Saturn’s Icy Moon May Hold the Building Blocks of Life
This artistic rendering shows ice plumes being ejected from Enceladus at speeds of up to 800 miles/hour.
NASA
As astrophysics technology and research continue to advance, one question persists: is there life elsewhere in the universe? The Milky Way galaxy alone has hundreds of billions of celestial bodies, but scientists often look for three crucial elements in their ongoing search: water, energy, and organic material. Evidence indicates that Saturn's icy moon Enceladus is an 'ocean world' that contains all three, making it a prime target in the search for life.
During its 20-year mission, NASA's Cassini spacecraft discovered that ice plumes spew from Enceladus' surface at approximately 800 miles per hour (400 m/s). These plumes provide an excellent opportunity to collect samples and study the composition of Enceladus' oceans and their potential habitability. However, until now, it was not known if the speed of the plumes would fragment any organic compounds contained within the ice grains, thus degrading the samples.
Now, researchers from the University of California San Diego have shown unambiguous laboratory evidence that amino acids transported in these ice plumes can survive impact speeds of up to 4.2 km/s, supporting their detection during sampling by spacecraft. Their findings appear in The Proceedings of the National Academy of Sciences.
Beginning in 2012, UC San Diego Distinguished Professor of Chemistry and Biochemistry Robert Continetti and his co-workers custom-built a unique aerosol impact spectrometer designed to study collision dynamics of single aerosols and particles at high velocities. Although not built specifically to study ice grain impacts, it turned out to be exactly the right machine to do so.
"This apparatus is the only one of its kind in the world that can select single particles and accelerate or decelerate them to chosen final velocities," stated Continetti. "From several micron diameters down to hundreds of nanometers, in a variety of materials, we're able to examine particle behavior, such as how they scatter or how their structures change upon impact."
In 2024, NASA will launch the Europa Clipper, which will travel to Jupiter. Europa, one of Jupiter's largest moons, is another ocean world, and has a similar icy composition to Enceladus. There is hope that the Clipper or any future probes to Saturn will be able to identify a specific series of molecules in the ice grains that could point to whether life exists in the subsurface oceans of these moons, but the molecules need to survive their speedy ejection from the moon and collection by the probe.