Trump wants to send humans back to the moon — here's what his administration has done to spur space exploration so far

President Donald Trump signed a directive on Monday directing NASA to start working on a program to get humans back on the moon and later to Mars. The directive is based on recommendations from the National Space Council, which Trump reestablished in June.

The move which follows a string of efforts by the Trump administration to spur manned space exploration.

Trump has long expressed an interested in space exploration, mentioning it in his inauguration speech and heaping praise on Elon Musk's private space-faring venture, SpaceX.

Before officially launching his presidential campaign, Trump lauded Musk's goal to bring humans to Mars on Twitter. Trump mentioned his desire "

In March, Trump signed the NASA Transition Authorization Act of 2017, which was created by Congress. The act allocated $19.5 billion in annual funding for NASA and directed the agency to put a man on Mars by 2033. It omits crucial earth-science funding, however.

Despite allocating funds to NASA, the act cuts funding for earth-science and climate research that has been a mainstay of the agency since 1958. Additionally, the act shifts the agency's priorities away from its Asteroid Redirect Mission, which would aim to pull an asteroid into Earth's orbit to study it.

In June, Trump reinstated the National Space Council, a body that hasn't been active since 1993.

Trump quite literally raised eyebrows — notably Buzz Aldrin's — with some off-the-cuff comments he made at the ceremony announcing the Council.

At the first official meeting of the National Space Council, Vice President Mike Pence, who heads the council, stated that its goal is to use the moon as a "stepping-stone" to Mars.

Pence hinted at collaboration with commercial space endeavors, but gave few details at the meeting. Many experts doubt that going to the moon would actually help in the push to put a man on Mars, however.

Trump's nominee to head NASA, Rep. Jim Bridenstine, hopes to increase cooperation with commercial space companies and supports NASA's current efforts to do that through its commercial crew program.

Bridenstine wants to terminate NASA's use of Russian rockets to carry personnel to the International Space Station. He has also stated that he will continue the development of NASA's new Space Launch System, and hopes to lay a groundwork for long-term missions that will withstand changing administrations.

Some space leaders, including Sean O'Keefe who headed NASA under former President George W. Bush, have praised Bridenstine's agenda. But many others have taken issue with the appointment of a sitting politician to a nonpartisan office. Bridenstine is also a frequent denier of climate change science — putting him at odds with one of NASA's key missions.

Although the details of the administration's intention to cooperate with commercial space companies remains unclear, it could be the key to solving an important obstacle to long-term space flight — expensive and bulky rockets.

NASA is currently developing its Space Launch System (SLS), which will reportedly be the most powerful rocket ever created. But the SLS costs a lot of money to launch and will likely be used infrequently, leading many to believe that using leaner commercial rockets would be more efficient.

But the Trump administration faces significant obstacles in the push for long-distance space travel — in the most likely scenario for travel to Mars, astronauts won't be able to make a landing.

NASA's plan to get to Mars entails a three-year journey in a tube that will end in an orbit of the planet — but no landing there.

Furthermore, some experts see more potential and opportunity for human habitation on the moon than on Mars.

"That'll definitely be the first place that we colonize outside of Earth," "The Martian" author Anthony Weir told Business Insider. "A lot of people who would like us to just leap-frog to Mars, but Mars is so much farther away. It would be like if the ancient British colonized North America before they colonized Wales."

Yet the biggest hurdle is money. Although Congress has allocated $19.5 billion for NASA, Trump's proposed budget seeks to give the agency less.

NASA currently gets less 0.5% of all federal money. In 1966, three years before NASA first landed on the moon, the federal government gave the agency nearly 4.5% of the national budget. Adjusted for inflation, that number today would be roughly $45 billion — more than twice what the US spends on NASA now.

With a comparatively small budget, the goal of manned space missions seems lofty. Even in collaboration with commercial ventures like SpaceX, NASA will have to overcome major budgetary challenges if it ever hopes to get Trump's ambitious programs off the ground.