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Cambridge University Science Magazine
Using the aptly named icebox-type Himalaya instrument, researchers at NASA’s Jet Propulsion Laboratory in California show how the soot-like ice on the outside of the comet would form crystals and harden when it came near to the sun- a bit like the top of a crème brûlée with a blow torch.

This deep-fried ice cream-like structure is not news to scientists; NASA’s Deep Impact and the ESA’s Rosetta crafts have both been able to feed back valuable close-up information of the comet’s outer shell. Exactly what makes up the surface though, and how it forms are uncertain.

In a new approach, researchers have turned their attention back to Earth to try and answer this question. They created porous (amorphous) ice (thought to make comets and cold moons) and supplemented it with polycyclic aromatic hydrocarbons (PAHs) found everywhere in deep space. Temperatures on Earth are not cold enough to make porous ice (all of the ice surrounding us is crystalline and has been formed relatively slowly) and so the scientists had to flash-freeze water to maintain its chaotic state and achieve their goal.

When the team slowly warmed their porous ice to mimic the Sun’s effects, they found that the PAHs were expelled to the surface, forming tightly packed crystalline ice. The team hope that this information will help us to understand how comets may have carried the building blocks of life to our planet.

The above story is based on information provided by NASA and the Jet Propulsion Laboratory.


Written by Joanna-Marie Howes.