Mars Has Cave Networks, New Photos Suggest

Researchers have been able to look into openings in the Martian surface using visual infrared imaging attached to the Odyssey spacecraft. Remarkably, no visible bottom can be seen in six of the openings, whereas some direct sunlight entering the seventh opening suggests the depth to be about 425 feet. The thermal imaging equipment shows that temperatures at the holes' openings are more constant than other surrounding areas that reach extremely cold temperatures. Therefore, the holes may be trapping daytime heat, which is good evidence that the holes are indeed very deep caves.

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