Could Humans Survive Deep Space?

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Could Humans Survive Deep Space?</h4>

What’s really happening out there in space? Will we ever get to see it up close, for ourselves? And if we did find ourselves coursing through the great beyond, then could we have any hope of staying alive?

This is Unveiled, and today we’re answering the extraordinary question; could humans survive deep space?

What exactly constitutes a solar system? Well, aside from the obvious requirement of a star, a solar system means more than just planets revolving around a ball of hydrogen and helium. Anything influenced by the star's gravitational pull is part of the system, and this includes asteroids, comets, meteoroids, and other natural satellites. Estimated to be more than 4.5 billion years old, our sun breathes life into our wider solar system. But, while this corner of the universe is big enough to keep the likes of NASA busy for the foreseeable future, it is but one tiny part of a larger galaxy; the Milky Way. 

To us, there is only one solar system – as other clusters are referred to as stellar or star systems – but estimates suggest there are approximately 200 billion stars in the Milky Way. Our galaxy's almost incomprehensible size puts things into perspective, but the Milky Way is also merely one small town. Modern estimates claim that there are upwards of two trillion galaxies, total, in the universe. So, how exactly does all of that come together? 

If someone were to leave the solar system, would they soon encounter a new collection of planets orbiting another ball of fire? Eventually, possibly. But not before some serious voyaging. Collectively known as the Interstellar Medium, the space separating star systems begins where a sun’s magnetic field stops influencing its surroundings. It chiefly consists of gas and dust because, regardless of what it seems, space isn’t truly a vacuum. The density varies widely from area to area, but none of it is ever truly empty. 

Again, in the grand scheme of things, the solar system is minuscule. And yet human ingenuity has yet to advance far enough to allow for a safe voyage into interstellar space. Due to the vast distances being calculated here, we use "Astronomical Units" to actually measure space – with 1 AU equivalent to the average gap between Earth and the Sun, which is approximately 93 million miles. Entering into only the first stretch of interstellar space means traveling farther than 120 AU, and even then the Sun's gravitational pull continues to wield some effect for roughly another 100,000 Units.

 Given that humans have made it to the moon but no further, with trips to other planets still seeming a far-off dream, getting people into interstellar space seems an impossible goal. However, while a manned shuttle isn’t currently on the cards, two spacecraft have successfully crossed into the interstellar; Voyagers 1 and 2. Launched in 1977, Voyager 1 has been flying away from the Sun towards the great unknown for decades. After completing its primary mission by 1980 - conducting flybys of Jupiter, Saturn and Titan – it just kept going and going. Until, in 2012, it became the first human-made spacecraft to enter the interstellar medium. Six years later, Voyager 2 repeated the same staggering feat, although it’s important to note that even these crafts have only actually left the heliosphere – which is essentially a bubble created by the Sun's solar wind – and not the entire solar system itself. 

Using Voyager 1 and 2 as blueprints, however, it’d take more than 30 years to travel the 11 billion-odd miles necessary to reach the interstellar medium. But, that’s assuming the human body could somehow withstand the 38,000 miles per hour velocity sustained by Voyager 1. Which it can’t. Say science does find a way for humans to complete such a journey, though, what sights can an astronaut look forward to? 

Putting aside the technological process needed to amass the necessary momentum to actually leave the solar system, the route involves crossing the Asteroid and Kuiper Belts towards the heliosphere's outer layer. Ranging from Mars to Jupiter, the Asteroid belt is unsurprisingly home to the majority of the solar system's asteroids. With the number of drifting stones in the thousands, you might think that this portion of the journey would coincide with quite a bit of turbulence. But, luckily, the asteroids are dispersed over such a massive area that avoiding a direct hit should be fairly simple. It’s just not as busy or dangerous as the Belt is made to seem in certain sci-fi books and films.

The Kuiper Belt covers the area past Neptune and, alongside other dwarf planets, includes Pluto. Like its predecessor, the Kuiper is sparsely littered with floating objects, although many here tend to be frozen due to the Sun's weakening rays once you get this far out. Following the Belts, the spacecraft steadily begins to approach the heliosphere's outer layers. On average, Pluto is around 40 AU away from the Sun; but, the heliosphere stretches on for another 80 units. It’s essentially a protective bubble created because our star exudes charged particles as solar wind – and the heliosphere is how far they stretch. Beyond this point, the sun does continue to exert a force on objects, but the particles are less densely packed – and the bubble breaks up. Which takes us to perhaps the first significant roadblock on this ultimate road trip; a stream of gas known as the termination shock. 

This layer coincides with the Sun's solar wind colliding with the interstellar wind on the ‘other side’. It’s where the sun’s influence truly starts to diminish. According to NASA, Voyager 1 crossed this threshold at approximately 94 AU. The termination shock leads into the heliosheath, which is the heliosphere's outermost layer. Theoretically, this area should be the most volatile of the lot, marking the point when the interstellar wind begins to match the sun's power – making conditions almost impossible to predict. Picture the solar system as a boat sailing across a sea of gas, and the heliosheath is the bow thrusting against the waves – taking most of the force. 

