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00:00What's really happening out there in space?
00:04Will we ever get to see it up close for ourselves?
00:07And if we did find ourselves coursing through the great beyond, then would we have any hope
00:12of staying alive?
00:13This is Unveiled, and today we're answering the extraordinary question, could humans survive
00:18deep space?
00:21Do you need the big questions answered?
00:23Are you constantly curious?
00:25Then why not subscribe to Unveiled for more clips like this one?
00:28And ring the bell for more thought-provoking content!
00:32What exactly constitutes a solar system?
00:34Well, aside from the obvious requirement of a star, a solar system means more than just
00:39planets revolving around a big ball of hydrogen and helium.
00:42Anything influenced by the star's gravitational pull is part of the system, and this includes
00:47asteroids, comets, meteoroids, and other natural satellites.
00:51Estimated to be more than 4.5 billion years old, our sun breathes life into our wider
00:57solar system.
00:58But while this corner of the universe is big enough to keep the likes of NASA busy for
01:02the foreseeable future, it is but one tiny part of a larger galaxy, the Milky Way.
01:09To us, there is only one solar system, as other clusters are referred to as stellar
01:14or star systems, but estimates suggest that there are approximately 200 billion stars
01:19in the Milky Way.
01:21Our galaxy's almost incomprehensible size puts things into perspective, but the Milky
01:25Way is also merely one small town.
01:29Modern estimates claim that there are upwards of two trillion galaxies total in the universe.
01:33So how exactly does all of that come together?
01:36If someone were to leave the solar system, would they soon encounter a new collection
01:40of planets orbiting another ball of fire?
01:43Eventually, possibly, but not before some serious voyaging.
01:47Collectively known as the interstellar medium, the space-separating star systems begin where
01:52the sun's magnetic field stops influencing its surroundings.
01:56It chiefly consists of gas and dust, because regardless of what it seems, space isn't
02:01truly a vacuum.
02:03The density varies widely from area to area, but none of it is ever truly empty.
02:08Again, in the grand scheme of things, the solar system is miniscule, and yet human ingenuity
02:13has yet to advance far enough to allow for a safe voyage into interstellar space.
02:18Due to the vast distances being calculated here, we use astronomical units to actually
02:23measure space, with one AU equivalent to the average gap between Earth and the sun, which
02:29is approximately ninety-three million miles.
02:32Entering into only the first stretch of interstellar space means travelling farther than one hundred
02:37and twenty astronomical units, and even then the sun's gravitational pull continues to
02:42wield some effect for roughly another one hundred thousand units.
02:47Given that humans have made it to the moon and no further, with trips to other planets
02:51still seeming a far-off dream, getting people into interstellar space seems an impossible
02:56goal.
02:57However, while a manned shuttle isn't currently on the cards, two spacecraft have successfully
03:01crossed into the interstellar.
03:04Voyagers One and Two.
03:06Launched in 1977, Voyager One has been flying away from the sun towards the great unknown
03:11for decades.
03:13After completing its primary mission by 1980, conducting flybys of Jupiter, Saturn and Titan,
03:19it just kept going and going… until, in 2012, it became the first human-made spacecraft
03:25to enter the interstellar medium.
03:27Six years later, Voyager Two repeated the same staggering feat, although it's important
03:32to note that even these crafts have only actually left the heliosphere, which is essentially
03:37a bubble created by the sun's solar wind, and not the entire solar system itself.
03:43Using Voyager One and Two as blueprints, however, it'd take more than thirty years to travel
03:48the eleven billion-odd miles necessary to reach the interstellar medium.
03:52But that's assuming the human body could somehow withstand the thirty-eight thousand
03:56miles per hour velocity sustained by Voyager One… which it can't.
04:01Say science does find a way for humans to complete such a journey, though… what sights
04:06can an astronaut look forward to?
04:08Putting aside the technological processes needed to amass the necessary momentum to
04:12actually leave the solar system, the route involves crossing the asteroid and Kuiper
04:17belts towards the heliosphere's outer layer, ranging from Mars to Jupiter.
04:22The asteroid belt is, unsurprisingly, home to the majority of the solar system's asteroids.
04:27With the number of drifting stones in the thousands, you might think that this portion
04:31of the journey would coincide with quite a bit of turbulence… but luckily, the asteroids
04:36are dispersed over such a massive area that avoiding a direct hit should be fairly simple.
04:41It's just not as busy or dangerous as the belt is made to seem in certain sci-fi books
04:47and films.
