No immune system....oh crap!

Xaliqen · 2005-10-13 17:38:18

Artificially-induced hibernation is one long-term possibility. Of course, if there is a necessity for active work while in low-g environments, this rules out the hibernation option. However, it is attractive for transporting people between planets.

Also see this article.

GCNRevenger · 2005-10-13 18:23:28

Okay okay, you have some of a point about high-level sanitizing and antibiotic agents should mitigate the bacterial problem Stanley, and shouldn't be a problem for early Mars missions where a little risk and alot of thurough decontamination should be sufficent.

However in the longer run, if we are going to be shuttling people back and forth to Mars in larger numbers but not large enough make artifical gravity trivially easy, then even a small risk of dangerous infection might wind up increasing the number of casulties too much.

But the implications to cancer risks kind of worry me, that are the other immune mechanisms besides T-cells that attack cancer cells suppressed by zero gravity too? The radiation risk posed by heavy nucleii ionization is still not that well understood, and if it is at the threshold of unacceptable with a functional immune system, then with a functioning one this might be an issue.

Maybe we ought to build a pair of NASA-DRM Mars HABs: the first one goes to the Moon, riding on top of a VSE decent stage, which should juuust handle the mass. The second one would be placed into GEO above the Van Allen belts with the ERV-type engine package, and a fully fueled Lunar-type CEV would use its TEI service module to reach it. There, crews would spend six months in zero gravity and cosmic radiation to guage health effects.

My first reflex to the situation is to build the crew's sleeping berths into a "central core" wrapped with H2O/polymer/aluminum radiation armor to lower their dose while they're asleep anyway.

Dook · 2005-10-13 18:30:52

I think any mission to mars needs to have simulated gravity and while I generally like Zubrin's low cost approach ideas I don't like his idea to use a cable to connect the spinning habitat and empty rocket stage.

A cable does not provide any rigidity in any direction. I really think this would be a tremendous hazard as you attempt to spin up two different objects separated by a cable. They must stay in the same rotation plane, they must increase speed the same and tension has to be kept on the cable at all times until the rotation is enough to do it.

I would rather they used a series of ISS truss, or some other stronger type of truss. Yes it would be heavier to launch but also safer and solar panels could be hard mounted on the truss to provide a solid fixture for them.

Also antibiotics have no effect on any virus or cancer.

GCNRevenger · 2005-10-13 18:55:52

I think that the jury is out about how important zero gravity is on account of the immune supression, that if it does impare the bodies' ability to fight cancer, then it might be a show-stopper given the six month transit through cosmic ray bombardment. Extra shielding (cast aluminum bunks for starters) might help, but its still a possible issue. Of course, there is the questionable morality about human testing...

As far as cable vs truss, a truss is not happening. Its simply impossible to make one long enough without becomming too heavy. Both vehicles must be far apart to minimize the corolis force, and especially if the rocket uses a nuclear upper stage, so a large several hundred or even thousand foot seperation is needed.

You also woefully underestimate the strength of modern polymer fibers Dook, a rope able to pull oil derricks made from Spectra probobly won't be much bigger or thicker then your belt. It'll be strong enough, because if the thing DID break, you would only lose your artifical gravity and need to make a small course correction. You wouldn't go sailing off course never to be heard from again. RCS thrusters are good enough to perform the spin-up/down if it is done carefully too. In fact, maybe you would cut the cable intentionally rather then bother spinning down, it might be easier.

Virii should not be a problem with sufficent sanitation either, at least for initial crews.

Dook · 2005-10-13 19:36:38

I didn't underestimate the strength of modern polymers at all. I don't think a cable will break.

But keeping a cable taught as both objects begin to spin and keeping them on the exact same axis and keeping them perfectly offset (180 degrees apart) could be very difficult. We just don't know for sure because we have never done it.

Commodore · 2005-10-13 19:53:44

As far as cable vs truss, a truss is not happening. Its simply impossible to make one long enough without becomming too heavy. Both vehicles must be far apart to minimize the corolis force, and especially if the rocket uses a nuclear upper stage, so a large several hundred or even thousand foot seperation is needed.

