Why Comets Are Like Deep Fried Ice Cream

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.

Read the full story at JPL News.

Written by Whitney Clavin