Dear Koala,
Thank you for the welcome! As I informed redwing, I plan to review exhaustively all data collected thus far, in addition to keeping a close eye on new developments.
There maybe objects that have been placed as "signposts" or other stationary communication landmarks which have not been recognized. Certain cultures, (the E-farang of Beti Scuti IV, for example)have a particular fondness for building what appear to be rock contructions under shallow bodies of water (on planets which have water). These constructs not only function as low-orbit markings for subsequent craft, but also reveal biographical information about the builder through the geometric formatting of the rocks. The fascinating thing is that each individual rock also contains information, generally information gathered about the planet. Sort of a litho-encyclopedia for anyone able to decode them.
Obviously we are less likely to find any greeting cards from the E-farang on Mars, due to their fondness for water, as there's been none on Mars for several hundred million years. However, I do not rule out the possibility that we may find other items, even by cultures other than the Ipsolstai.
Much work to do on my part!