NASA's official plans to build a permanent base on the Moon have leaked online, revealing how and when astronauts will return to the rocky world for the first time in 50 years.

Internal documents show how Nasa wants to launch 37 rockets to the Moon within the next decade, with at least five of these carrying astronauts.

Starting with an unmanned rover in 2023, the space agency is expected to land people on the Moon in 2024.

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NASA will then fire manned missions to Earth's neighbor every year between 2024 and 2028, according to the documents, which were obtained by Arstechnica.

Speaking to The Sun, a NASA spokeswoman confirmed the documents are real and revealed the plans were briefed today during a public session of the Science Committee to the Nasa Advisory Council (NAC).

They show a decade-long program that culminates with a permanent lunar base, which NASA will begin building in 2028.

They are in part a response to recent calls from U.S. Vice President Mike Pence to take astronauts back to the Moon.

"In the nearly two months since Pence directed Nasa to return to the Moon by 2024, space agency engineers have been working to put together a plan that leverages existing technology, large projects nearing completion, and commercial rockets to bring this about," Arstechnica's Eric Berger wrote.

"Last week, an updated plan that demonstrated a human landing in 2024, annual sorties to the lunar surface thereafter, and the beginning of a Moon base by 2028, began circulating within the agency."

Berger did not say how he obtained the plans, which have not yet been made public.

They do appear to line up with previous statements from NASA about its lunar program, codenamed Artemis.

As with any space exploration project, the main obstacle is cash.

NASA reckons it will need $4.7 billion to $8.2 billion per year on top of NASA's existing budget of about $20 billion.

Boss Jim Bridenstine recently asked for an extra $1.6 billion in fiscal year 2020 to start developing a lunar lander.

The plan also relies heavily on contractors delivering ambitious hardware on time, which has hindered Nasa in the past.

Boeing has been developing the core stage of the agency's next-gen rocket, the Space Launch System, for eight years – but has yet to come up with the goods.

Boeing's handling of the multi-billion-pound contract, which is now twice over budget, has been blasted by NASA's Inspector General.

NASA was not immediately available for comment.

This story originally appeared in The Sun.