Launching the European Space Agency's (ESA) comet-chasing spacecraft Rosetta into space requires a lot of money. The total cost of the mission is about $1.68 billion but there certainly are a number of advantages of studying comet 67P/Churyumov-Gerasimenko at close range. Capturing a phenomenon recently photographed by Rosetta's navigation camera is one of them.

On Sept. 26, Rosetta witnessed an activity at the comet's neck that is attributed to 67P/C-G getting closer to the sun. As comets get nearer the sun, their surface becomes hotter, triggering an increased level of activity. Since frozen water does not melt into liquid in space, the heated ice transforms directly from its solid state into gas without passing through the liquid phase, a process known as sublimation. The increased heat thus caused the ice locked in the comet to release vapor.

Rosetta's camera captured images of the comet's ice sublimating and causing jets of gases and dust blasting into space from the comet's neck as it hovers at a distance of about 16 miles from the center of 67P/C-G.

The four image-montage of the comet shows a region of jet activity visible at its neck. The jets appear to come from several locations and were caused by sublimating ice and gases escaping from the comet's nucleus.

The montage is also marked by overlapping and dissimilar angles, and the ESA pointed out that these were caused by the comet rotating between the first and fourth image in the sequence and Rosetta moving during that same period.

"We have not made a proper mosaic on this occasion, because it is becoming extremely difficult at these close distances due to the combined effect of the comet rotating between the first and last images taken in the sequence (about 10 degrees over 20 minutes) and the spacecraft moving by some 1-2 km in the same time," ESA explained.

What makes the mosaic of pictures, which ESA made available for the public on Oct. 2, more interesting is the fact that it has captured a phenomenon wherein the vapor that has been in its frozen state and locked in the comet since the birth of the solar system has been released.

Rosetta documenting this event is comparable to taking a photo of a historic occasion, apparently in line with its main objective of providing data that scientists could potentially use to shed light on the origin and evolution of the Solar System.