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Is Human Hibernation Possible? Going to Sleep for Long Duration Spaceflight - YouTube
Channel: Fraser Cain
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We鈥檝e spent a few episodes on the Guide
to Space talking about just how difficult
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it鈥檚 going to be to travel to other stars.
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Sending tiny unmanned probes across the vast
gulfs between stars is still mostly science
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fiction.
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But to send humans on that journey?
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That鈥檚 just a level of technology beyond
comprehension.
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For example, the nearest star is Proxima Centauri,
located a mere 4.25 light years away.
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Just for comparison, the Voyager spacecraft,
the most distant human objects ever built
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by humans, would need about 50,000 years to
make that journey.
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I don鈥檛 know about you, but I don鈥檛 anticipate
living 50,000 years.
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No, we鈥檙e going to want to make the journey
more quickly.
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But the problem, of course, is that going
more quickly requires more energy, new forms
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of propulsion we鈥檝e only starting to dream
up.
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And if you go too quickly, mere grains of
dust floating through space become incredibly
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dangerous.
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Based on our current technology, it鈥檚 more
likely that we鈥檙e going to have to take
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our time getting to another star.
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And if you鈥檙e going to go the slower route,
you鈥檝e got a couple of options.
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Create a generational ship, so that successive
generations of humans are born, live out their
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lives, and then die during the hundreds or
even thousands of year long journey to another
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star.
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Imagine you鈥檙e one of the people destined
to live and die, never reaching your destination.
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Especially when you look out your window and
watch a warp ship zip past with all those
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happy tourists headed to Proxima Centauri,
who were start enough to wait for warp drives
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to be invented.
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No, you want to sleep for the journey to the
nearest star, so that when you get there,
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it鈥檚 like no time passed.
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And even if warp drive did get invented while
you were asleep, you didn鈥檛 have to see
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their smug tourist faces as they zipped past.
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Is human hibernation possible?
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Can we do it long enough to survive a long-duration
spaceflight journey and wake up again on the
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other side?
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Before I get into this, we鈥檙e just going
to have to assume that we never merge with
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our robot overlords, upload ourselves into
the singularity, and effortlessly travel through
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space with our cybernetic bodies.
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For some reason, that whole singularity thing
never worked out, or the robots went on strike
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and refused to do our space exploration for
us any more.
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And so, the job of space travel fell to us,
the fragile, 80-year lifespanned mammals.
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Exploring the worlds within the Solar System
and out to other stars, spreading humanity
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into the cosmos.
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Come on, we know it鈥檒l totally be the robots.
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But that鈥檚 not what the science fiction
tells us, so let鈥檚 dig into it.
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We see animals, and especially mammals hibernating
all the time in nature.
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In order to be able survive over a harsh winter,
animals are capable of slowing their heart
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rate down to just a few beats a minute.
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They don鈥檛 need to eat or drink, surviving
on their fat stores for months at a time until
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food returns.
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It鈥檚 not just bears and rodents that can
do it, by the way, there are actually a couple
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of primates, including the fat-tailed dwarf
lemur from Madagascar.
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That鈥檚 not too far away on the old family
tree, so there might be hope for human hibernation
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after all.
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In fact, medicine is already playing around
with human hibernation to improve people鈥檚
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chances to survive heart attacks and strokes.
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The current state of this technology is really
promising.
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They use a technique called therapeutic hypothermia,
which lowers the temperature of a person by
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a few degrees.
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They can use ice packs or coolers, and doctors
have even tried pumping a cooled saline solution
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through the circulatory system.
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With the lowered temperature, a human鈥檚
metabolism decreases and they fall unconscious
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into a torpor.
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But the trick is to not make them so unconscious
that they die.
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It鈥檚 a fine line.
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The results have been pretty amazing.
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People have been kept in this torpor state
for up to 14 days, going through multiple
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cycles.
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The therapeutic use of this torpor is still
under research, and doctors are learning if
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it鈥檚 helpful for people with heart attacks,
strokes or even the progression of diseases
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like cancer.
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They鈥檙e also trying to figure out if there
are any downsides, but so far, there don鈥檛
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seem to be any long-term problems with putting
someone in this torpor state.
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In a moment, I鈥檓 going to talk about a project
that NASA is actually considering to test
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out if this therapeutic hypothermia will be
useful for long duration human spaceflight,
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but first I鈥檇 like to thank Donald Jackson,
Mike and Sherri Reed, Andrew Wasko, and the
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rest of our 743 patrons for their generous
support.
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If you love what we鈥檙e doing and want to
get in on the action, head over to patreon.com/universetoday
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A few years ago, SpaceWorks Enterprises delivered
a report to NASA on how they could use this
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therapeutic hypothermia for long duration
spaceflight within the Solar System.