Eventually, we reach the heliopause, which is the final, final border separating the heliosphere and interstellar space. At this point, the solar and interstellar winds emit equal but opposing pressures, causing the sun's particles to flip inwards towards their source of origin. It’s a point of no return for most of anything linked to our solar system. With the heliopause in the rear-view mirror, astronauts can look forward to drifting through empty, seemingly endless space before ultimately entering the solar system's true final layer, the Oort Cloud. 

Thought to consist of comets requiring approximately 200 years to orbit the sun, astronomers believe the Oort Cloud commences at a distance of 1,000 AU from the sun and stretches on for approximately 100,000 Units. If Voyager 1 required 35 years to leave the heliosphere, the spacecraft has to continue moving forward at the same speed for roughly another 250 years to reach the Oort Cloud. 

If humankind could make this trip, then what happens next? By now, assuming that we a) somehow had the technology to take us this far, and b) had devised some way of stalling our natural aging process so that we’re still alive, our minds and bodies will’ve gone through some major transformations. Earth's atmosphere protects against the Sun's radiation, and an astronaut's body tends to weaken after only a couple of months away from the planet's surface. 

So, in reaching the heliopause astronauts would risk exposure to an immeasurable amount of radiation over an incredible time period. Even with some kind of radiation immunity medicines or technologies, and even though they would be steadily moving away from the sun, any interstellar astronaut will’ve had to have undergone some form of adaptation to their surroundings. Throw into the mix infinitely heightened concerns over muscle atrophy and bone mass decline due to shifting gravity… plus inevitable challenges regarding mental health… and unknowable problems linked with the endless isolation… and you end up with a traveler who’s almost unrecognizable from that which had set off. 

Assuming you somehow manage to enter interstellar space in one piece, the Oort Cloud should take around 30,000 years to traverse. Of course, the painstaking commute could be avoided if we managed to develop a viable method of traveling at lightspeed. In fact, taking into account that the Sun's rays need a bit more than 8 minutes to hit Earth, a shuttle traveling at the speed of light should be able to leave the entire solar system in less than 600 days. In this hypothetical reality, we’d certainly benefit from some kind of lightspeed breakthrough.

Whichever way you get there, though, with the solar system finally behind you, the question becomes “what's next?” The Alpha Centauri system is closest to ours and houses three stars, with the red star Proxima Centauri being the nearest of all. So, that would be your next port of call. But, here’s hoping you’re not running low on fuel, and you’re still somehow keeping old age at bay… because getting there from the outer edge of the Oort Cloud, even at lightspeed, would take another four years. Travel at anything less than lightspeed, and you’re talking centuries. 

What would you see on the way? Unsurprisingly, we’re low on first-hand accounts. But the light from Proxima Centauri would always be in your sights, growing just that little bit brighter day by day. If humans ever were headed that way, then chances are they’d be beelining for the exoplanet Proxima Centauri b – as it’s the closest exoplanet to us, and it orbits within a potentially habitable zone. So, if there is life outside the solar system, then it would be a good bet to host our closest neighbors. 

And from there, if we’ve advanced enough as a species to survive such a monumental trip, then the entire universe is ours to explore. Again, the Milky Way (housing us, Alpha Centauri, and billions of others) is simply one member in a gigantic universe of other galaxies. Andromeda is the next nearest similarly-sized galaxy to ours. So, if we ever could go galaxy gallivanting, then we’d wind up in Andromedean territories next. 

Even Andromeda is estimated to be around 2.5 million light-years away from us, though. So we’ll need lightspeed travel to stand even a slim chance of seeing it. But, this time, lightspeed travel plus another ever-present concept in speculative thinking and far-future planning; the generation ship.

Despite being among the fastest objects ever built by humanity, space shuttles are slow. They’re not nearly powerful enough to truly explore the universe, or even the solar system. The harsh reality is that we may never be able to build the machines needed to practically send people to other planets. So, if speed isn’t the answer to interstellar travel, then what is? Another option is to travel at achievable speeds instead, but over a long period of time.

The universe places a speed limit on matter; the speed of light. And that’s a big problem for us because, given how massive space is, it means that most of the stars and planets out there… are also out of our reach forever. If an astronaut-carrying ship were to travel to the next nearest star - Alpha Centauri - at speeds we’re currently capable of for a ship of that size, then everyone on board would have died of old age long, long before arriving. But - and here’s the important part - if that original crew were to have children during the journey, then the next generation could keep on traveling. And so on, and so on.

That’s the idea behind a generation ship; a spaceship large enough to house a group of people that will live and die in transit. But, by continually allowing future generations to take over, humanity as a whole could survive the long, long stretches of time needed to voyage across space. One day, we would make it to another distant star system. In theory, a generation ship makes interstellar travel to anywhere possible. In practice, it’s arguably the best bet we have.

