When renowned British gerontologist Aubrey de Grey said a decade ago that there were people on earth today who would live to be 1,000 years old, he didn’t merely lift the lid on Pandora’s box: he kicked it wide open.

If medical technology was indeed advancing so rapidly that we would soon have the treatments available to keep us alive for many times longer than ever before, how could society as we know it possibly keep up? How long would we have to work for? Where would we all live?

With the seven billion people on Earth already the cause of endless headlines about overcrowding, the environmental horrors caused by a mega-swarm of long-living, energy-sapping homo sapiens can only be imagined.

If the UN’s latest worst-case projections – that the global population could be as high as 36 billion by 2300 – were to come true, it would make this little planet of ours a very busy place indeed.

The problem, however, is somewhat diminished if you embrace the idea that Earth will one day be but one of a number of places that mankind can call home.

Crane your neck to the night sky and that infinite number of planets you look out on is also an infinite number of possibilities for thriving inter-galactic colonies – places where mankind can not only spread out, but ensure the continued existence of our species should Earth suffer some kind of cataclysmic event.

Getting there, however, is the tricky part…

A matter of small obstacles

Though 46 years have now passed since Neil Armstrong first stamped his boot-print on the surface of the Moon, the idea of putting a man on a rocket and sending him to live on a distant planet is still the stuff of science fiction. The obstacles are frankly dizzying.

For a start, the distances involved in serious space travel beggar belief. While you might “only” need six to ten months to get to Mars, travelling at similar speeds it would take more than 100,000 years to get to Alpha Centauri, the nearest star system outside of our solar system.

If we were able to go any faster, Nick Beckstead, a research fellow at Oxford University’s Future Of Humanity Institute, raises the question of how we might slow down the spaceship when we arrive at our new planet. To a long list of hurdles he considered when writing a paper on the subject of space colonisation last year, he also added the colossal challenge of physically building a civilisation once settlers arrive at their new home.

Obstacles that stand between us and life on other planets include cosmic rays, problems associated with microgravity and the dangers of reproduction from a very small gene pool

Other obstacles that stand between us and life on other planets include cosmic rays (scientists in Nevada claimed last year that anyone spending time in space receives doses of radiation that exceeded normal lifetime limits after just two years); cost (in the many billions, if not trillions); problems associated with microgravity (including bone and sight disorders); the dangers of reproduction from a very small gene pool; suitable propulsion systems (Beckstead, for the record, posits that a nuclear option is currently the “least speculative” of all the ideas on the table); high-speed collisions with space debris and the not insubstantial matter of how to keep would-be colonists fed, watered and entertained for the many years it would likely take them to reach such distant destinations.

But first things first. Because none of this will happen before we’ve put a man on Mars.

The race for Mars

At the time of writing there were three – possibly four – main players in the race to conquer Mars. They are NASA, which has publicly stated it would like to put someone on the red planet sometime during the 2030s; entrepreneur Elon Musk’s privately-owned SpaceX; and Mars One, a Dutch-led initiative that has captured countless Mars headlines over the last few years thanks to its unique ‘one-way-trip’ angle.

The fourth contender is China, which is rumoured to be planning on sending a robot to Mars within five years. The country’s’ long-term goals are unknown, though way back in 2002 the UK’s Daily Telegraph newspaper reported how China was boasting it would “beat the US” in a manned mission to Mars.

NASA has publicly stated it would like to put someone on the red planet sometime during the 2030s

But how are these big players planning to get there? For NASA’s part, the agency is currently developing an expendable launch vehicle called the Space Launch System (its replacement for the Space Shuttle) and is expected to base any future Mars launches around this and its successors. It is also developing a reusable deep-space capsule called Orion, which is expected to be ready for use in 2021.

SpaceX, meanwhile, is working on a launch vehicle called the Falcon Heavy and has a crew capsule known as Dragon, an adapted version of which is expected to be the preferred option for Mars. SpaceX and NASA may also combine their talents for a joint mission to Mars: Musk has already taken cargo into space for NASA and has signed a deal to take their astronauts to the ISS by 2017.

