Skeleton decay during long spaceflights

[Andy44]

Was that for a bomb in LEO or for bombs used to launch an Orion from the surface?

 

[jedidia]

As far as I know, a nuclear explosion in vacuum doesn't produce any EMP at all, so I don't think the satelites would be in danger, unless one happens to be too close to be killed off by shere luminosity or fried by radiation... But the radiation might be able to screw with data-transfer for some time even when the explosion wasn't too close.

However, I have no Idea how the radiation would behave exactly. I mean, detonating a bomb in LEO seems like a pretty efficient way of spreading fallout uncontrolably over a very large area, doesn't it? It would probably not be a really dangerous level, but I don't think anyone would apreciate it much.
especially not anyone that doesn't like the nation launching the ship, which brings us back to "a few political issues", which are not few at all, and which are not less real just because they are not technical or physical. If any nuclear power were attempting to launch an orion drive, all other powers would certainly consider it an attempt to break the balance of power, and a new arms-race would pretty certainly ensue. (a question to all americans: would you be thrilled by the perspective of china detonating nukes over your heads??)

anyways, we're getting pretty of-topic, the talk was about artificial gravity.

a thing I am not sure about: what is the minimum g it takes to prevent bones from degrading? as far as I remember, Clarkes centrifuge didn't produce a full G, only about one third. It was still rotating pretty fast. However, you could just put a tether to the hab, extend it to like 100m and spin the whole ship rather slowly. That should take care of motion sickness.
The "tumbling pidgeon" might seem like a very good way to save on mass, but depending on the size of the ship it might take quite an amount of fuel to make it rotate around it's X-axis with sufficient speed.

a mechanical centrifuge, again, would be quite a heavy thing, and a maintenance nightmare (read: lots of moving parts, and lubricants that have to work reliably close to absolute zero...). I vote tethers.

Alternatively, we might find biochemical ways of counteracting bone-degradation (read: drugs). I don't know jack about medicine and biochemistry, however, so I have no Idea how feasible this is.

 

[wehaveaproblem]

It won't be so much of a problem when people actually live in space... afterall, if it were me, I would have my useless, heavy, pointless, energy consuming, wasted-mass legs amputated. Upper body muscle/bone workouts are much more easily achieved with resistance machines and the right nutritional suppliments... For astronauts who want to actually get off the space ship, however, legs may be of some use...

 

[Sky Captain]

Is there any info available how much acceleration is needed to prevent bone degradation? I`m thinking if you could get away with 1/3 or 1/4 G it would make centrifuge much smaller and lighter. Also what about strapping some weights to astronaut`s body to add additional downward pressure (Something like heavy body armor that increases astronaut`s weight in 1/3 gravity to a weight in normal 1 G gravity.

 

[Andy44]

Nobody knows for sure how much G is required to preserve bone mass. Humans have spent lots of time in freefall, and of course spend most of our lives in 1 G, but there isn't any way to test people in anything in between until we fly a centrifuge or spend lots of time on the moon or Mars. Mars exploration proponents are banking on Mars' 0.6 G being enough, but no one really knows.

 

[T.Neo]

It won't be so much of a problem when people actually live in space... afterall, if it were me, I would have my useless, heavy, pointless, energy consuming, wasted-mass legs amputated. Upper body muscle/bone workouts are much more easily achieved with resistance machines and the right nutritional suppliments... For astronauts who want to actually get off the space ship, however, legs may be of some use...

When we eventually live in space long-term, we'll live in rotating habitats. Humans have trouble living in freefall.

And legs are not totally useless in space, they can be used to push off of things and anchor someone to a surface.

 

[wehaveaproblem]

You assume humans will always have those difficulties in freefall, T.Neo. But if there were ever a species capable of playing god with itself and manipulating it's biology to allow for a healthy life in microgravity, it is humans. I don't think gravity will be such an issue by the time we are actually living in space, and I mean generations living in space, not just 6 month stays on the ISS or on transfer to Mars.

But yes, the leg thing was half jest, but only half.

 

[JEL]

Apparently the ISS was close to getting a centrifuge module for experiments:

http://ti.arc.nasa.gov/projects/ssrl/centrifuge.html

The wiki says JAXA built it but that it was cancelled in 2005 due to costs, and is now on display at a japanese space-center:

http://en.wikipedia.org/wiki/Centrifuge_Accommodations_Module

 

[Andy44]

I thought it got canceled when the shuttle launch schedule was trimmed down to retire STS by 2010?

 

[JEL]

The wiki agrees with you

Here's what it says:

It was cancelled in 2005 alongside the Habitation Module and the Crew Return Vehicle, because of ISS cost overruns and scheduling problems in Shuttle assembly flights.

 

[Ghostrider]

if there were ever a species capable of playing god with itself and manipulating it's biology to allow for a healthy life in microgravity, it is humans

It's all fun and games until a third hand grows out of your head...

