B Survival on Mars: Radiation & Temperature Challenges

[D H]

Oxygen is a piece of cake. It can be produced from CO2 (reverse water gas shift reaction + water splitting, for example).

No, it is not. It is at best TRL (technology readiness level) 6, more likely TRL 4 or 5. The one way we do know how to produce oxygen at TRL 9 involves plants. That of course brings up yet another issue, which is that growing plants on Mars is at best TRL 4 or 5.

This exemplifies the key problem with this thread, and elsewhere. While science fiction is easy (Captain Picard: "Make it so!"), engineering is hard, expletively deleted hard. There are boatloads upon boatloads of technologies that are "a piece of cake" from the perspective of science fiction but that are <expletive deleted> hard from the perspective of engineering. Boatloads of these "piece of cake" technologies never make it beyond the TRL 4, 5, or 6 because they in fact are anything but a "piece of cake". This wall where science fiction conflicts with reality is why NASA and the Department of Defense created the concept of technology readiness levels.

 

[rootone]

... the concept of technology readiness levels.

Had not heard of this before, seems eminently sensible.

 

[nikkkom]

> Oxygen is a piece of cake. It can be produced from CO2 (reverse water gas shift reaction + water splitting, for example).

No, it is not. It is at best TRL (technology readiness level) 6, more likely TRL 4 or 5. The one way we do know how to produce oxygen at TRL 9 involves plants. That of course brings up yet another issue, which is that growing plants on Mars is at best TRL 4 or 5.

Unfortunately, almost everything Mars-base-related is at about TRL 5 ("Component and/or breadboard validation in relevant environment") at best. Not even NASA builds and tests (for example) an oxygen-generating chemical plant in simulated Mars environment (which would be 0.008 bar Carbon dioxide 95.9% Argon 1.9% Nitrogen 1.9% Oxygen 0.15% Carbon monoxide 0.05% input, purely electric power supply, closed cycle long-term operation).

However, the chemistry involved is not only well known, it is used (for other purposes) on Earth on a large scale. I stand by my point that _as Mars base preparations go_, O2 production on Mars is not a problem.

 

[mfb]

It is probably easier than various other challenges. However, consider that the ISS still doesn't have a closed gas cycle. Water is recycled, CO2 -> O2 is not done, although it could save payload.

 

[1oldman2]

This is not only relevant, its a good example of what becomes of one "wanting to understand why"
http://www.nasa.gov/feature/scientists-innovation-began-with-wanting-to-understand-why

 

[GTOM]

About producing oxygen, could the peroxides of the ground help?
I heard that an early probe could produce oxygen with pour warm soup onto it.

 

[D H]

The recent posts on Mercury have been moved to https://www.physicsforums.com/threads/colonizing-mercury.878108/ .

 

[1oldman2]

This is going to have a huge effect on manned spaceflight in the future.
From, http://www.nature.com/articles/srep29901
From, http://www.nbcnews.com/health/heart...used-heart-problems-apollo-astronauts-n618116
"We've probably underestimated the impact of deep-space radiation on not
just cardiovascular disease but health in general", said lead author of the
study, exercise physiologist Dr. Michael Delp of Florida State University.

The Apollo astronauts-the first men to land on the moon took a giant
leap for mankind. But the deep space radiation that dosed the men who left
the Earth's orbit may have damaged their hearts, according to a new study
published Thursday in the journal Science.

 

[mfb]

Seriously? No.

In total, 24 astronauts went to the moon, three of them twice. Blindly using the ~10% CVD mortality for non-flight and LEO astronauts, we expect 2.4 of them to die from CVD - but most of them are still alive. 8 of the 24 died so far, we expect 0.8 deaths among them. 43% of 8 are 3.44. No, not significant.

Can it get worse? Yes of course, you can make the moon group even smaller and pick tiny control groups. Their moon group just has 7 astronauts (all male), the LEO group just 35 (including 5 women), the non-spaceflight astronauts just 42 (5 women). Edgar Mitchell (went to the moon) died recently, I guess that's the reason the moon group has just 7 people.
43% of 7 astronauts are 3, with expected 0.7 if we take the other astronauts as comparison. Oh come on. Yes technically it gives p<0.05, but with such a small sample size you can find everything.