“Our ultimate objective is Mars and it always has been,” Musk told Space.com in 2012, and he aims to do it in ten to twelve years. In the longer term, the PayPal and Tesla Motors co-founder envisions a colony there that will number in the tens of thousands.

The most maligned of the major contenders is Mars One, whose proposals have been ridiculed by a growing number of experts. MIT researchers calculated that crew members would start dying within three months of arrival, while former NASA astronaut James F. Reilly told a private audience in Wembley this April that the idea was “half-baked”. Undeterred, the Mars One team says it will blast off in 2027, though critics point out that they don’t yet have clear plans for a launch vehicle.

Mars on Earth

In the deserts of Utah – about as inhospitable a spot as you can find on a map of America – an organisation named The Mars Society is taking the idea that we will one day set foot on distant planets as read. Here, crews of volunteers don space-suits, buzz around on quad-bikes and spend weeks in isolation in domed buildings to get an idea of what life on Mars will be like.

The goal is to iron out all the cracks before a Mars mission even leaves Earth.

“Volunteers do everything under Mars mission constraints, and based on their findings we can try to drive out where the problems are and look for solutions,” says Dr Robert Zubrin, president of the Mars Society. “It’s important to design things right,” he adds, “but it’s even more important to design the right things.”

Volunteers don space-suits, buzz around on quad-bikes and spend weeks in isolation to get an idea of what life on Mars will be like

More than 150 simulated Mars missions have now been overseen by Zubrin and his colleagues, and the participants are making new discoveries all the time. It is now widely accepted, for example, that the best vehicle for pootling around the red planet is not a large, SUV-sized rover, but smaller ATVs.

Zubrin says that from a technological point of view a manned Mars mission is almost within our grasp, and he’s putting his money on SpaceX.

“NASA talks about sending humans to Mars, but it’s sizzle without the steak,” he says. “They have a vision, but no programme, and there’s a big difference. Musk, however – he’s on the march. I have little doubt that he wants to get to Mars.”

To infinity

Conquer Mars, and colonising the further reaches of outer space seems a logical next step. Aubrey de Grey, whose ‘live-forever’ projections perhaps ignited the idea that we must dash for the skies in the first place, isn’t so sure.

“Mass emigration into space has no chance of working,” he says. “It’s not because space is a risky place to spend time but because we wouldn’t be able to reach enough space quickly enough.”

He argues that if you do the numbers it is a “total non-starter” and says that the best answer to the planet’s increasing population is technologies that will increase the Earth’s “carrying capacity”, such as renewable energy and nuclear fusion.

But Dr Zubrin thinks he’s missing the point. Zubrin says that Mars represents more than just a solution to overcrowding: it represents hope, innovation and an “open future”.

There’s little doubt that Dr Zubrin sees space colonisation coming, though at 63 he might not see it within his lifetime. “It will be a process,” he says. “First to our solar system and after that I do believe we’re going to the stars. In 500 years from now we’ll be on hundreds of planets on nearby solar systems and spreading out from there.”

And, he predicts, people will be able to travel to Mars in 100 years from now “at least as fast as Europeans were able to travel to America in the 1800s.” Indeed, just this month NASA was reported to be secretly testing a new “warp drive” system – an electromagnetic propulsion drive – which would be significantly faster than anything currently available.

Powered by solar energy, it would need no propellant and could theoretically put humans on Alpha Centauri in 100 years, with the first settlers actually being born on the mothership, or ‘generation ship’ as Nick Beckstead calls it. Beckstead says that supporters of this idea think these vehicles would be designed so that children born on the journey would be trained to continue the voyage mid-flight.

Ray Hammond, a noted futurist, certainly sees a sky without limits – though he has a slightly different take on things: “It is not we biological humans who will explore and colonise our solar system and, in time, our galaxy,” he says. “Humankind will most probably explore and colonise space through our successor species – a new species which will be a blend of human and intelligent machine.”

Humans already use technological prosthetics, he points out, and we are already copying small parts of our intelligence into machines. “The process has begun,” he says, “and by the second half of this century the new species will be distinguishable and will have embarked on space colonisation.”