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Currently, a trip to Mars takes about 6-9
months.
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And during that time, the human passengers
are going to be using up precious air, water
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and food.
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But in this torpor state, SpaceWorks estimates
that the crew will a reduction in their metabolic
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rate of 50 to 70%.
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Less metabolism, less resources needed.
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Less cargo that needs to be sent to Mars.
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The astronauts wouldn鈥檛 need to move around,
so you could keep them nice and snug in little
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pods for the journey.
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And they wouldn鈥檛 get into fights with each
other, after 6-9 months of nothing but day
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after day of spaceflight.
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We know that weightlessness has a negative
effect on the body, like loss of bone mass
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and atrophy of muscles.
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Normally astronauts exercise for hours every
day to counteract the negative effects of
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the reduced gravity.
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But SpaceWorks thinks it would be more effective
to just put the astronauts into a rotating
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module and let artificial gravity do the work
of maintaining their conditioning.
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They envision a module that鈥檚 4 metres high
and 8 metres wide.
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If you spin the habitat at 20 revolutions
per minute, you give the crew the equivalent
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of Earth gravity.
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Go at only 11.8 RPM and it鈥檒l feel like
Mars gravity.
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Down to 7.8 and it鈥檚 lunar gravity.
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Normally spinning that fast in a habitat that
small would be extremely uncomfortable as
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the crew would experience different forces
at different parts of their body.
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But remember, they鈥檒l be in a state of torpor,
so they really won鈥檛 care.
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Current plans for sending colonists to Mars
would require 40 ton habitats to support 6
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people on the trip.
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But according to SpaceWorks, you could reduce
the weight down to 15 tons if you just let
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them sleep their way through the journey.
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And the savings get even better with more
astronauts.
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The crew probably wouldn鈥檛 all sleep for
the entire journey.
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Instead, they鈥檇 sleep in shifts for a few
weeks.
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Taking turns to wake up, check on the status
of the spacecraft and crew before returning
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to their cryosleep caskets.
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What鈥檚 the status of this now?
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NASA funded stage 1 of the SpaceWorks proposal,
and in July, 2016 NASA moved forward with
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Phase 2 of the project, which will further
investigate this technique for Mars missions,
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and how it could be used even farther out
in the Solar System.
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Elon Musk should be interested in seeing their
designs for a 100-person module for sending
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colonists to Mars.
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In addition, the European Space Agency has
also been investigating human hibernation,
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and a possible way to enable long-duration
spaceflight.
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They have plans to test out the technology
on various non-hibernating mammals, like pigs.
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If their results are positive, we might see
the Europeans pushing this technology forward.
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Can we go further, putting people to sleep
for decades and maybe even the centuries it
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would take to travel between the stars?
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Right now, the answer is no.
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We don鈥檛 have any technology at our disposal
that could do this.
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We know that microbial life can be frozen
for hundreds of years.
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Right now there are parts of Siberia unfreezing
after centuries of permafrost, awakening ancient
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microbes, viruses, plants and even animals.
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But nothing on the scale of human beings.
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When humans freeze, ice crystals form in our
cells, rupturing them permanently.
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There is one line of research that offers
some hope: cryogenics.
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This process replaces the fluids of the human
body with an antifreeze agent which doesn鈥檛
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form the same destructive crystals.
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Scientists have successfully frozen and then
unfrozen 50-milliliters (almost a quarter
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cup) of tissue without any damage.
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In the next few years, we鈥檒l probably see
this technology expanded to preserving organs
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for transplant, and eventually entire bodies,
and maybe even humans.
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Then this science fiction idea might actually
turn into reality.
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We鈥檒l finally be able to sleep our way between
the stars.
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Obviously, I鈥檇 like to know, would you do
it?
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Would you get into a device that allowed you
to sleep through the journey to a distant
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world or star system?
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I鈥檇 love to know your thoughts in the comments.
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In the next episode, we look at some newly
announced missions to Uranus and Neptune.
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That鈥檚 right, I鈥檓 going to talk about
sending a probe to Uranus to study its gas.
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Time for another playlist, so you can dig
much deeper into this really interesting topic.
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First up, a cool video about hibernating bears.
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Not sure if it鈥檚 super useful, but aww,
look at those baby bears sleeping.
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An episode on the topic from SciShow.
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A report from the Wall Street Journal about
NASA鈥檚 hibernation plans.
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And finally, two lectures from researchers
in the field of human hibernation.
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Would you get into a device that allowed you
to sleep through the journey to a distant
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world - oh, let's go back.
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