A renewed era of space exploration is upon us, and many exciting missions will be headed to space in the coming years. These include crewed missions to the Moon and the creation of permanent bases there. Beyond the Earth-Moon system, there are multiple proposals for crewed missions to Mars and beyond. This presents significant challenges since a one-way transit to Mars can take six to nine months. Even with new propulsion technologies like nuclear rockets, it could still take more than three months to get to Mars.
In addition to the physical and mental stresses imposed on the astronauts by the duration and long-term exposure to microgravity and radiation, there are also the logistical challenges these types of missions will impose (i.e., massive spacecraft, lots of supplies, and significant expense). Looking for alternatives, the European Space Agency (ESA) is investigating hibernation technology that would allow their astronauts to sleep for much of the voyage and arrive at Mars ready to explore.
There’s a disturbing lack of hibernation in our space-faring plans. In movies and books, astronauts pop in and out of hibernation—or stasis, or cryogenic sleep, or suspended animation, or something like it—on a regular basis. If we ever figure out some kind of hibernation, can we take advantage of it to get by with smaller spacecraft?
The European Space Agency (ESA) is working to answer that question.
It’s a staple of science fiction, and something many people have fantasized about at one time or another: the idea of sending out spaceships with colonists and transplanting the seed of humanity among the stars. Between discovering new worlds, becoming an interstellar species, and maybe even finding extra-terrestrial civilizations, the dream of spreading beyond the Solar System is one that can’t become reality soon enough!
We’ve spent a few articles on Universe Today talking about just how difficult it’s going to be to travel to other stars. Sending tiny unmanned probes across the vast gulfs between stars is still mostly science fiction. But to send humans on that journey? That’s just a level of technology beyond comprehension.
For example, the nearest star is Proxima Centauri, located a mere 4.25 light years away. Just for comparison, the Voyager spacecraft, the most distant human objects ever built by humans, would need about 50,000 years to make that journey.
I don’t know about you, but I don’t anticipate living 50,000 years. No, we’re going to want to make the journey more quickly. But the problem, of course, is that going more quickly requires more energy, new forms of propulsion we’ve only starting to dream up. And if you go too quickly, mere grains of dust floating through space become incredibly dangerous.
Based on our current technology, it’s more likely that we’re going to have to take our time getting to another star.
And if you’re going to go the slower route, you’ve got a couple of options. Create a generational ship, so that successive generations of humans are born, live out their lives, and then die during the hundreds or even thousands of year long journey to another star.
Imagine you’re one of the people destined to live and die, never reaching your destination. Especially when you look out your window and watch a warp ship zip past with all those happy tourists headed to Proxima Centauri, who were start enough to wait for warp drives to be invented.
No, you want to sleep for the journey to the nearest star, so that when you get there, it’s like no time passed. And even if warp drive did get invented while you were asleep, you didn’t have to see their smug tourist faces as they zipped past.
Is human hibernation possible? Can we do it long enough to survive a long-duration spaceflight journey and wake up again on the other side?
Before I get into this, we’re just going to have to assume that we never merge with our robot overlords, upload ourselves into the singularity, and effortlessly travel through space with our cybernetic bodies.
For some reason, that whole singularity thing never worked out, or the robots went on strike and refused to do our space exploration for us any more. And so, the job of space travel fell to us, the fragile, 80-year lifespanned mammals. Exploring the worlds within the Solar System and out to other stars, spreading humanity into the cosmos.
Come on, we know it’ll totally be the robots. But that’s not what the science fiction tells us, so let’s dig into it.
We see animals, and especially mammals hibernating all the time in nature. In order to be able survive over a harsh winter, animals are capable of slowing their heart rate down to just a few beats a minute. They don’t need to eat or drink, surviving on their fat stores for months at a time until food returns.
It’s not just bears and rodents that can do it, by the way, there are actually a couple of primates, including the fat-tailed dwarf lemur from Madagascar. That’s not too far away on the old family tree, so there might be hope for human hibernation after all.
In fact, medicine is already playing around with human hibernation to improve people’s chances to survive heart attacks and strokes. The current state of this technology is really promising.
They use a technique called therapeutic hypothermia, which lowers the temperature of a person by a few degrees. They can use ice packs or coolers, and doctors have even tried pumping a cooled saline solution through the circulatory system. With the lowered temperature, a human’s metabolism decreases and they fall unconscious into a torpor.
But the trick is to not make them so unconscious that they die. It’s a fine line.
The results have been pretty amazing. People have been kept in this torpor state for up to 14 days, going through multiple cycles.
The therapeutic use of this torpor is still under research, and doctors are learning if it’s helpful for people with heart attacks, strokes or even the progression of diseases like cancer. They’re also trying to figure out if there are any downsides, but so far, there don’t seem to be any long-term problems with putting someone in this torpor state.
A few years ago, SpaceWorks Enterprises delivered a report to NASA on how they could use this therapeutic hypothermia for long duration spaceflight within the Solar System.
Currently, a trip to Mars takes about 6-9 months. And during that time, the human passengers are going to be using up precious air, water and food. But in this torpor state, SpaceWorks estimates that the crew will a reduction in their metabolic rate of 50 to 70%. Less metabolism, less resources needed. Less cargo that needs to be sent to Mars.
The astronauts wouldn’t need to move around, so you could keep them nice and snug in little pods for the journey. And they wouldn’t get into fights with each other, after 6-9 months of nothing but day after day of spaceflight.
We know that weightlessness has a negative effect on the body, like loss of bone mass and atrophy of muscles. Normally astronauts exercise for hours every day to counteract the negative effects of the reduced gravity. But SpaceWorks thinks it would be more effective to just put the astronauts into a rotating module and let artificial gravity do the work of maintaining their conditioning.
