0009-ESS?topic=floors-conductive-contamination https://www.ibm.com/docs/en/power9/0009-ESS?topic=floors-con...
- senectus1 5y ago
  it might also attract other particles to it, growing it in size and potential to obstruct etc...
- jasonwatkinspdx 5y ago
  Not an expert but I'm acquainted with someone that builds high vacuum stuff for physics experiments. Cold welding is an issue. Essentially if two sufficiently clean metal surface come in contact in sufficient vacuum, they weld together without any heat or liquefaction. So if you had conductive metal dust shavings contaminating the sat, once it's in space they may find their way to a spot where they can create a short circuit. Apparently the welds behave pretty differently from ordinary welds like allowing movement.
- aaron695 5y ago
  > How does a single dust particle interrupt a circuit? It doesn't, it's wrong. Clearly, since massive amounts of dust are on circuits on earth. There are other things on satellites than circuits. > during the planned lifetime. It would be interesting to know how dust moves around on a satellite. Changes in orbit of course. Temperature changes maybe?
- sytelus 5y ago
  I also don't get this. Most circuits are usually vacuum sealed already. Hack, I can drop my iPhone in water, let alone dust. Reminds me of old days when people used to insist that PCs must be kept in air conditioned rooms.
- marsokod 5y ago
  That's a bit of an exaggeration for sure. But dust can be an issue in connectors, making the connection not as stable as expected or even break the connection on a pin if there is enough. There is also the risk of short circuit on non-coated PCB, increased ESD risk. And beyond PCB, there are a lot of other risks mitigated by clean room environments: dust on sensors, dust on bearings or gears, dust on optical cameras... And any deposit of dust will float around everywhere once in orbit, especially after being shaken and vented during launch. Could you make a satellite in your garage without a clean room environment? Yes sure, and you would even have a decent chance to have a working satellite once in orbit if you know what you are doing. Would you accept a 50% failure rate if you are flying a payload worth a few millions and need to spend a similar amount on launch cost? Probably not.
shermozle 5y ago
Great article!
masteruvpuppetz 5y ago
Just to be clear, the article says only one para about the heading "DUST REDUCES THE RELIABILITY OF SATELLITES". Other than that, it talks about cleanliness and standards.
- tsjq 5y ago
  thanks for the TLDR
- gumby 5y ago
  That was so annoying! It was all I wanted to know.
  - Cadwhisker 5y ago
    Yep, me too. It read like a damned advert for clean rooms towards the end.
breput 5y ago
They aren't satellites and they haven't made it even close to orbit yet, but I recently had a chance to make it down to Boca Chica, TX recently where SpaceX is building rockets. Granted the incredibly complex engines are built off-site and only installed at Boca Chica, but the entire facility is a gigantic dusty, oily, noisy construction site with guys in hard hats and driving lifted trucks. My kind of place, tbh. In college I worked at a physics lab that built an instrument that was on the Cassini probe to Saturn. The amount of effort that went into the supply chain and maintaining even jellybean components under a constant nitrogen atmosphere (to prevent any oxidation) was crazy. Meanwhile, Ingenuity[0] is flying around Mars with running Linux and literally off the shelf components[1]. [0] https://mars.nasa.gov/technology/helicopter/ https://mars.nasa.gov/technology/helicopter/ [1] https://www.zdnet.com/article/to-infinity-and-beyond-linux-and-open-source-goes-to-mars/ https://www.zdnet.com/article/to-infinity-and-beyond-linux-a...
- giantrobot 5y ago
  > Meanwhile, Ingenuity[0] is flying around Mars with running Linux and literally off the shelf components[1]. Ingenuity was built in a clean room. It uses some off the shelf components mated to space qualified components. You're describing it like it's a drone from Best Buy that was duct taped to the rover at the last minute.
jtchang 5y ago
All this sounds insanely expensive. Just makes me double down on the fact that it is cheaper to make disposable satellites than make them last forever. Especially if it is cheaper to get them into space as well.
- PabloRobles 5y ago
  The problem is that high performance optical systems are expensive. There are physical limits that forces them to have big mirrors and other expensive and relatively bulky optical elements. Also, there is no mass production due to small batch sizes (typically one or two). So if they have a two year life span, it will not be economically viable.
- OrvalWintermute 5y ago