04:48The Kuiper belt covers the area past Neptune and, alongside other dwarf planets, includes
04:54Pluto.
04:55Like its predecessor, the Kuiper belt is sparsely littered with floating objects… although
04:59many here tend to be frozen due to the sun's weakening rays once you get this far out.
05:05Following the belts, the spacecraft steadily begins to approach the heliosphere's outer
05:09layers.
05:10On average, Pluto is around forty astronomical units away from the sun… but the heliosphere
05:15stretches for another eighty units.
05:17It's essentially a protective bubble created because our star exudes charged particles
05:23as solar wind, and the heliosphere is how far away they stretch.
05:27Beyond this point, the sun does continue to exert a force on objects… but the particles
05:32are less densely packed, and the bubble breaks up.
05:36Which takes us to perhaps the first significant roadblock on this ultimate road trip, a stream
05:40of gas known as the Termination Shock.
05:44This layer coincides with the sun's solar wind colliding with the interstellar wind
05:48on the other side.
05:49It's where the sun's influence truly starts to diminish.
05:53According to NASA, Voyager 1 crossed this threshold at approximately ninety-four astronomical
05:58units.
05:59The Termination Shock leads into the heliosheath, which is the heliosphere's outmost layer.
06:04Theoretically, this area should be the most volatile of the lot, marking the point when
06:09the interstellar wind begins to match the sun's power, making conditions almost impossible
06:14to predict.
06:15Picture the solar system as a boat sailing across a sea of gas, and the heliosheath is
06:20a bow thrushing against the waves, taking most of the force.
06:24Eventually, we reach the heliopause, which is the final, final border separating the
06:30heliosphere and interstellar space.
06:33At this point, the solar and interstellar winds emit equal but opposing pressures, causing
06:38the sun's particles to flip inwards towards their source of origin.
06:41It's a point of no return for most of anything linked to our solar system.
06:46At the heliopause in the rearview mirror, astronauts can look forward to drifting through
06:51empty, seamlessly empty space before ultimately entering the solar system's true final layer,
06:57the Oort Cloud.
06:59Thought to consist of comets requiring approximately two hundred years to orbit the sun, astronomers
07:04believe the Oort Cloud commences at a distance of one thousand astronomical units from the
07:08sun and stretches on for approximately one hundred thousand units.
07:13If Voyager 1 required thirty-five years to leave the heliosphere, the spacecraft has
07:18to continue moving forward at the same speed for roughly another two hundred and fifty
07:22years to reach the Oort Cloud.
07:25If humankind could make this trip, then what happens next?
07:28By now, assuming that we A, somehow had the technology to take us this far, and B, had
07:35devised some way of stalling our natural ageing process so that we're still alive, our minds
07:40and bodies will have gone through some major transformations.
07:44Earth's atmosphere protects against the sun's radiation, and an astronaut's body tends to
07:49weaken after only a couple of months away from the planet's surface.
07:53So, in reaching the heliopause, astronauts would risk exposure to an immeasurable amount
07:58of radiation over an incredible time period, even with some kind of radiation immunity
08:04medicines or technologies.
08:06And even though they would be steadily moving away from the sun, any interstellar astronaut
08:11will have had to have undergone some form of adaptation to their surroundings.
08:15Throw into the mix infinitely heightened concerns over muscle atrophy and bone mass decline
08:20due to shifting gravity, plus inevitable challenges regarding mental health and unknowable problems
08:26linked with the endless isolation, and you end up with a traveller who's almost unrecognisable
08:31from that which had set off.
08:33Can you somehow manage to enter interstellar space in one piece?
08:37The Oort Cloud should take around 30,000 years to traverse.
08:41Of course, the painstaking commute could be avoided if we manage to develop a viable method
08:45of travelling at light speed.
08:47In fact, taking into account the sun's rays need a bit more than eight minutes to hit
08:51Earth, a shuttle travelling at the speed of light should be able to leave the entire solar
08:55system in less than 600 days.
08:58In this hypothetical reality, we'd certainly benefit from some kind of light-speed breakthrough.
09:03Whichever way you get there, though, with the solar system finally behind you, the question
09:07becomes what's next?
09:09The Alpha Centauri system is closest to ours and houses three stars, with the red star
09:14Proxima Centauri being the nearest of all.
09:16So that would be your next port of call.
09:19But here's hoping you're not running low on fuel, and you're still somehow keeping
09:22old age at bay, because getting there from the outer edge of the Oort Cloud, even at
09:27light speed, would take another four years.
