Martin Rees: For our future in space, China must aim further than the Moon

 

A famous picture in the English edition of Newton’s “Principia” shows cannon balls being fired from the top of a mountain. If they go fast enough, their trajectory curves downward no more steeply than the Earth curves away underneath it – they go into orbit. This picture is still the neatest way to explain orbital flight. Newton calculated that, for a cannon-ball to achieve an orbital trajectory, its speed must be 18000 miles per hour – far beyond what was then achievable.

Indeed, this speed wasn’t achieved until 1957, when the Soviet Sputnik was launched. Four years later Yuri Gagarin was the first human to go into orbit. Eight years after that, Neil Armstrong made his “one small step”. The Apollo programme was a heroic episode. And it was a long time ago – ancient history to today’s young people.

Had the momentum of the 1960s been maintained over the next 40 years, there would be footprints on Mars by now. But after Apollo, the political impetus for manned spaceflight was lost.

The most crucial impediment to space flight stems from the intrinsic inefficiency of chemical fuel, and the consequent requirement to carry a weight of fuel far exceeding that of the payload. This is a generic constraint, based on fundamental chemistry. If a planet’s gravity is strong enough to retain an atmosphere, at a temperature where water doesn’t freeze, and metabolic reactions aren’t too slow, the energy required to lift a molecule from it will require more than one molecule of chemical fuel.

Launchers will get cheaper when they can be designed to be more fully reusable. It will then be feasible to assemble, in orbit, even larger artifacts than the International Space Station. But so long as we are dependent on chemical fuels, interplanetary travel will remain a challenge.

Nuclear power could be therefore be transformative. By allowing much higher in-course speeds, it would drastically cut the transit times to Mars or the asteroids. And it could transform manned spaceflight from 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 program the entire journey beforehand, with minimal opportunities for steering on the way. If there were an abundance of fuel for mid-course corrections (and to brake and accelerate at will), then interplanetary navigation would be a doddle – indeed simpler than driving a car or ship, in that the destination is always in clear sight.

In the light of this, I would venture a confident forecast that during this century, all the planets, moons, and asteroids of the solar system will be explored and mapped. The Hubble Telescope’s successors, with huge gossamer-thin mirrors assembled under zero gravity, will further expand our vision of stars, galaxies and the wider cosmos.

To infinity and beyond? Probably not NASA. NASA

But the role that humans will play in this is debatable. There’s no denying that NASA’s “Curiosity,” now trundling across Martian craters, may miss startling discoveries that no human geologist could overlook. But robotic techniques are advancing fast, allowing ever more sophisticated unmanned probes. And the cost gap between manned and unmanned missions remains huge. The practical case for manned spaceflight gets ever weaker with each advance in robots and miniaturisation. Indeed, as a scientist I see little purpose in sending people into space at all.

But as a human being, I’m an enthusiast for manned missions. I hope some people now living will walk on Mars – as an adventure, and as a step towards the stars. They may be Chinese: China has the resources, the dirigiste government, and maybe the willingness to undertake an Apollo-style programme. And China would need to aim at Mars, not just at the Moon, if it wanted to assert its super-power status by a “space spectacular”.

However, NASA’s manned programme, ever since Apollo, has been impeded by public and political pressure into being too risk-averse. Unless motivated by pure prestige and bankrolled by superpowers, manned missions beyond the Moon will need perforce to be cut-price ventures, accepting high risks – perhaps even one-way tickets. Such missions would need to be privately funded. No Western governmental agency would expose civilians to such hazards.

Nonetheless, a century or two from now, there may be small groups of pioneers living independent from the Earth – on Mars or on asteroids. Whatever ethical constraints we impose here on the ground, we should surely wish these adventurers good luck in genetically modifying their progeny to adapt to alien environments. This might be the first step towards divergence into a new species: the beginning of the post-human era.

And machines of human intelligence could spread still further. Whether the long-range future lies with organic post-humans or with intelligent machines is a matter for debate. Either way, dramatic cultural and technological evolution will continue not only here on Earth, but far beyond.

By Martin Rees , University of Cambridge

Martin Rees does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

The Conversation

This article was originally published at The Conversation. Read the original article.

