In movies and books, fictional astronauts enter ‘suspended animation’ to cross the vastness of space. Recently ESA investigated how real-life crew hibernation would impact a space mission to Mars.

Fictional image of hibernating astronauts, via ESA.

The European Space Agency (ESA) said on November 18, 2019, that its scientists have recently been investigating the process of placing astronauts into hibernation to cross the vastness of space. These scientists met at ESA’s Concurrent Design Facility to assess the advantages of human hibernation for a trip to a neighboring planet, such as Mars. They took as their reference an existing study that described sending six humans to Mars and back on a five-year timescale. They studied how crew hibernation would impact space mission design, and put some numbers to known advantages to human hibernation for space travel, for example, that a smaller space capsule could be used if the crew were hibernating, rather than awake, for the months-long journey to Mars.

Jennifer Ngo-Anh, a team leader in ESA’s Science in Space Environment (SciSpacE) program, commented:

For a while now hibernation has been proposed as a game-changing tool for human space travel.

If we were able to reduce an astronaut’s basic metabolic rate by 75% – similar to what we can observe in nature with large hibernating animals such as certain bears – we could end up with substantial mass and cost savings, making long-duration exploration missions more feasible.

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Here is ESA’s Concurrent Design Facility, which hosts representatives of all space mission disciplines in order to design future space missions.

Image via ESA.

Why do we need to put astronauts into hibernation at all? The reason is that space is vast. Even our own neighborhood of space – our solar system – is subject to a space-is-vast issue that factors heavily into our missions to explore the other planets near us in space. Consider that the New Horizons mission to Pluto, for example – launched in 2006 – needed nine years to get to its flyby.

To get an idea of the distance scale of our solar system, visit “If the moon were only 1 pixel” showing the relative distances of the planets to scale on a single extra-wide page. Then try – if you can – to extend what you’ve learned to the billions of other likely solar systems in our galaxy alone.

As Joe Hansen – host of the PBS series “It’s Okay to be Smart” – says in the video below:

The human brain just can’t fathom how big things like the solar system are.

Robin Biesbroek of ESA – who has worked in the past on the removal of space debris from low-Earth orbit – was part of the recent ESA study on human hibernation. He commented:

We worked on adjusting the architecture of the spacecraft, its logistics, protection against radiation, power consumption and overall mission design.

We looked at how an astronaut team could be best put into hibernation, what to do in case of emergencies, how to handle human safety and even what impact hibernation would have on the psychology of the team.

Finally we created an initial sketch of the habitat architecture and created a roadmap to achieve a validated approach to hibernate humans to Mars within 20 years.

The scientists found that the mass of a spacecraft for human hibernation could be reduced by a third.

The ESA scientists quantified what might seem fairly obvious … that a spacecraft for hibernating astronauts could be on the small side. This comparison shows the size of a module for a crewed Mars mission with its hibernation-based equivalent.

Image via ESA.

If the crew were hibernating, you wouldn’t need extensive crew quarters, or as much storage room for consumables (like food and water).

Hibernation module design via ESA.

ESA said hibernation would take place in small individual pods that would double as cabins while the crew are awake.

Hibernation pod design via ESA.

What would it be like for the astronauts? ESA explained:

The assumption was that a drug would be administered to induce ‘torpor’ – the term for the hibernating state. Like hibernating animals, the astronauts would be expected to acquire extra body fat in advance of torpor. Their soft-shell pods would be darkened and their temperature greatly reduced to cool their occupants during their projected 180-day Earth-Mars cruise.

ESA said the hibernating cruise phase would end with a 21-day recuperation period. It said that – based on the experience of animal hibernation – the crew would likely not experience bone or muscle wastage. ESA also explained:

Radiation exposure from high-energy particles is a key hazard of deep space travel, but because the hibernating crew will be spending so much time in their hibernation pods, then shielding – such as water containers – could be concentrated around them.

And ESA also spoke of the “largely autonomous operations, with optimum use of artificial intelligence” and “fault detection, isolation and recovery” needed on a spaceship where most humans are hibernating.

