Because the moon's body blocks direct radio communication with a probe, China first had to put a satellite in orbit above the moon in a spot where it could send signals to the spacecraft and to Earth.

America's forthcoming "Prompt Global Strike" non-nuclear hypersonic missiles will be able to hit almost any spot on earth in less than an hour-provided excellent satellite data is available.

Oil slicks are notoriously difficult to spot in natural-color (photo-like) satellite imagery because a thin sheen of oil only slightly darkens the already dark blue background of the ocean.