Hibernation!
The only way to get out of the solar system deceiving space and time
The colonization of space is a recurring theme in human desires, at least in the last century.
Science fiction does nothing but make explicit the hopes that the future technological revolution
fuels.
Many scientists are fans of science fiction: perhaps this literary genre allows them to
enjoy the extraordinary possibilities that research lets them glimpse even before these
same possibilities, through study and work, are actually discovered and tested.
How to move from one planet to another, from one star to another, or from one galaxy to
another?
Very fast engines and wormholes would offer a practical and seductive solution to the
problem of long-distance star travel, but they hide a difficulty: we do not have the
slightest idea of what a wormhole or a wormhole looks like, and physics does not yet allow
us to exploit engines so powerful to push us beyond the speed of light.
Then another solution appears on the horizon: hibernation.
The idea of cryogenic suspension, or cryosleep, has always been one of the markers of “hard”
science fiction.
Instead of hand-waving some way to cheat Einstein, movies like Alien and authors like Alastair
Reynolds have shown people going to sleep and waking up months, years, or even centuries
later, in another part of the universe.
It’s a pretty huge leap from what we know about hibernation among mammals on Earth.
But in reality, many scientists are convinced that cryosleep is the only hope we have to
make an interstellar journey during our lifetime; without relying on collective solutions such
as those of the "generational spaceships".
Cryosleep involves huge challenges that we have no idea how to get around, but we already
know that traveling faster-than-light is plain impossible, or would require an unattainable
amount of energy.
We cannot even come up with a physically consistent theory for how faster than light travel would
work, much less conceive of engineering such a thin.
the faster-than-light method is, in our universe as we understand it today, a complete fantasy
rather than merely an ‘as-yet undeveloped technology.
Even a tantalizing idea such as the Alcubierre drive, a concept for a faster-than-light engine
that NASA has been researching for years, requires an impossible substance with negative
mass to run it.
But wait... what about wormholes?
Wormholes basically tunnel from one part of spacetime to another, allowing us to leap
across unimaginable distances.
But wormholes may actually be impossible too.
The laws of the universe may not actually allow wormholes to exist, at least not in
a form that we could take advantage of.
This term was coined to indicate the wormholes that (theoretically) could connect two black
holes.
These tunnels would be created by the immense gravitational force of black holes, and within
them space and time (closely related concepts) would be very different from how we know them.
According to Kip Thorne and Michael Morris, physicists at CalTech, the "wormholes" could
be used to jump from one point to another in the universe exceeding the speed of light.
However, it has been proved that wormholes can exist only if there is matter with negative
energy of which, so far, there is no experimental evidence.
Even if this exotic matter existed, it would take a very high concentration to create a
wormhole, equal to the energy density of the Universe fractions of a second after the Big
Bang.
Finally, even overcoming these difficulties, the wormhole would not be traversable: a particle
of positive energy that tried to cross it would cancel the effect of exotic matter that
keeps it open, destroying it.
So if we can’t magically travel faster than light, or build a large wormhole, then getting
to other star systems is going to take a long, long time.
Here’s a pretty good rundown of just how long it would take to reach our nearest star,
Proxima Centauri, with propulsion methods that we currently know are possible.
Estimates range from 80,000 years to a mere 1,000 years.
There are a few potentially faster methods, but they involve huge logistical nightmares.
OK, but then what do we do?
Do we have to give up the stars forever?
Are we going to have to settle for exploring our solar system?
It's painful to admit, but maybe so.
Many scientists think in fact that we will never be able to colonize the planets of other
stars... and as for the exploration of our solar system... well, that wouldn't be such
an easy thing to do either.
Suffice it to say that it took the Voyager probes almost half a century to reach its
"boundaries"...
What manned mission could afford to do the same?
But engineers believe they have found the key to solving this puzzle: put your space
travelers to sleep.
