President Trump will sign Space Policy Directive 1 at 3:00 pm tomorrow (Monday, December 11) at a White House ceremony. The directive apparently will make a human return to the lunar surface part of U.S. space policy. That will override the Obama Administration’s policy to eschew a return to the lunar surface in favor of focusing on sending humans to Mars with an encounter with an asteroid as an interim goal.

The event apparently will be carried live on YouTube [https://www.youtube.com/watch?v=7fuer5ws6ZY].

Signing of the directive is timed to coincide with the 45th anniversary of the Apollo 17 mission — the last time humans walked on the surface of the Moon. The crew launched on December 7, 1972 and returned to Earth on December 19, 1972.

Tomorrow, December 11, is the exact anniversary of the date that Apollo 17 commander Gene Cernan and Lunar Module Pilot Harrison “Jack” Schmitt landed on the Moon while Command Module Pilot Ron Evans orbited overhead. Cernan died earlier this year. Evans died in 1990. Schmitt is still active in space policy and is expected to be at the White House ceremony tomorrow.

Vice President Mike Pence chairs the White House National Space Council. At the first meeting of the Council on October 5, he directed that a Decision Memorandum be prepared for the President to amend U.S. National Space Policy to say: “We shall lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the solar system to bring new knowledge and opportunities. Beginning with missions beyond low Earth orbit, the United States will lead to return humans to the Moon for long term exploration followed by human missions to Mars and other destinations.”

It is that Decision Memorandum that apparently will be signed tomorow.

Along with Schmitt, other invited guests are rumored to be from Congress and space organizations including the Commercial Spaceflight Federation, the Coalition for Deep Space Exploration, and the American Institute of Aeronautics and Astronautics.

President Obama cancelled the George W. Bush Administration’s Constellation program to return humans to the Moon by 2020 and then go on to Mars. In an April 15, 2010 speech at Kennedy Space Center, he said there was no need to return to the Moon’s surface: “We’ve been there before. … There’s a lot more of space to explore.” Instead, he directed NASA to focus on sending humans to an asteroid as a steppingstone to Mars. Over the years, that morphed into the controversial Asteroid Redirect Mission (ARM) that would have used a robotic spacecraft to divert an asteroid into lunar orbit where it could be studied by astronauts. ARM never won widespread support in Congress or the space community and Trump’s proposal to terminate the program shortly after taking office was not challenged.

Note: This story has been updated.