[Editor’s note: President Trump signed SPD-1 at 3 p.m. Eastern during a brief ceremony at the White House]

Updated 9:55 a.m. Eastern.

NEW ORLEANS — President Donald Trump is scheduled to sign his administration’s first space policy directive in a White House ceremony Dec. 11, one that will formally direct NASA to send humans back to the moon.

A White House schedule of the president’s activities, released late Dec. 10, includes a 3 p.m. Eastern “signing ceremony for Space Policy Directive 1.” The schedule didn’t provide additional details about the event or the document, but a White House official later confirmed that the directive is linked to human space exploration policy.

“The president, today, will sign Space Policy Directive 1 (SPD-1) that directs the NASA Administrator to lead an innovative space exploration program to send American astronauts back to the Moon, and eventually Mars,” Deputy White House Press Secretary Hogan Gidley said in an statement Dec. 11.

The directive, Gidley said, was prompted by initial work of the National Space Council, which was reconstituted by the president in a June 30 executive order and held its first public meeting Oct. 5. “The president listened to the National Space Council’s recommendations and he will change our nation’s human spaceflight policy to help America become the driving force for the space industry, gain new knowledge from the cosmos, and spur incredible technology,” he said.

The event will coincide with the 45th anniversary of the last crewed mission to land on the moon. The Apollo 17 lunar lander touched down on the moon on Dec. 11, 1972. Statements from administration officials, including Vice President Mike Pence, has have made clear their interest in human lunar missions.

“We will return American astronauts to the moon, not only to leave behind footprints and flags, but to build the foundation we need to send Americans to Mars and beyond,” Pence said at the first meeting of the reconstituted National Space Council Oct. 5 at the National Air and Space Museum’s Udvar-Hazy Center.

Pence, at that meeting, directed NASA to provide a 45-day report on plans to carry out such missions. “The Council is going to need the whole team at NASA to work with the Office of Management and Budget to provide the president with a recommended plan to fill that policy,” Pence told NASA Acting Administrator Robert Lightfoot at the meeting.

Lightfoot, speaking at a meeting of the NASA Advisory Council Dec. 7, said the agency had delivered a version of the report on those plans to the Council. “We continue to work with the Space Council on that action, and they’re reviewing the preliminary draft of that now,” he said. “Once that report becomes more final, we’ll share more information.”

Some space advocates fear that a renewed emphasis on a human return to the moon could delay plans for eventual human missions to Mars. At a Dec. 7 briefing by Explore Mars, a Mars advocacy group that recently held the fifth in a series of workshops on affordable Mars mission architectures, representatives said they were not opposed to human lunar missions provided they fit into a broader plan that supported Mars missions as well.

“The one thing we want to make sure is to follow the guidelines that the National Academies set out in their ‘Pathways’ report, which is don’t go down any dead ends,” said Joe Cassady, a member of the board of directors of Explore Mars, referring to the 2014 “Pathways to Exploration” report by the National Academies that examined the various approaches to human missions to the moon, Mars and asteroids.

“Anything we do there should have a feed-forward component that takes us in the direction of Mars,” he said of any lunar missions.

NASA’s planning for the Deep Space Gateway, a cislunar outpost, could support lunar missions while also laying the groundwork for expeditions to Mars, he said. “You can envision that, with partners, surface exploration can be undertaken utilizing the gateway.”

Congress has already offered its view of NASA exploration priorities in the form of NASA authorization legislation. The latest NASA authorization, signed into law in March, endorses a “stepping stone approach to exploration” with “missions to intermediate destinations in sustainable steps” while maintaining a long-term goal of human missions to Mars.

That bill directed NASA to develop an “initial exploration roadmap” that outlined its plans, to be delivered to Congress by Dec. 1. A separate provision instructed NASA to perform an independent assessment of the feasibility of a human mission to Mars specifically in 2033, due 180 days after the bill’s enactment in March. NASA has not announced the status of either report.

Those reports, and the administration’s actions, have given space exploration advocates some hope for a more detailed strategy for human missions beyond Earth orbit, be they to the moon or Mars. Jeff Bingham, a former Senate staffer, said at the Explore Mars event that the National Space Council can play a key role in creating a “final consensus” on those plans.

“I think we’re coming close now to an opportunity that I think was presented by the more recent legislation that Congress passed,” he said, referring to the roadmap provision in the 2017 authorization act.