3
$\begingroup$

In this answer the recent question Are and should satellites use wireless communication internally, rather than cables? it is stated that:

This is actually an open research area and despite everyone here seeming to think it's a bad idea, companies still want to do it....

note: I'm going to use the term 'radio' for internal point-to-point data links. While some would call it 'wireless', other's would say that wireless includes free-space optical (IRDA would be am historical example but there will be others)

If the goal for those companies is to reduce spacecraft mass by replacing data communications cables (one example of that would be Ethernet cables but there are others) and their associated electronics with radio (one example of which would be WiFi but there are others), wouldn't a better choice be the use of Plastic Optical Fiber (POF)?

This could potentially provide the same high speed network architecture as a hard wired network, while radio might create a nightmare of hot-spots and dead spots within a spacecraft, requiring major mechanical redesign.

Multi-mode POF is often made from PMMA with a diameter of a few hundred microns to almost 1 millimeter, and I don't know if there are issues with radiation damage - would the attenuation of light in the range 750 to 950 through say 10 meters of the stuff be a problem? For short distances (tens of meters) POF has been demonstrated to Gigabit/sec speeds and is much more forgiving to bends and connection issues compared to the single mode or few mode glass optical fibers used in long haul.

I'm not in any way advocating this, I'm asking if this would be a better choice than intra-spacecraft radio when spacecraft mass reduction is the goal, as discussed in the linked question and answer.

Read more at ieee802(dot)org (two sources in case one link rots):

Random examples - no affiliation:

$\endgroup$
  • 2
    $\begingroup$ This is a guess, but that key word "plastic" might be part of your answer. Lots of plastics that work just fine on Earth can do really nasty things in space - they turn brittle in the cold, they shrink, they expand, they outgas and deposit themselves on other components. Are you asking specifically about these POF cables, or about optical fiber in general? $\endgroup$ – Bear Dec 8 '16 at 13:43
  • $\begingroup$ @kekenkenka Apparently it is a "proven" technology in automotive applications including "terrestrial winter cold" and "engine compartment hot" but I suspect spacecraft components should tolerate larger extremes even while in use, and even larger extremes during deployment, or an unexpected event without catastrophic failure. And while most optical telecom hardware will have some spec (since optical surfaces are nearby, and could be mixed in proximity with glass SMF where even tiny contamination can be catastrophic due to high power density) temperature extremes combined with vacuum may be unte $\endgroup$ – uhoh Dec 8 '16 at 14:08
  • 2
    $\begingroup$ Thermal considerations are important, but the key limiting factors regarding use of plastic in space are vacuum compatibility (specifically outgassing and degradation due to loss of volatile compounds), UV exposure (much worse than terrestrial applications and absolute murder on most plastics), and atomic oxygen compatibility (especially problematic for carbon-based polymers, which can completely erode away given enough exposure -- silicone polymers do much better, but there are still issues). $\endgroup$ – Tristan Dec 8 '16 at 18:45
  • $\begingroup$ @Tristan that makes a lot of sense, thanks! In this internal, optically shielded application it probably won't receive much UV radiation from the Sun, but damage from other forms of radiation (from Sun and space) could be substantial, considering it must remain transparent as the light passes through meters or tens of meters of thickness. Small craft in LEO may be especially "leaky" and let in atomic oxygen and that's certainly something to watch out for. Loss of volatiles would have to be addressed head-on. These are really insightful points! $\endgroup$ – uhoh Dec 9 '16 at 0:04
  • $\begingroup$ For Gigabit/sec over a distance of only 10 m no plastic or glas fiber is needed, a copper cable will do. $\endgroup$ – Uwe Nov 12 '18 at 20:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.