OT: Ceres more interesting than previously thought

[Suicide Junkie]

What the heck are you talking about? Where did 1G come in?

And WTF is "natural spin"? There is absolutely no preferred spin direction around here in the universe.

Adding too much mass would obviously cause Ceres to spin down too quickly and the weakened gravity well would essentially force Ceres apart.
No way.
More mass -> more gravity.
Slower spin -> less centrifugal force.
Which means objects on the surface feel even more force downwards.
The rate of mass change is completely irrelevant.

This is grade nine or lower physics here.
Please, look up ANGULAR MOMENTUM.

[inigma]

My info on "natural spin" comes from Dr. Ning Li formerly of the University of Alabama.

I had meant to say that "adding too much mass too quickly would obviously cause Ceres to spin down and the weakened gravity well would essentially allow Ceres to spin itself apart".

This was also with the assumption that rockets were being added to the surface, with enough mass to spin Ceres. That mass would cause Ceres to slow down its spin, destabilizing its gravity well, and the rockets would attempt to spin Ceres in that destabilized condition.

[Suicide Junkie]

Reducing spin DOES NOT decrease the gravity by any measureable amount.
The rate at which you add mass means absolutely nothing.

The spin-rockets would have to be landed on the surface carefully, which means matching the spin rate of the surface so as not to plow into the asteroid and leave a crater full of expensive shrapnel. Installing the rockets would not change the spin rate of Ceres, and would increase its mass and angular momentum by an unnoticable fraction.

---

Unfortunately, searching for '"Ning Li" site:ua.edu' turns up zero items.
Ning and Li appear separately, though, as different people.

And if you open it to non - University of Alabama sites relating to spin and gravity, you get a buttload of crackpots, alien/UFO sites and such.

I'm sorry, but Newton's laws are the way it is, to great precision on the scales we are talking about.

Again, this is simple grade 9 physics.
Learn the basics, please.

[NullAshton]

Rig up a solar powered superconducting coil, let energy collect, and generate gravity!

[dogscoff]

inigma said:
That 0.03G is what is holding Ceres together. Force Ceres to spin at a 1G centripetal rate, and you can imagine the concequence.

I'm not sure that's the case. What's holding it together is not gravity. Gravity brings the material together in the first place and maybe later compresses it into denser material, but once it's all in place it's the atomic bonds between the atoms making up the rock that keep it from expanding to fill the vacuum around it. Otherwise, small rocks floating alone in space with negligible gravity would spontaneously vapourise the moment they got a sniff of a gravity well, and we know that don't happen.

Here's an experiment you can try at home: Take a big lump of rock. Drill a hole into it and then firmly screw or cement a hook into the hole. Use the hook to suspend the rock from above. Does the rock split in two, with the bottom half shearing away and crashing to the floor because of the 1G force pulling it downwards? Your hook might well pop out, depending on the weight of the rock and your metho of fastening, or the chain or crane might break, but the rock will be just fine.

Anyway, we established some time ago that we don't actually need to alter Ceres' spin at all, just its orbit. It's the coin surrounding Ceres that needs to spin.

And yes, you are right about the amazing properties required of the materials required to build this thing. I stated in an earlier post that such a material might be beyond credibility. However I have a feeling that it might work for smaller coins- perhaps only significantly smaller than Ceres, i don't know (Hell, you could you could use glass and steel up to a kilometre or ten, I reckon)- but I know for a fact that vast, Banksian structures would require bucketloads of unobtainium.

All that said, read up on carbon fullerenes. They have the potential to be insanely strong, and (I believe) transparent too.

[Parasite]

Spin "Gravity" and the gravity from mass are two very very different things. The maximum spin "gravity" you can generate depends mostly on the strength of the steel, Plexiglass, or clear aluminum you use. It also depends some on the radius of your wheel and how much it weights (mass), but only this because it takes a stronger rope to swing a 2 ton bucket around than a 2 kg bucket. The spin would also need to be in the plane of the orbit if you wanted to keep the light coming in through the floor.

There are issues with the conservation of rotational momentum if you want to add more mass to the ring or shift stuff around from the center to the edge. I believe these could be easily solved given that we could build it in the first place. Venus Equilateral lives again! (V.Equ. is a book by the way)

(Edit: what I get for starting and then getting pulled off to work on my real job )

[Suicide Junkie]

dogscoff said:
And yes, you are right about the amazing properties required of the materials required to build this thing. I stated in an earlier post that such a material might be beyond credibility. However I have a feeling that it might work for smaller coins- perhaps only significantly smaller than Ceres, i don't know (Hell, you could you could use glass and steel up to a kilometre or ten, I reckon)- but I know for a fact that vast, Banksian structures would require bucketloads of unobtainium.

All that said, read up on carbon fullerenes. They have the potential to be insanely strong, and (I believe) transparent too.

All you gotta do is make the coin spin slow enough for your materials . Depending on how much water you want to put in it, that might be significantly less than 1g.

However, even a small fraction of 1g should be sufficient to keep your environmental bits sorted properly. Fishing will certainly be interesting when the bass can jump out of the water and land halfway around the world

[Strategia_In_Ultima]

/me pictures a fish jumping out of the water and continuing straight up intil it hits water again

/me pictures SJ sitting on a boat with a look on his face saying "OK..... WTF?!?"

[dogscoff]

I was also thinking: Assuming you take Ceres out of the coin so that you can have sunlight coming from overhead, and assuming that overhead sunlight is sufficient to live by, you could actually have two landmasses: Each one would be a ring around the coin's circumference, with a ring shaped ocean seperating them. At midday you could look stright up and see the far side of the coin as three stripes: Land, sea, land. The sun would be shining down on you through the distant sea. for people on the far side (midnight for them) it would be dark, unless they were on the water where they'd have bright sunlight shining up at them from underneath.

Strolling along the beach at midnight would be spectacular.

[inigma]

Strolling along the beach at midnight would be spectacular.

And instead of jet lag, people would get "strolling lag" as you could probably walk faster than the rotation, and could essentially walk into multiple timzones on just one stroll

And riding a speed bike in the opposite direction of the spin would be out of the question - as the faster you travel counter to the direction of spin, the more of the centripetal effect you will negate.

Some interesting side effects: When you jump, you won't always land in the same place you started.

And throwing a football would require additional knowledge of flight trajectory in relation to the spin of the coin, and throw it hard enough, then what goes up most certainly won't come back down.