Nasa needs saving from itself – but is this billionaire right for that job? 

He set off on his first mission to space in 2021 – a private journey he paid an estimated $200m (£160m) for – and announced that he wanted space travel to be for the masses, not only for the 600 who have experienced it to date – most of them professional astronauts employed by Nasa and the wealthy.

"We want it to be 600,000," he told reporters.

Later, he added: "I drank the Kool-Aid in terms of the grand ambitions for humankind being a multi-planet species… I think that we all want to live in a Star Wars, Star Trek world where people are jumping in their spacecraft."

Mr Isaacman, who made much of his $1.9bn (£1.46bn) fortune from a payment processing company that he founded in 1999 aged 16, is said to have bankrolled the rest of the crew of four aboard the SpaceX craft in the 2021 mission, fuelled by a longstanding love of flying and fascination with space.

During the mission, he tested an experimental spacesuit and a new cost-saving protocol to exit and re-enter the spacecraft without using an airlock.

The photograph of Mr Isaacman, silhouetted with the world at his feet, is now iconic – it demonstrated that this was not a playboy billionaire paying to act out Star Trek, but someone pushing the envelope of what was possible with current technology.

And yet it is a more recent achievement that has drawn greater attention still – being nominated by Donald Trump in December to be the new head of Nasa.

The question is why Trump chose him and what has he asked him to do – especially in the context that the President has appointed SpaceX owner Elon Musk to a government role to cut $2 trillion (£1.6 trillion) off the Federal budget.

The Nasa post is a presidential appointment, though it requires the confirmation of the US Senate. And if confirmed, Mr Isaacman's appointment will also raise broader questions about the future of humanity in space, given his vision for space travel for the masses – but also the implications for the space agency if Mr Isaacman's role leads to Nasa's greater use of the private sector.

There is concern in some quarters about the close relationship between Mr Isaacman and Mr Musk. Mr Isaacman paid SpaceX for his two ventures into space. The company has already received $20bn (£16bn) in contracts from government since 2008.

But if SLS is scrapped, and SpaceX were to receive the lion's share of Nasa's Moon programme work, Mr Musk's firm stands to receive contracts that might be ten or even a hundred times greater, possibly at the expense of other private-sector players.

And there are many innovative US start-up companies hoping to build parts for spacecraft and infrastructure in Nasa's return-to-the-Moon programme, including Texas-based Firefly, which has a spacecraft on its way to land on the Moon in March.

But industry analysts say that the US government has a long tradition of breaking up monopolies so that they don't stifle innovation. And in any case, just because Mr Isaacman has worked with Mr Musk, it does not mean that any outcome is inevitable, argues Prof Logsdon.

"Isaacman is his own man," he adds. "He is not a disciple of Elon Musk."