Radio Astronomy and Spectroscopy: Bell labs to ALMA

For many, it was hard to comprehend that the search for the first molecules in space at radio frequencies in the late 1960’s would lead to the wealth of interstellar molecules that we see today — a total that is well over 200 individually detected species and several factors more if all isotopologues and higher vibrational states are included. The prevailing attitude at the time was that the physical conditions in astronomical environments were too harsh to drive the formation of any molecules, let alone molecules more complex than simple diatomic hydrides. Yet, against all odds, the science of radio astrochemistry accelerated, especially after the early detections of water (H₂O), ammonia (NH₃) and formaldehyde (H₂CO) between 1968 and 1969. This presentation will cover these first early detections with single dish telescopes, through the search, detection and subsequent non-detection of several molecules that are considered significantly biologically interesting and the concluding with future prospects of new molecule searches with new facilities (e.g. SKA and ngVLA) and new analysis techniques (e.g. machine learning, MCMC and matched filters).