Are We on the Verge of a New Space Age? Discover the Chemistry Behind the Mysteries
Who are we? Why are we here? As the Crosby, Stills, Nash & Young song suggests, we are stardust—products of cosmic chemistry in vast interstellar clouds. To understand how this chemistry might create prebiotic molecules—the seeds of life on Earth and possibly elsewhere—researchers have examined the role of low-energy electrons generated by cosmic radiation interacting with ice particles. These findings may also impact medical and environmental applications on Earth.
Undergraduate student Kennedy Barnes will present her team’s results at the fall meeting of the American Chemical Society (ACS), held virtually and in person from August 18-22, 2024. This meeting features about 10,000 presentations on various science topics.
“The first detection of molecules in space was made by Wellesley College alum Annie Jump Cannon more than a hundred years ago,” says Barnes, who, along with fellow undergraduate Rong Wu, led this study at Wellesley under the guidance of chemistry professor Christopher Arumainayagam and physics professor James Battat. Since Cannon’s discovery, scientists have been keen to understand how extraterrestrial molecules form.
“Our goal is to explore the relative importance of low-energy electrons versus photons in initiating the chemical reactions responsible for extraterrestrial synthesis of prebiotic molecules,” Barnes explains.
Previous studies suggested that both electrons and photons could catalyze similar reactions. However, Barnes and her colleagues’ research indicates that the yield of prebiotic molecules from low-energy electrons and photons might differ significantly in space.
“Our calculations suggest that the number of cosmic-ray-induced electrons within cosmic ice could greatly exceed the number of photons striking the ice,” Barnes notes. “Therefore, electrons likely play a more significant role than photons in extraterrestrial prebiotic molecule synthesis.”
Barnes’ research into low-energy electrons and radiation chemistry also has implications on Earth. Her team recently studied the radiolysis of water, observing electron-stimulated release of hydrogen peroxide and hydroperoxyl radicals, which can damage stratospheric ozone and act as reactive oxygen species in cells.
“Our findings could be applied in medical contexts, such as using high-energy radiation for cancer treatment,” Barnes says. “We are also investigating how low-energy electrons affect DNA molecules.”
Additionally, their research is relevant to environmental remediation efforts where high-energy radiation is used to treat wastewater, producing low-energy electrons that help destroy hazardous chemicals.
To explore prebiotic molecule synthesis, the researchers simulated space conditions in the lab using an ultrahigh-vacuum chamber with an ultrapure copper substrate cooled to ultralow temperatures. They employed an electron gun and a laser-driven plasma lamp to bombard nanoscale ice films with electrons or photons to observe the resulting molecules.
“Although our focus has been on interstellar submicron ice particles, this research is also relevant to cosmic ice on a larger scale, such as the 20-mile-thick ice shell of Jupiter’s moon Europa,” says Barnes.
She hopes their findings will aid astronomers in interpreting data from space missions like NASA’s James Webb Space Telescope and the Europa Clipper, expected to launch in October 2024. Barnes encourages other researchers to integrate low-energy electrons into astrochemistry models simulating cosmic ices.
Barnes and her team are also experimenting with different molecular compositions of ice films and exploring atom addition reactions to see if low-energy electrons can produce other prebiotic chemistries. This work is in collaboration with the Laboratory for the Study of Radiation and Matter in Astrophysics and Atmospheres in France.
“We’re on the brink of discovering new insights, which is truly exciting,” says Barnes, heralding what she views as a new Space Age.
Source: Are We on the Verge of a New Space Age? Discover the Chemistry Behind the Mysteries
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