These objects, however, are nonetheless artifactual, not products of the mindless interplay of wind, rain, gravity, etc. Some of those tools in the Smithsonian are pretty crude, although they might have been really high-tech for their time. I'm trusting the archeologists on that one, that they can see design where the uninitiated might see merely an oddly-shaped lump of stone. An apparently random pattern of letters might be a coded message. Cryptographers detect and interpret codes.
Space is full of radiation of various frequencies.
We scan the skies for evidence that some of those waves have been emitted by an alien intelligence. We find a body at the bottom of a cliff. We search for clues. Let us assume that there actually is no good reason for science to arbitrarily restrict the scope of its investigations just because the topic under discussion is living things rather than non-living. I don't see why not.