09:30Call it anything less than light speed, and you're talking centuries.
09:34What would you see on the way?
09:36Unsurprisingly, we're low on first-hand accounts.
09:39But the light from Proxima Centauri would always be in your sights, growing just that
09:43little bit brighter, day by day.
09:45If humans ever were headed that way, then chances are they'd be bee-lining for the
09:50exoplanet Proxima Centauri b.
09:52It's the closest exoplanet to us, and it orbits within a potentially habitable zone.
09:57So, if there is life outside the solar system, then it would be a good bet to host our closest
10:02neighbours.
10:03And from there, if we've advanced enough as a species to survive such a monumental
10:07trip, then the entire universe is ours to explore.
10:11Again, the Milky Way, housing us, Alpha Centauri, and billions of others, is simply one member
10:17in a gigantic universe of other galaxies.
10:20Andromeda is the next nearest similarly sized galaxy to ours, so if we ever could go galaxy
10:26gallivanting, then we'd wind up in Andromedan territories next.
10:30Even Andromeda is estimated to be around 2.5 million light-years away from us, though,
10:35so we'll need light-speed travel to stand even a slim chance of seeing it.
10:40But this time, light-speed travel plus another ever-present concept in speculative thinking
10:46and far-future planning… the Generation Ship.
10:49Despite being among the fastest objects ever built by humanity, space shuttles are slow.
10:54They're not nearly powerful enough to truly explore the universe, or even the solar system.
10:59The harsh reality is that we may never be able to build the machines needed to practically
11:03send people to other planets.
11:05So, if speed isn't the answer to interstellar travel, then what is?
11:09Another option is to travel at achievable speeds instead, but over a long period of
11:14time.
11:15The universe places a speed limit on matter… the speed of light.
11:19And that's a big problem for us because, given how massive space is, it means that
11:24most of the stars and planets out there are also out of our reach forever.
11:29If an astronaut-carrying ship were to travel to the next-nearest star, Alpha Centauri,
11:34at speeds we're currently capable of for a ship of that size, then everyone on board
11:39would've died of old age, long, long before arriving.
11:42But, and here's the important part, if that original crew were to have children during
11:47the journey, then the next generation could keep on travelling.
11:51And so on, and so on.
11:54That's the idea behind a generation ship.
11:56A spaceship large enough to house a group of people that will live and die in transit.
12:00But by continually allowing future generations to take over, humanity as a whole could survive
12:05the long, long stretches of time needed to voyage across space.
12:09One day, we would make it to another distant star system.
12:13In theory, a generation ship makes interstellar travel to anywhere possible.
12:17In practice, it's arguably the best bet we have.
12:21These ships are a popular subject in science fiction because of this, but also for a few
12:25other reasons.
12:26For one, there's the feeling that they truly could one day be needed in real life.
12:30If any kind of catastrophe were to happen to us on Earth, like an extinction or an unprecedented
12:35natural disaster, then a generation ship out in the cosmos would survive us.
12:40Our species would have spread, and anyone on board would suddenly become the last of
12:45life from this planet.
12:46But even without some kind of Armageddon, proposed generation ships would be on the
12:50front line of our search for new home planets.
12:53Right now, we have only a few Second Earth candidates, based on brief sightings made
12:58by our most powerful telescopes.
13:00But reaching any of them is a task that would take hundreds or thousands of years.
13:05By the time a generation ship had journeyed to them, then, it will have staged whole eras
13:09of human history within itself.
13:11But if the crew members alive at the time of arrival were able to start colonies on
13:15other habitable worlds, then they will still have succeeded in spreading humanity across
13:20the cosmos.
13:21They will still have ensured that our species lived on.
13:24Where generation ships are concerned, it's a case of playing the long game.
13:27So, what would a ship like that actually look like?
13:30First, it would have to be massive… as in almost inconceivably huge.
13:35And it would have to house an initial crew of at least 500 people… ideally more.
13:40While estimates on the minimum viable population for humans do vary… that is, the minimum
13:45number of people required for long-term survival… 500 is usually held as the lower limit.
13:51Life for these 500 would be so far removed from life on Earth, though.
13:54It's thought that human beings would suffer various health issues if they lived in zero
13:59or low-gravity environments for a long time… so reliably simulating gravity would be key.
14:05It's another reason why the size of the ship would be so important.
14:08Not only would those on board require space to live, but the vessel would also need to
14:13be large enough and built in such a way to produce the centrifugal force necessary for
14:17sufficient anti-gravity.
