If the UPs had been created by Feds from UAs then UPs would be pointing to, and sending their transmission to, a planet in Fed space, not Merope 5C! The UPs are now sending that transmission, so it's nothing to do with any historical launching of them from 5C hundreds of years ago.
5C is logically at the heart of this puzzle. Since there is no Imp or Fed base there then there is something else's base there, as we can't find it then it has been hidden there. Tie that in with the Galnet hint of metamaterials being able to bend light in strange ways and you have the basis for a camouflage mechanism. How do we uncover that camouflaged presence- the obvious things are either (a) the UP EMP or (b) Electronic Countermeasures since Galnet recently hinted they may be derived from alien technology.
I was just reading the GalNet article about the Thargoids...
https://community.elitedangerous.com/galnet/uid/57ada8969657baeb6e876c6c
...and then this (above), and not having played the earlier games, it sounds, from the article, like things went sort of this way (which probably kinda matches what happened in the earlier games, i assume):
- Colonists kill Thargoid "first contact" party
- Thargoids begin attacking human ships in witch-space in retaliation
- INRA develops mycoid virus and infects Thargoid ships and Thargoids themselves
- Thargoids vanish, as far as we know for a long time, probably trying to deal with virus and figure out retaliatory plan
Well, if *I* were them, I'd be tempted to try to respond in kind. Rather than trying to shoot human ships down, I'd go for the 'disabling their ships and themselves' approach to attack the enemy from within.
But to make sure a plan work, you'd need to experiment.
First, you need to be able to reliably identify the enemy's ships. Oh wait, UAs learned how to do that. (At first they could identify their surroundings so they'd know where they were, then they learned/adapted to improved accuracy to the point where they could identify ships. We know they learned to identify the shape, but who's to say they don't (or won't learn to) record and/or transmit much more specific information about us, to the point of either identifying human ships apart from other types of ships (Thargoid ones?) to know how to respond, or even individual ships themselves (i.e., one Cobra from another, using their unique energy patterns, etc.) And those little canisters on the UAs? For now, they've been (as far as we know) idle, but who's to say those couldn't eventually turn up to be bombs.... or filled with infecting agents that could infiltrate our ships or ourselves. And how do you get close enough to humans to test all this? That's easy -- just put them in non-hostile mode and let human curiosity do the rest. (The Thargoids had lots of encounters with us before, and certainly would've had a lot of time to discreetly study humanity since our last run-in.)
Another thing that would be really handy is the ability to disable ships. So, devise a prototype device for that, too. UPs. Send them out. But since these are more "hostile" by design -- disabling a ship rather than just scanning it -- would you have to put them someplace more out-of-the-way? Or maybe you've got multiple bases out there, doing concurrent development of the various prototypes and modules needed for your ultimate plan.
but in each case, each prototype orients itself in some way pertaining to the Merope system. Either this is for functional reasons -- perhaps there's a hidden base there, or a relay which then transmits test results back to the Thargoids. Or perhaps, knowing humanity's weakness -- its curiosity -- you point them first to the Merope system itself, and then to Merope 5C, and maybe eventually to a specific location (if we eventually discover the third and final form of the artifact/probes; the one with both ship-disabling capabilities AND the canisters of destruction) where they will gather, like rats to a trap, for slaughter.
In the mean time, things go better than you could perhaps have hoped, as the major influences in human space -- the Federation and the Empire and perhaps others -- also bring more and more forces to this place YOU have designated, like flies to honey. Capital ships, bases, more and more humans themselves, all ripe for the slaughter. And all you had to go was just POINT them there.....
TOO easy.
Soon...... very soon. They will pay for what they've done to us. What they've ... turned us into with their horrific virus. Payback will be so, so sweet.
(Or something like that. Just throwing it out there. )