UPDATE: NASA issued a statement at about 19:30 PT / 22:30 ET July 5 / 02:30 UT July 6 saying that the cause of the safe mode is understood, and that New Horizons will resume science operations on July 7

These are the most recent high-resolution views of Pluto sent by NASA’s New Horizons spacecraft, including one showing the four mysterious dark spots on Pluto that have captured the imagination of the world. The Long Range Reconnaissance Imager (LORRI) obtained these three images between July 1 and 3 of 2015, prior to the July 4 anomaly that sent New Horizons into safe mode.
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The color version of the July 3 LORRI image was created by adding color data from the Ralph instrument gathered earlier in the mission.

Made of Stars wrote:Interesting how ruddy it is. Must be hydrocarbons.

CdesignProponentsist wrote:Doesn't oxidation slow or cease at some lower temperature threshold? Also I think Pluto's surface temperature is below the melting point for oxygen.

Made of Stars wrote:Given the proximity of Charon, I'm guessing there will be volcanic activity. Whether we'll be able to see it is another question.

New Horizons Map of Pluto: The Whale and the Donut
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“We’re at the ‘man in the moon’ stage of viewing Pluto,” said John Spencer of the Southwest Research Institute, Boulder, Colorado, deputy leader of the Geology, Geophysics and Imaging team. “It’s easy to imagine you’re seeing familiar shapes in this bizarre collection of light and dark features. However, it’s too early to know what these features really are.”

Made of Stars wrote:Interesting how ruddy it is. Must be hydrocarbons.