But interest in the moon has perked up again. Russia and India plan to send robotic landers. NASA was going to send astronauts back there until the Obama administration changed course a couple of years ago.

Most crucially, the Google Lunar X Prize, a competition among 26 teams to become the first private organization to put a spacecraft on the moon, offered a $1 million bonus for visiting a historic site there. At least one team announced it was heading for Tranquillity Base.