BINGO!!!!More likely the Guardians. An ammonia prepped planet would not have been much use for humans (except for all the barnacles).
Attempts at terraforming Mars failed, until shortly after the relic was discovered. The relic may have given blue prints or started a hidden terrafoming machine.
The relic could also be unrelated to the terraforming, but that wouldn't be much fun.
"The Alien World: A Complete Illustrated Guide" by Steven Eisler (aka Robert Holdstock) actually stated the Guardians (the Tholmathon in TAW) had a colony on Earth and Mars in the Permian and that "no artifacts of such martians had ever been found". Tholmathon died officially via civil war just like the Guardians (though there were some external factors too). Well, apparently, that Mars Non-Human artifact might just be Guardian. The Oisir-Raxxla were also in Sol very early and built focusers for the Talmor Lens at Earth (or its nearby vicinity - personally I lean towards this is the lore reason for the Moon permit). Humans also in the book are stated as having had colonies on the Moon (in fact the Moon lander is one of the first things mentioned) and this may have been hinted at in official Elite lore via tourist beacons. We found something on Moon and the Federation permit locked it (well the Club -- read up on presidential succession in Sol). They then find something on Mars bury it in a safe and pray it never sees the light of day. I think the true story of Elite Dangerous is a lot more like the books than anyone has dared thought possible.