Sunday, January 25, 2015

Comet 67P surprises

In August 2014, the European Space Agency’s Rosetta spacecraft arrived at comet 67P/Churyumov-Gerasimenko. Once in orbit, it swooped as low as 10 kilometers to get unprecedented data from the comet.

Images reveal 67P to be a far more diverse place than anyone expected.

Due to the comet’s lopsided shape and weak gravity, boulders and dust appear to move in strange ways. In this image, red regions show unstable slopes that sit at more than 45° angles to the local gravity field.

A pit that seems to have belched out a fluid material—a sign that gas pressures can build up in the subsurface and create complex, fluid mixtures of gas and dust.

The gases don’t only shoot up; they may also work sideways, creating ripples and other wind-like features that look out of place on a body without an atmosphere.

The comet spews material into space from the pits that dot the surface. Some are inactive and are partly filled with dust. Others appear to be turning on again: As 67P approaches the sun, subsurface ice deposits heat up and create jets of gas and dust.

67P might not keep its shape for long. Cracks around the neck suggest that the comet’s “head” and “body” flex there. Someday the two lobes could rupture and go their separate ways.