ESA/DLR/FU Berlin; Nasa MGS MOLA Science Team; PASCAL PAVANI/AFP/Getty Images

Among my favourite things to read during my childhood (in England, way back in the 1950s), was a comic called the Eagle, especially the adventures of Dan Dare: Pilot of the Future — where the brilliant artwork depicted orbiting cities, jet packs, and alien invaders. When spaceflight became real, the suits worn by Nasa astronauts (and their Soviet ‘cosmonaut’ counterparts) were therefore familiar, as were the routines of launching, docking, and so forth.

My generation avidly followed the succession of heroic pioneering exploits: Yuri Gagarin’s first orbital flight, Alexey Leonov’s first space walk, and then, of course, the lunar landings. I recall a visit to my home town by John Glenn, the first American to go into orbit. He was asked what he was thinking while in the rocket’s nose cone, awaiting launch. He responded, ‘I was thinking that there were twenty thousand parts in this rocket, and each was made by the lowest bidder’. (Glenn later became a US senator, and, later still, the oldest astronaut when, at age seventy-seven, he became part of the STS-95 Space Shuttle crew.)


Only 12 years elapsed between the flight of the Soviet Sputnik 1 — the first artificial object to go into orbit — and the historic ‘one small step’ on the lunar surface in 1969. I never look at the Moon without being reminded of Neil Armstrong and Buzz Aldrin. Their exploits seem even more heroic in retrospect, when we realise how they depended on primitive computing and untested equipment. Indeed, president Nixon’s speechwriter William Safire had drafted a speech to be given if the astronauts had crash landed on the Moon or were stranded there: “Fate has ordained that the men who went to the Moon to explore in peace will stay on the Moon to rest in peace. [They] know that there is no hope for their recovery. But they also know that there is hope for mankind in their sacrifice”.

The Apollo programme remains, a half century later, the high point of human ventures into space. It was a ‘space race’ against the Russians — a contest in superpower rivalry. Had that momentum been maintained, there would surely be footprints on Mars by now; that’s what our generation expected. However, once that race was won, there was no motivation for continuing the requisite expenditure. In the 1960s, Nasa absorbed more than four per cent of the US federal budget. The current figure is 0.6 per cent. Today’s young people know Americans landed men on the Moon. They know the Egyptians built pyramids. But these enterprises seem like ancient history, motivated by almost equally bizarre national goals.

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Hundreds more have ventured into space in the ensuing decades — but, anticlimactically, they have done no more than circle the Earth in low orbit. The International Space Station (ISS) was probably the most expensive artefact ever constructed. Its cost, plus that of the shuttles whose main purpose was to service it (though they have now been decommissioned) ran well into twelve figures. The scientific and technical payoff from the ISS hasn’t been negligible, but it has been less cost effective than unmanned missions. Nor are these voyages inspiring in the way that the pioneering Russian and US space exploits were. The ISS only makes news when something goes wrong: when the loo fails, for instance; or when astronauts perform ‘stunts’, such as the Canadian Chris Hadfield’s guitar playing and singing.

The hiatus in manned space exploration exemplifies that when there’s no economic or political demand, what is actually done is far less than what could be achieved. (Supersonic flight is another example — the Concorde airliner went the way of the dinosaurs. In contrast, the spin-offs from IT have advanced, and spread globally, far faster than forecasters and management gurus predicted.)


Space technology has nonetheless burgeoned in the last four decades. We depend routinely on orbiting satellites for communication, sat-nav, environmental monitoring, surveillance, and weather forecasting. These services mainly use spacecraft that, though unmanned, are expensive and elaborate. But there is a growing market for relatively inexpensive miniaturised satellites, the demand for which several private companies are aiming to meet.

The San Francisco–based company PlanetLab has developed and launched swarms of shoebox-sized spacecraft with the collective mission of giving repeated imaging and global coverage, albeit at not-specially-sharp resolution (3–5 metres): the mantra (with only slight exaggeration) is to observe every tree in the world every day. Eighty-eight of the craft were launched in 2017 as payload on a single Indian rocket; Russian and US rockets have been used to launch more, as well as a fleet of somewhat larger and more elaborately equipped SkySats (each weighing 100 kilograms).

For much sharper resolution, a larger satellite with more elaborate optics is needed, but there is nonetheless a commercial market for the data from these tiny cubesats to monitor crops, construction sites, fishing boats, and suchlike; they are also useful for planning a response to disasters. Even smaller wafer-thin satellites can now be deployed – exploiting the technology that has emerged from the colossal investment in consumer microelectronics.

