Some facts about distance and space. From certain perspectives, the planet seems crowded. The world’s population recently reached 7 billion. Even in the remotest wilderness, roads tend to pop up every couple of hundred kilometres. On the other hand, if New South Wales had the population density of New York City, every one of those 7 billion people would fit into its borders. In that scenario, there’d be an awful lot of empty space elsewhere.
Yet viewed on even larger scales, the sense of our tenure here can become positively claustrophobic. There’s really nowhere to go when you step out the door, and in any case, you’re not getting off the property any time soon. Voyager 1, the fastest man-made object in existence – coasting now at the far edges of our solar system at 61,000 kilometres per hour – will finally reach a distance of one light-day away from Earth in 2050. By then it will have been travelling for 73 years. It will be another 26,000 years before it is a light-year from us. The nearest star, Proxima Centauri, is four light-years away.
To put that in context: if Earth were the Melbourne GPO, and Proxima Centauri were Perth, then the Voyager probe has travelled about 1 kilometre from the GPO so far, taking 34 years to do it. In fact, Voyager is not heading in the direction of Proxima Centauri; it’s no longer heading anywhere in particular. Its primary tasks, fly-bys of Jupiter and Saturn, were completed by 1980. For what it’s worth, in about 40,000 years Voyager 1 will pass within 1.6 light-years of the star AC+79 3888, in the constellation Camelopardalis. Were we to anthropomorphise the tiny craft, we might speak of its majestic loneliness, hurtling into vast voids far from home – and never to return.
Notions of departure and return were sometimes explicit and always implicit in talks given at the recent 100 Year Starship Symposium in Orlando, Florida, an extraordinary three-day convention backed by NASA and DARPA (the Defense Advanced Research Projects Agency) at which scientists and thinkers met to talk about the everyday challenges and the short- and long-term future of interstellar space travel. “A thousand years from now,” said journalist Dan Grech, speaking of the symposium later on the radio show This American Life, “when people are writing the history of interstellar space travel, people will look back at this conference and see this as the first small step.”
I wanted to see what the panellists would have to say about the psychology that would one day lead people to climb on board spaceships knowing not only that they would die on board but that so would several generations of their descendants. In terms of the very long-term future, there was a general consensus that no particular psychology was needed if it’s a matter of ‘jump or fry’: interstellar travel is the only opportunity humankind has for survival, given the death-by-searing of the Earth that will long precede the Sun’s cataclysmic end. Assuming we survive as a species for another couple of billion years, there will come a time when we need to hightail it.
At a more practical level, Arlan Andrews of SIGMA, a think-tank founded by scientists and science-fiction writers, spoke in his talk on multi-generation spaceships of the need to set up “legacy trusts” for the descendants, relatives or chosen recipients of those first-epoch travellers, “that first generation willing to die in space” – an idea which takes the basic concept of the miner’s ‘danger and isolation’ pay to its extreme. When the audience at one panel were asked whether they would go on a likely one-way trip to set up a forward station on Mars, about a quarter raised their hands. Nor did anyone blink at the suggestion that if making a reality TV program of such a mission would help get it funded (think global Nielsen ratings, advertising dollars) then that was definitely something to consider. The issue is not so much time – at current speeds we can make it to Mars in about six months – but rather cost: one speaker estimated the current cost of a one-way trip and base set-up to be around $20 billion. A return journey would be more like $100 billion.
There was general agreement among the speakers that a journey to Mars, and the setting up of a permanent base there, were our training wheels – a practice run which could conceivably take place in the span of current lifetimes. In the 1960s the Russian astronomer Nikolai Kardashev developed a three-stage “scale” by which we could measure the level of advancement of spacefaring, space-manipulating civilisations. In more recent years the scale has been further developed, so that at the Starship Symposium, scientists were speaking of six distinct phases. In a Stage Zero civilisation people are bound by local geographical regions. That’s the entirety of our history. By Stage I we are not geographically bound; we have a minimal capacity to get into orbit but are essentially still confined to the planet. A Stage II civilisation routinely travels into Earth’s orbit and the planetary system, but remains “solar system–bound”. By Stage III we engage in routine interstellar travel but are still bound by the stars of one galaxy – for us, the Milky Way. In Stage IV, a civilisation controls the energy output of the visible universe. Stage V, even more theoretical than the bizarre Stage IV, is all about wormholes, superluminal travel, and the multiverse. We are, by these measures, in late Stage Zero – in truth, fewer than 500 people have ever been outside our thin blue atmosphere – and peering, barely, over the wall into Stage I.
The time frames are dizzying. At the symposium, the scientists’ enthusiasm in engaging with them was both exhilarating and deeply poignant. The parallel that springs to mind is the building of Europe’s great Gothic cathedrals, those edifices of thrusting stone and light – themselves endeavours to transcend the restrictions of gravity, with tools and ingenuity, for some grander purpose – over time frames of up to one or two centuries. The monumental patience of the mason. NASA scientist Geoffrey Landis spoke of the need for incremental steps. “Conventional nuclear thermal rockets are just not good enough, and they cannot be made good enough [for feasible interstellar space travel]. But the nuclear thermal rocket is the pick-up truck which your construction workers use to drive around the solar system to pick up resources and put them together to make the incremental parts of the ultimate starship propulsion system. You don’t start out building a 747, you start out with Model Ts.”