Sound a bit creepy or lonely? Maybe. But Ngo-Anh commented:

… the basic idea of putting astronauts into long-duration hibernation is actually not so crazy: a broadly comparable method has been tested and applied as therapy in critical care trauma patients and those due to undergo major surgeries for more than two decades. Most major medical centres have protocols for inducing hypothermia in patients to reduce their metabolism to basically gain time, keeping patients in a better shape than they otherwise would be.

We aim to build on this in future, by researching the brain pathways that are activated or blocked during initiation of hibernation, starting with animals and proceeding to people.

NASA has contracted studies on human hibernation in space, too. This image is a “settlement-class Mars Transfer Habitat” designed by NASA contractor SpaceWorks in 2017. 

Read more: Sleeping their way to Mars.

By the way, if you’re interested in reading a wonderful recent science fiction series depicting deep-space travel via human hibernation – two of the best sci-fi books I’ve ever read (and I’ve read a bunch) – try “Children of Time” and “Children of Ruin” by Adrian Tchaikovksy. Both have all the things I love in science fiction: travel over millenia among the stars, how the hibernating travelers perceive time passing, strange planets, weird aliens, a human love story. Human hibernation plays a big role in these awesome books!

The cover of “Children of Time” by Adrian Tchaikovksy.

Bottom line: The European Space Agency has been studying how real-life human hibernation would impact space mission design.

Via ESA

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Scientists are still trying to figure out where Mars’ methane comes from. Now there’s a new mystery that might be connected: unusual fluctuations of oxygen in Mars’ atmosphere, detected by the Curiosity rover.

Recent self-portrait of NASA’s Curiosity on Mars, stitched together from 57 individual images taken by a camera on the end of Curiosity’s robotic arm on October 11, 2019 (Sol 2,553).

Image via NASA/JPL-Caltech/MSSS. Curious about Curiosity’s self-portraits? Here’s the story behind them.

The presence of methane in Mars’ atmosphere has been a fascinating puzzle for planetary scientists. That’s because, on Earth, methane is linked to life, but it can also be produced geologically. Some of the best data about Mars’ methane has come from the Curiosity rover, which landed on Mars after a daring descent through the atmosphere in August, 2012. Now Curiosity has made another intriguing discovery: oxygen at the rover’s location is behaving in ways that haven’t yet been explained by any known atmospheric or chemical process. The levels of the gas increase much more in the spring and summer months than had been predicted, similar to the still-mysterious methane. The big question, of course, is why?

The baffling peer-reviewed results were just published in the November 12, 2019, issue of the Journal of Geophysical Research: Planets.

Sushil Atreya, professor of climate and space sciences at the University of Michigan, said:

The first time we saw that, it was just mind boggling.

So just what is happening?

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Seasonal variations in oxygen levels in Gale Crater from 2012-2017. So far, scientists haven’t been able to explain these changes.

Image via Melissa Trainer/Dan Gallagher/NASA Goddard/NASA.

Curiosity analyzed the composition of the air at Gale Crater over three Mars years (about six Earth years), using its Sample Analysis at Mars (SAM) portable chemistry lab. The results were pretty much what had been expected, and known for years: 95% carbon dioxide (CO2), 2.6% molecular nitrogen (N2), 1.9% argon (Ar), 0.16% molecular oxygen (O2), and 0.06% carbon monoxide (CO). (The methane is normally in much smaller amounts, about 0.00000004% on average).

The nitrogen and argon tend to follow a predictable pattern each year, increasing and decreasing relative to how much carbon dioxide there is. This is related to changing air pressure during the year, since carbon dioxide freezes as snow and ice over the planet’s poles during the winter, which lowers the air pressure. The air pressure rises again when the carbon dioxide evaporates in the spring and summer.

This is where it gets weird. Scientists had expected that the oxygen would follow the same pattern as the nitrogen and argon, but it didn’t. The oxygen level increased much more in spring and summer – as much as 30% – and then dropped back to normal levels, and even below, in the fall. This same process was observed by Curiosity each Martian spring and summer.