Isn't that distance just tad bit exaggerated? I think I remember a similar discussion several months ago concluded that 40m would do the trick.

GCNRevenger · 2005-10-13 20:02:09

I didn't underestimate the strength of modern polymers at all. I don't think a cable will break.
But keeping a cable taught as both objects begin to spin and keeping them on the exact same axis and keeping them perfectly offset (180 degrees apart) could be very difficult. We just don't know for sure because we have never done it.

Difficult? Ummm, no, no it wouldn't be. All you need to do is spin such that you have tension on the cable, and that will keep things nice and seperated. Fine maneuvering control is capable of millimeters per second adjustments, which shoud be plenty.

Commodore · 2005-10-13 21:02:17

SpinCalc

Depending entirely on how many revolutions per minute our crew can handle, and what g is considered enough to maintain the immune system, I think we can wittle down the radius to be feasable for a nuclear electric powered mechanical solution.

You'll have a very hard time selling a tethered system to congress and the American people. We'll have enough issues with the things we can't see, we don't need to add to it with ones we can.

GCNRevenger · 2005-10-13 21:20:05

Nuclear electric? Non-tether? Commodore, we're pinching [I]tens of kilograms[I] for the mission, no big heavy battlecrusier type ship is ever going to fly! Its either Zubrins way for artifical gravity, or no way at all for the foreseeable future. I think the public will think it quite clever, not sissy or too Rube-Goldberg. The problems with spinning about a tether are all simple ones engineering wise, and a cable break is inconsequential.

RobS · 2005-10-14 00:04:37

A cable break is inconsequential if you've designed for it. For example, there's no way on ISS to wash clothing. No one has designed a clothes washer and drier for zero gee. One wouldn't want a cable break on a flight to Mars to render your clothes washer/drier inoperative because it was dependent on gravity to work. Bathrooms are the other thing that work very differently with and without gee, and it would be pain flying two different types of bathrooms to Mars.

-- RobS

Austin Stanley · 2005-10-14 02:11:22

yes but spaceships in microgravity are really difficult places to keep clean when they are in use the place gets covered in dead skin cells hairclippings and there is the ever present moisture and spilt food. In short a haven for all bugs. And the viruses and germs we will find will be carried on board all right that is aboard inside the astronauts

I was under the (perhace incorrect) impression that the issues of cleanliness and hygiene had been solved. If not they certianly should be because an unsanitary work enviroment is unsafe regardless of the state of your immune system. But I don't think they are that difficult to solve. Powerful air-filters/exchangers will certianly be present and will eliminate the airborn contaminates, which in zero -g, should be practicaly everything. Re-usable cleaning devices (ie. absorbent rags that are re-sterilised) and antiseptics cleansers should deal with anything stuck to a surface.

As for naturaly imported germs, these are less of an issue. Firstly while the human body does carry some germs on our skin and digestive track, these are generaly benign and not infectious. Most infectious bacteria/viruses are highly adapted to life within the human body and cannot survive on these surfaces which are also specific adapted to killing them. The rest of a healthy human body is essentialy steril with respect to germs. There simply aren't any swimming about the blood stream, this would make us sick.

I suppose there are a few diseases in which a person can be a carrier of the disease and not actualy harmed themselves, but these are the exception rather than the rule, and they can be tested for in advanced. Being a carrier is much more common among diseases not specificly targeting the carrier (like Malaria for example) but there shouldn't be any of these animials abord the flight. And if there were, they likely can be tested as well.

In addition any disease that might be lingering in a person for some reason are still not likely to cause a problem. Since the immune system has already been exposed to them, the old antibodies it created to detect them and mark them for destruction will still be floating around as well. So the immune system should already be prepared for them. This is part of why people stop getting sick as frequently as they get older, they have already been exposed to those germs and are ready to fight them.

