Abstract:
Astrobiology
undoubtedly begins with the formation of prebiotic molecules in
interstellar clouds. The inventory of interstellar molecules
presently stands at ~140 different species. In the last two years,
our team has used the GBT to detect 8 new interstellar molecules --
all are large (6 to 11 atoms), organic, and prebiotic in some
measure. The reason for this unprecedented success is three-fold: The
GBT is very sensitive with substantial beam efficiency in the range
of 300 MHz to 50 GHz; the rotational transitions between low-energy
levels of most prebiotic molecules fall in the range of 300 MHz to 50
GHz; and the GBT beam couples well to prototypical prebiotic molecule
sources (e.g., SgrB2[N-LMH] and TMC-1) which are found to be very
cold (~10 K) and spatially extended. Thus, we propose to conduct a
GBT legacy spectroscopic survey of SgrB2(N-LMH) and TMC-1 in order to
provide a complete inventory of known and unidentified species in the
range of 300 MHz to 50 GHz. This survey will be the deepest spectral
line survey to date toward these sources and the data will be
provided to the astronomical community on a quarterly basis (as
available) as data accumulate in order to facilitate the
identification of new interstellar species and
deduce likely molecular formation chemistry.