There is a largely unexplored alien country that is so close to Earth it would take a beam of light less than two seconds to get there.
This is the farside of on moon, often misrepresented and the "dark side" (with apologies to Pink Floyd). Because the moon keeps one hemisphere gravitationally locked on Earth, only the eyes of a handful of astronauts have directly seen the lunar farside.
ANALYSIS: Strip Mine the Moon to Fuel Space Exploration
The glorious NASA Apollo missions only explored half of the moon, the Earth-facing side dominated by frozen lava oceans - the mare. The farside bears unique invaluable secrets to 4 billion years of solar system evolution.
The farside is dramatically different from the nearside. It has the largest and deepest basin on the moon, and possibly the oldest impact site in the inner solar system. It offers fossil evidence for a tremendous lunar cataclysm and lunar magma ocean that once existed.
An eventual human return to the moon –- call it Apollo 2.0 - should be targeted for the farside. But it is very costly to conduct astronaut landings. If flown today, the Apollo missions would cost a staggering $18 billion per flight.