We are not talking short durations are we this is 6 months or more in a high radiation enviroment without an immune system. And it is hard to check to see who actually will suffer the effects as people are different and what one person can shrug off another will fall ill too.
But if this study is proved correct this previous rendering of risk is no longer valid. It is based upon a healthy person with an active immmune system and what the effects of radiation exposure would do to that person. This is from data compiled on Earth from the results of the nuclear tests. But if we then go to space and discover that gravity and its lack causes immune deficiences in a severe scale as this report seems to say then that means simply risk is increased and by a lot more than a factor of 10% over a lifetime. Worse is that it is the immune system that fights the damage radiation exposure does and so the effects of an increased dose is now also magnified.

Re-read the article again. The immune system is a complex and multi-tiered system with many components independant, dependant, and interdependent. The concurns in zero-G relate to the bodies ability to defend itself against infection, specificly the failure in certian T-cells. Cancer is mainly fought by the bodies ability to determine that the cells are mutant and should be destroyed. Since cancer moves rather slowly in comparision to most infections it is typicaly handled by the bodies constant gurdians the Macrophages and other killer cells. If they are able to detect the infection the will destroy it there. This will triger a response from the active immune system, (which is partialy T-cell dependent) but may very well be delt with there. If the Macrophages or other killer cells are unable to detect the cancerous cell, then it doesn't really matter if the T-cell's are functioning or not as it will never be detected.

Also, we have had people up in space for much longer periods than 6 months, (I think the record is like 500+ days) and have not noticed micro-gravity having an increased effect on cancer. Truth is, 6 months realy isn't that long when it comes to most cancers, which develop over a longer period of time. If one of the crew started to develop Cancer during the trip it could be several years untill it had even progressed to the point it was detectible.

SpaceNut · 2005-10-14 05:45:09

I have only heard of cataracts thus far.

GCNRevenger · 2005-10-14 06:29:06

"Also, we have had people up in space for much longer periods than 6 months, (I think the record is like 500+ days) and have not noticed micro-gravity having an increased effect on cancer. Truth is, 6 months realy isn't that long when it comes to most cancers."

Zero gravity? Yes, we have had people in zero-gee, but not in zero-gee AND exposed to cosmic rays. The cancer-inducing power of heavy nucleii radiation is not well understood, but it is probobly quite a big risk. Six months soaked in that without a functional immune system would be long enough to get a cancer started I would think.

As far as designing a spacecraft for exteneded gravity and zero gravity operation, I don't think that this is a huge hurdle. About the only big technical issue I see with the Zubrin artifical gravity method is how you would execute course corrections while spinning. You might have to turn around your ship to re-dock with the TMI stage too like the Apollo capsule to the LEM too to connect the cable initially.

SpaceNut · 2005-10-14 10:38:43

This reference points out why it still maybe dangerous to us long after we have gone.
[url=http://pubs.acs.org/subscribe/journals/ci/31/special/digreg/08digregorio.html]The dilemma of Mars sample return
The battle rages on: Does the scientific value of bringing Martian samples to Earth to study outweigh the risks of introducing alien organisms to our planet?[/url]

In April 1967, the unmanned Surveyor III landed near the eastern shore of Oceanus Procellarum on the lunar surface. It stayed on the Moon for 21/2 years—in a near vacuum, at temperatures of +250 °F in the sunlight and –250 °F in the dark, and completely exposed to solar and cosmic radiation (UV, -, and X-rays)—until November 20, 1969, when the crew of Apollo 12 landed only 535 ft away. Part of the mission’s objective was to retrieve selected components of the probe’s camera, place them in sterile containers, and return them to Earth for analysis.
Incredibly, scientists working at the LRL isolated a colony of 50–100 Streptococcus mitis bacteria that were still viable from a sample of polyurethane foam insulation taken from inside the Surveyor III camera housing (39). Here was strong evidence that NASA’s decision to have COSPAR eliminate the sterilization protocols for lunar probes was completely wrong. Just as in the case of British Health Minister Dorrell’s erroneous comments on BSE, NASA and COSPAR based their decision on belief rather than hard scientific evidence. If terrestrial microbes could survive on the Moon for 21/2 years, what might happen on Mars?