They envision a module that’s 4 metres high and 8 metres wide. If you spin the habitat at 20 revolutions per minute, you give the crew the equivalent of Earth gravity. Go at only 11.8 RPM and it’ll feel like Mars gravity. Down to 7.8 and it’s lunar gravity.
Normally spinning that fast in a habitat that small would be extremely uncomfortable as the crew would experience different forces at different parts of their body. But remember, they’ll be in a state of torpor, so they really won’t care.
Current plans for sending colonists to Mars would require 40 ton habitats to support 6 people on the trip. But according to SpaceWorks, you could reduce the weight down to 15 tons if you just let them sleep their way through the journey. And the savings get even better with more astronauts.
The crew probably wouldn’t all sleep for the entire journey. Instead, they’d sleep in shifts for a few weeks. Taking turns to wake up, check on the status of the spacecraft and crew before returning to their cryosleep caskets.
What’s the status of this now? NASA funded stage 1 of the SpaceWorks proposal, and in July, 2016 NASA moved forward with Phase 2 of the project, which will further investigate this technique for Mars missions, and how it could be used even farther out in the Solar System.
Elon Musk should be interested in seeing their designs for a 100-person module for sending colonists to Mars.
In addition, the European Space Agency has also been investigating human hibernation, and a possible way to enable long-duration spaceflight. They have plans to test out the technology on various non-hibernating mammals, like pigs. If their results are positive, we might see the Europeans pushing this technology forward.
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.
It’s not quite the cryogenic sleep featured in Interstellar, but all the same, NASA’s New Horizons probe has spent most of its long, long journey to Pluto in hibernation. So far it’s been asleep periodically for 1,873 days — two-thirds of its journey in space since 2006 — to save energy, money and the risk of instrument failure.
But it’s just about time for the probe to wake up. On Dec. 6, seven months before New Horizons encounters Pluto, the spacecraft will emerge from its last long nap to get ready for humanity’s first flight past the dwarf planet.
“New Horizons is healthy and cruising quietly through deep space – nearly three billion miles from home – but its rest is nearly over,” stated Alice Bowman, New Horizons mission operations manager at the Johns Hopkins University Applied Physics Laboratory (JHUAPL) in Maryland. “It’s time for New Horizons to wake up, get to work, and start making history.”
Hibernation periods have lasted anywhere from 36 days to 202 days. Controllers usually rouse the spacecraft about twice a year to make sure all is well, and to do a little bit of science (such as taking distant pictures of Pluto of its moons). This means the next wakeup will be a new phase for the mission — a sustained effort instead of a burst of activity.
Confirmation of the wakeup should come six hours after it takes place, around 9:30 p.m. EST (2:30 p.m. UTC). This will be after the light signal takes an incredible 4.5 hours to reach Earth from New Horizons. What’s next will be a very busy few days — checking out navigation, downloading new science data, then getting the spacecraft ready for Pluto’s big closeup July 2015.
“Tops on the mission’s science list are characterizing the global geology and topography of Pluto and its large moon Charon, mapping their surface compositions and temperatures, examining Pluto’s atmospheric composition and structure, studying Pluto’s smaller moons and searching for new moons and rings,” JHUAPL stated.
Manned missions to deep space present numerous challenges. In addition to the sheer amount of food, water and air necessary to keep a crew alive for months (or years) at a time, there’s also the question of keeping them busy for the entirety of a long-duration flight. Exercise is certainly an option, but the necessary equipment will take up space and be a drain on power.
In addition, they’ll need room to move around, places to sleep, eat, work, and relax during their down time. Otherwise, they will be at risk of succumbing to feelings of claustrophobia, anxiety, insomnia, and depression – among other things.
While many kids in the U.S. are starting their school summer vacations, New Horizons is about to get back to work! Speeding along on its way to Pluto the spacecraft has just woken up from hibernation, a nap it began five months (and 100 million miles) ago.
The next time New Horizons awakens from hibernation in December, it will be beginning its actual and long-awaited encounter with Pluto! But first the spacecraft and its team have a busy and exciting summer ahead.
After an in-depth checkout of its onboard systems and instruments, the New Horizons team will “track the spacecraft to refine its orbit, do a host of instrument calibrations needed before encounter, carry out a small but important course correction, and gather some cruise science,” according to principal investigator Alan Stern in his June 11 update, aptly titled “Childhood’s End.”
What’ll be particularly exciting for us space fans is an animation of Pluto and Charon in motion around each other, to be made from new observations to be acquired in July. Because of New Horizons’ position, the view will be from a perspective not possible from Earth.
The next major milestone for New Horizons will be its crossing of Neptune’s orbit on August 25. (This just happens to fall on the 25th anniversary of Voyager 2’s closest approach in 1989.) “After that,” Stern says, “we’ll be in ‘Pluto space!'”
Launched on Jan. 19, 2006, New Horizons will make its closest approach to Pluto on July 14, 2015 at 11:49 UTC. Traveling nearly 35,000 mph (55,500 km/h) it’s one of the fastest vehicles ever built, moving almost 20 times faster than a bullet.
Read more from Alan Stern in his latest “PI Perspective” article on the New Horizons web site here, and check out NASA’s mission page here for the latest news as well.
“There is a lot to tell you about over the next 12 weeks, and this is just the warm-up act. Showtime — the start of the encounter — begins in just six months. This is what New Horizons was built for, and what we came to do. In a very real sense, the mission is emerging into its prime.”
– Alan Stern, New Horizons principal investigator
Also, check out a video on Pluto and the New Horizons mission here.