On July 20, the unfathomably wealthy Amazon founder Jeff Bezos will strap himself to a rocket built by Blue Origin, his private space company. If all goes according to plan, Bezos, his brother Mark, an as-of-yet anonymous person who paid about £20 million in an auction for a seat, and Wally Funk – an 82-year-old test pilot who was denied her deserved place on a spacecraft in the 1960s – will be launched skyward. Their New Shepherd capsule, operating autonomously, will take them into space for a few minutes before they tumble back to terra firma.
Earlier this month, Richard Branson, another seriously wealthy individual with his own space company, Virgin Galactic, declared that he, too, was briefly flinging himself into space. He would be joining the two pilots and three other passengers of the VSS Unity, a spaceplane, as it launched from New Mexico on July 11 – a full nine days before the Bezos brothers and their guests take off from Texas.
These technologically impressive endeavours are framed in philanthropic terms, with both companies suggesting this work will pave the way for commercialised spaceflight. Branson recently denied that the two men are vying to get themselves into space before the other. Let’s not be naïve. One day, perhaps the wealthy, and not just the mind-bogglingly wealthy, will be regularly taking short trips into space. But right now, this is a race between two billionaires hurrying to the azure edges of the Earth to obtain bragging rights – a story of the fast and the vainglorious.
There is, however, a weirdly fundamental problem with both missions. Have you ever stopped to wonder where, exactly, Earth ends and space itself begins? Countless experts the world over have ruminated on the same question for decades and, astonishingly, have failed to agree on an answer.
Both Bezos and Branson say they are flying into space. The former will reach an altitude of a little over 100 kilometres; the latter, around 80 to 90 kilometres. Depending on who you ask, both of them, one of them or none of them will reach space and become astronauts. All we can say with any certitude is that these rich boys are flying really, really high in their own personal spaceships while we gawp at them from below.
Humanity has always had trouble grasping the daunting expanse of space. The word itself has Latin roots, and has meant a room, area, distance or stretch of time for millennia. But one of the first Anglophonic uses of the word in the astronomical sense appeared in Milton’s 1667 poetic epic, Paradise Lost, in which one character, considering the cosmos, describes Earth as “an atom” compared to the vast heavens “And all her numbered stars, that seem to roll/Spaces incomprehensible”.
Astronomy – the study of everything that isn’t Earth – has made space a little less incomprehensible. But defining the boundary between Earth and space has continued to bamboozle the brightest minds throughout the centuries. You would think that the Outer Space Treaty, a 1967 tome that spelled out the first laws that everyone must abide by in space, would explicitly state what space itself is. But the failure of the writers to shake hands on a set altitude precluded any such definition from being featured.
In your own attempts to define space’s beginning, your macabre mind may turn to Hollywood-inflected thoughts of astronauts perishing in space, freezing and asphyxiating in equal measure. But defining space as a place that’s lethally devoid of sufficient oxygen and warmth won’t work. If you find yourself on a mountain that’s more than eight kilometres tall, and you linger up there, the minimal oxygen in the rarefied air will speedily result in your death – if the bone splintering frigidity of the environment doesn’t kill you first. But only exceedingly outré individuals would say Mount Everest’s peak, for example, is in space.
So what about getting high up enough to leave all of Earth’s atmosphere behind? To do that, you would need to get almost 1,000 kilometres above sea level. This sounds like a reasonable definition of space until you consider the fact that the International Space Station itself – a famously space bound piece of astral architecture – is ‘only’ 400 kilometres or so above the planet’s surface.
Back in 2009, scientists at the University of Calgary reckoned that the liminal chasm between Earth and the firmament was far lower. Specialised equipment found that the planet’s shifting atmosphere gives way to the cascade of charged cosmic and stellar particles at a mere 118 kilometres above sea level.
The most commonly cited altitude for the border between Earth and space is the one used by the Fédération Aéronautique Internationale (FAI), the international governing body of air sports: 100 kilometres.
This value largely owes its origins to Theodore von Kármán, a Hungarian polymath. Over half a century ago, he postulated that the edge of space would be where aeroplanes couldn’t fly because the atmospheric forces that provide lift, and thereby make controlled flight possible, had faded away. Putting this concept through a gauntlet of calculations in the early 1960s, Andrew Gallagher Haley, the world’s first space lawyer, determined that this boundary would be 84 kilometres up.
Jonathan McDowell, an astronomer at the Center for Astrophysics in Cambridge, Massachusetts, explains that this was occasionally rounded up to 100 kilometres, partly because scientists like showing values as orders-of-magnitude – 10, 100, 1,000, and so on. But von Kármán never explicitly declared the edge of space to be 100 kilometres high. And yet, that value stuck.
