Planetary Science

Coloring Europa with Impacts

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Science  07 Mar 2003:
Vol. 299, Issue 5612, pp. 1487
DOI: 10.1126/science.299.5612.1487a

The Galileo spacecraft sent home stunning images of Europa. Its water-ice surface was covered with arcuate cracks, finely to coarsely hachured areas, chaotic terrains, and, perhaps most dramatically, more colors than expected for an icy body. Some of the brown-yellow ice patches may be due to contamination of the water-ice surface by solid organic macromolecules. Laboratory experiments have shown that macromolecules can be produced in gas mixtures and on ices by energetic reactions with carbon, nitrogen, and water.

Borucki et al. considered possible sources of energy on Europa and tested the possibility that hypervelocity impacts of small meteors are involved by performing shock wave experiments on ice. Three types of electrical discharges occurred in their experiments: a short-duration pulse associated with the impact; a longer, secondary pulse associated with the propagation of cracks after impact; and a short, tertiary pulse associated with plasma-like reactions. All three types could supply enough energy to create organic macromolecules in Europan ice. — LR

J. Geophys. Res. 10.1029/2002JE001841 (2002).

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