That is not bad enough? Let's look at more details:

The study did not check CVD exlusively. They studied "(CVD), cancer, accidents and all other causes of death". Let's ignore the last group, that gives at least 12 different places to look:
- CVD, cancer, accidents
- fraction who died already compared to sample size, or compared to the number of people who died
- is the rate different for all astronauts in space vs. is it higher for Apollo astronauts only

They find a p<0.05 effect when looking at 12 different places? Surprise, surprise.

 

[1oldman2]

Seriously? No.

Well it is possible that I have cited the latest "doom and gloom" study,
I'm curious to see if NASA mentions it, on the bright side I did learn that Scott Kelly grew two inches while on his one year mission.

 

[Fervent Freyja]

This is going to have a huge effect on manned spaceflight in the future.
From, http://www.nature.com/articles/srep29901
From, http://www.nbcnews.com/health/heart...used-heart-problems-apollo-astronauts-n618116

Massive budget cuts for space exploration must be underway...

You never know, the study could be politically motivated. I sure wouldn't want something published that give the public further reason to holler more budget cuts- one little news article published on a trend site is all they really need.

 

[mfb]

I don't think news about radiation effects on humans in outer space would influence the NASA budget so significantly. The SLS/Orion concept is aimed at those missions, but not exclusively.

@1oldman2: I can't comment on the medical part of the animal studies done on Earth, maybe those have some relevance. Anyway, the more I read the worse it gets:

Deaths due to heart failure, myocardial infarction, stroke, brain aneurysm, or blood clots were classified as CVD.

Oh great, even more subgroups to pick from. I guess a single blood cloth death in the Apollo group would already give "significance".

The significance of differences in cause-specific deaths between groups was assessed with Fisher’s exact probability test. Due to this test being considered extremely conservative, a value of P ≤ 0.10 was considered statistically significant.

What? Now we are at 32 groups and they consider P ≤ 0.10 significant? I would be surprised if they found nothing!

 

[1oldman2]

with such a small sample size

This is the fatal flaw in all studies, I watch for that and take it into account. It will be interesting to watch studies like this evolve and learn just how much the figures change as the sample pool grows. (by the way thanks for the statistical perspective on the study, that helps me understand the results much better.)

 

[1oldman2]

You never know, the study could be politically motivated. I sure wouldn't want something published that give the public further reason to holler more budget cuts- one little news article published on a trend site is all they really need.

I like to take the "okay what's the agenda" approach when reading news of any kind. The political aspect of a study can't be ignored in the age of "I got mine". One thing seems pretty certain, the study raised enough legitimate points to warrant more studies, (the government loves to study studies). We are sure to hear more on this, it would be a shame having to launch more materials for rad shielding than equipment and supplies on a trip to Mars.

 

[mfb]

Unfortunately the sample size won't grow much soon. We have the remaining 16 people who went to moon - 45 years ago. Astronauts today tend to be a bit older than the Apollo astronauts, but they are rarely old. More astronauts leaving low Earth orbit again in ~2025 means we get more equivalent data in 2055-2065. Unless there is some serious issue, then we get data sooner.

 

[D H]

Can it get worse?

Much worse. Astronauts are not average, and they are not perfect. They own Corvettes (or even hotter cars) in much higher numbers than average, they race motorcycles in much higher numbers than average, they philander in much higher numbers than average, ... That's what astronauts do. They work very, very hard, and when they're not working they play very hard. While insanely intelligent, they also are willing to take somewhat insane risks. As a result they tend to die rather young. Studies need to factor in NASA's (and also Roscosmos's) selectivity from the very tip of the Bell curve.Full disclosure: My baby is a "little red Corvette", vintage 2002 (Z06). The first owner was a top engineer at NASA who unfortunately developed Alzheimer's. The second owner was (briefly) the *top* engineer at NASA JSC, but his wife said "sell this car, or divorce me!" I'm the third owner. Knock on wood.

 

[mfb]

They compared Apollo astronauts to other astronauts. You could still argue for some selection effect there, but it is not as bad as comparing them to the general population (which they also included as group, but not as main comparison for their study).

 

[Dotini]

Cardiovascular disease (Photo: Michael Delp)

Exposure to cosmic radiation—specifically, charged high-energy protons—causes permanent tissue damage to DNA molecules, effectively shutting down the body’s ability to repair itself. Previous studies have also shown the increasing risks of cardiovascular disease from exposure to low-energy radiation like x-rays or gamma rays.