Long-term cryogenic and hibernative sleep may be the key to getting humans to Mars,
and beyond.
The cold is something that man has always feared, since the dawn of history man has
sought ways to defend himself against the frost that penetrates his bones.
We discovered fire, created clothes, houses and heating systems to escape them, and today,
as we hardly fear it, we are learning to tame it and use it for our benefit.
It’s from last month the news of the first suspended animation case obtained through
hibernation to slow down a person’s metabolism and save his life.
The medical field, however, is not the only one in which this technique could be fundamental.
The exploration of space could benefit greatly from hibernation.
Space travel of the future will be long, very long.
To reach Mars it takes about 7 months, to go to Jupiter it takes up to 6 years.
With current technologies, such journeys would require the construction of complex spaceships
capable of comfortably accommodating a crew and everything necessary for their survival.
Add to this the fact that space is permeated by radiation, a stay too long without adequate
protection could be lethal for future space travelers.
The solution could be just hibernation: if we could discover the formula to slow down
exponentially the human metabolism we could send astronauts in deep sleep for long journeys,
then awakening them once they reach their destination.
Yeah, but how do we do that?
Aerospace company SpaceWorks, with funding from NASA's Innovative Advanced Concepts program,
is exploring the idea of having voyagers to Mars do what all professional travelers do
when confronted by uncomfortably long transit times: use whatever technologies or pharmaceuticals
are available in order to make themselves totally unaware of as much of the experience
as possible.
A trip to Mars is going to take more than a couple of Ambien (Elon Musk’s favorite
sleeping pill), though.
That’s why SpaceWorks is working on space habitats that will keep humans comfortably
in stasis for the entire trip.
When it says “stasis”, SpaceWorks is talking about putting astronauts in an “inactive,
low-metabolic torpor state for mission transit phases”.
So, it's not the kind of sci-fi stasis where people are completely frozen and inert, but
rather something more akin to hibernation, where the body’s systems just slow way,
way down.
Fortunately, we know that it's possible to do this because, for many animals, it's a
seasonally recurring phenomenon that’s no big deal.
What SpaceWorks is trying to figure out is how humans can snooze away for months at a
time like bears do.
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There are many reasons why putting humans into torpor for long-duration spaceflight
is a good idea.
One of the biggest is psychological.
Spending months in a cramped spacecraft with the same people and nothing new to do or see
will be a challenge for even the most disciplined astronauts.
And just the thought of the return trip could be super depressing if anything goes wrong.
But the primary reason for torpor, however, is mass.
A conscious, active human demands an enormous amount of air, water, and food.
And as by-products of that activity, the body yields liquid and solid waste, poisonous gas,
and excess heat - all of which need to be handled within the closed system of an interplanetary
spacecraft.
We have the technology to do this, but it involves hauling around tons and tons of extra
stuff.
And when it comes to space travel, extra stuff is usually what you're trying hardest to avoid
because more stuff means more mass, more mass means more engines and more fuel, and all
of it together means a staggering increase in cost.
This reduction in human-related mass leads to reductions in several areas, including
power requirements and the overall structure.
The result: the spacecraft could do less than one hundred tons of engines and fuel.
This is just over the maximum lifting capacity of the heaviest version of NASA's Space Launch
System, which will probably cost something like $5 billion per launch, not including
the hardware that it would be carrying.
This cost stuff can be looked at from another perspective, as SpaceWorks points out: If
you're going to spend all of this time and money going to Mars, by putting astronauts
in torpor you can send twice as many of them for the same price.
This would result in more international participation, and (most important) more exploration and
science on Mars itself, which is the whole reason we're going.
Getting humans into torpor and keeping them there safely might not be as science fiction-y
as it sounds, SpaceWorks hopes.
Humans may not naturally hibernate, but we can fake it for a few days without much trouble.
Therapeutic hypothermia is a relatively common medical treatment where hospitals put patients
into a sedated hypothermia in the aftermath of a traumatic injury, giving the body a couple
of days of healing in a low metabolic state.
