Rosetta Plays Doctor: Takes Comet's Temperature

The European Space Agency's (ESA) Rosetta spacecraft is only five days away from reaching its comet quarry after beginning a chase that started in 2004. Earlier this month, the craft was able to measure the temperature of the comet for the first time.

As of Friday, the Rosetta's quarry - comet 67P/Churyumov-Gerasimenko - is now only about 700 miles away from the ESA spacecraft.

As of mid-July, Rosetta has closed to about 3,100 miles from 67P - more than close enough for the comet-chaser's visible, infrared and thermal imaging spectrometer (VIRTIS) to start picking up an average surface temperature of about 94 degrees Fahrenheit below zero (-70 Celsius).

At the time of this measurement, the comet was about three times further from the Sun than the Earth is. Interestingly, even at this great distance, the comet was still much warmer than experts had expected.

"This result is very interesting, since it gives us the first clues on the composition and physical properties of the comet's surface," VIRTIS principal investigator Fabrizio Capaccioni said in a statement.

Capaccioni explains that this temperature confirms that the icy comet must be covered in dust, making it more prone to emitting heat compared to clean-reflective ice.

"This doesn't exclude the presence of patches of relatively clean ice, however, and very soon, VIRTIS will be able to start generating maps showing the temperature of individual features," he added.

This data will prove very important to the ESA, who will used thermal imaging coupled with other data to find an ideal landing site for Rosetta's deployable landing unit.

"With only a few days until we arrive at just 100 kilometers distance from the comet, we are excited to start analyzing this fascinating little world in more and more detail," said Matt Taylor, ESA's Rosetta project scientist.

NASA also recently released images from Rosetta's onboard OSIRIS instrument from a distance of only 1,210 miles away - providing the most detailed images of 67P yet.