For the first time, we have scientific data on Comet 67P/Churyumov-Gerasimenko, thanks to a NASA instrument on-board the Rosetta spacecraft that's currently in orbit around the comet.
The instrument, a UV spectrograph dubbed "Alice," started mapping the surface of the comet once Rosetta was in its orbit. Alice views the comet at ultraviolet wavelengths, which allows it to accurately detail the comet's surface.
Alice is taking high-resolution UV images of the comet and gathering information that Earth-based instruments cannot get. Although the instrument weighs less than nine pounds and only uses four watts of power, it has at least 1,000 times more capability for gathering data than similar scientific instruments used just several years ago.
Alice recently sent its measurements to Earth, where scientists analyzed them. Some of the findings surprised the investigative team.
First, the comet is dark, darker than even a charcoal shade of black. The "coma" around it, contains an atmosphere of hydrogen and oxygen. However, scientists were most surprised when they realized that they saw no large patches of ice on the comet. They expected ice because the comet is so far away from the sun's heat.
"We're a bit surprised at just how unreflective the comet's surface is and how little evidence of exposed water-ice it shows," says Alan Stern, an Alice investigator from the Southwest Research Institute in Boulder, Co.
Alice continues its study of the comet, as scientists search for other signs of ice patches on its surface. Alice is one of 11 instruments on-board the spacecraft, with three of those funded by NASA.
NASA's other two instruments will study the composition of the comet's coma and analyze its plasma content.
"As the mission progresses, we will continue to search for surface ice patches and ultraviolet color and composition variations across the surface of the comet," says Dr. Lori Feaga, an Alice investigator at the University of Maryland.
Last month, the Rosetta spacecraft made history when it became the first spacecraft to ever orbit a comet. The mission, led by the European Space Agency, will make history again in November when Rosetta's Philae Lander becomes the first vehicle to ever land on a comet.
Scientists hope that learning more about the comet will provide insight into how our solar system originated and became what it is today. The comet could also provide further proof that comets brought water, and even life, to Earth.