PROMOTED VIDEO
Life and Style
beautyBelgian fan lands L'Oreal campaign after being spotted at World Cup
Arts and Entertainment
Characters in the new series are based on real people, say its creators, unlike Arya and Clegane the Dog in ‘Game of Thrones’
tv'The Last Kingdom' embraces politics, religion, warfare, courage, love and loyalty, say creators
News
people
Life and Style
tech
News
Justin Bieber performing in Paris earlier this year
people
Arts and Entertainment
Martin Freeman and Lauren O'Neil in Jamie Lloyd's Richard III
theatreReview: The monarch's malign magnetism and diabolic effrontery aren’t felt
Arts and Entertainment
'Molecular Man +1+1+1' by Jonathan Borofsky at Yorkshire Sculpture park
tv
News
Glamour magazine hosts a yoga class with Yogalosophy author Mandy Ingber on June 10, 2013 in New York City.
newsFather Padraig O'Baoill said the exercise was 'unsavoury' in a weekly parish newsletter
Extras
indybest
News
people'She is unstoppable', says Jean Paul Gaultier at Paris show
Sport
Alexis Sanchez and apparently his barber Carlos Moles in Barcelona today
football

Day In a Page

The true Gaza back-story that the Israelis aren’t telling this week

The true Gaza back-story that the Israelis aren’t telling this week

A future Palestine state will have no borders and be an enclave within Israel, surrounded on all sides by Israeli-held territory, says Robert Fisk
A History of the First World War in 100 Moments: The German people demand an end to the fighting

A History of the First World War in 100 Moments

The German people demand an end to the fighting
New play by Oscar Wilde's grandson reveals what the Irish wit said at his trials

New play reveals what Oscar Wilde said at trials

For a century, what Wilde actually said at his trials was a mystery. But the recent discovery of shorthand notes changed that. Now his grandson Merlin Holland has turned them into a play
Can scientists save the world's sea life from

Can scientists save our sea life?

By the end of the century, the only living things left in our oceans could be plankton and jellyfish. Alex Renton meets the scientists who are trying to turn the tide
Richard III, Trafalgar Studios, review: Martin Freeman gives highly intelligent performance

Richard III review

Martin Freeman’s psychotic monarch is big on mockery but wanting in malice
Hollywood targets Asian audiences as US films enjoy record-breaking run at Chinese box office

Hollywood targets Asian audiences

The world's second biggest movie market is fast becoming the Hollywood studios' most crucial
Grindr founder Joel Simkhai: 'I've found love on my dating app - and my mum keeps trying to hook me up!'

Grindr founder Joel Simkhai: 'I've found love on my dating app'

Five years on from its launch and Grindr is the world's most popular dating app for gay men. Its founder Joel Simkhai answers his critics, describes his isolation as a child
Autocorrect has its uses but it can go rogue with embarrassing results - so is it time to ditch it?

Is it time to ditch autocorrect?

Matthew J X Malady persuaded friends to message manually instead, but failed to factor in fat fingers and drunk texting
10 best girls' summer dresses

Frock chick: 10 best girls' summer dresses

Get them ready for the holidays with these cool and pretty options 
Westminster’s dark secret: Adultery, homosexuality, sadomasochism and abuse of children were all seemingly lumped together

Westminster’s dark secret

Adultery, homosexuality, sadomasochism and abuse of children were all seemingly lumped together
A History of the First World War in 100 Moments: Dulce et decorum est - a life cut short for a poet whose work achieved immortality

A History of the First World War in 100 Moments

Dulce et decorum est: a life cut short for a poet whose work achieved immortality
Google tells popular music website to censor album cover art in 'sexually explicit content' ban

Naked censorship?

The strange case of Google, the music website and the nudity take-down requests
Howzat! 8 best cricket bats

Howzat! 8 best cricket bats

As England take on India at Trent Bridge, here is our pick of the high-performing bats to help you up your run-count this summer 
Brazil vs Germany World Cup 2014 comment: David Luiz falls from leader figure to symbol of national humiliation

David Luiz falls from leader figure to symbol of national humiliation

Captain appears to give up as shocking 7-1 World Cup semi-final defeat threatens ramifications in Brazil