massive gravity effects

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rgrove0172
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massive gravity effects

Postby rgrove0172 » Fri May 03, 2013 3:53 am

Your an earth-born human on your first trip to King (Gravity just over 3Gs) As your ship descends you;

A) feel an unpleasant heaviness as you near the ground and find once disembarking you are almost immediately exhausted, straining just to move around. After about an hour you are forced to accept the offer of a motorized cart by your hosts to continue your tour.

B)feel an oppressive weight building as you descend and upon reaching the ground realize you can barely breathe, much less move on your own two legs. The crew administers oxygen and places you on a cart to carry you to your destination where you will have to conduct your affairs under constant assistance and supervision.

C) pass out, your circulatory and respiratory system not able to maintain circulation under the extreme mass you are suddenly subjected to. You are quickly returned to orbit and a replacement with the King augmentations sent for to replace you.
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Re: massive gravity effects

Postby Captain Jonah » Fri May 03, 2013 9:24 am

B or C depending on how strong/tough you are.

3G means your body mass is three times higher which imparts some serious problems to start with.

Walking is not going to happen. Top level weight lifters don’t walk around with twice their own body weight. The King colonists are no longer human, they are a considerable way outside of the limits of humanity and as such are almost a new species.

Sitting down is also out. Your upper body is still upright which means that your neck and spine are still supporting three times the normal weight. Roughly two thirds of a man’s body mass are the torso from the hips up, arms and head. So a 200lb man is going to have roughly 120lbs on his spine sitting down, on King this is 360lbs. That means almost twice his entire body weight on his spine all the time while sitting. The back and neck muscles will fatigue and fail very quickly under these conditions. Neck braces and supports help somewhat but sitting for more than a short while is not going to be viable.

Laying on a full length recliner. Here your full weight is being supported by the recliner which significantly eases strain on the bones and muscles. Also being flat significantly lowers strain on the heart since it is not having to pump blood 6 feet up and down under 3G. Over a short period this is viable however you will be under considerable stress. Breathing is going to be a lot more difficult since your chest is pressing down on your lungs and diaphragm with three times its normal weight.
More than a few hours of this and you will begin to suffer long term damage to internal organs as they are slowly compressed and deformed by the weight of the body. Fluid within the body will fall to the lowest levels as your body struggles under the 3G pressure, minor effects of this will include eyes and skin drying out on your face and swelling along your back and legs . Blood pressure is going to spike both due to the heart working harder to handle the extra weight and due to the fluid loss.

Un-diagnosed ailments will very quickly manifest, heart attacks will be a risk for everyone even laid flat. Fit people will be able to handle it for some time, hours certainly and a day or two at most. In terms of the heart and lungs working it may well be akin to having just run a half marathon except that feeling that tired will last for your entire visit. Anyone with the slightest heart weakness is asking for a heart attack.

The long term effects of this gravity are going to be lethal, King colonists are the end result of extensive Genetic modification, they are no longer baseline human and they have a short life span on world. For a Terran human you will most likely start to suffer organ failures within days to a few weeks.

To be honest why would you want to go down to the surface. The world has vast orbital facilities maintained at 1G and 2300 communications technology is well up to the task of holding meetings.
On the surface unless you are a native all you can do is get wheeled around on a trolley and talk. Unless you are a junior management type that has really really made your boss angry I cannot see why any 1G human would be sentenced to a visit to the surface.
Traveller: Nonsense, those rumours about me and crashes, no truth in them at all. I never had a landing I didn't walk away from!

ACTA-SF: Who are we, GORN. What do we want, Cruisers that can turn.... Wait, OK Escorts... Wait. I'll get back to you !
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Re: massive gravity effects

Postby rust » Fri May 03, 2013 12:28 pm

rgrove0172 wrote:Your an earth-born human on your first trip to King (Gravity just over 3Gs) As your ship descends you;
D) use any means available, legal or illegal, to convince or force
the ship's captain to return to orbit, because even a short stay on
the planet's surface might well kill you. :wink:
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Re: massive gravity effects

Postby F33D » Fri May 03, 2013 2:19 pm

E: As soon as you leave the ships artificial grav field of 1G (the ship's captain has an Int >2) you collapse, tumbling down the gangway breaking many bones on the way down... You die shortly thereafter.
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Re: massive gravity effects

Postby CosmicGamer » Fri May 03, 2013 2:44 pm

Check out the "Human Tolerance for Gs" thread for a discussion that might provide some useful bits.

The space shuttle does/did 1.7Gs to 3 G's during the different fazes of the takeoff.
Early experiments at 6 g for 10 minutes produced no long lasting medical issues. Tolerance was quite subjective, with only the most motivated non-pilots capable of completing perform simple physical and communication tasks. (Traveller Adventurers)

Most of the info I find is on long duration zero G. Part of the testing for reducing zero-g muscle loss included subjecting people to 2.5G's for an hour a day.
Granted, this still isn't that long.

