This would link with what I thought was the most interesting theory about the size of the shell - that it was to observe what happened in Merope between 125-150 years ago.
At first I didn't understand this; but I think I do now but require clarification. Is what you're saying:
- "Aliens" from (possibly) another galaxy haven't heard from their allies for over 125+ years;
- Should the local allies still be alive, arrival of the UPs would have resulted in immediate transmission back to their allies in "another galaxy/place"; But no transmission received, so...
- Perhaps they knew earlier that transmissions stopped but it "took a while" to plan and get here;
- The shell reflects the last position of their lost comrades they knew about;
- The distance reflects the ability (I'm picking this up from what someone else on here commented about a Star Trek NG episode) to "look back in time" to establish what happened at some central point (the 7 Sisters) and view what happened;
- Not understanding what happened, or establishing that the former allies disappeared, now send scout ships to "search for survivors" (Or: CULPRITS!)
Would I be on the right track here with your reasoning?
If so cracking the transmission bar code would be key, but might not be possible.
Back in a while - UP(S!) just turned up with a biscuit delivery and 16 rolls of 30m premium tinfoil...