杏吧原创

鈥淭 minus 10 seconds.鈥澛犅犅犅犅犅犅犅犅犅犅�

Imagine you鈥檙e a space tourist, preparing for lift-off. Yet rather than a deafening roar, followed by shaking and shuddering as the rocket engine fires up, you experience a serene stillness as the countdown continues.

鈥�5, 4, 3, 2, 1鈥︹�� And you鈥檙e away. You are pressed into your seat as the spacecraft ascends into the sky. But it鈥檚 a gentle push, not a blood-draining, face-distorting squeeze. And apart from the voices of the pilots beside you and the rush of air around the capsule, there is only silence. Outside, the darkening sky outlines the steadily growing curvature of the Earth. Before long, the sky is completely black, while the planet below has turned blue. You have reached the edge of space, and there鈥檚 not a rocket in sight.

Several companies hope to make their fortune by opening up space travel to people with the right stuff 鈥� money, in this case. Almost all the firms plan to do so using rockets, though, and rockets are dangerous. Of the 500-odd people launched into space so far, . For some people, the risk is surely part of the attraction. But what if you wanted the serene experience of looking at the blue marble without the risk of meeting a sticky end? Jos茅 Mariano L贸pez-Urdiales thinks he has the answer: space ballooning.

The company he founded, Zero2Infinity, based in Barcelona, Spain, hopes to start taking people up to near-space as early as 2013. Balloons cannot go as high as rockets, but in theory at least they should be far safer, since passengers won鈥檛 be sitting on tonnes of explosives. Their environmental impact is also far lower than that of smoke-belching rockets.

L贸pez-Urdiales was inspired by his father, an atmospheric physicist who was involved in sending probes to Titan and Mars. 鈥淚鈥檝e always seen him working, seen all the excitement of years of work going into a flight. That鈥檚 what got me excited about space in general,鈥� he says. Then, in 2000, his father told him about how the Huygens probe that explored Titan was tested by dropping a prototype from a balloon around 40 kilometres up. 鈥淎fter our conversation, I thought if there鈥檚 going to be space tourism, then let鈥檚 try this way,鈥� he says.

There is no doubt that it is possible, because it has been done many times before. In the 1950s and 1960s, more than a dozen crewed balloons journeyed to near-space. In 1957, for instance, Joe Kittinger of the US air force ascended to a height of 29 kilometres in a capsule attached to a helium balloon. He enjoyed the ride so much that when ordered to descend, he replied: 鈥淐ome and get me.鈥�

Zero2Infinity hopes to spread that joy to the civilian population. The company has carried out several test flights of uncrewed balloons, and earlier this year got the funding needed to carry out its first flight carrying people.

The plan is to use a massive helium 鈥渂loon鈥�, as the company likes to call it, to carry a pressurised capsule with space for two pilots and two passengers up to 34 kilometres above the Earth. You can book now 鈥� but at 鈧�110,000 per ticket, you鈥檒l need a little spare cash.

Will all that money really get you into space? According to one widely accepted definition, space begins 100 kilometres above the Earth鈥檚 surface, so most space tourism groups, such as Virgin Galactic, aim to take their passengers that far up.

That is more than twice the height a balloon can reach, and Zero2Infinity鈥檚 website uses the term 鈥渘ear-space鈥� rather than 鈥渟pace鈥�. L贸pez-Urdiales, however, points out that there is no clear physical boundary. At 34 kilometres, you are above more than 99 per cent of the atmosphere, he told attendees last October at a sustainability in the Maldives. And even 400 kilometres up, at the height of the International Space Station, there is still a very thin atmosphere.

The balloon鈥檚 altitude is not the only issue. Passengers will also miss out on the thrill of high g-forces and subsequent weightlessness. But is the point of space travel to get funfair thrills that you could experience far more cheaply by taking a plane ride on a weightlessness-producing 鈥渧omit comet鈥�?

L贸pez-Urdiales thinks the defining experience of space travel isn鈥檛 the vomiting, weightlessness or g-forces. It鈥檚 the 鈥渙verview effect鈥� 鈥� the blissful sense of connection so many astronauts report after gazing down at our blue planet from above. According to anecdotal reports, this experience has lasting effects on those who experience it.

鈥淭he defining experience of space travel is the blissful sense of connection you get from gazing down at Earth鈥�

It remains to be seen whether bloon passengers will feel the same way, but they probably have a much better chance than rocketeers. Because 100 kilometres is not high enough to go into orbit, rocket-propelled craft such as Virgin Galactic鈥檚 SpaceShipTwo will immediately begin falling back to Earth, giving passengers only a few minutes to take in the views. Bloon passengers will have more time; after ascending for about an hour, the bloon will remain at its maximum height for double that time.

When it is time to descend, the balloon will be jettisoned and retrieved later. The passenger capsule will descend by guided parachute, its landing cushioned by airbags. A balloon should not travel more than a few hundred kilometres during a flight, and wind models are now good enough to predict where they will end up, L贸pez-Urdiales says, so ground crews can be standing by. 鈥淥ur test flights have landed where we expected,鈥� he says.

Even the competition is charmed by the idea. 鈥淲hat you are doing is magnificent,鈥� Richard Branson told L贸pez-Urdiales at the symposium. And Branson, the founder of Virgin Galactic, knows a thing or two about ballooning.

A greener way to go

For those seeking a truly uplifting experience, there鈥檚 another reason why bloons are better: they鈥檙e the greenest way to go by far.

All rockets inject pollutants directly into the stratosphere, which has various effects. In particular, hydrocarbon-fuelled rockets, such as the kerosene-powered Soyuz, produce a lot of soot, which warms the planet by absorbing the sun鈥檚 heat. While soot in the lower atmosphere usually rains out after days, it can remain in the stratosphere for a decade or more, massively amplifying its effect. In 2010, Martin Ross and his colleagues at The Aerospace Corporation, a non-profit institution based in El Segundo, California, modelled each year with a rubber-burning engine like that of . The study concluded that the climatic effect of this kind of space tourism could be on a par with that of all commercial aeroplane flights put together.

By comparison, the impact of bloons on the planet should be tiny. 鈥淭he whole operation can easily be done with zero emissions,鈥� L贸pez-Urdiales says. That will not be true at first. Helium is obtained from natural gas, and it is liquefied after being separated, which is currently done using fossil-fuel electricity. According to New 杏吧原创鈥榮 calculations, producing the 4000 cubic metres of helium needed for a bloon flight will generate around 4 tonnes of CO₂, around the same per passenger as a long-haul flight.

Far more important than how much CO₂ is produced, though, is the fact that no climate-altering substances will be pumped directly into the stratosphere. 鈥淚 don鈥檛 see a problem,鈥� says Ross. 鈥淚f it does not involve chemical combustion, it will be a lot less of a concern.鈥�

So if you鈥檝e always longed to travel into space but don鈥檛 want to trash the planet doing so, space ballooning is the way to go. Start saving your pocket money now. Up, up and away!