Apollo 17 astronaut Eugene Cernan, pictured here on Dec. 12, 1972, was among the last people to visit the moon.

President Trump has formally told NASA to send U.S. astronauts back to the moon.
“The directive I’m signing today will refocus America’s space program on human exploration and discovery,” he said.
Standing at the president’s side as he signed “Space Policy Directive 1” on Monday was Apollo 17 astronaut Harrison Schmitt, one of the last two humans to ever walk on the moon, in a mission that took place 45 years ago this week.
Since that time, no human has ventured out beyond low-Earth orbit. NASA doesn’t even have its own space vehicle, having retired the space shuttles in 2011. Americans currently ride up to the International Space Station in Russian capsules, though private space taxis are expected to start ferrying them up as soon as next year.
For now, the ultimate goal for human exploration in space remains Mars.
“This time, we will not only plant our flag and leave our footprint, we will …