This is done by cooling the body down (using one of any number of methods, including non-invasive
ones) by just 5 degrees Celsius.
This reduces the body’s metabolic rate by between 50 and 70 percent.
No drugs are necessary, just the temperature reduction.
Unlike naturally hibernating animals like bears, astronauts aren’t expected to live
off of their body fat for eight months.
Liquid nutrients can be fed directly into the bloodstream, bypassing the digestive system
completely.
This technique is called Total Parenteral Nutrition; it's common for people with gastrointestinal
disorders.
A human in torpor would need only about 300 grams of liquid nutrients per day, whereas
astronauts on the ISS consume about 2,000 grams of food per day.
What’s more, you wouldn't have to worry about solid waste: A simple catheter would
take care of everything.
Here's what astronauts in a torpor habitat might look like:
So why aren't we doing this already?
Mostly because we haven't tried yet.
There's no medical reason for people to be kept in low metabolic states through therapeutic
hypothermia for more than about five days, so there isn't a lot of data on how to manage
longer-term hibernation.
SpaceWorks says that they're starting to see limited experimental data for hibernation
of up to 14 days.
Two weeks is a critical time span.
Being able to keep humans in stasis for at least that long makes NASA’s vision start
to become viable.
Astronauts could be rotated through repeating cycles of activity and hibernation, keeping
their consumption, waste, and boredom to a minimum.
SpaceWorks is targeting torpor for the entire trip to Mars, though, and they've got some
problems to solve.
There are known complications for long-duration intravenous feeding, for example.
And it also takes time to safely wake people up, which would be a problem if there's an
emergency in the spacecraft or a medical issue.
Or, maybe you'd just have robots on hand to manage everything:
Long term, the argument for torpor becomes even more compelling as you start thinking
about what it would take to colonize Mars with hundreds of people at a time.
SpaceWorks has been toying with the idea of a transfer vehicle capable of hauling 100
passengers to Mars at once using two 48-person torpor modules along with a 4-person active
crew: Nobody is quite sure exactly what spending
months and months in torpor might do to a human - mentally and physically.
SpaceWorks is now in phase II of the NASA-funded research study on the subject.
The company will be focusing on medical assessments and evaluations, exploring different approaches
for metabolic suppression and nutritional support.
Another big unknown they’ll seek to explore: what prolonged hypothermia does to non-hibernating
mammals.
Prolonged microgravity might also be an issue, but SpaceWorks is exploring ways of spinning
their stasis habitat to generate artificial gravity - a move that conscious astronauts
wouldn’t be able to handle - as well as using direct electrical stimulation to keep
muscle mass from decreasing.
At the same time, SpaceWorks is thinking much farther ahead, to what would come next, after
Mars.
The ability to put humans in torpor indefinitely would potentially open up the asteroid belt
and both Jupiter and Saturn to human exploration.
OK, but…
Can we go further, putting people to sleep for decades and maybe even the centuries it
would take to travel between the stars?
Right now, the answer is NO.
We don’t have any technology at our disposal that could do this.
We know that microbial life can be frozen for hundreds of years.
Right now there are parts of Siberia unfreezing after centuries of permafrost, awakening ancient
microbes, viruses, plants and even animals.
But nothing on the scale of human beings.
When humans freeze, ice crystals form in our cells, rupturing them permanently.
There is one line of research that offers some hope: cryogenics.
This process replaces the fluids of the human body with an antifreeze agent which doesn’t
form the same destructive crystals.
Scientists have successfully frozen and then unfrozen 50-milliliters (almost a quarter
cup) of tissue without any damage.
In the next few years, we’ll probably see this technology expanded to preserving organs
for transplant, and eventually entire bodies, and maybe even humans.
Then this science fiction idea might actually turn into reality.
We’ll finally be able to sleep our way between the stars.