Detection of complex molecules in planetary atmospheres with high-resolution infrared spectroscopy
The atmospheres of planets and moons in the outer solar system - such as Jupiter, Saturn, Neptune, Titan, Triton and Pluto – are hydrogen and methane-rich, chemically-reducing environments. These atmospheres favor photochemically-driven organic chemistry, leading to the formation of complex molecules such as benzene (C6H6), cyano-acetylene (HC3N) and ethyl cyanide (C2H5CN). Of these worlds, Titan leads the pack with by far the largest number of atmospheric molecules in any planetary atmosphere detected by remote sensing (24), not to mention many more detected directly by in-situ mass spectroscopy. In this regard, these worlds exceed the known molecular complexity of the more oxidizing atmospheres of the inner planets such as Venus and Mars. On Titan, six new molecular detections have come via remote sensing in the past decade: two by IR spectroscopy (propene, propadiene) and four by sub-millimeter astronomy. Efforts are currently underway to make further new detections on Titan using SOFIA-EXES, and will be reported on in this talk. The next generation of SOFIA instruments presents an opportunity to further increase the capability of SOFIA to assist with molecular hunting in planetary atmospheres, both for solar system planets and for exoplanets. Capabilities such as wider spectral grasp, more sensitive detectors and other improvements could greatly enhance SOFIA’s ability to pursue the important astrobiological question of the formation of complex molecules in the universe.