And we had never landed - soft-landed an object on the surface of Mars, and there was no textbook.

NPR: Revisiting the Viking Missions to Mars

Eventually, scientists would like prosthetic hands to provide information about an object's surface directly to the user, so he or she can consciously feel what the hand touches, Loeb said.

CNN: Fingerprint study offers inspiration for robotics research

Electrostatic self-assembly, however, coats every exposed surface of an object, and does it at room temperature.

ECONOMIST: MONITOR

The laser would only singe the surface of an object in space, but that tiny burn could still help point it downward, Dr. Campbell says.

WSJ: A Cosmic Question: How to Get Rid Of All That Orbiting Space Junk?

This takes pictures of the surface of an object.

ECONOMIST: Connectomics aims to map the atlas of the brain

But as an object gets smaller, the ratio between its surface area and its volume rises.

ECONOMIST: Small wonders

Previous studies of Trois Hommes Armes de Lances had used X-ray fluorescence - which yields a list of all the atoms within an object - but showed that there were atoms present in the work that were not present on the surface.

BBC: Terahertz scanner reveals hidden fresco at Louvre