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It was all the way back in 1972 when humans last set foot on the moon during the Apollo 17 mission. It could happen again with President Donald Trump's signing later Monday of Space Policy Directive 1, which will push NASA to send astronauts back to the moon.

The move will direct NASA's energy to our close lunar neighbor, which represents a shift from President Obama's emphasis on sending humans to Mars.

Vice President Mike Pence heads up a revived National Space Council, an administrative group that advises the president on space-related issues and goals. In early October, Pence stated that America will return to the moon. Space Policy Directive 1 formalizes this sentiment.

We won't be back on the moon anytime soon. The directive marks the beginning of what could be a very lengthy process as NASA works on new technologies that can safely transport astronauts back and forth from Earth. It's been a long time since the Apollo era.

This afternoon's signing ceremony, beginning at 3 p.m Eastern, is streaming live on the White House site and through NASA TV online.