It’s important to note that according to the Review of NASA’s Longitudinal Study of Astronaut Health by the Institute of Medicine, astronauts have a significantly higher quality of life. Their incomes are relatively high, they are physically fit, and they have lifetime access to premium medical care. These factors should give them a substantially lower chance of cardiovascular-related illness compared to the similarly-aged general population. For the lunar astronauts, it didn’t, and it’s because of the unique environmental conditions they experienced.
http://observer.com/2016/07/space-radiation-devastated-the-lives-of-apollo-astronauts/

 

[mfb]

For the lunar astronauts, it didn’t, and it’s because of the unique environmental conditions they experienced.

That conclusion is just nonsense, given the small sample size they have and the large number of causes of death they studied.

 

[Dotini]

That conclusion is just nonsense, given the small sample size they have and the large number of causes of death they studied.

IMHO wrong to say "just nonsense". I could go with "unproven". At a minimum it is "interesting" and maybe even "important".

 

[mfb]

Stating unproven things as fact? I would call that nonsense. It is interesting, and worth a follow-up check once more Apollo astronauts died (or maybe one taking into account the medial records while they are still alive, if available), but the authors are way too confident that they found something.

If we would use the same approach in particle physics, we would "find" new particles every week.

 

[Drakkith]

Their moon group just has 7 astronauts (all male), the LEO group just 35 (including 5 women), the non-spaceflight astronauts just 42 (5 women). Edgar Mitchell (went to the moon) died recently, I guess that's the reason the moon group has just 7 people.

Good lord, a sample size of seven?! That's ridiculous!

 

[Chronos]

Adding error bars to tiny sample sizes gives you a whole new perspective on the reliability of such statistics. They clearly fall short of the customary 5 sigma significance limit.

 

[enorbet]

In a less technical analysis I think there is some value in realizing that most of the 12 astronauts that walked on the moon were born in the 1930s, made trips into orbit as well as to the Moon, some more than once, and still lived into their quite active 80s, excepting catastrophic accidents. While even Harrison Schmidt, the first of the scientist-astronauts and the only one to walk on the Moon, was also screened for excellent health though moderately relaxed, it may be useful to remember that average life expectancy for US men born before 1940 was under 70. It is only now 78. Schmidt, Cernan and several others are still alive today.

That astronauts would be on the high side, above average, is to be expected provided they were not impacted by traumatic injury or exposure to dangerous environments. That test pilots and astronauts were and are subjected to all manner of dangerous environments should temper these statistics but the bottom line is that it has been 50 years since Space related radiation exposure and who wouldn't trade such an adventure knowing one would "only" live into their 80s?

The minuscule sample size certainly means more study is necessary but also should mean, given such longevity, it is not an alarming situation requiring any major action and certainly not budget cuts or manned program scrubs..

 

[mfb]

Astronauts are selected based on their health (among other things, but if you pick 5-10 astronauts out of 10,000 candidates you can be really picky in every aspect). They are under constant medical monitoring, have access to excellent healthcare in general, and get a good income. While they are also selected for taking more risks than average persons, the chance to die in an accident are not that high compared to medical issues. You would expect astronauts to have an above-average life expectancy.

It is certainly not alarming, and it is not even significant.

 

[aardwolf.sg]

Massive budget cuts for space exploration must be underway...

You never know, the study could be politically motivated. I sure wouldn't want something published that give the public further reason to holler more budget cuts- one little news article published on a trend site is all they really need.

With that anti-alien guy rallying around, cuts is expected once he's in office.

 

[Fervent Freyja]

With that anti-alien guy rallying around, cuts is expected once he's in office.

You mean the illiterate pig? I resent *it* entering my cognitive space so frequently. I cannot stand the sound or sight of it anymore!

 

[rootone]

The Illiteratti pigs, they are worse then the Vogons.
https://en.wikipedia.org/wiki/Vogon

 

[Fervent Freyja]

The Illiteratti pigs, they are worse then the Vogons.
https://en.wikipedia.org/wiki/Vogon

Now, look here, a cutie with at least some manners. So, I take it back, a pig could be misinterpreted as a compliment!

 

[rootone]

Now that is an honest politician.
A well made proposal without requiring orange fake tan to get the point across.

Hmm. back to Mars htough,
I think the question is about is there anything there worth risking one or more human lifes.
It seems that much more useful science can be done with increasingly capable robots.