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Unmanned Missions to Mars
The invasion of probes to Mars with Kelly Beatty of Sky and Telescope Magazine
The invasion of probes to Mars with Kelly Beatty of Sky and Telescope Magazine.
The moon formed when the Earth experienced a large impact - discussion with Lunar Prospector mission manager Scott Hubbard.
Plus what was happening among the stars and planets in April 1999.
This is a programme from the 大象传媒 World Service Archive and was originally broadcast in 1999.
