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By Lord Martin Rees on

The Future of Spaceflight 

The Astronomer Royal, Lord Martin Rees, gives his verdict on the long-term future of space exploration. 

I’m going to speculate about the far future of spaceflight.

But let’s start with the near term. The Apollo programme – humans’ first footprints on another world – was an epochal event.  The Apollo astronauts were heroes – they accepted high risks and pushed technology to the limit.

The primary objective of Apollo 11 was to complete a national goal set by President John F. Kennedy on May 25, 1961: perform a crewed lunar landing and return to Earth. Apollo 11 launched July 16, 1969 and landed back on Earth on July 24, 1969. In this photograph, astronaut Edwin (Buzz) Aldrin takes his first step onto the surface of the Moon. Credit: NASA.

There have been huge advances since then in space technology. We depend on it every day for satnav, communications and so forth. And it’s led to wonderful scientific discoveries. But only now, 50+ years after Apollo, are there plans for a return to the moon. The US is spending 90-billion dollars on the Artemis program – which is touted as a precursor of human voyages to Mars.

But at the risk of being unpopular, I’d like to explain why I don’t think taxpayers should fund any such venture.

Unlike in the Apollo era, we now have robotic explorers, exemplified by the suite of rovers on Mars, where Perseverance, and its Chinese counterpart, can drive through rocky terrain with only limited guidance from Earth.  Within 10 or 20 years, AI advances will close the gap between robotic and human capabilities, rendering human flights to Mars even poorer practical or scientific value.

Moreover, flotillas of robotic craft could explore the planets and moons of the outer solar system with little additional expense. Multi-year journeys present little more challenge to a robot than the six-month voyage to Mars.

The Mars 2020 Perseverance Rover searches for signs of ancient microbial life, to advance NASA’s quest to explore the past habitability of Mars. The rover is collecting core samples of Martian rock and soil (broken rock and soil), for potential pickup by a future mission that would bring them to Earth for detailed study. Credit: NASA/JPL-Caltech/ASU/MSSS.

The next step will be the deployment in space of robotic fabricators, which can build large structures – for instance, giant successors to the James Web Space Telescope, with huge gossamer-thin mirrors assembled under zero gravity. These will further enhance our imaging of exoplanets and the wider cosmos.

The practical case for human spaceflight gets ever weaker with each advance in robots and miniaturization. Astronauts need far more ‘maintenance’ than robots, simply because their activities require air, water, food, living space, and protection against harmful radiation.

Moreover, safety and reliability standards must be more stringent, and therefore more expensive, when human lives are at stake. Already substantial for a trip to the moon, the cost ratios between human and robotic journeys grow much larger for any long-term mission.

Astronaut Serena Auñón-Chancellor harvests red Russian kale and dragoon lettuce from Veggie on Nov. 28, 2018, just in time for Thanksgiving. The Vegetable Production System, known as Veggie, is a space garden residing on the International Space Station. Veggie’s purpose is to help NASA study plant growth in microgravity, while adding fresh food to the astronauts’ diet and enhancing happiness and well-being on the orbiting laboratory. Credit: ESA/Alexander Gerst.

A Martian mission, taking six months to get there, and including provisions, and rocketry for a return trip, could cost NASA a trillion dollars. The cost would rise so high because NASA has developed a ‘safety culture’ – a response to the national trauma that followed the Space Shuttle disasters in 1985 and 2003, which each sadly killed the seven civilians on board.

The Shuttle had 135 launches altogether, and represented a failure rate below two percent. But it had, unwisely, been promoted as a safe vehicle for civilians. So, each failure was followed by a hiatus while costly efforts were made (with very limited effect) to reduce the risk still further. It would be utterly unrealistic to expect a 98 percent probability of a safe return from Mars.

But thrill-seekers and adventurers would willingly accept higher risks. Cut-price trips to Mars, bankrolled by billionaires and private sponsors, could be crewed by willing volunteers. The public wouldn’t be paying and would cheer on these brave adventurers.

The uncrewed SpaceX Crew Dragon spacecraft is the first Commercial Crew vehicle to visit the International Space Station. Here it is pictured with its nose cone open revealing its docking mechanism while approaching the station’s Harmony module. Credit: NASA EHDC S/N 1004 103.1F

As an American or European I’d argue that inspirationally led private companies should ‘front’ all human missions beyond low-earth-orbit 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.

That is why 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 ‘sold’ as dangerous sports, or intrepid exploration.

By 2100 thrill-seekers and adventurers may have established a base on Mars – under a dome or in a cave…  Elon Musk says he wants to die on Mars – but not on impact. He’s 52 now, so it’s a realistic goal.

But don’t ever expect mass emigration from Earth. And here I disagree strongly with Musk, Zubrin and others who advocate a 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 here. Coping with climate change may seem daunting, but it’s a doddle compared to terraforming Mars.

Nowhere in our Solar system offers an environment even as clement as the Antarctic, the ocean bed, or the top of Everest. There’s no ‘Planet B’ for ordinary risk-averse people.

Antarctica is Earth’s fifth largest continent. Image credit: NASA

But we humans should cheer on the risk-taking space adventurers, because they will have a pivotal role in spearheading humanities in the 22nd century and far beyond.

This is why.

The pioneer Martian explorers will be ill-adapted to their new habitat, so they will have a compelling incentive to re-design themselves – exploiting the super-powerful genetic and cyborg technologies that will be developed in coming decades.

These techniques will, one hopes, be heavily regulated on Earth, on prudential and ethical grounds; but ‘settlers’ on Mars will be far beyond the clutches of the regulators. We should surely wish them good luck in modifying their progeny to adapt to hostile unearthly environments. This would lead towards divergence into a new species.

So, it’s these spacefaring adventurers, not those of us comfortably adapted to life on Earth, who will spearhead the post-human era. Their population will evolve not via Darwinian selection but by the much faster process I’d call ‘secular intelligent design’.

Artist’s concept of Mars mission. Credit: NASA

What will they be like?

There are chemical and metabolic limits to the size and processing power of flesh and blood brains. Maybe we’re close to these already. But no such limits constrain electronic computers.

We are perhaps near the end of Darwinian evolution, but the technological evolution of intelligent beings is only just beginning. It will happen fastest away from the Earth – I wouldn’t expect (and certainly wouldn’t wish for) such rapid changes in humanity here on the Earth though our survival will depend on ensuring that AI remains ‘benevolent’.

We humans thrive on a planetary surface; but if posthumans make the transition to fully inorganic intelligences, then they won’t need an atmosphere.  And they may prefer zero-g, especially for constructing massive artefacts. So, it’s in deep space – not on Earth, nor even on Mars – that non-biological ‘brains’ may develop powers that humans can’t even imagine.

The text of this blog post was based on a speech given by Lord Rees at the Starmus VII Conference, Bratislava, May 2024.