SETI
From Memory Alpha, the free Star Trek reference
SETI, which stands for "Search for Extra Terrestrial Intelligence", was a 20th century Earth effort to explore, understand and explain the origin, nature and prevalence of life - most notably alien intelligence - in the universe.
The SETI greeting was displayed on a plaque on the hull of such NASA probes as Voyager 6 and Pioneer 10. (Star Trek: The Motion Picture; Star Trek V: The Final Frontier)
In a revised 1996 Earth timeline, a young researcher, Rain Robinson, detected the USS Voyager and transmitted the standard SETI greeting. (VOY: "Future's End")