The FAI, among other groups, say that anyone flying above that boundary – now known as the Kármán Line – is an astronaut. Blue Origin agrees: Bezos et al will be spending a few hundred precious seconds above the Kármán Line. And, as a company spokesperson says, this line “is the internationally recognised boundary of space as designated by the [FAI], who establishes standards for international record-keeping”.
“Blue Origin designed New Shepard to go above the Kármán Line from the beginning,” the spokesperson adds. As it happens, early designs for Virgin Galactic’s space planes suggested they would breach the Kármán Line too, but Branson’s upcoming flight will only hit 80 to 90 kilometres.
But fret not, Branson stans: McDowell is in your corner. His own calculations of where the Kármán Line should be, which were based on von Kármán’s original postulations and published in 2018, suggests that 80 kilometres (plus or minus ten) makes more sense than 100. If a craft rises above 80, the atmosphere mostly gives way to gravity, which becomes the dominant force acting on the vessel. This value is supported by the behaviour of satellites: 80 kilometres is “the lowest you can be and still survive for another orbit,” says McDowell; any lower, and satellites will fall to Earth or burn up.
That, he says, is the true height of the Kármán Line. “It doesn’t astonish me that Virgin Galactic likes my results, and Bezos isn’t really so interested,” says McDowell.
Whether or not that is the right definition of space’s edge, he adds, is arguable – but if you had to pick an altitude, McDowell thinks that 80 kilometres is a pretty reasonable one to go for. As it happens, NASA and the US military settled on that value too: anyone that spends any amount of time above that height gets astronaut wings.
By these measures, Branson and his crew will, on July 11, reach space before Bezos. “We are going above the astronaut line,” Virgin Galactic CEO Michael Colglazier told CNBC.
Blue Origin is sticking to its 100-kilometre Kármán Line definition of space. “None of our astronauts will have an asterisk next to their flight, as nearly the entire world recognises this line as the official designation to space,” a spokesperson says. Virgin Galactic did not respond to a request to comment.
As is clear by this point, trying to define an unambiguous boundary between Earth and space is a thankless enterprise. That’s because natural phenomena are rarely black and white. They exist not on a binary, but a spectrum – an opulence of tinctures, constantly blurring, changing and intermingling like paint on an artist’s canvas.
Nature resists our attempts to compartmentalise its constituents. New species, for example, don’t abruptly come into existence; instead, genetic mutations occurring from generation to generation engender incremental physiological changes that, eventually, produce descendants that are considered to be different enough from their ancestors. At that subjective and arbitrary point, scientists label them as novel.
Labels are frequently arbitrary. A ‘supereruption’ is any volcanic paroxysm that jettisons at least 1,000 cubic kilometres of fresh volcanic matter; anything less is just a regular eruption. Why 1,000, and not 990, or 1,110? Because 1,000 is a more mathematically pleasing number. But in practical terms, the distinction between any of these extraordinary huge volumes of volcanic violence is meaningless.
The same inherent vacuity applies to Earth’s atmosphere. It doesn’t just disappear at a certain altitude – it gradually dissipates with altitude. Drawing a line and declaring that to be space’s fringe, even if it’s an altitude backed by science, means nothing to the natural world. It only means something to humans because we don’t deal well with nebulous concepts and uncertainty.
As James O’Donoghue, a planetary astronomer at the Japan Aerospace Exploration Agency, points out, the beginning of space on other planets can start wherever you like. On Jupiter or Saturn, he says, it could be where the aurorae are, where the atmospheric pressure drops to a certain value, or where there are no clouds. These gas giants don’t even really have a solid surface like Earth, so any comparison with our pale blue dot is moot.
“I’ve never come across anyone even mentioning or caring about where the boundary between the atmosphere and space is,” he says of Jupiter and Saturn. The only reason Bezos and Branson do care about the definition of space is that they can’t win a race without one. Space, in their eyes, is the finish line – and a buzzword used for marketing purposes.
That’s not to say that there is no societal value in defining space. Earth’s loftier skies are getting busier, and legal conundrums are creeping over the horizon. Nations have jurisdiction over their own airspace, but anything in space proper, wherever that may be, is a bit like the high seas: it belongs to all. But, says McDowell, some may ask: what altitude is it acceptable to shoot down a hypersonic missile? When would a high-altitude flying aircraft be making an illegal incursion into a country’s airspace, and when would it simply be flying in international space? If any international demarcation agreement is eventually struck, perhaps there will be multiple boundaries between space and Earth – with military space being distinct from civilian space, say.
This fundamental yet frivolous puzzle won’t be resolved anytime soon. For the foreseeable future, space will linger vaguely above our heads. Wherever it is, it will remain an intangible partition that billions will never cross, even if billionaires are already racing to claim it.
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This article was originally published by WIRED UK
