Scientists Investigate Cosmic Chemistry for Clues to Life's Origins
Barnes is scheduled to present the research at the American Chemical Society's (ACS) Fall 2024 meeting, which is being held both virtually and in person from August 18-22. The event will feature around 10,000 presentations on various scientific subjects.
"The first detection of molecules in space was made by Wellesley College alum Annie Jump Cannon more than a hundred years ago," said Barnes. "Our goal is to explore the relative importance of low-energy electrons versus photons in instigating the chemical reactions responsible for the extraterrestrial synthesis of these prebiotic molecules."
While earlier research suggested that both electrons and photons could trigger similar reactions, Barnes and her team's study indicates that the yield of prebiotic molecules from low-energy electrons and photons might vary significantly in space. "Our calculations suggest that the number of cosmic-ray-induced electrons within cosmic ice could be much greater than the number of photons striking the ice," Barnes explained. "Therefore, electrons likely play a more significant role than photons in the extraterrestrial synthesis of prebiotic molecules."
The team's research also has potential applications beyond space. For example, they have studied the radiolysis of water and observed the electron-stimulated release of hydrogen peroxide and hydroperoxyl radicals-compounds that can destroy stratospheric ozone and act as reactive oxygen species in cells. These findings could be relevant to medical fields, such as in cancer treatment, as well as in environmental efforts like wastewater remediation, where high-energy radiation is used to treat water, producing large amounts of low-energy electrons.
In their experiments related to space chemistry, the team replicated extraterrestrial conditions in the lab using an ultrahigh-vacuum chamber and nanoscale ice films. They exposed these films to low-energy electrons and photons to observe the resulting molecular formations. "Although we have previously focused on how this research is applicable to interstellar submicron ice particles, it is also relevant to cosmic ice on a much larger scale, like that of Jupiter's moon Europa," said Barnes.
The research aims to enhance the understanding of data from space missions, including NASA's James Webb Space Telescope and the upcoming Europa Clipper mission, which is slated for launch in October 2024. Barnes hopes their findings will encourage other researchers to include low-energy electrons in astrochemistry models that simulate the processes within cosmic ices.
The team is also investigating the effects of changing the molecular composition of ice films and studying atom addition reactions to determine if low-energy electrons can produce other prebiotic chemistries. This work is being conducted in collaboration with researchers at the Laboratory for the Study of Radiation and Matter in Astrophysics and Atmospheres in France.
"There's a lot that we're on the cusp of learning, which I think is really exciting and interesting," Barnes said, describing the research as part of a new Space Age.
Visit the ACS Fall 2024 program to learn more about this presentation, "Extraterrestrial synthesis of prebiotic molecules," and other science presentations.