Mars Mission Discussion thread.

[NSEP]

This topic has sort of leaked in the SpaceX and SLS threads. I thought it deserved a seperate thread.

This thread is not about the colonization aspect. If you want to discuss the colonization of Mars, go here:

 

[DAL59]

9 hours ago, NSEP said:

This topic has sort of leaked in the SpaceX and SLS threads. I thought it deserved a seperate thread.

This thread is not about the colonization aspect. If you want to discuss the colonization of Mars, go here:

 

I already have a thread for this purpose:

 

[DeltaDizzy]

I put other, and the Mars Direct method.

[PB666]

Those 4 russian astronauts are all still alive.  

Radiation Hucksters Strike Again
By Dr. Robert Zubrin, Mars Society President, 06.08.17

According to a publicity campaign launched on behalf of a paper authored by University of Nevada Las Vegas Professor Frank Cucinotta, new findings show "collateral damage from cosmic rays increases cancer risks for Mars astronauts."

However an examination of the paper itself shows no discussion of experimental methods or results, because no experiments were done and no data was taken. Rather the much-ballyhooed paper is a discussion of a computer model that Prof. Cucinotta has created that claims to have the power to predict radiation-induced cancer occurrences. In short, there’s no real news. Furthermore, to the extent that the model in question has any empirical foundation, it is based on irrelevant prior experiments done in which researchers subjected mice to radiation dose rates millions of times greater than astronauts would receive on their way to Mars.

. . . . . . . .

Galactic cosmic radiation is not a show stopper for human Mars exploration and should not be used as an excuse for delay.  The space program costs many billions of dollars, which are spent at a real cost to meeting human needs elsewhere. That fact imposes a moral obligation on the program to move forward as quickly and efficiently as possible. It is understandable that radiation researchers should want to justify their funding, but they should not spread misinformation to promote themselves at such extraordinary expense to the public.

This posting had nothing to do with SLS launch system. Finally moved here others have commented about how the Mars stuff.

Zubrin is not an expert in risk analysis and his comments should be taken with a grain of salt.

Short and sweet. Envirnomental risk analysis is extremely difficult to parse out even when the total risk is known, its not that the risk is absent, it because the methods and numbers of participants required to determine risk are much larger than it is feasible to study. I can only tell you this, at high radiation levels there are associated neuropathies, for example sub-lethal exposure of gamma radiation causes tingling sensations is the radiated areas. People who undergo radiation therapy sometimes lose or alter their taste of food. Risk is not about lab animals, risk spreads out widely a few individuals are at high risk at low exposures, and others can survive superlethal doses. Thats the way naturally breeding populations are.
The public sector agencies are not looking at risk from the perspective of how to keep that last man alive, they look at it from the perspective of how to keep the first man healthy and free of lifelong risk. In a vacuum of information they guess at what that level is.

I should point out that Zubrin did cherry pick his data, the more recent data is the most accurate, and he refutes it.

 

 

[NSEP]

9 hours ago, DAL59 said:

I already have a thread for this purpose:

 

Merge?

[PB666]

Once again moving posts to this thread.
The problem is more specific to flight. Basic assumption is that Kids will not be playing on the surface of Mars. Logic. Atmosphere is much, much riskier than cosmic radiation.
Since they are not going to be playing on the surface then all facilities for childrearing can be buried, which means if you get Atmosphere control issue taken care of, then burial issue, and the gravity issue . . . . .

But the child bearers are going to have to pass from MEO to Mars. What is the profile, males and females. Well educated, late 20s to late 30s in age, extensive trained technicians (post graduate + 4-8 additional years of additional training and 2 years in flight related. So here is the problem, the rate of SNP mutation is something like 3.5 time higher in the male gonad that the female. These are largely unrepaired errors (DNA polymerase errors and uncorrected damage repair). In males risk of damage increases linearly from age 13 to Death. In females the SNP risk is largely from birth to 10 years of age (females have a higher risk of autosomal recombination with advanced age). 

If a male passes through a zone of 150 days in which is gonadal exposure is 1000 times higher than the general population, its as if his guys aged 300 years in a year. So what you would expect in his offspring is a higher than average occurrence of leukemia, lymphoma, schizophrenia and autism in a naive population of males (if you select non-naive males-see reference below). In addition within a few generations, because population is small, a much higher occurrence of rare autosomal recessive mutations. These mutations would increase during the exposure but would not be evident for at least 2 generations and more likely around 4 generations. We can compare this with acute radiation exposure (e.g. a blast) the risk is immediate, only the cells involved in a replication phase are at high risk. Some cells are permanently transformed and others are not. In the case of chronic exposure all cells will be damaged because all cells are exposed in all phases and risk accumulates with time. There will be some individuals, unknown apriori, who are resilient to radiation damage of this type, and there will be individuals who are more susceptible, and so there is an expected evolutionary outcome. If you are talking about static populations with a sustainable resource base (e.g. some village on the s. coast of the Caspian Sea) then overtime the rate of damage will decrease and all individuals will become resilient to mutation due to natural selection.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030667/

If you are sending elderly couples to Mars, you hardly care. This has been recommended, don't send reproductive age adults to Mars.

Next issue, is there a way to defend against the radiation. 4 cm of water in a shell around the spacecraft will suffice. So if the craft has an aluminum hull, just split the thickness of the wall and fill it with 4 cm of water. That's it. Well, not so, you probably will have to aim at doing a hohmann from E-L2 to M-L1 (taking longer) and then taking a different craft to re-enter Mars, carrying a big bucket of water to martian surface is not wise.

[kerbiloid]

This explains a lot...

Spoiler

 

[tater]

https://www.lpi.usra.edu/lunar/strategies/HumanstoMars.pdf