14:19Even then, the conditions would take some getting used to.
14:22For anyone on board, though, this ship is life.
14:26Their long-distance mission may have started with strong links to the Earth it was leaving
14:30behind… but those connections would fade over time, and later generations could even
14:35grow to forget Earth altogether, living their lives without ever seeing much besides the
14:39stars outside and infinite stretches of darkness.
14:43Naturally, then, a unique society would form… but one where discipline and order were key.
14:49Children growing up wouldn't have many options for careers, understanding that everything
14:53they'd do would be for the better of the ship.
14:56But the idea of purpose would likely be passed from generation to generation… the belief
15:00that their own seemingly limited lives were allowing for intergalactic exploration.
15:05In the event that the ship was actually escaping on Earth in some kind of trouble, then there'd
15:10also be the knowledge on board that they had somehow evaded their own planet's demise.
15:15Clearly, tensions could run high, especially given the probable monotony of everyday life…
15:20even if those on the ship had futuristic ways to change and update the entertainment options
15:25available to them, including movies, music and books.
15:29Being endlessly confined within the same metallic structure, always cast thousands of miles
15:34from anything else of note, could have a dramatic impact on a person's mental health.
15:38They'd walk the same corridors every day, speak to the same people every day, and be
15:43greeted by the same endless view whenever they passed a window.
15:48They say variety is the spice of life, but there'd be precious little variety here.
15:52Maintaining the ship's gardens would be one of the most crucial tasks, seeing as they'd
15:57be a source of oxygen, food, and a tangible reminder of Earth.
16:01In terms of produce, food from the gardens would need to offer big yields that are quick
16:06to grow and have a high energy content.
16:09In the movie, The Martian, the main character opts for potatoes, but other top contenders
16:14from space farming include tomatoes and corn.
16:17Whatever the case, diet on a generation ship is another aspect of life that would become
16:21very predictable, very quickly.
16:24And it doesn't get a great deal better when we consider the water that would be available
16:27to wash it all down.
16:29Water would be recycled in much the same ways as it is for astronauts on the International
16:34Space Station, as a filtered product of everyone else's sweat, urine, and wash water.
16:40But if that sounds disgusting, that actually shouldn't.
16:43Astronaut water is said to be cleaner than what most of us drink on Earth.
16:46Other than food, drink, mental strain, and the effects of anti-gravity, arguably the
16:51most pressing concern for those on a generation ship would again be radiation.
16:56For NASA, prolonged radiation exposure is one of the chief threats on any prospective
17:01deep space mission, let alone a continuous voyage across the universe.
17:06On Earth, we're protected from the effects of radiation by our magnetosphere… but on
17:10spaceships as we currently understand them, there's no such cover.
17:14In a hypothetical time when generation ships are a reality, perhaps radiation-proofing
17:20will have also improved enough to make the ship impenetrable.
17:23If it hasn't, then those inside would be at far higher risk of developing some cancers.
17:28And seeing as high levels of radiation can even damage our DNA, it'd pose not just
17:33a risk to the individual, but also to the future generations that the mission relies
17:37on.
17:38Elsewhere, the focus would simply be on keeping the ship running.
17:42Engine failures, power outages, damage to the outer walls… they could all prove deadly,
17:47and could all happen at any moment.
17:49Say the means of artificial gravity faltered.
17:52Everyone and everything on board, from the food to the furniture, would suddenly be scattered.
17:57Say the thrusters shut down.
17:59An already incredibly long journey just got a little longer.
18:03In reality, living on a generation ship would be a round-the-clock job.
18:07With so many imminent dangers and potential problems to contend with, even during downtime,
18:12it'd be impossible to totally switch off from the task at hand… which is surviving.
18:17From the moment you were born to the moment you died, you'd be a vital component to
18:21a small and unique social setup suspended in space.
18:25There'd be no time for childhood, and no option of retirement.
18:29By simply existing on the ship, you'd be a valuable part of it.
18:32The daily grind could prove almost unbearable at times, but there'd be little choice other
18:38than to complete it, in the hope that you, your children, or your children's children
18:43could one day step off the ship and come onto a brand new and exciting planet.
18:49Could humans survive deep space?
18:51The odds are very clearly stacked against us, but in our imaginations, and through our
18:56most ambitious scientific endeavours, it perhaps isn't quite impossible.
19:01There's always just a little bit of hope.
19:04What do you think?
19:05Is there anything we missed?
19:06Let us know in the comments, check out these other clips from Unveiled, and make sure you
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