4 ms·

As a young engineer working in aerospace I found it both surprising and remarkable that the satellites we worked with were all designed to operate at and around

As a young engineer working in aerospace I found it both surprising and remarkable that the satellites we worked with were all designed to operate at and around room temperature [1]. I could understand that you want to avoid temperature changes as much as possible to avoid stress on the components. But why settle on an arbitrary temperature that is comfortable for humans? Of course I learnt quickly that a room temperature design makes a lot of things much easier;-) [1] An interesting tidbit is that in certain fields room temperature is used as a technical term to really mean a well defined temperature, and that there is a difference between North American (25 °C) and the European (20 °C) convention.

comboy 5y ago
Clueless questions: 1. Assuming it's easy to keep 20C (I thought it's problematic to keep such a low temp for satellite which has problem radiating heat away), what about transfer, is electronics not yet operating back then or do you use some heating elements specifically for bootstrap? 2. Just to be clear 25C is what is used as room temp in electronics and not something you set your thermostat too at home, right? 3. (easily googlable feel free to skip) - how does heat management look for satelatie electronics? Are peltiers used? Do you just put everything in some heat conductive material? Is there some gas sealed around PCB or is it vacuum? In case of the latter and if everything is not surrounded by some heat conductive substance how do you deal with thermal runaway? Is maybe PCB itself and paths enough to make it less bad than I imagine? Thanks a lot, I'm sorry about so many questions, just got curious.
- souprock 5y ago
  25C is something you set your thermostat to at home. Well, it would be 77F, which is the same. (note: Florida Man Sets Thermostat)
madengr 5y ago
I have designed some satellite microwave PA, and the thermal ranges were -20C to +70C, but yes, not even an industrial temperature range. The biggest issue is getting heat out, though my module was on a cold plate and I doubt it was ever cycled to those ranges. The concern was keeping output power and current within spec over those ranges; getting enough output power (within distortion specs) at hot, and keeping the current under spec at cold (so as not to trip a breaker).

comboy 5y ago

Clueless questions: 1. Assuming it's easy to keep 20C (I thought it's problematic to keep such a low temp for satellite which has problem radiating heat away), what about transfer, is electronics not yet operating back then or do you use some heating elements specifically for bootstrap? 2. Just to be clear 25C is what is used as room temp in electronics and not something you set your thermostat too at home, right? 3. (easily googlable feel free to skip) - how does heat management look for satelatie electronics? Are peltiers used? Do you just put everything in some heat conductive material? Is there some gas sealed around PCB or is it vacuum? In case of the latter and if everything is not surrounded by some heat conductive substance how do you deal with thermal runaway? Is maybe PCB itself and paths enough to make it less bad than I imagine? Thanks a lot, I'm sorry about so many questions, just got curious.

souprock 5y ago
25C is something you set your thermostat to at home. Well, it would be 77F, which is the same. (note: Florida Man Sets Thermostat)

madengr 5y ago

I have designed some satellite microwave PA, and the thermal ranges were -20C to +70C, but yes, not even an industrial temperature range. The biggest issue is getting heat out, though my module was on a cold plate and I doubt it was ever cycled to those ranges. The concern was keeping output power and current within spec over those ranges; getting enough output power (within distortion specs) at hot, and keeping the current under spec at cold (so as not to trip a breaker).