These ships are a popular subject in science fiction because of this, but also for a few other reasons. For one, there’s the feeling that they truly could one day be needed in real life. If any kind of catastrophe were to happen to us on Earth - like an extinction or an unprecedented natural disaster - then a generation ship out in the cosmos would survive us. Our species will have spread and anyone on board would suddenly become the last of life from this planet. But, even without some kind of Armageddon, proposed generation ships would be on the frontline of our search for new home planets. Right now, we have only a few Second Earth candidates based on brief sightings made by our most powerful telescopes. But reaching any of them is a task that would take hundreds or thousands of years. 

By the time a generation ship had journeyed to them, then, it will have staged whole eras of human history within itself. But, if the crew members alive at the time of arrival were able to start colonies on other, habitable worlds, then they will still have succeeded in spreading humanity across the cosmos. They will still have ensured that our species lived on.

Where generation ships are concerned, it’s a case of playing “the long game”. So, what would a ship like that actually look like? First, it would have to be massive. As in, almost inconceivably huge. And it would have to house an initial crew of at least 500 people - ideally more. While estimates on the minimum viable population for humans do vary - that is, the minimum number of people required for long-term survival - 500 is usually held as the lower limit. Life for these 500 would be so far removed from life on Earth, though. It’s thought that human beings would suffer various health issues if they lived in zero or low-gravity environments for a long time… so reliably simulating gravity would be key. It’s another reason why the size of the ship would be so important. Not only would those on board require space to live, but the vessel would also need to be large enough and built in such a way to produce the centrifugal force necessary for sufficient anti-gravity. Even then, the conditions would take some getting used to! 

For anyone on-board, though, this ship is life. Their long-distance mission may have started with strong links to the Earth it was leaving behind, but those connections would fade over time, and later generations could even grow to forget Earth altogether - living their lives without ever seeing much besides the stars outside and infinite stretches of darkness. Naturally, then, a unique society would form, but one where discipline and order were key. Children growing up wouldn’t have many options for careers - understanding that everything they do should be for the better of the ship. But the idea of “purpose” would likely be passed from generation to generation; the belief that their own seemingly limited lives were allowing for intergalactic exploration. 

In the event that the ship was actually escaping an Earth in some kind of trouble, then there’d also be the knowledge on board that they had somehow evaded their own planet’s demise. Clearly, tensions could run high… especially given the probable monotony of everyday life. Even if those on the ship had futuristic ways to change and update the entertainment options available to them - including movies, music and books - being endlessly confined within the same metallic structure, always cast thousands of miles from anything else of note, could have a dramatic impact on a person’s mental health. They’d walk the same corridors every day, speak to the same people every day, and be greeted by the same endless view whenever they passed a window. They say; “variety is the spice of life”, but there’d be precious little variety here! 

Maintaining the ship’s gardens would be one of the most crucial tasks, seeing as they’d be a source of oxygen, food and a tangible reminder of Earth. In terms of produce, food from the gardens would need to offer big yields that are quick to grow and have a high energy content. In the movie, “The Martian”, the main character opts for potatoes, but other top contenders for space farming include tomatoes and corn. Whatever the case, diet on a generation ship is another aspect of life that would become very predictable very quickly. And it doesn’t get a great deal better when we consider the water that would be available to wash it all down. Water would be recycled in much the same ways as it is for astronauts on the International Space Station - as a filtered product of everyone else’s sweat, urine and wash water. But, if that sounds disgusting, it actually shouldn't - astronaut water is said to be cleaner than what most of us drink on Earth. 

Other than food, drink, mental strain and the effects of anti-gravity, arguably the most pressing concern for those on a generation ship would again be radiation. For NASA, prolonged radiation exposure is one of the chief threats on any prospective deep space mission - let alone a continuous voyage across the universe! On Earth, we’re protected from the effects of radiation by our magnetosphere, but on spaceships as we currently understand them there’s no such cover. In a hypothetical time when generation ships are a reality, perhaps radiation-proofing will have also improved enough to make the ship impenetrable. If it hasn’t, then those inside would be at far higher risk of developing some cancers. And, seeing as high levels of radiation can even damage our DNA, it’d pose not just a risk to the individual but also to the future generations that the mission relies on. 

Elsewhere, the focus would simply be on keeping the ship running. Engine failures; power outages; damage to the outer walls… they could all prove deadly and could all happen at any moment. Say the means of artificial gravity faltered; everyone and everything on board - from the food to the furniture - would suddenly be scattered. Say the thrusters shut down; an already incredibly long journey just got a little longer. In reality, living on a generation ship would be a round-the-clock job. With so many imminent dangers and potential problems to contend with, even during downtime it’d be impossible to totally switch off from the task at hand - which is surviving. 

From the moment you were born to the moment you died, you’d be a vital component to a small and unique social set-up suspended in space. There’d be no time for childhood and no option of retirement. By simply existing on the ship you’d be a valuable part of it. The “daily grind” could prove almost unbearable at times. But there’d be little choice other than to complete it in the hope that you, your children or your children’s children could one day step off of the ship and onto a brand-new and exciting planet.

Could humans survive deep space? The odds are very clearly stacked against us. But, in our imaginations, and through our most ambitious scientific endeavors, it perhaps isn’t quite impossible. There’s always just a little bit of hope.