  It depends on the orbit, the function, sensors, and the size of the satellite. If you want to go to an L2 orbit with a 10,000 Kg satellite with one of a kind sensors (relatively speaking) for earth observations, disposable doesn't make sense. Low earth orbits with low weight satellites, pico/nano/micro/femtos - cheap disposable constellations with mass produced widgets make sense, particularly when you can launch them on another mission.
edrxty 5y ago
This article is missing some big details. Dust is a concern for sure, but it's way more complicated than that. Basically most satellites fall into three camps, communication, optical imaging, and radar imaging. The most sensitive of these are in the optical category. High performance optical satellites (think JWST, Hubble, Kepler, KH-x series, worldview, etc) are absurdly sensitive to contamination. The clean rooms exist in no small part to keep people from using or introducing substances and chemicals that will destroy mirrors, lenses and focal plane arrays (image sensors). By far the biggest threat is anything silicone related as in a vacuum environment, silicone will off-gas and coat optical surfaces fogging them. If this happens on the ground during thermal vacuum testing the satellite would need to be completely disassembled and decontaminated. If it happened on orbit it would effectively kill the satellite. As such volatile compounds that are likely to emit any vapor are carefully controlled during assembly. The other side of the coin is electrical static discharge. Pretty much all satellites are extremely susceptible to this including the optical sats as the focal plane arrays are absurdly sensitive. The white suits you see in the cleanroom are not only to contain dust but also electrically conductive to ground any buildup of static charge. By maintaining a controlled environment with trained workers you can combat this much more easily along with humidity control to reduce buildup of charges. It's worth noting that the charge levels at work here are far lower than the ones you've experienced on doorknobs or are worried about assembling ie. a computer. As little as a few volts of buildup can destroy or degrade some parts and the normal human body can almost instantly build up hundreds of volts just moving around under normal circumstances. Finally a big issue is large FOD (foreign object damage) and having a nice controlled environment is beneficial for keeping it under control. Stuff like hair and wire clippings would be common examples. You need to control that stuff as it can either short out circuits or be heated and vaporize to coat optics/controlled impedance circuits. Everything in space behaves like a giant vacuum plating chamber so the less stuff floating around the better.
- breput 5y ago
  You're not wrong, especially about optical components. But there has been a general overreaction about ESD and milspec/spacespec components since, I don't know...maybe the mid-1970s budget cuts? And we have a lot more knowledge about cosmic rays and other bit flipping events now. It wasn't unusual to launch a Pioneer 10 and 11 or Voyager 1 and 2 back in the day both because the launch vehicle wasn't super reliable and also because the overall system and the environment it was going to wasn't fully known. Now we have Hubble, which initially a disaster but after multiple manned servicing missions, was turned into a glorious scientific instrument. But we also have a couple equivalents sitting around in a warehouse[0] that could have been launched (at least now) for much less money. I'm very concerned that JWST will be the next. [0] https://www.space.com/16000-spy-satellites-space-telescopes-nasa.html https://www.space.com/16000-spy-satellites-space-telescopes-...
retSava 5y ago
How does the launch prep, launch, and deployment compare to the assembly of the sat? I was under the impression that eg fairing separation likely is quite messy, perhaps even metal flakes dropping of due to abrasion and such. Silicone off-gassing perhaps not so much of an concern then.
axg11 5y ago
I hope this article ages badly. We're at the tail end of the "mainframe" age of satellites. Expensive, long development times, low-risk projects. Hopefully with launch prices dropping, satellite development can become cheaper and iteration can become faster. We'll likely always require clean rooms for optical satellites but this doesn't have to be the case for other types.
- yencabulator 5y ago
  For optical, I'd love to see a comparison between standards for terrestrial use mirrors vs satellite ones. Surely the ones used on earth are manufactured well, but end up with dirt on them anyway? Is the difference because the earth based ones can be cleaned earlier during use? Would a future path to better ability for optical imaging satellites to self-clean be a game-changer?

