It is almost 47 years since human beings last ventured into deep space.
The crew of Apollo 17 – Eugene Cernan, Ronald Evans and Harrison Schmitt – returned home from the last mission to the Moon on December 7, 1972.
Since then, our trips have been restricted to short orbital flights and stays on the International Space Station. We still call them astronauts but their missions take them barely out of Earth’s atmosphere.
To give this some perspective, the crew of Apollo 17 travelled 400,000 kilometres to reach the landing site in the Taurus-Littrow Valley.
Reaching the ISS is a journey of 400km. It is as if the bus from Abu Dhabi to Dubai now runs barely two city blocks from the station on Airport Road before turning back.
Now it seems humanity may be back in the deep, or at least deeper, space game. The successor to the likes of Apollo 17’s Cernan, who died in January last year at the age of 82, is Yusaku Maezawa, a Japanese online shopping billionaire and former punk rock drummer.
Mr Maezawa, whose brands include the made-to-measure online clothing store Zozo, is the first customer for Elon Musk’s long-heralded project to fly a private citizen round the Moon.
Details are scarce but he will lift off in the still-untested SpaceX Big Falcon Rocket accompanied by up to eight artists who, in Mr Maezawa’s words, will “create something after they return to Earth. These masterpieces will inspire the dreamer within all of us”.
No details have been released about the price tag for the mission, which Mr Musk originally proposed for this year but is now tentatively set for 2023, when Mr Maezawa will be 47.
Presumably, the ticket is fully refundable. SpaceX has yet to make a manned flight even in low-Earth orbit and of the larger rocket, Mr Musk has said that “it’s not 100 per cent certain we can bring this to flight”.
But what seems at first like the latest act of extravagance by a Japanese billionaire may be of much greater significance for space travel. It reminds us how limited our experience of deep space is.
Only 24 people have travelled there and they were all men, all Americans and all white.
Nasa was born out of the rivalry between communist Russia and capitalist America, with the latter emerging victorious after outspending its rival and almost bankrupting both in the process.
Six missions after the first Moon landing in 1969, American politicians refused to keep paying Nasa’s enormous bills, killing off further manned deep-space exploration.
Despite much talk of returning to the Moon and even manned missions to Mars, it has stayed that way for nearly half a century.
Merely the idea of Mr Maezawa and his fellow “artstronaughts” raises questions about the nature of future deep space exploration – and who will pay for it.
Several prominent scientists now question whether governments should be in the manned deep space game.
In a lecture in London this month, Britain’s Astronomer Royal, a venerable title that goes back to 1675, argued that if rich people wanted to pay to go into space, that was probably the only way forward.
The future for manned space flight, Martin Rees predicted, “lies with the private sector, wealthy individuals accepting higher risks than Nasa can impose on civilian astronauts – and doing things more cheaply”.
Mr Rees is not alone in his belief that the future of space travel could be in tourism – people rich enough and brave enough to pay for the ultimate thrill ride.
There are plenty of them out there. Mr Maezawa is estimated to be worth $3.6 billion (Dh13.22bn) but he is only the 14th richest man in Japan.
There are now more than 2,200 billionaires in the world, a number that continues to rise, with a total worth of $9.1 trillion. That is three times the US federal budget and enough money to fund Nasa for the next 500 years.
Those wealthy enough to want to go to space will probably have a growing range of choices.
SpaceX is merely the best known of several private companies investing in space flight.
Most are angling for government contracts, with the US ready to start sending astronauts back into orbit after relying on the ageing Russian Soyuz aircraft to fly to the International Space Station since the launch of the last Space Shuttle in 2011.
Jeff Bezos of Amazon is pushing ahead with his Blue Origin rocket and planning the first manned flights of the New Shepard capsule, named after Alan Shepard, the first American in space.
Mr Bezos has already said he would take passengers on the New Shepard, the design of which features reclining seats and picture windows. The price is rumoured to be between $200,000 and $300,000 for a return ticket.
The growing competition and market for private space flight is likely only to increase the capacity to carry passengers and the likelihood that prices will be driven down.
Some entrepreneurs are already talking about more distant journeys. Mr Musk has expressed a desire to die on Mars, “but not on impact”.
Travelling into low Earth orbit to watch as the world revolves below and experience the thrill of zero gravity, is likely to become the ultimate travel bucket-list experience for those who can afford it.
It is already the business model for Virgin Galactic, the space tourism business developed by Richard Branson, with Unity, a reusable space plane and a waiting list of several hundred customers prepared to pay $250,000 for a flight that will last about two hours.
Abu Dhabi bought a major stake in Virgin Galactic through its investment company Aabar, as part of the country’s burgeoning space industry, which includes a planned probe to Mars to be launched in 2021, the UAE’s golden jubilee.
The UAE also has plans to build the first city on the Red Planet by 2117.
Mr Branson’s plans have been much delayed by technical challenges and a crash of a prototype in 2014 that killed one of the test pilots, but the British billionaire still talks of being in space within the year.
For those looking for a longer vacation, the current talk is of space hotels – essentially more luxurious versions of the ISS.
The most ambitious of these is Aurora Station, billed as "the world's first luxury space station". At about $9 million for a 12-day holiday in space, the Aurora Station will house four guests and two crew, along with high-speed Wi-Fi.
Frank Bunger, the American founder and chief executive of Orion Span – the company behind the space hotel, which is set to open in 2022 – says that rooms on the Aurora Station are already sold out for the first six months.
“Our goal is to make space accessible to all by continuing to drive greater value at lower cost,” Mr Bunger says.