I can't find results for more recent centrifuge testing for long distance space flight simulation but I'd guess, even at our current tech level, a properly medicated, trained and equipped person could handle 3Gs for several hours without any major medical issues.

Necessity is the mother of invention. I believe as the need grows and space flight to Mars progresses, the research will advance and the level of function and the length of duration will both increase, as will the amount of g-force.

For the King example, the anti-g suit would have medical monitoring with wireless data feed built in and a vehicle to keep a persons body in the optimal position might be needed. You wouldn't just step off the ship and walk to the local watering hole. lol
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Re: massive gravity effects

Postby Strithe » Fri May 03, 2013 7:52 pm

F33D wrote:E: As soon as you leave the ships artificial grav field of 1G (the ship's captain has an Int >2) you collapse, tumbling down the gangway breaking many bones on the way down... You die shortly thereafter.
Unless you're running a crossover campaign, this isn't an option as there's no grav plates in the 2300ad setting.
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Re: massive gravity effects

Postby Strithe » Fri May 03, 2013 8:07 pm

CosmicGamer wrote:Check out the "Human Tolerance for Gs" thread for a discussion that might provide some useful bits.

The space shuttle does/did 1.7Gs to 3 G's during the different fazes of the takeoff.
Early experiments at 6 g for 10 minutes produced no long lasting medical issues. Tolerance was quite subjective, with only the most motivated non-pilots capable of completing perform simple physical and communication tasks. (Traveller Adventurers)

Most of the info I find is on long duration zero G. Part of the testing for reducing zero-g muscle loss included subjecting people to 2.5G's for an hour a day.
Granted, this still isn't that long.

I can't find results for more recent centrifuge testing for long distance space flight simulation but I'd guess, even at our current tech level, a properly medicated, trained and equipped person could handle 3Gs for several hours without any major medical issues.

Necessity is the mother of invention. I believe as the need grows and space flight to Mars progresses, the research will advance and the level of function and the length of duration will both increase, as will the amount of g-force.

For the King example, the anti-g suit would have medical monitoring with wireless data feed built in and a vehicle to keep a persons body in the optimal position might be needed. You wouldn't just step off the ship and walk to the local watering hole. lol
If I recall correctly 3g's is about the upper limit of where you'd need a G-suit to function as a pilot.

I don't know that the weight lifter analogies are that accurate: your own body weight is going to be much more evenly distributed than lifting weights outside your body. Still, the strain is going to be extreme. Sitting or semi-reclining is going to be the way to go for all but the briefest activities, and except for the most athletic of individuals you're going to risk a back injury just by bending over the wrong way.

That being said I've been subjected to around 1.5-2.0 G's for short periods of time, and even performing relatively simple tasks while sitting (in this case driving a car) is pretty damn fatiguing. Formula 1 drivers experience higher G-loads (about twice as much) and the races are longer but you're still talking around 2 hours total, with only a tiny fraction of the time under peak G-loading (maybe 5-10 minutes over the course of an hour of driving).

In general I assume that a healthy Earth-normal human on the surface of King is going to be as frail as someone at the extreme edge of old age (say a 90+ year old right now) with severe arthritis: movement is going to be a shuffling, very slow gait and walking across a small room is going to be exhausting. Any kind of fall is potentially very hazardous.

As I recall, the original Colonial Atlas stated that they initially tried Walkers (basically exoskeletons) initially, but even that didn't work out long term. I'd imagine that if one simply HAD to go to the surface of King they could use such a device with something similar to the G-suits fighter pilots use to avoid blacking out in air combat maneuvers. Even then, I don't think they'd manage more than a couple hours at a stretch. Given the huge expense of going into and out of King's massive gravity well even if you weren't risking long-term damage it's still probably more trouble than it's worth.

Either hire some locals to perform your mission for you for a short-term task, and long term tasks will mandate taking the King DNAM (or paying the locals more).

Remote control drones would be another option, and the time lag would not be too bad if from geosynchronous orbit.
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Re: massive gravity effects

Postby F33D » Fri May 03, 2013 9:23 pm

I queried a friend of mine as he worked in the astronaut pgm. He told me that the med test data he studied showed that long term (days) at 3G would be deadly for many and debilitating for all.
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Re: massive gravity effects

Postby ShawnDriscoll » Fri May 03, 2013 9:51 pm

I'm not fit to be near 3G. Spine compression on top of the hip is no fun.
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Re: massive gravity effects

Postby Lemnoc » Fri May 03, 2013 10:33 pm

F33D wrote:I queried a friend of mine as he worked in the astronaut pgm. He told me that the med test data he studied showed that long term (days) at 3G would be deadly for many and debilitating for all.
Yeah, I'd expect the cardiovascular strain would be the killer in the medium-to-long haul. A trip and fall could be a death sentence.
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Re: massive gravity effects

Postby Wil Mireu » Fri May 03, 2013 10:43 pm

3G surface gravity? Is the planet made entirely of Lead or something?
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Re: massive gravity effects