126 points by ricw 5y ago

> Once launched into space, satellites can no longer be serviced and contaminations increase the probability of malfunctions occurring during the planned lifetime. Even a single dust particle can interrupt a circuit. How does a single dust particle interrupt a circuit? (I know nothing about this; it's interesting.)

rtkwe 5y ago
If it's conductive at all it could bridge contacts on a circuit board.
- userbinator 5y ago
  Due to https://en.wikipedia.org/wiki/Whisker_(metallurgy) https://en.wikipedia.org/wiki/Whisker_(metallurgy) I believe leaded solder is still the norm for aerospace applications.
  - pipe2devnull 5y ago
    It is, also in my experience boards get a conformal coating to minimize baby risk of FOD being an issue with the electronics.
    - rtkwe 5y ago
      Yeah they do a lot of individual things to bullet proof satellites because you can't repair them and they cost millions (generally, cheaper satellites are starting to be used more and more).
    - marsokod 5y ago
      They do, but for small scale projects like satellites we tend to push con-coat until we have a good confidence the unit is working. Removing conformal coating to replace a failed component or change a resistor can be quite tricky, especially for epoxy based coatings. So there is a long time without any coating (up to spacecraft assembly).
bArray 5y ago
I'm assuming it's the connectors and/or soldering. Given the pressure difference I imagine you could see a connector blow off or solder joints explode. I still imagine it's insanely overkill, but when you're paying millions of dollars to send something into orbit, you probably want to make sure it works well first time. With regards to malfunctions, I imagine this risk would actually be better mitigated with (fail-safe) circuit redundancy. After all, radiation is going to be causing bit flips and all sorts of weirdness.
- edrxty 5y ago
  Space is only ~14 psi of pressure differential from sea level, far less than in your car tires. Nothing is exploding. The issue is mostly off gassing contamination of critical surfaces like optics and sensitive circuit boards.
- giantrobot 5y ago
  Added circuitry is not free. Every gram or redundancy is one less gram of mission payload. Added circuitry is also increasing the number of failure modes. That's not to say redundancy is bad or should never be considered but it needs to be weighed (literally and figuratively) against every other part of the mission. Optimizing for mass and mission capability means manufacturing will get more expensive.
dkdk8283 5y ago
Material science is hard. Conductive contamination will destroy circuits in unpredictable ways. This also makes debugging and future iteration difficult as the satellite cannot be inspected. https://www.ibm.com/docs/en/power9/0009-ESS?topic=floors-conductive-contamination https://www.ibm.com/docs/en/power9/0009-ESS?topic=floors-con...
senectus1 5y ago
it might also attract other particles to it, growing it in size and potential to obstruct etc...
jasonwatkinspdx 5y ago
Not an expert but I'm acquainted with someone that builds high vacuum stuff for physics experiments. Cold welding is an issue. Essentially if two sufficiently clean metal surface come in contact in sufficient vacuum, they weld together without any heat or liquefaction. So if you had conductive metal dust shavings contaminating the sat, once it's in space they may find their way to a spot where they can create a short circuit. Apparently the welds behave pretty differently from ordinary welds like allowing movement.
aaron695 5y ago
> How does a single dust particle interrupt a circuit? It doesn't, it's wrong. Clearly, since massive amounts of dust are on circuits on earth. There are other things on satellites than circuits. > during the planned lifetime. It would be interesting to know how dust moves around on a satellite. Changes in orbit of course. Temperature changes maybe?
sytelus 5y ago
I also don't get this. Most circuits are usually vacuum sealed already. Hack, I can drop my iPhone in water, let alone dust. Reminds me of old days when people used to insist that PCs must be kept in air conditioned rooms.
marsokod 5y ago
That's a bit of an exaggeration for sure. But dust can be an issue in connectors, making the connection not as stable as expected or even break the connection on a pin if there is enough. There is also the risk of short circuit on non-coated PCB, increased ESD risk. And beyond PCB, there are a lot of other risks mitigated by clean room environments: dust on sensors, dust on bearings or gears, dust on optical cameras... And any deposit of dust will float around everywhere once in orbit, especially after being shaken and vented during launch. Could you make a satellite in your garage without a clean room environment? Yes sure, and you would even have a decent chance to have a working satellite once in orbit if you know what you are doing. Would you accept a 50% failure rate if you are flying a payload worth a few millions and need to spend a similar amount on launch cost? Probably not.

shermozle 5y ago

Great article!

masteruvpuppetz 5y ago

Just to be clear, the article says only one para about the heading "DUST REDUCES THE RELIABILITY OF SATELLITES". Other than that, it talks about cleanliness and standards.

tsjq 5y ago
thanks for the TLDR
gumby 5y ago
That was so annoying! It was all I wanted to know.
- Cadwhisker 5y ago
  Yep, me too. It read like a damned advert for clean rooms towards the end.

breput 5y ago

They aren't satellites and they haven't made it even close to orbit yet, but I recently had a chance to make it down to Boca Chica, TX recently where SpaceX is building rockets. Granted the incredibly complex engines are built off-site and only installed at Boca Chica, but the entire facility is a gigantic dusty, oily, noisy construction site with guys in hard hats and driving lifted trucks. My kind of place, tbh. In college I worked at a physics lab that built an instrument that was on the Cassini probe to Saturn. The amount of effort that went into the supply chain and maintaining even jellybean components under a constant nitrogen atmosphere (to prevent any oxidation) was crazy. Meanwhile, Ingenuity[0] is flying around Mars with running Linux and literally off the shelf components[1]. [0] https://mars.nasa.gov/technology/helicopter/ https://mars.nasa.gov/technology/helicopter/ [1] https://www.zdnet.com/article/to-infinity-and-beyond-linux-and-open-source-goes-to-mars/ https://www.zdnet.com/article/to-infinity-and-beyond-linux-a...

giantrobot 5y ago
> Meanwhile, Ingenuity[0] is flying around Mars with running Linux and literally off the shelf components[1]. Ingenuity was built in a clean room. It uses some off the shelf components mated to space qualified components. You're describing it like it's a drone from Best Buy that was duct taped to the rover at the last minute.

jtchang 5y ago

All this sounds insanely expensive. Just makes me double down on the fact that it is cheaper to make disposable satellites than make them last forever. Especially if it is cheaper to get them into space as well.

