Brave blue world.
D000864:Antarctic Regions; D018480:Astronauts / Q000191:economics / Q000639:trends; D018534:Earth, Planet; D016081:Moon; D013026:Space Flight / Q000191:economics / Q000639:trends*; D014481:United States; D018557:United States National Aeronautics and Space Administration / Q000191:economics / Q000639:trends*