So what are the possible explanations? The researchers have considered several possibilities, but none of them explain all of the results.

Was there a problem with the SAM lab? The researchers checked but the instrument was fine and working properly.

Could carbon dioxide or water molecules have released oxygen when they broke apart in the atmosphere due to solar radiation? Probably not, since it would take five times more water vapor than exists to produce the amount of oxygen observed. Carbon dioxide would break up too slowly to generate the same amount of oxygen over such a short time period.

As for the oxygen decrease seen later, could that have been caused by solar radiation breaking apart oxygen molecules? No, since that would be an even slower process, taking up to 10 years.

The scientists involved also think it is unlikely to be caused simply by atmospheric circulation patterns. According to Melissa Trainer, a planetary scientist at NASA’s Goddard Space Flight Center (GFSC) who led the research:

We’re struggling to explain this. The fact that the oxygen behavior isn’t perfectly repeatable every season makes us think that it’s not an issue that has to do with atmospheric dynamics. It has to be some chemical source and sink that we can’t yet account for.

As Timothy McConnochie, assistant research scientist at the University of Maryland, also noted:

We have not been able to come up with one process yet that produces the amount of oxygen we need, but we think it has to be something in the surface soil that changes seasonally because there aren’t enough available oxygen atoms in the atmosphere to create the behavior we see.

Diagram showing the seasonal cycle of methane as detected by the Curiosity rover in Gale Crater. The methane also varies in concentration on a daily basis as well as seasonal.

Image via NASA/JPL-Caltech/Mars Exploration Program.

The paper itself goes into more detail about each of these hypotheses and how none of them adequately explain the results so far. Yet something is producing a lot more oxygen during the warmer months than there should be. Intriguingly, both the oxygen and methane have been observed to fluctuate like this in tandem on at least some occasions, suggesting there may be a common source. As Atreya also noted:

We’re beginning to see this tantalizing correlation between methane and oxygen for a good part of the Mars year. I think there’s something to it. I just don’t have the answers yet. Nobody does.

On Earth, having oxygen and methane together is regarded as a biosignature, since they tend to destroy each other unless they are being continuously produced and fluxed into the atmosphere at relatively high rates. Because of this, the two gases are said to be in a state of thermodynamic disequilibrium.

By far, most of the oxygen and methane on Earth are produced by and/or consumed by life. Could that really be what’s happening on Mars? Or is there still some other unknown chemistry occurring? The Curiosity data showed that the background methane levels decreased at the same time as the oxygen levels did in the last half of each year, although the oxygen increases again earlier in the year than the methane, and is more variable year-to year. The larger “spike” in methane seen by Curiosity however, also occurred during the same period of time as the increase of oxygen in the spring. What all this means isn’t clear yet, and more study will be needed.

Melissa Trainer at Goddard Spaceflight Center (GFSC), who led the new research.

Image via NASA/GFSC.

If there really is a correlation between the oxygen and methane on Mars, that could be a potential biosignature. A previous study in 2014 by Shawn Domagal-Goldman of NASA’s Goddard Space Flight Center found that while oxygen and methane by themselves could sometimes be created by non-biological processes, on exoplanets for example, but finding them together would be a more convincing biosignature:

However, our research strengthens the argument that methane and oxygen together, or methane and ozone together, are still stro-ng signatures of life. We tried really, really hard to make false-positive signals for life, and we did find some, but only for oxygen, ozone, or methane by themselves.

These odd fluctuations in the oxygen levels at Gale Crater – with a possible connection to the methane fluctuations and spikes – are a fascinating new mystery for Mars scientists to try and solve. As Trainer summarized:

This is the first time where we’re seeing this interesting behavior over multiple years. We don’t totally understand it. For me, this is an open call to all the smart people out there who are interested in this: See what you can come up with.

• Bottom line: NASA’s Curiosity rover has detected unusual increases and decreases in the level of oxygen in the air at Gale Crater. In some ways these are similar to the fluctuations of methane, and may even be connected.
• Source: Seasonal variations in atmospheric composition as measured in Gale Crater, Mars
• Via NASA

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