As this indicates even in the extremes of the moon stuff can still survive...

Mundaka · 2005-10-15 13:26:46

Dook · 2005-10-15 17:05:21

What if the shuttles main tank was modified so that it has locking collars on each end and used as the center support for the future spinning mars vehicle and it's spent rocket section?

The main tanks could be carried by the shuttle to the ISS and attached/stored there. Each successive main tank attached to the previous one.

Then when we are ready to go to mars we use the space shuttle to attach the mars vehicle to one end and the spent rocket (from the mars vehicle launch) to the other. It blasts off to mars and is then spun to create artificial gravity.

Maybe space walks from the ISS could attach solar panels to the empty tanks?

GCNRevenger · 2005-10-15 17:59:24

No, no, and no

-The main tank is too thin and flimsy to safely hold an atmosphere I bet compared to a similar sized and massed TransHAB, and has no radiation shielding at all. Its also too small to spin except Zubrin style opposit of a large counterweight some hundred or more feet away, because of the coriolis force. Astronauts couldn't even stand up.

-You can't store anything big on the ISS, even the Shuttle's mass creates high torque on the modules whenever the ISS rotates, and would present moment of inertia problems.

-Adding ANYTHING to the main tank of the Shuttle means its too heavy to haul ISS modules. The Shuttle can just barely haul the heaviest modules at all, and actually the original main tank was already modified to weigh less to accomodate them.

Dook · 2005-10-15 18:26:16

The idea isn't to use the main tanks as a habitat but to link them together to become a firm fixture that would be the centerpiece of a spinning mars vehicle and spent rocket. An external tank is 153.8 feet long so we could connect six of them to make it long enough.

The old heavyweight tanks weighed 77,000 pounds empty and could be manufactured again if necessary to have a stronger apparatus. The new external tanks are 66,000 lbs, compared to the 230,000 lb space shuttle I'm sure that six wouldn't be that much of a problem. And if they are then simply attach four in succession using the ISS then detach them from the ISS and place them in orbit where two more shuttle missions can finish the job.

Adding one pound to the external tank means the shuttle loses one pound of cargo ability but you would only have to add a strong locking collar on each end. What would that weigh? At most 1,000 lbs?

Also the external tanks already have built in LOX and hydrogen tanks that could be serviced (with a shuttle mission) in space to then reduce the amount of weight for the Mars Direct or NASA DRM mission to mars.

The neat thing about this idea, if we can get all the kinks worked out, is that it does not require any more shuttle missions. It's simply using the main tank rather than sending them to burn up over the Indian Ocean.

Mars_B4_Moon · 2022-06-24 13:04:12

Andromeda Strain scare once more?

Controversy Grows Over whether Mars Samples Endanger Earth
https://www.scientificamerican.com/arti … ger-earth/

Space health research investigates the specific health risks faced by astronauts living and working beyond Earth.
http://hhp.ufl.edu/articles/2022/seidler-research.html

Last edited by Mars_B4_Moon (2022-06-24 13:07:39)

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#26 2005-10-13 17:38:18

Re: No immune system....oh crap!

#27 2005-10-13 18:23:28

Re: No immune system....oh crap!

#28 2005-10-13 18:30:52

Re: No immune system....oh crap!

#29 2005-10-13 18:55:52

Re: No immune system....oh crap!

#30 2005-10-13 19:36:38

Re: No immune system....oh crap!

#31 2005-10-13 19:53:44

Re: No immune system....oh crap!

#32 2005-10-13 20:02:09

Re: No immune system....oh crap!

#33 2005-10-13 21:02:17

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#34 2005-10-13 21:20:05

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#35 2005-10-14 00:04:37

Re: No immune system....oh crap!

#36 2005-10-14 02:11:22

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#37 2005-10-14 05:45:09

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#38 2005-10-14 06:29:06

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#39 2005-10-14 10:38:43

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#40 2005-10-15 13:26:46

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