The prime directive of the Shanghai-Hawaii-Hefei Advanced Research Center for Astrochemistry is to explore experimentally in an innovative ultra-high vacuum space simulation chamber coupled to a vacuum ultraviolet (VUV) beamline of a synchrotron the formation of key classes of complex organic molecules (COMs) – organics containing atoms of carbon, hydrogen, oxygen, nitrogen, and phosphorus - upon interaction of ionizing radiation in the form of Lyman α photons with interstellar ice analog samples and to constrain the level of molecular complexity that can ultimately be synthesized in the interstellar medium (ISM). These key classes are amino acids (C1), sugars (C2), nitrogen bases (C3), phosphates (C4), glycerol (C5), and fatty acids (C6) along with their polypeptides (B1), nucleotides (B2), adenosine triphosphate (B3), phospholipids (B4), and triglycerides (B5) linkages. Those species resemble vital molecular building blocks in contemporary biochemistry connected to genetic information, cellular energy storage, cell membranes, and metabolisms. Since the densest parts of molecular clouds eventually undergo gravitational collapse leading to material, which in turn supplies the basic ingredients for Solar Systems including our own, our studies also define the key classes of COMs synthesized in deep space prior to their delivery to early Earth via comets and meteorites thus providing the feedstock of organic molecules for the earliest stages of biochemical evolution and hence for the Origins of Life. Those objectives are achieved by systematically replicating the conditions of ice-coated interstellar grains in a next-generation ultra-high vacuum surface scattering machine through the exposure of interstellar ice analog samples resembling ices in cold molecular clouds as well as in low- and high-mass star forming regions at astrophysically relevant temperatures) to ionizing radiation in form of Lyman α photons (10.2 eV) and electrons as a proxy of secondary electrons generated by galactic cosmic rays (GCRs) penetrating interstellar ices. Compared to previous studies, we follow a radically different approach and apply for the very first time a transformative methodology by probing the synthesis of COMs upon their sublimation into the gas phase via tunable, near threshold fragment-free vacuum ultraviolet (VUV) photoionization exploiting quasi continuous light from a synchrotron. This unique space simulation chamber allows the extraction of transformative concepts on the synthesis of biorelevant COMs in deep space upon exposure to ionizing radiation by exploiting a novel and unique technology through the implementation of cutting edge photoionization techniques.
The significance of this project is that our studies elucidate for the first time the origin of biorelevant molecules in deep space and in our Solar System, define the level of molecular complexity which can be achieved, and transform our knowledge of the chemical and astrobiological evolution of the interstellar medium and of our Solar System. Since icy planetesimals have been observed around stars like Fomalhaut and Vega as well, this strategy predicts an inventory of biorelevant molecules, which could have seeded the evolution of life in extrasolar systems thus revolutionizing our understanding of the origin of cosmic life as we know it and eventually revealing the molecular birthplace of life.
The centerpiece of the Shanghai-Hawaii-Hefei Advanced Research Center for Astrochemistry is a novel ultra high vacuum (UHV) surface science machine cable of mimicking the chemical evolution of extraterrestrial ices in deep space. This setup is one of its kind and allows for the very first time a systematic investigation of the formation of key classes of biorelevant molecules in low temperature ices by ionizing radiation under a wide range of conditions (radiation, temperature, (mineral doped) ices). Organics will be identified on line and in situ via novel synchrotron based mass spectrometry at the Astrochemistry Beamline of the National Synchrotron Radiation Laboratory (NSRL) of China (Hefei) interfaced for the very first time to a space simulation chamber. Synchrotron light has several key advantage compared to laser based experiment such as a tunability from 7 eV to 15 eV, an enhanced duty cycle by a factor of at least 106, and the capability to carry out experiments with intense beams of circularly polarized light – a crucial prerequisite to untangle the source homochirality as found in sugars and aminoacids in contemporary terrestrial biochemistry. Therefore, considering the availability of tunable vacuum ultraviolet light at the synchrotron, the Shanghai-Hawaii-Hefei Advanced Research Center for Astrochemistry is exceptional in its combination of scientific and technological capabilities standing at the forefront of astrochemically related research. The center structure breaks down the barriers and cultivates new collaborations that would not be possible otherwise with the pooled innovations and complementary research expertise being considerably more than just the sum of the parts.
This endeavor comes at an exciting time for space exploration and is particularly timely offering a once in a life-time opportunity for discovery as evident from the recently commissioned Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST), the James Clerk Maxwell telescope (JCMT) on Mauna Kea, and the prospective Thirty Meter Telescope (TMT). The new center will play a critical role in an understanding of the astronomical data obtained from those telescopes by merging them with experimental results from our Center.