What The Surface Of Comets Are Like

The European Space Agency has just released high resolution images of Comet 67P/Churyumov-Gerasimenko taken by their Rosetta Spacecraft on its most recent flyby yet. The pictures, released on Monday, but taken on February 14th, highlight the “stunning details of the contrasting terrain,” according to the ESA.

The encounter, which occurred on Valentine’s Day this year, February 14 at 12:41 GMT, was the Rosetta probe’s closest encounter with its comet yet, passing just 6 km from its surface, over the Imhotep region. The comet, which is known to be very dark, reflects only 6% of the light that falls on it. However, on this particular occasion, the Rosetta spacecraft entered the “zero phase” angle, with the Sun exactly behind the spacecraft. This allowed the spacecraft’s navigation camera to obtain shadow-free images of the comet’s surface, providing us with well-lit high resolution pictures.

When interviewed before the encounter, Matt Taylor, ESA’s Rosetta Project Scientist, stated that the images gathered will offer “unique scientific observations, providing us with high-resolution measurements of the surface over a range of wavelengths and giving us the opportunity to sample – taste or sniff – the very innermost parts of the comet’s atmosphere.”

The images have shown the comet’s diverse topography, featuring smooth floors, and elevated irregular land formations, to angular and rugged terrain, even showing the fractured lower left side of the comet. The images also show that boulders found on its surface greatly differ in size, from a few meters to tens of meters and can be found “scattered across the whole surface of the comet.”

The Rosetta spacecraft just “woke up” in January of this year from its deep-space hibernation mode since June 2011 and has been tracking Comet 67P/Churyumov-Gerasimenko since its launch in 2004. The spacecraft consists of the Rosetta orbitter and the Philae lander. Aside from flybys of Mars and two asteroids, 21 Lutetia and 2867 Šteins, its Philae lander also made history when it made its first soft landing on a comet on November 12 2014.

The comet, 67P/Churyumov-Gerasimenko, was discovered in 1969 by Klim Ivanovych Churyumov of the then Soviet Union. Previous images from Rosetta show the comet as having two distinct lobes with an irregular nucleus, probably created by either a contact binary (two touching astral bodies) or its own asymmetric erosion.

The close encounter has also provided the ESA with a better analysis of the comet’s atmosphere, or coma, specifically its gas, dust and plasma, which will also allow better understanding of its observed activity and its wider coma.

Rosetta, which has already entered the next phase of the mission, has now moved away from the comet and will take far-view images ranging from 15 km to 100 km in the next set of flybys. Comet 67P/Churyumov-Gerasimenko and Rosetta will be in perihelion, at their closest to the Sun, in August of this year, and will be 186 km from the Sun, between the orbits of Earth and Mars.

The missions team will determine after perihelion how long the Rosetta will operate beyond 2015.