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All the existent satellite constellations and the proposed ones talk about inter-plane communications as a very challenging issue due to:

  • High relative velocities between satellites
  • Tracking control problems as antennas must slew around
  • Doppler shift

I wonder why a different approach is not considered. Is it possible for a hybrid topology: combining a ring topology with a star topology? In other words, satellites from one plane can communicate among themselves (ring), and if they want to "talk" to a satellite in another plane, they could use a higher orbit satellite (something as a hub) and do the whole routing.

What are the pros and cons fo this approach against typical inter-planar communication?

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It's a good solution to a sticky problem, pointing accuracy is a real pain in the butt on Earth (when you're stationary) let alone when in orbit (not quite so stationary).

The Cons...

  1. MONEY - this is a big one. It's not cheap to get a satellite to orbit. Depending on your requirements, might be as cheap as a couple million dollars or as expensive as a couple hundred million dollars. Whichever number you think is feasible, double it. Now double it again. 1 satellite means the Earth might be between your constellation and your communication hub; 2 could probably do the job though, but what if something does wrong.. heck let's stick a couple of redundancies in orbit as well... which brings me to...
  2. To solve the problem of a constellation you've made a constellation - seriously.. try selling this to the guys who count the money. All these extra satellites actually increase all sorts of risks (eg. Space debris collision, launch failure, etc.).
  3. Does this really fix the issue? A satellite in a high orbit does move slower, and if it's further from the final inter-plane satellite then the relative angular change would be lower. However, the question of what's the ideal orbit soon brings up other problems like communication power requirements (further = bad).

The Pros...

  1. The chosen one - the hub satellite (or satellites) could be fitted with better momentum wheels and communication systems so they can easily target the out of plane satellites. This hardware would likely be heavy and expensive (my phone autocorrected to expansive and it could be that too). You can't afford to outfit your 57 constellation satellites with this kind of gear, who are you Tony Stark!
  2. Duel purpose - or triple, quadruple etc.. This hub satellite system could be used by everyone (for a small fee I'm sure). That means less stuff in orbit, better standardization of satellite hardware and more cash in your pocket!
  3. Redundant redundancies - having satellites in more than one plane helps mitigate the possibility that you'll lose everything in orbit when I test my anti-satellite weapons. No offensive intended.. I picked your constellations orbit by chance.. no it has nothing to do with my competing communications constellation. When something collides or explodes in orbit it could be truly catastrophic for that orbital region.. and I'm talking for hundreds, thousands or millions of years (increases exponentially with altitude).

So that's a few Pros and Cons. Certainly not an exhaustive list. If I ever figure out how to include hyperlinks on the mobile version of SE I'll pepper this with appropriate websites.

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  • $\begingroup$ Could someone please format this for me... list does no equal code apparently! $\endgroup$
    – user6916458
    Commented Nov 7, 2016 at 6:37
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    $\begingroup$ There's another drawback: the high-altitude satellites add lots of latency to the link. That's rather annoying for voice comms. $\endgroup$
    – Hobbes
    Commented Nov 7, 2016 at 12:16
  • $\begingroup$ Oh how appropriate it is that I only noticed your comment 13 hours after you posted! Very true! $\endgroup$
    – user6916458
    Commented Nov 8, 2016 at 2:08
  • $\begingroup$ Thanks for the shared view! I agree with most of the points you have mentioned. I hope that the last case scenario is not a a common practice nowadays though! After further thoughts about this, I would also add the Con of the added complexity to the overall system. Two different satellites architectures to be designed and especially, different launchers requirements for them as well. $\endgroup$
    – B.N
    Commented Nov 13, 2016 at 0:17
  • $\begingroup$ @B.N if you're interested in the last scenario (and it really could happen without any anti-satellite weapons) have a look into Kessler Syndrome (just Google it). I didn't even think of complexity, good catch! $\endgroup$
    – user6916458
    Commented Nov 13, 2016 at 11:21

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