Large patches of water ice found on comet surface
At the end of April 2015, Rosetta's OSIRIS narrow angle camera detected two unusually large patches of water ice on Comet 67P/Churyumov-Gerasimenko, between the southern regions of Anhur and Bes.
The graphic shows the appearance of the two bright spots (indicated as A and B), which persisted for about 10 days before they completely disappeared.
The two ice-rich areas span some 30 m × 40 m each – larger than the size of an Olympic swimming pool – and are much larger than the many metre-sized patches of exposed water ice that had been previously spotted at the comet.
The two patches contain 20–30% of water ice mixed with darker material, forming a layer up to 30 cm thick of solid ice. The water ice patch indicated as A was likely lurking underneath the carbon dioxide ice sheet revealed by Rosetta's VIRTIS instrument about a month before.
This finding is part of a broader study on seasonal and daily colour variations on the surface of the comet based on OSIRIS images obtained throughout the course of the mission.
For more information see: Icy surprises at Rosetta's comet