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Telescopes in space offer astronomy a huge boost. Orbiting far above the blurring and absorptive effects of Earth’s atmosphere, they have beamed back sharp images from the remotest parts of the cosmos. They have surveyed the sky in infrared, UV, X-ray, and gamma ray bands that don’t penetrate the atmosphere and therefore can’t be observed from the ground. They have revealed evidence for black holes and other exotica and have probed with high precision the ‘afterglow of creation’ – the microwaves pervading all space whose properties hold clues to the very beginning, when the entire observable cosmos was squeezed to microscopic size.


Of more immediate public appeal are the findings from spacecraft that have journeyed to all the planets of the solar system. Nasa’s New Horizons beamed back amazing pictures from Pluto, ten thousand times farther away than the Moon. And the European Space Agency’s Rosetta landed a robot on a comet. These spacecraft took five years to design and build and then nearly ten years journeying to their remote targets. The Cassini probe spent thirteen years studying Saturn and its moons and was even more venerable; more than twenty years elapsed between its launch and its final plunge into Saturn in late 2017. It is not hard to envisage how much more sophisticated today’s follow-ups to these missions could be.

During this century, the entire solar system – planets, moons, and asteroids – will be explored and mapped by fleets of tiny robotic space probes, interacting with each other like a flock of birds. Giant robotic fabricators will be able to construct, in space, solar energy collectors and other objects. The Hubble telescope’s successors, with oversize mirrors assembled in zero gravity, will further expand our vision of exoplanets, stars, galaxies, and the wider cosmos. The next step would be space mining and fabrication.

But will there be a role for humans? There’s no denying that Nasa’s Curiosity, a vehicle the size of a small car that has since 2011 been trundling across a giant Martian crater, may miss startling discoveries that no human geologist could overlook. But machine learning is advancing fast, as is sensor technology. In contrast, the cost gap between manned and unmanned missions remains outsized. The practical case for manned spaceflight gets ever weaker with each advance in robots and miniaturisation.

If there were a revival of the ‘Apollo spirit’ and a renewed urge to build on its legacy, a permanently manned lunar base would be a credible next step. Its construction could be accomplished by robots – bringing supplies from Earth and mining some from the Moon. An especially propitious site is the Shackleton crater, at the lunar south pole, 21 kilometres across and with a rim four kilometres high. Because of the crater’s location, its rim is always in sunlight and so escapes the extreme monthly temperature contrasts experienced on almost all the Moon’s surface. Moreover, there may be a lot of ice in the crater’s perpetually dark interior – crucial, of course, for sustaining a ‘colony’.

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It would make sense to build mainly on the half of the Moon that faces the Earth. But there is one exception: astronomers would like a giant telescope on the far side because it would then be shielded from the artificial emission from the Earth – offering a great advantage to radio astronomers seeking to detect very faint cosmic emissions.

Nasa’s manned space programme, ever since Apollo, has been constrained by public and political pressure to be risk-averse. The space shuttle failed twice in 135 launches. Astronauts or test pilots would willingly accept this level of risk – less than two per cent. But the shuttle had, unwisely, been promoted as a safe vehicle for civilians (and a female schoolteacher, Christa McAuliffe, in the Nasa Teacher in Space Project, was one of the casualties of the Challenger disaster). Each failure caused a national trauma in the United States and was followed by a hiatus while costly efforts were made (with very limited effect) to reduce risks still further.

I hope some people now living will walk on Mars – as an adventure, and as a step towards the stars. But Nasa will confront political obstacles in achieving this goal within a feasible budget. China has the resources, the dirigiste government, and maybe the willingness to undertake an Apollo-style programme. If it wanted to assert its superpower status by a ‘space spectacular’ and to proclaim parity, China would need to leapfrog, rather than just rerun, what the United States had achieved fifty years earlier. It already plans a ‘first’ by landing on the far side of the Moon. A clearer-cut ‘great leap forward’ would involve footprints on Mars, not just on the Moon.

Leaving aside the Chinese, I think the future of manned spaceflight lies with privately funded adventurers, prepared to participate in a cut-price programme far riskier than western nations could impose on publicly supported civilians. SpaceX, led by Elon Musk (who also builds Tesla electric cars) or the rival effort, Blue Origin, bankrolled by Jeff Bezos, founder of Amazon, have berthed craft at the space station and will soon offer orbital flights to paying customers. These ventures –bringing a Silicon Valley culture into a domain long dominated by Nasa and a few aerospace conglomerates – have shown it’s possible to recover and reuse the launch rocket’s first stage – presaging real cost savings. They have innovated and improved rocketry far faster than Nasa or ESA has done – the latest Falcon rocket is able to put a fifty-ton payload into orbit. The future role of the national agencies will be attenuated – becoming more akin to an airport than to an airline.

