Impact-Induced Chemistry on Exoplanets
There is strong evidence that the Earth experienced a number of large impacts during the first 700 million years of its history. These impacts may have temporarily transformed Earth’s atmosphere from a neutral CO2/N2 rich atmosphere to a reducing, warm Titan-like atmosphere. If this transformation occurred, a large amount of hydrogen cyanide (HCN) would be generated in the atmosphere, raining down on the surface to be preserved by any reduced iron in the form of ferrous cyanide and other organometallic compounds. These compounds, when combined with water in the presence of ultraviolet light, can form the building blocks of life. It is likely that some exoplanet systems, plausibly including the TRAPPIST system, are experiencing or have recently experienced periods of heavy bombardment. Observations by JWST may be able to detect molecular signatures of these impacts, and could be used to better constrain the chances of starting life on other planets, as well as the means by which life may have originated on our own.