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Thread: electronics in space

  1. #1 electronics in space 
    Forum Cosmic Wizard
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    I was told transistors don't do well exposed to radiation, so what happens to them in space where there is lots of radiation?


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  3. #2  
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    Quote Originally Posted by dan hunter View Post
    I was told transistors don't do well exposed to radiation, so what happens to them in space where there is lots of radiation?
    Depends where in space. Earth orbit is pretty benign. Deep space probes generally have hardened electronics. (What you think of as transistors don't care about radiation much, but thin film MOSFET's on IC's are prone to damage.)


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    Quote Originally Posted by dan hunter View Post
    I was told transistors don't do well exposed to radiation, so what happens to them in space where there is lots of radiation?
    Precisely what happens depends on the specific type of radiation and dose, but here are some general observations:

    MOSFETs undergo cumulative threshold voltage shifts, owing to charge deposited in the gate dielectric (or the formation of traps). If these shifts are large enough, the circuits will stop working as expected.

    Bipolar transistors undergo cumulative beta degradation and increase in noise, both as a consequence of recombination centers created from the damage.

    There are transient effects as well, where an ionisation event causes a (hopefully) temporary malfunction.

    Hardening against these effects involves the use of multiple strategies, including shielding (which can be expensive because of weight), careful choice of orbit to avoid high-flux regions, and fault-tolerant device and circuit design.

    Telstar was designed with good estimates of expected exposure. Unfortunately, the US DoD decided to detonate a hydrogen bomb over Hawaii a day before the launch of Telstar. The H-bomb flooded the trajectory with highly energetic particles (mainly betas), frying Telstar's electronics. A heroic effort by ground crews restored some functionality for a few weeks, after which Telstar fell silent permanently.
    Last edited by tk421; April 20th, 2014 at 04:54 PM. Reason: corrected relative launch date for Telstar
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