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NASA is working on a so-called 'Cryosleep Chamber', but why do they need it so badly?

There must be a lot of benefits attached to this technology..

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    $\begingroup$ It is hoped that an astronaut in cryosleep needs much less food, water and muscle training. But was there any demonstration of cryosleep over months on Earth? $\endgroup$ – Uwe May 26 at 15:34
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    $\begingroup$ @Uwe could save on oxygen too, which means lower power requirements for CO2 scrubbers. $\endgroup$ – Criggie May 26 at 22:10
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    $\begingroup$ Possibly reduce radiation damage? $\endgroup$ – Greg May 27 at 0:09
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    $\begingroup$ @Greg: yes that's plausible. If they don't have to move, they can be inside a small better-shielded enclosure. $\endgroup$ – Peter Cordes May 27 at 3:35
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    $\begingroup$ @Greg: It doesn't yet exist, so we can't tell. For all we know, the natural DNA repair would be slowed down, making radiation damage worse. $\endgroup$ – MSalters May 27 at 8:08
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What are the benefits of cryosleep?

  • Don't need as much volume/mass for living space
  • Don't need as much volume/mass/energy for life support
  • Don't need breathable atmosphere or airtight ship
  • Can have the ship be at much lower temperature
  • Travel time not limited by how long food supplies last or the passengers' lifespan
  • If cryosleep chamber also immerses people in liquid, passengers can potentially tolerate stronger accelerations
  • Heavy radiation shielding needs to cover less of the ship
  • Can also use it on Earth for time travel (to the future), cheaper terrestrial transportation and keeping sick or injured people alive on lengthy trips to care facilities

There must be a lot of benefits attached to this technology..

NASA is a government agency, and it is in their interest to act in such a way as to make it politically expedient for politicians to favor funding them. One way to do this is to make the public excited about NASA. Cryosleep has been a staple of science fiction for decades and it's a "cool" technology, bound to be popular with many people. Therefore it is not rule that everything NASA does has a lot of benefits, it may instead just be popular or easy to get funding for.

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    $\begingroup$ lifespan is still an issue, though it is hoped/thought aging may slow down, thus making longer trips possible. $\endgroup$ – jwenting May 28 at 5:43
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    $\begingroup$ @jwenting, "lifespan", in this case, is tied to radiation poisoning. Cryosleep means you're a human popsicle, as dead as a particularly famous Norwegian Blue parrot (lovely plumage). Humans themselves are radioactive (c14, potassium, other common unstable isotopes), but these isotopes decay slowly enough that a person's normal metabolism is more than enough to repair the damage.. However, if a person doesn't have a metabolism, then radiation damage isn't repaired, and when they're revived they will experience acute radiation sickness. $\endgroup$ – Ghedipunk May 28 at 18:35
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    $\begingroup$ @Ghedipunk Cryosleep slows down metabolic processes, doesn't stop them completely. At least any realistic system would work that way. I'm not talking handy wavy sci-fi scenarios here... $\endgroup$ – jwenting May 29 at 3:40
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    $\begingroup$ That would be torpor chambers, not cryosleep chambers. Cryo- means frozen, and is often used to mean extremely cold. (Space engineers are more pedantic than I am, and far, far more pedantic than people who write news articles saying that NASA is working on cryosleep chambers.) $\endgroup$ – Ghedipunk May 29 at 4:03
  • $\begingroup$ @Ghedipunk, oo! That's interesting. I thought you were about to talk about cosmic radiation or something, but you're saying we'd actually damage ourselves! $\endgroup$ – ikegami May 29 at 7:28
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NASA is working on a so-called 'Cryosleep Chamber', but why do they need it so badly?

NASA does not "need it so badly". If it did "need it so badly", NASA would be spending tens to hundreds of millions of dollars (or more) per year on this technology. Instead, NASA is spending half a million dollars on this technology, spread out over two or three years.

NASA would be remiss if it didn't invest small amounts of money on what appear to be ridiculous science fiction ideas. Sometimes those apparently ridiculous ideas are worth every cent spend on them. NASA would also be remiss if it invested huge amounts of money on such ideas. A half of a million dollars spread over a two or three years is a tiny amount of money compared to NASA overall budget.