Richard Obousy of Project Icarus summarised something of both the recent history and current thinking of interstellar space travel methods. Nuclear pulse propulsion was first touted in the 1950s – basically, large numbers of nuclear bombs, or “pulse-units”, are launched out of the back of the spacecraft and detonated about 90 metres from the rear of the craft, generating huge amounts of thrust. With this method it’s theoretically possible to reach about 3% of the speed of light, enabling a spaceship to reach Proxima Centauri (that close neighbour, again) in 130 years.
For Obousy, a propulsion system based on matter–antimatter annihilation might be one of the most efficient future long-distance transport methods. For now, though, there’s one problem: “We only have the capability to produce a few tenths of a billion of a gram of antimatter – in fact, that’s about the level that CERN is creating at the moment. And if you extrapolate the cost you get into trillions of dollars per gram of antimatter. But CERN isn’t optimised for antimatter creation. It’s a nice by-product of the experiments they do, but it’s like building an entire McDonald’s chain just to get a single French fry.”
There was much talk of solar sails, AKA light sails: giant sails pushed by light, not wind, since photons carry momentum that can generate thrust. Using a slingshot manoeuvre around the Sun for a massive bombardment of ‘solar wind’, one can acquire a high velocity; later fall-off can be mitigated by beamed laser or microwave energy. The first prototypes are currently in orbit around Earth. They measure metres across, not the kilometres they will eventually need to be for the purpose of interstellar travel. Eventually, the problem (for your great-grandchildren, at least) becomes stopping. Magnetic braking, even over a five-year period, won’t take you down to zero velocity. Geoffrey Landis proposed an “optimum system” of “a sail at the beginning, a long coast, a magnetic brake, and then a very high efficiency rocket at the far end” of a decades- or centuries-long journey.
Philosopher Christian Weidemann was playfully hilarious with his paper ‘Did Jesus Die for Klingons Too?’ There are between 200 and 400 billion stars in our own Milky Way galaxy, Weidemann informed us, and, by current estimates, perhaps 125 billion galaxies in the observable cosmos. In addition there is a growing number of valid, viable multiverse theories, in which our universe is only one of an incredibly large number of other universes – maybe an infinite number. “So the cosmos is very, very big,” said Weidemann, deadpan. “I will try to make a case for the incompatibility of classical Christian doctrine with the belief in extraterrestrial life.”
He went on to delve deeply into doctrinal Christianity – if Jesus died for ‘our’ sins, does the ‘our’ mean we on Earth, or all of ‘creation’? If we assume extraterrestrials to be sinners too, would they not also qualify for redemption? – while at the same time invoking the ‘mediocrity principle’, a philosophical idea that states we should assume there’s nothing unusual or privileged about our position in the universe or even about our existence. The age of the universe, coupled with scientists’ mediocrity principle–based estimates of the number of extraterrestrial civilisations we can assume to exist (billions, at a low estimate), led Weidemann to the conclusion that God would have to be sending His only begotten son to 250 separate civilisations throughout the universe at any given time in order to keep up with even the most basic redemption/dying-for-their-sins requirements.
Weidemann is right. The cosmos is very, very big. We’ll never get off this patch of dirt, not those of us alive right now. And yet, surely, the proper response to all this incomprehensible vastness – to these vast for-now unbridgeabilities of time and space – is not to feel dread or despair but to become ennobled by our contingent lives down here. “The most salient feature of existence,” wrote the novelist Richard Powers, “is the unthinkable odds against it. For every way there is of being here, there are an infinity of ways of not being here. Historical accident snuffs out whole universes with every clock tick. Statistics declare us ridiculous. Thermodynamics prohibits us. Life, by any reasonable measure, is impossible, and my life – this, here, now – infinitely more so.”
When we do make it into space, said William Kramer of the Hawaii Research Center for Futures Studies, we must guard against the “hubris” we will inevitably travel with if we continue to draw on the old mythologies of the frontier. Robert Zubrin, founder of the Mars Society, wrote in his book The Case for Mars, “Every feature of frontier American life that acted to create a practical can-do culture of innovative people will apply to Mars a hundredfold.” Kramer’s comment on this: “The frontier American life he references is largely a fictional one, written by the colonisers – those with a financial, political, or social stake in its success.”
Michael Griffin, who as administrator of NASA should surely have known better, remarked in 2005 that when human civilisation reaches the point where more people are living off-Earth than on it, “we want their culture to be Western”. I love Western culture – not least its rich heritage of wanderlust – but this to me is not so much hubris as cultural solipsism. On another occasion, Griffin said: “North Americans are the way we are because of the challenges of the frontier. […] I believe that Western thought, civilization and ideals represent a superior set of values.” Elsewhere the metaphors of interstellar exploration tend to centre around concepts of destiny and conquest. Manifest destiny: that old chestnut.
Our only destiny should be awe. If we go into space with Bible in one hand and American flag in the other, then we go not with our best but with our most parochial selves; as a species we infantilise our future cultural heritage at the moment of one of its great leaps forward. If ultimately we were to find no other intelligences out there, our date with awe, with wonder, should be no less spectacular.
We should also keep in mind that absence of evidence of other intelligences is not the same as evidence of absence. Arlan Andrews was asked why, if the mediocrity principle suggests there should be an abundance of extraterrestrial civilisations, none had yet contacted us. “Let me suggest,” said Andrews, “that all aliens finally hit that point where they invent Google and Facebook, and they go inside their navel. And that’s it.”
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