Seriously, humans manage to live an unhealthy life on Earth. Once in microgravity what do you think they will do? Booze, designer drugs and junk food.

Hm, seems a good program...

 

[T.Neo]

But if there were ever a species capable of playing god with itself and manipulating it's biology to allow for a healthy life in microgravity, it is humans.

Manipulating the species makes no sense when a spacecraft or habitat could simply be spun...

 

[Andy44]

Manipulating the species makes no sense when a spacecraft or habitat could simply be spun...

In the short term, that may be correct.

But in the long run, humans will eventually be living off of Earth. (Or we will go extinct). In order to adapt to the varied environments, each with different gravity and other unique features, the human body will have to evolve, either the hard way (natural selection), or with technological assistance.

This basically means that humans from different worlds may split off into diffeent breeds, and perhaps eventually into different species, which is a little disturbing, but logical.

Finally, we will evolve into super-beings living in crystal spires and wearing togas...

 

[tblaxland]

Manipulating the species makes no sense when a spacecraft or habitat could simply be spun...

Creating a spinning habitat is no "simple" engineering task. Whether or not it is more simple than bio-engineering for survival in microgravity is open for speculation...

 

[T.Neo]

Creating a spinning habitat is no "simple" engineering task. Whether or not it is more simple than bio-engineering for survival in microgravity is open for speculation...

It almost certainly easier then bioengineering humans, especially considering ethical factors as well. The human organism has been evolving under 1 g for millions of years- I doubt any modifications would be simple.

This basically means that humans from different worlds may split off into diffeent breeds, and perhaps eventually into different species, which is a little disturbing, but logical.

I agree there, and humans have already adapted to certain environments here on Earth.

 

[wehaveaproblem]

Yeah, I think it's a matter of timescales, T.Neo. Depending on that, I think both sides of the argument are correct.

All that said, I vote for Ghostrider's prediction!

 

[T.Neo]

Also consider adaptability- a human from Earth, Mars or Venus would not be able to live long-term in freefall, and genetically engineered jellypeople would not be able to survive on any of those planets. It is rather limiting.

That is what humans do- we adapt the environment to suit us, not the other way around. And that is what has contributed to our success.

When the ability (or perhaps more importantly the acceptance of such an ability) comes around to engineer the human organism in such a manner, we might have been building rotating habitats for decades- in deep time, space and weightlessness may have a looser association with each other.

 

[wehaveaproblem]

Also consider adaptability- a human from Earth, Mars or Venus would not be able to live long-term in freefall, and genetically engineered jellypeople would not be able to survive on any of those planets. It is rather limiting.

But we are talking about living in space/freefall aren't we? That to me means living your life there, not just a 6 month sojourn to our nearest neighbour. So being restricted by the need for gravity when you live in freefall is even more limiting in my book. But, yes, we may need different branches on our geneticly altered family tree... or of course, in the long run, it may be possible to engineer (and combine with physical technology) a single human that can adapt to a range of environments.

That is what humans do- we adapt the environment to suit us, not the other way around. And that is what has contributed to our success.

So far that has been key to our success, yes. But we are more capable now than we ever have been and that is still increasing. Why keep redisgining and rebuilding the road, when you can make a car that doesn't need a road... for a cheap example. Changing us, rather than the environment, would arguably be easier to some extent.

When the ability (or perhaps more importantly the acceptance of such an ability) comes around to engineer the human organism in such a manner, we might have been building rotating habitats for decades- in deep time, space and weightlessness may have a looser association with each other.

This is a fair point, and quite possibly a truth. Chances are, we will see both these technologies exist. It will be an interesting future... which we shall likely never see.

 

[T.Neo]

So being restricted by the need for gravity when you live in freefall is even more limiting in my book.

But you are limited anyway- you are limited by the need for air, and radiation shielding and temperature control.

Changing us, rather than the environment, would arguably be easier to some extent.

Sure, but is it moral to do so?

 

[wehaveaproblem]

But you are limited anyway- you are limited by the need for air, and radiation shielding and temperature control.

Well quite, so why add to the list of need/requirements, why not aim to reduce it as far as possible?

Sure, but is it moral to do so?

aaahhh the ambiguity of morals and ethics! For me, to alter and change willing subjects who would require/desire the changes in order to survive healthily, then yes I think it is moral. What is immoral about that?
Should we also ban the ability for your gran to get a new 'fake' hip or have radiation treatment for cancer? I think not, personally I call it progress.

That said there are ethics to consider. If the only way to get there was to, for example, disect 8month old aborted babies, then we would have an issue for sure. But medical ethics is a seriously grey area at the best of times - prolly best not to get too deep into it here. Fundamentaly I agree with medical research and progress, but yes it is a fine line we tread.

Interesting debate btw mate, thanks.