I’m old enough to have watched the grainy TV images of the first moon landings by Apollo 11 in 1969. I can never look at the moon without recalling this heroic exploit. It was achieved only 12 years after the first object, Sputnik-1, was launched into orbit. Had that momentum been maintained, there would surely have been footprints on Mars a decade or two later. That’s what many of our generation expected. However, this was the era of the space race between the United States and the USSR, when Nasa absorbed up to 4% of the US federal budget. Once that race was won, there was no motivation for continuing this huge expenditure. To young people today, these exploits are ancient history. Yet space technology has burgeoned. We depend on satellites every day, for communication, weather forecasting, surveillance and satnav. Robotic probes to other planets have beamed back pictures of varied and distinctive worlds; several have landed on Mars. And telescopes in space have revolutionised our knowledge of the cosmos. What’s more, humanity, or rather a narrow sliver of us, may be on the verge of an era of space exploration that makes the moon landings seem parochial by comparison. The last visitors to the moon – Harrison Schmitt and Eugene Cernan, on Apollo 17 – returned in 1972. During the subsequent 50 years, human spaceflight has seemingly regressed: hundreds have ventured into space but, anticlimactically, none has done more than circle the Earth in low orbit, mainly in the International Space Station (ISS). The scientific and technical payoff from the ISS isn’t trivial, but it has been less cost-effective than robotic missions. Nor are these voyages inspiring in the way that the pioneering Soviet and US adventures were. The space shuttle was, until its decommissioning, the main vehicle for transporting people to and from the ISS. It failed twice in 135 launches. Astronauts or test pilots would willingly accept this level of risk – less than 2%. But the shuttle had, unwisely, been promoted as a safe vehicle for civilians (a female schoolteacher, Christa McAuliffe was one of the casualties of the Challenger disaster in 1986). Each failure caused a national trauma in the US and was followed by a hiatus while costly efforts were made, with very limited effect, to reduce risks still further. During this century, our whole solar system will be explored by flotillas of miniaturised probes. These technologies are far more advanced than Nasa’s wonderful Cassini probe, which was launched nearly 25 years ago on a seven-year journey, and spent 13 years exploring Saturn and its moons. In coming years, robotic fabricators may assemble vast lightweight structures in space: huge, gossamer-thin mirrors, for telescopes or solar energy collectors, perhaps using raw materials mined from the moon or asteroids. Such robots could repair spacecraft even in high orbits. Advances in robotics and artificial intelligence (AI) are eroding the need for humans in space. The fact that the Apollo 17 astronaut Schmitt was a geologist enabled him to gather especially interesting samples of lunar rocks and soil. But future probes to Mars will be able to make such choices themselves. If you can get a robot to do it, why send a human at all? Nonetheless, I hope people do follow the robots – as adventurers, rather than for practical goals. Private-enterprise ventures such as SpaceX and Blue Origin have brought a Silicon Valley culture into a domain long dominated by Nasa and a few aerospace conglomerates. They have managed to improve rocketry and cut costs. Moreover, they can be less risk-averse than Nasa, and still find volunteers willing to tolerate higher risks than a western government could impose on publicly funded civilian astronauts. So it’s these cut-price ventures – with private sponsorship, rather than public money – that should be at the forefront of human space travel. The phrase “space tourism” should be avoided. It lulls people into believing that such ventures are routine and low-risk. And if that’s the perception, the inevitable accidents will be as traumatic as those of the space shuttle were. These exploits must be “promoted” as dangerous sports or intrepid exploration. Later this century, courageous thrill-seekers – in the mould of, say, Ranulph Fiennes or the early polar explorers – may well establish “bases” independent of the Earth. Elon Musk, the richest man on the planet, himself says he wants to die on Mars – but not on impact. But what is the longer-range goal? Musk and my late colleague Stephen Hawking envisaged that the first “settlers” on Mars would be followed by literally millions of others. But this is a dangerous delusion. Coping with the climate crisis is a doddle compared to terraforming Mars. Nowhere in our solar system offers an environment even as clement as the top of Everest. There will be no “planet B” for most of us. But I still want to cheer on those pioneer “Martians” because they will have a pivotal role in shaping what happens in the 22nd century and beyond. This is because the pioneer settlers – ill-adapted to their new habitats – will have a more compelling incentive than those of us on Earth to literally redesign themselves. They’ll harness the super-powerful genetic and cyborg technologies that will be developed in coming decades. These techniques will be, one hopes, heavily regulated on Earth – but those on Mars will be far beyond the clutches of the regulators. We should wish them luck in modifying their progeny to adapt to alien environments. This might be the first step towards divergence into a new species. It’s these space-faring adventurers, not those of us contentedly adapted to life on Earth, who will spearhead the post-human era. It’s perhaps in deep space – not on Earth, or even on Mars – that non-biological “brains” may develop powers that humans can’t even imagine. The sun will survive six billion more years before its fuel runs out. And the expanding universe will continue far longer – perhaps for ever. So even if intelligent life had originated only on the Earth, it need not remain a trivial feature of the cosmos: it could jump-start a diaspora whereby ever more complex intelligence spreads through the whole galaxy. Interstellar – or even intergalactic – voyages would hold no terrors for near-immortals. Even though we are not the terminal branch of an evolutionary tree, we humans could claim truly cosmic significance for jump-starting the transition to electronic entities, spreading our influence far beyond the Earth. But this raises a further question: will our remote progeny be the first intelligences to spread through the galaxy? Or will they encounter something already out there, whose origins lie on a planet around an older star where evolution had a head start over us? Martin Rees is the astronomer royal and a former president of the Royal Society. His new book, co-authored with Donald Goldsmith, is The End of Astronauts: Why Robots Are the Future of Exploration