- Video report by ITV News Correspondent Geraint Vincent
The pressure is on Nasa to put astronauts on the Moon once again, after US Vice President Mike Pence called on the space agency to up its pace and return to the Moon within five years.
Mr Pence's words come at a time of heightened interest in the Moon and space exploration more widely, with multiple countries and private companies making progress on their own attempts, helped by greater access to technology, resources and talent.
So what is the fascination with the Moon? Here is everything you need to know so far:
- What has Mike Pence said?
The US vice president told Nasa he wants the US to return to the Moon within five years, specifically the lunar south pole, which he said "holds great scientific, economic and strategic value".
"America will once again astonish the world with the heights we reach and the wonders we achieve, and we will lead the world in human space exploration once again," he said at a meeting of the National Space Council in Huntsville, Alabama, on Tuesday.
Mr Pence also warned the US government would need to "change the organisation, not the mission," if Nasa is unable to fulfil the goal.
- Why is the US government interested in the Moon now?
Nasa has long been the leader in space exploration, alongside Russia, but more recently other countries have been making progress, including China.
US President Donald Trump put the Moon at the forefront of his administration’s policy, especially returning astronauts to the lunar surface.
In December 2017, he said: "The directive I am signing today will refocus America’s space programme on human exploration and discovery."
He added: "It marks a first step in returning American astronauts to the Moon for the first time since 1972, for long-term exploration and use.
"This time, we will not only plant our flag and leave our footprints - we will establish a foundation for an eventual mission to Mars and perhaps, someday, worlds beyond."
- When was the last manned Moon landing?
The last manned Moon landing happened in 1972, as part of the Apollo 17 mission.
There have only ever been six times that astronauts have walked on the Moon, all of which were carried out by Nasa as part of its Apollo programme.
- Why has it taken so long to return to the Moon?
Nasa and other space agencies have continued to study the Moon with unmanned spacecraft and probes, but have also started to focus further afield with the arrival of improved technology.
The American space agency landed its first spacecraft on Mars, called Viking 1, in July 1976, and became the first to successfully perform its mission on the planet - the Soviet’s Mars 3 space probe beat it to become the first spacecraft to carry out a soft-landing on Mars, though it failed shortly after landing.
Alternative priorities of new presidential administrations force Nasa to change direction, making it difficult to co-ordinate missions which take many years to plan.
In recent years, former president Barack Obama targeted Mars as the next big destination for astronauts, while his successor at the White House, Donald Trump, favoured the Moon.
- Who else is exploring the Moon?
While there have only been a handful of manned landings on the Moon, there have been multiple unmanned missions by various countries.
These missions have primarily been led by the US and Russia in the early years, but by the 1990s Japan launched its efforts, and into the 2000s, Europe, China, and India entered the ring.
Israel also launched a lander in February, which is currently on its way to the Moon.
- Where does China come into it?
By successfully landing on the far side of the Moon in January, China has put itself on the map and proved that its growing space programme means business.
The far side of the Moon - also known as the dark side - is relatively unexplored, as it faces away from Earth.
Space exploration is among Chinese President Xi Jinping’s top national development priorities and the far side mission offers a chance for China to do something not previously done by any other country.
"In the past, we were always rushing to catch up to the advanced global standards” in space, said Wu Weiren, the chief designer of China’s lunar exploration project, earlier this year.
China is planning to launch "Chang’e 5" sometime at the end of 2019, which will collect and bring back samples from the near side of the Moon, the first time that has been done since 1976.