Astronomers tinkering with ice and organics in the lab may have discovered why comets are encased in a hard, outer crust.
Using an icebox-like instrument nicknamed Himalaya, the researchers show that fluffy ice on the surface of a comet would crystalize and harden as the comet heads toward the sun and warms up. As the water-ice crystals form, becoming denser and more ordered, other molecules containing carbon would be expelled to the comet's surface. The result is a crunchy comet crust sprinkled with organic dust.
"A comet is like deep fried ice cream," said Murthy Gudipati, a principal scientist at JPL and corresponding author of a recent study appearing in The Journal of Physical Chemistry. "The crust is made of crystalline ice, while the interior is colder and more porous. The organics are like a final layer of chocolate on top."
The lead author of the study is Antti Lignell, a postdoctoral scholar in Caltech's Division of Chemistry and Chemical Engineering, who formerly worked with Gudipati at JPL. Caltech manages JPL for NASA.
Written by Whitney Clavin