OT: Ceres more interesting than previously thought

[Wolfman77]

Inigma, I believe you are confusing force with acceleration. Not hard to do in this context. The "force" being refered to in this thread is similar to gravity, which is technicaly an acceleration, m/s^2. Force, as you are refering to, would be like Newtons, which is Kg*m/s^2. If you work the math out with their label on you will find that it makes more sense.

On that note however, if the ring were 1,000Km it would need the outside of the ring spinning at 2213m/s to achieve 9.7947m/s^2, approximately 1g. Also 1Km in from the surface would still have approximately 9.756m/s^2, less than 1/2 percent difference.

Don't ask me how you could get it to stay together at those speeds though.

I've also found out that about 4 inches (9cm) of water will block gamma rays, 3ft (1m) will block about 20% UV.

[dogscoff]

Wolfman77 said:
On that note however, if the ring were 1,000Km it would need the outside of the ring spinning at 2213m/s to achieve 9.7947m/s^2, approximately 1g. Also 1Km in from the surface would still have approximately 9.756m/s^2, less than 1/2 percent difference.

Cool! Numbers! Thanks. I wonder how low you could take the (apparent) gravity for people to feel uncomfortable/ suffer ill health effects. I reckon most ppl (particularly the arthritic and the overweight=-) would enjoy bouncing around in .75G. What about half a G? Fine for an afternoon on the bouncy castle, but what about long term?

Don't ask me how you could get it to stay together at those speeds though.

Smaller ring and/or settle for lower gravity, I guess. Or use better unobtanium.

I've also found out that about 4 inches (9cm) of water will block gamma rays, 3ft (1m) will block about 20% UV.

[/quote]

Wow, is that it? I thought it would be a lot more than that. I wonder if NASA's Mars design will have the water tanks wrapped around the ship to shield the crew from radiation. Are those the only dangerous rads to worry about out there, or would there be others?

[Wolfman77]

UV, X-ray, and gamma rays mostly. stray neutrons could be a problem for deep space/interstellar, possibly. Keep in mind I only found one source for those numbers using google. It is possible there are high level gamma rays not blocked by it. I have heard that some could pass right through the earth, so I'm sure it would only block them to a certain point. I believ in the context of the page refered more to background gamma rays. I'm looking into it further

[Suicide Junkie]

Cool! Numbers! Thanks. I wonder how low you could take the (apparent) gravity for people to feel uncomfortable/ suffer ill health effects. I reckon most ppl (particularly the arthritic and the overweight=-) would enjoy bouncing around in .75G. What about half a G? Fine for an afternoon on the bouncy castle, but what about long term?

Heh, just a wild guess, but I suspect that an active worker in a 0.2g environment would be far healthier than the average north american couch potato.

[Wolfman77]

Is there anything less healthy than an average american couch potato?

[douglas]

dogscoff said:

Wow, is that it? I thought it would be a lot more than that. I wonder if NASA's Mars design will have the water tanks wrapped around the ship to shield the crew from radiation. Are those the only dangerous rads to worry about out there, or would there be others?

Any kind of radiation harmful to humans has to react/be blocked by something on the order of the thickness of the human body, otherwise it would just go right on through without doing anything. Therefore, it should in principle be possible to build radiation shielding for any conceivable kind of harmful radiation without making it more than a few times as thick as a typical human body.

[Wolfman77]

Neutron radiation seems to be the most penetrating. They can pass through quite a bit, because of their weight. Not the most abundant type of radiation, but one of the more dangerous. When it is absorbed, it typicaly releases gamma radiation, which must then be shielded against. Earths atmosphere absorb most of it, in fact background radiation at ground level is primarily from the Earth itself. The human body itself does not always stop it, so if you shield stoped the same ammount some would still get through, which could then be absorbed by a human on the other side. Although it does seem water is good at absorbing it. Light atoms absorb more of it, hydrogen is very light, and makes up 2/3 of a water molecule (by number, 11.19% by mass).

Still can't find any good sites on the subject though.

[NullAshton]

Just use depleted uranium. Volia, cheap radiation shielding!

[ToddT]

NullAshton said:
Just use depleted uranium. Volia, cheap radiation shielding!

Hmm not sure about the cheap part, especial given the quantitiie invovled.

Someone mentiond story referrencing tranparent shup hulls, the only one i can think of was "ringworld Engineers" by Larry Niven. and the race that built/sold them physically resembled the cue cappa.

As for meterrilas strong enought oto build such a structure. well as someone suggested reguarding Buckyballs i just read a recent article Regaring Carbon nanotubes. They have in th lab at least, created nanotube sheets at rates up 7 Meters per minute. Carbon nanotube cables would have the strength necessary to build a space elevator.
which there has been a revived intrest in, theres now a robotics contest for build a climber.

[Kamog]

I thought depleted uranium emits its own radiation, doesn't it? So although it may stop outside radiation, it probably won't be very healthy to live inside walls made of the material. Also, I don't understand why radiation that passes through the human body won't do any damage. Wouldn't it still do damage as it passes through, just like a bullet that passes through the body?