Why NASA Is Trying to Go Back to the Moon

NASA is aiming to send astronauts back to the moon, because that is what President Trump set as the destination of the agency’s human spaceflight program during his first term.

On Dec. 11, 2017, Mr. Trump signed what the White House called Space Policy Directive 1, which stated that “the United States will lead the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations.”

The people attending Mr. Trump’s signing of the directive included Buzz Aldrin, the second person to step on the moon during the Apollo 11 mission after Neil Armstrong, and Harrison Schmitt, an astronaut on Apollo 17, the last time people were on the moon.

Three reasons are often offered for NASA to send astronauts back to the moon:

  • Much knowledge about the solar system can be gleaned from the moon, especially in the eternally shadowed craters in the polar regions that appear to hold frozen water.

  • The moon is the logical next stop for astronauts.

  • The United States needs to get back to the moon before China gets there.

For a couple of decades after the Apollo moon landings, not many people paid much attention to the moon. The moon was a “been there, done that” place, a lifeless, airless world of rocks and dust and not much else. Scientists and NASA looked to explore Mars and other planets.

The discovery of frozen water in the craters rekindled interest in the moon.

Moon water could simplify astronaut missions going there. Humans need to drink water to survive, and water molecules can be split into hydrogen and oxygen. Oxygen provides air to breathe, and hydrogen and oxygen can also be used as rocket propellants to return home to Earth, or to travel elsewhere in the solar system.

Layers of ice in the craters could also provide a history of the solar system, much as ice cores from Greenland and Antarctica provide a record of Earth’s climate.