If I were an American, I would not support Nasa’s manned programme – I would argue that inspirationally led private companies should ‘front’ all manned missions as cut-price high-risk ventures. There would still be many volunteers – some perhaps even accepting ‘one-way tickets’ – driven by the same motives as early explorers, mountaineers, and the like. Indeed, it is time to eschew the mind-set that space ventures should be national (even international) projects – along with pretentious rhetoric where the word ‘we’ is used to denote the whole of humanity. There are some endeavours – tackling climate change, for instance – that can’t be done without concerted international action. The exploitation of space need not be of this nature; it may need some public regulation, but the impetus can be private or corporate.

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There are plans for week-long trips round the far side of the Moon – voyaging farther from Earth than anyone has gone before. Earlier this month Elon Musk announced that Yusaku Maezawa, a Japanese billionaire, had bought a ticket for the first flight, for him and six friends, with 2023 as the expected launch-date. And Denis Tito, an entrepreneur and former astronaut, has proposed that when a new heavy-life launcher is available, to send people to Mars and back – without landing. This would require five hundred days in isolated confinement. The ideal crew would be a stable middle-aged couple – old enough to not be bothered about the high dose of radiation accumulated on the trip.

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. These exploits must be ‘sold’ as dangerous sports, or intrepid exploration.

The most crucial impediment to space flight, in Earth’s orbit and for those venturing farther, stems from the intrinsic inefficiency of chemical fuel and the consequent requirement for launchers to carry a weight of fuel far exceeding that of the payload. So long as we are dependent on chemical fuels, interplanetary travel will remain a challenge. Nuclear power could be transformative. By allowing much higher in-course speeds, it would drastically cut the transit times to Mars or the asteroids (reducing not only astronauts’ boredom but also their exposure to damaging radiation).

Greater efficiency would be achieved if the fuel supply could be on the ground and not carried into space. For instance, it might be technically possible to propel spacecraft into orbit via a ‘space elevator – a carbon-fibre rope 30,000 kilometres long anchored to the Earth (and powered from the ground), extending vertically up beyond the distance of a geostationary orbit so that it is held taut by centrifugal forces. An alternative scheme envisages a powerful laser beam generated on Earth that pushes on a ‘sail’ attached to the spacecraft; this might be feasible for lightweight space probes and could in principle accelerate them to a fraction of the speed of light.

Incidentally, more efficient on-board fuel could transform manned spaceflight from a high-precision to an almost unskilled operation. Driving a car would be a difficult enterprise if, as at present for space voyages, one had to programme the entire journey in detail beforehand, with minimal opportunities for steering along the way. If there were an abundance of fuel for midcourse corrections (and to brake and accelerate at will), then interplanetary navigation would be a low-skill task – simpler, even, than steering a car or ship, in that the destination is always in clear view.

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By 2100 thrill-seekers in the mould of (say) Felix Baumgartner (the Austrian skydiver who in 2012 broke the sound barrier in free fall from a high-altitude balloon) may have established ‘bases’ independent from the Earth – on Mars, or maybe on asteroids. Elon Musk (born in 1971) of SpaceX says he wants to die on Mars – but not on impact. But don’t ever expect mass emigration from Earth. And here I disagree strongly with Musk and with my late Cambridge colleague Stephen Hawking who enthuse about rapid build-up of large-scale Martian communities. It’s a dangerous delusion to think that space offers an escape from Earth’s problems. We’ve got to solve these problems here. Coping with climate change may seem daunting, but it’s a doddle compared to terraforming Mars. No place in our solar system offers an environment even as clement as the Antarctic or the top of Everest. There’s no ‘Planet B’ for ordinary risk-averse people.

But we (and our progeny here on Earth) should cheer on the brave space adventurers, because they will have a pivotal role in spearheading the post-human future and determining what happens in the twenty-second century and beyond.

This is an extract from On the Future: Prospects for Humanity (Princeton University Press) by Martin Rees

Want to know more about the future of space exploration?

This article is part of our WIRED on Space series. From the global fight over how we handle first contact with aliens to the endless search for dark matter and the inside story of China's top-secret space ambitions, we're taking an in-depth look at humanity's future amongst the stars.


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