PabloRobles 5y ago
The problem is that high performance optical systems are expensive. There are physical limits that forces them to have big mirrors and other expensive and relatively bulky optical elements. Also, there is no mass production due to small batch sizes (typically one or two). So if they have a two year life span, it will not be economically viable.
OrvalWintermute 5y ago
It depends on the orbit, the function, sensors, and the size of the satellite. If you want to go to an L2 orbit with a 10,000 Kg satellite with one of a kind sensors (relatively speaking) for earth observations, disposable doesn't make sense. Low earth orbits with low weight satellites, pico/nano/micro/femtos - cheap disposable constellations with mass produced widgets make sense, particularly when you can launch them on another mission.

edrxty 5y ago

This article is missing some big details. Dust is a concern for sure, but it's way more complicated than that. Basically most satellites fall into three camps, communication, optical imaging, and radar imaging. The most sensitive of these are in the optical category. High performance optical satellites (think JWST, Hubble, Kepler, KH-x series, worldview, etc) are absurdly sensitive to contamination. The clean rooms exist in no small part to keep people from using or introducing substances and chemicals that will destroy mirrors, lenses and focal plane arrays (image sensors). By far the biggest threat is anything silicone related as in a vacuum environment, silicone will off-gas and coat optical surfaces fogging them. If this happens on the ground during thermal vacuum testing the satellite would need to be completely disassembled and decontaminated. If it happened on orbit it would effectively kill the satellite. As such volatile compounds that are likely to emit any vapor are carefully controlled during assembly. The other side of the coin is electrical static discharge. Pretty much all satellites are extremely susceptible to this including the optical sats as the focal plane arrays are absurdly sensitive. The white suits you see in the cleanroom are not only to contain dust but also electrically conductive to ground any buildup of static charge. By maintaining a controlled environment with trained workers you can combat this much more easily along with humidity control to reduce buildup of charges. It's worth noting that the charge levels at work here are far lower than the ones you've experienced on doorknobs or are worried about assembling ie. a computer. As little as a few volts of buildup can destroy or degrade some parts and the normal human body can almost instantly build up hundreds of volts just moving around under normal circumstances. Finally a big issue is large FOD (foreign object damage) and having a nice controlled environment is beneficial for keeping it under control. Stuff like hair and wire clippings would be common examples. You need to control that stuff as it can either short out circuits or be heated and vaporize to coat optics/controlled impedance circuits. Everything in space behaves like a giant vacuum plating chamber so the less stuff floating around the better.

breput 5y ago
You're not wrong, especially about optical components. But there has been a general overreaction about ESD and milspec/spacespec components since, I don't know...maybe the mid-1970s budget cuts? And we have a lot more knowledge about cosmic rays and other bit flipping events now. It wasn't unusual to launch a Pioneer 10 and 11 or Voyager 1 and 2 back in the day both because the launch vehicle wasn't super reliable and also because the overall system and the environment it was going to wasn't fully known. Now we have Hubble, which initially a disaster but after multiple manned servicing missions, was turned into a glorious scientific instrument. But we also have a couple equivalents sitting around in a warehouse[0] that could have been launched (at least now) for much less money. I'm very concerned that JWST will be the next. [0] https://www.space.com/16000-spy-satellites-space-telescopes-nasa.html https://www.space.com/16000-spy-satellites-space-telescopes-...

retSava 5y ago

How does the launch prep, launch, and deployment compare to the assembly of the sat? I was under the impression that eg fairing separation likely is quite messy, perhaps even metal flakes dropping of due to abrasion and such. Silicone off-gassing perhaps not so much of an concern then.

axg11 5y ago

I hope this article ages badly. We're at the tail end of the "mainframe" age of satellites. Expensive, long development times, low-risk projects. Hopefully with launch prices dropping, satellite development can become cheaper and iteration can become faster. We'll likely always require clean rooms for optical satellites but this doesn't have to be the case for other types.

yencabulator 5y ago
For optical, I'd love to see a comparison between standards for terrestrial use mirrors vs satellite ones. Surely the ones used on earth are manufactured well, but end up with dirt on them anyway? Is the difference because the earth based ones can be cleaned earlier during use? Would a future path to better ability for optical imaging satellites to self-clean be a game-changer?