President Donald Trump is officially directing NASA to send astronauts back to the Moon, as a pit stop to eventually send people to Mars. The move is part of a new order, Space Policy Directive-1, which Trump signed today during a very brief ceremony at the White House. The directive is meant to reorient NASA’s focus from the Red Planet to the Moon, at least in the short term, shifting away from the priorities set forth by the Obama administration.

The signing appropriately coincides with the 45th anniversary of the Apollo 17 landing, the last time humans ever landed on the Moon. At the event, Trump said the directive will re-establish American leadership in space, while creating jobs and enhancing US national security. “We’ll refocus American space program on human exploration and discovery,” Trump said. “This time, we will not only plant our flag and leave our footprint, we will establish a foundation for an eventual mission to Mars and perhaps someday to many worlds beyond.”

The Trump administration has made it clear that it wants NASA to go to the Moon for a while now. In October, Vice President Mike Pence announced that Trump’s NASA would send astronauts back to the Moon during the first meeting of the National Space Council — a newly resurrected executive group that Pence leads and that is aimed at guiding the US space agenda. The directive is now following through on what the National Space Council had recommended. “Establishing a renewed American presence on the Moon is vital to achieve our strategic objectives and the objectives outlined by the National Space Council,” Pence said today. It will enhance national security, spur innovation, and create jobs, the VP added. “We’ll see jobs created that we couldn’t even image could be created today.”

Many other state agencies have their eyes on the Moon, as well as commercial companies like Moon Express, which plans to mine the lunar surface for water and minerals. The Moon also offers a good testing ground for trying out technologies that could be useful for keeping humans alive on Mars, such as habitats. Plus, it’s also much closer than the Red Planet, making it easier to travel to. Both presidents George H. W. Bush and George W. Bush had called for NASA to return to the Moon, but none of those plans worked out because of a lack of funding and delays. Eventually, Obama canceled the later Bush's plan and reoriented NASA toward Mars.

Trump didn’t provide many details about Space Policy Directive-1 at the signing today, so it’s unclear what exactly will change at NASA because of the new policy, or whether the space agency will put together a solid long-term plan for how it will go to the Moon, or Mars. For the last decade, the space agency has been developing a new rocket and spacecraft to take astronauts into deep space and onto Mars. The so-called Space Launch System and Orion could be reoriented to take astronauts to the Moon’s surface instead.

But what’s still lacking is the funds needed to turn this mission to the Moon into a reality. Already, NASA’s human exploration programs suck up $4 billion each year, and there’s little money leftover for other programs. And NASA is going to need more key hardware — notably a lunar lander — if it wants to put humans on the Moon’s surface again. "The Moon is great, but the plans and partnerships matter more than dates and destination,” Phil Larson, a former space advisor for the Obama administration and assistant dean at the University of Colorado's College of Engineering, tells The Verge.

The policy directive does call for NASA to work with its commercial and international partners to pull off the human lunar mission, several sources told The Verge. The European Space Agency, Russia, Japan, and China are all interested in putting people on the Moon, and these agencies could provide crucial components needed for a lunar return. And it’s possible that NASA could partner with commercial companies, buying their services at relatively low costs. Private companies like Blue Origin and SpaceX are developing their own monster rockets already, which could be incorporated into a long-term Moon mission.

And the commercial space industry seems eager to jump on board. "[The Commercial Spaceflight Federation] applauds President Trump for signing Space Policy Directive 1, which directs NASA to partner with the US commercial space industry to return Americans to the Moon,” Eric Stallmer, president of the Commercial Spaceflight Federation, a coalition of more than 70 space companies, said in a statement.

We could learn more details about a long-term plan soon. Early next year, Trump will make his annual budget request, where he could potentially ask for more money for NASA to build new hardware for a human Moon mission. At one point, NASA estimated that going back to the Moon would cost upwards of $100 billion. Of course, money is tight and the administration claims to want to decrease the deficit. If Trump isn’t interested in a budget increase for NASA, it’s possible the administration may try to free up money by slashing other programs at the space agency.

Until then, the Trump administration has only said a lot of words about going to the Moon. It’s going to take more than signing this directive to put people on the lunar surface again.