Postby Jeraa » Sat May 04, 2013 12:11 am

Wil Mireu wrote:3G surface gravity? Is the planet made entirely of Lead or something?
No, its just really big. By Traveller standards, it a size class J (thats 19). (Actually, I think it is size K. As far as I know, the letter "I" isn't used, as its to easily confused with the number 1.)
King: This oversized "terrestrial" planet is the first of the colony worlds encountered as one travels along the arm. With a diameter of just over 30,000 km, King lies in the first orbit of the K-class star DM+2 3312. The planet's great mass gives it a crushing surface gravity of 3.08 gees.
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Re: massive gravity effects

Postby Lemnoc » Sat May 04, 2013 1:35 am

Jeraa wrote:
Wil Mireu wrote:3G surface gravity? Is the planet made entirely of Lead or something?
No, its just really big. By Traveller standards, it a size class J (thats 19). (Actually, I think it is size K. As far as I know, the letter "I" isn't used, as its to easily confused with the number 1.)
King: This oversized "terrestrial" planet is the first of the colony worlds encountered as one travels along the arm. With a diameter of just over 30,000 km, King lies in the first orbit of the K-class star DM+2 3312. The planet's great mass gives it a crushing surface gravity of 3.08 gees.
I think it is both big and dense, metals rich, and one of the best mining resources in known space.
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Re: massive gravity effects

Postby Beastttt » Sat May 04, 2013 2:56 am

what about battle dress and a grav belt
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Re: massive gravity effects

Postby Lemnoc » Sat May 04, 2013 3:00 am

Beastttt wrote:what about battle dress and a grav belt
No grav tech in 2300U.
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Re: massive gravity effects

Postby spirochete » Sat May 04, 2013 3:14 am

Lemnoc wrote: I think it is both big and dense, metals rich, and one of the best mining resources in known space.
Did you know that the delta-v to reach low orbit is the equivalent of a moon-shot? It would take a mammoth launcher comparable to a Saturn V to put a small amount of ore in low orbit.

LOL, King is just a huge worldbuilding boondoggle.
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Re: massive gravity effects

Postby Lemnoc » Sat May 04, 2013 3:38 am

Was just thinking about King a few weeks ago, trying to get at a back-of-the-envelope calculation for just how much force and velocity it would take to throw a object there into orbit. It seems beyond the capacity of any described 2300 vehicle.

I’m not even sure a catapult could generate sufficient Mach in atmosphere to throw an object into orbit. Theoretically, I guess, if it was an evacuated tube of considerable length. An object exiting the end of it would cause a shattering sonic cataclysm that would make Big Bertha seem like a pea shooter, so I suppose you’d have to lift that end almost out of the lower atmosphere.

The only vehicle that would seem to do the trick would be a Big Dumb Booster that would make the old Saturn V seem like a firecracker. Think five Saturn Vs wired together.

The sorts of forces such vehicles would place on a human body seem beyond the capacity for a human body to endure. Would like to see those numbers.

---

EDIT: Sorry, spirochete. I wrote on top of you.
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Re: massive gravity effects

Postby spirochete » Sat May 04, 2013 3:57 am

Lemnoc wrote:Was just thinking about King a few weeks ago, trying to get at a back-of-the-envelope calculation for just how much force and velocity it would take to throw a object there into orbit. It seems beyond the capacity of any described 2300 vehicle.
It could be done with 3 liquid hydrogen stages, burning somewhere around 3,000 tons of LH2/LOX to orbit 2 tons of ore. The launch stack would be colossal. It must be some really badass ore to justify it.
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Re: massive gravity effects

Postby Wil Mireu » Sat May 04, 2013 6:07 am

Jeraa wrote:
King: This oversized "terrestrial" planet is the first of the colony worlds encountered as one travels along the arm. With a diameter of just over 30,000 km, King lies in the first orbit of the K-class star DM+2 3312. The planet's great mass gives it a crushing surface gravity of 3.08 gees.
Its density (to get that gravity) would have to be around 7000 kg/m² (which is not in itself unreasonable for a planet of that size), but itwould be about 18 times more massive than the Earth! It would be tidelocked to the star (there is no chance that it wouldn't be, given its orbital distance and radius), and it would very easily hold onto hydrogen and helium gas so it should really be a gas giant.

So yes, King is a 'worldbuilding boondoggle'!
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Re: massive gravity effects

Postby spirochete » Sat May 04, 2013 1:07 pm

Wil Mireu wrote: Its density (to get that gravity) would have to be around 7000 kg/m² (which is not in itself unreasonable for a planet of that size), but itwould be about 18 times more massive than the Earth!
Solid planets conform to a logarithmic scaling law of mass vs radius. If King obeyed that law, it would have 33 earth masses inside its 30,000 km diameter and the gravity would be closer to 6 gees instead of 3 gees. The density would be 14 g/cc instead of 7, so the planet is only half as massive as it should be.

More boondoggle.

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