Spacecraft Draws Closer to its Comet Quarry

A European Space Agency (ESA) craft will soon become the first to orbit a comet and land a probe on its surface. Even now, as the Spacecraft draws closer, scientists are learning new things about comet behavior.

The ESA has released an image that the unmanned Rosetta spacecraft snapped earlier this month showing the comet 67P/Churyumov-Gerasimenko as it streaks through our solar system.

However, it appears that the comet in question is no longer leaving much of a streak. As Rosetta closed the 430,000 km gap between it and 67P, images revealed that the comet was no longer leaving an extended dust trail - commonly called a coma.

"The comet is now almost within our reach - and teaching us to expect the unexpected," Holger Sierks from the Max Planck Institute for Solar System Research in Germany said in a statement.

"After its onset of activity at the end April, our images are currently showing a comet back at rest."

This must be a bit disappointing for ESO researchers, who had expected Rosetta to be probing an active comet by the time it reaches 67P this August.

However, it's not unheard of for comets to slip in and out of activity with apparent spontaneity as they draw closer to the Sun.

The dud Camelopardalids meteor shower of last month is a prime example of such unpredictable behavior. NASA and ESA researcher alike had suspected that the Earth would be passing through a thick could of dust shed from the comet 209P/LINEAR as the Sun's heat vaporized more of its nucleolus - made of compact layers of rock and ice. Being a fresh coma stream, some experts expected even a meteor storm, as hundreds to thousands of dust particles burned up in Earth's atmosphere.

However, the meteor must have been practically inactive when crossing in front of the Earth's path, as only a few meteor streaks were seen that night.

Still, as the Rosetta closes in on 67P, researchers will soon have more to look at than just the absence of a coma, explained Carsten Güttler, the project manager of the Rosetta's Onboard Scientific Imaging System (OSIRIS).

"It will still take a few weeks before we can discern a detailed shape," Güttler said in a statement. "But we are now no longer restricted to studying the brightness of the nucleus."