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    $\begingroup$ Full and open disclosure: I have nothing to do with this idea. On the other hand, I have proposed some cockamamie ideas to NASA, and sometimes I / my employer received funding for those ideas. A few of those ideas actually had merit. After the fact, several did not. $\endgroup$ – David Hammen May 26 at 14:06
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    $\begingroup$ You can't say something like that and not follow it up with some examples! $\endgroup$ – Starfish Prime May 26 at 15:55
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    $\begingroup$ @StarfishPrime - How's using craters for navigation grab you? It grabbed NASA at one time. sbir.gov/sbirsearch/detail/254723 $\endgroup$ – David Hammen May 26 at 21:06
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    $\begingroup$ "Fusion of Inertial Navigation and Imagery Data" looks a lot like TERCOM. $\endgroup$ – RonJohn May 28 at 4:42
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    $\begingroup$ @Michiel - That's okay. That you selected another answer meant that I received the rather difficult to obtain Populist badge. Thanks! $\endgroup$ – David Hammen May 28 at 5:32
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From their own page: https://www.nasa.gov/content/torpor-inducing-transfer-habitat-for-human-stasis-to-mars

We believe the crew habitat mass can be reduced to only 5-7 mt (for a crew of 4-6), compared to 20-50 mt currently. The total habitat module volume would be on the order of 20 m3, compared to 200 m3 for most current designs.

That's a pretty substantial reduction in weight and size, which brings a concomitant reduction in cost and launch requirements (or increases the budget available for other parts of the mission).

I suspect that also sleeping crew will be happier to be packed into a tiny shielded space for the whole trip, so it'd probably reduce their total radiation exposure by a small amount.

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    $\begingroup$ 'mt' is a milli tonne so a kilogram? No of course it's a metric tonne, so 1000 kg. Gah those units make me go crazy at one point... $\endgroup$ – Arsenal May 27 at 14:46
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    $\begingroup$ @Arsenal Mg would be much more sensible! $\endgroup$ – pipe May 27 at 15:43
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Food. Sure, you have other consumables like CO2 scrubbers, but the big problem is food. NASA says:

When astronauts travel into space, NASA scientists determine how much food will be needed for each mission. For example, an astronaut on the ISS uses about 1.83 pounds (0.83 kilograms) of food per meal each day. About 0.27 pounds (0.12 kilograms) of this weight is packaging material. Longer-duration missions will require much more food.

A trip to Mars and back, for instance, may take more than three years and require the provision of thousands of kilograms of food. A crew of four on a three-year martian mission eating only three meals each day would need to carry more than 24,000 pounds (10,886 kilograms) of food.

So a crew of 4 needs 8000 pounds or about 3700kg of food per year. I call it "The tyranny of the hungry dude equation."

A very long-duration mission, say to Jupiter, would take much longer then 3 years, it would take double that just to get there and the same to get back, maybe longer. A 12 year mission would require close to 100,000 pounds of food! It would be an enormous and expensive challenge to get all this to orbit, and launch a rocket big enough to move it! To reduce the food budget you have 2 choices:

  1. Reduce the mission duration by going faster: the faster you get there and back the shorter the mission and less food your crew needs. This means more advanced propulsion systems, which NASA is researching
  2. Reduce the amount of food astronauts need for the mission

Cryosleep is all about option 2, it makes manned missions to far off destinations possible with existing propulsion technology as the astronauts only need food while they are awake, which is weeks or months instead of years.

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  • $\begingroup$ Surely there's a third choice, recycling at least some of the waste stream into more food. Of course, equipment to support this would also have mass and occupy volume. $\endgroup$ – jeffB May 29 at 18:21
  • $\begingroup$ I did consider putting that in @jeffB, but I decided not to as that seems further off, however it is a valid option. $\endgroup$ – GdD May 29 at 18:28
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There are lots of problems with being in space for an extended period of time. These include:

  • Low gravity can cause loss of bone and muscle mass

  • It is difficult to farm foods and you can only lift so much into space - the more food you send up, the more fuel it will take

  • A baby has never been born anywhere other than Earth. We can't risk leaving people for generations if we don't know that they will be alright

  • It takes hundreds of days just to get to Mars at its closest. People would go crazy living with the same people in the same small space for so long (there was an experiment on this; I'll link to it if I find it)

Cryosleep takes a lot of the work out of it. An astronaut in cryosleep does not need as many resources to stay alive.

There can be some drawbacks, e.g. if the crew were about to land on Mars and there were an error, it would take 20 minutes to alert Earth and another 20 minutes to wake up one of the crew, but this could be resolved by automatically waking a crew member if something goes wrong.

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  • $\begingroup$ We can't risk not sending people, the second it's even possible that they'll reach a habitable planet, even if it's a great risk to the people we send. The risk to not sending them is that something happens to Earth (like we mess up the environment badly enough) then the whole species could be wiped out. $\endgroup$ – user3067860 May 28 at 19:06

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