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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
by 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-...
- edrxty 5y agoI'm not sure what you mean. ESD is a big deal with sensors, namely optical FPAs and ADCs for radios. Their voltage tolerance is well established and the ESD generated by humans is easily measured. It's not that this stuff isn't necessary or we don't understand it so we overreact, it's a calculated risk decision that's currently changing with cheaper launch costs. Satellites are starting to get smaller as the components are being miniaturized much like most tech and launch costs are falling. Small-sats are frequently built in much less strict clean environments and instead of massive controlled transporters, are shipped in crates by Fedex. It just depends on the reliability profile of the mission and the type of instruments in use.
- breput 5y agoESD is a huge deal with passive component too, and honestly even with components that you never thought could fail in the past like resistors, lately. Obviously an instrument that is never going to be serviceable deserves the best components and handling, but they will fail eventually and you either have a redundant circuit or another fallback.
- breput 5y agoI guess my only point was that I've seen both approaches - you either over-spec the components and when it doesn't fail like you think the spec was the secret, or you design for unreliable parts and when they don't fail as expected, you look like a genius.
- Cadwhisker 5y agoIn addition to the above, the effects of ESD are cumulative. You may think you're getting away with not following correct ESD procedures until one day something stops working and you're left wondering why, because nothing you did has changed.
- bryananderson 5y agoOne of the “equivalents” will be launched in a few years as the Nancy Grace Roman Space Telescope (formerly WFIRST). It isn’t quite an equivalent: it was designed to image the Earth, not distant objects. It has a wider field of view than Hubble, but is less useful for imaging distant galaxies and exoplanets in detail. Unfortunately it also doesn’t deliver the expected cost savings, since the telescopes came without instruments or electronics. Different people at NASA made different estimates, but most showed the NRO telescope as being roughly a wash compared to the earlier WFIRST concept, and it has overrun its cost substantially since then.
- credit_guy 5y agoIf these satellites were designed to point at Earth, why didn't they donate them to NOAA, instead of NASA? Or why isn't NASA giving them to NOAA now?
- bryananderson 5y agoA condition of the NRO donation was that the telescopes must not be used for Earth observation.