Toughguy Gravity and zero g pregnancy

[Spacescifi]

 

 

Two scenarios here:

 

Scenario 1. You have some variation of a nuclear rocketship on it's way to mars. In order to keep the crew of 30 healthy the rocket begins to roll/rotate.

The crew has a hollow cylinder area ten feet wide, and the rocket spins up to 1g.

Could the crew function well enough in this environment for 6 months or longer? I know it is not ideal since gravity will be stronger at the foot than the head, but some g is better than zero g I say. I also know it will be disorienting, but can't they just tough it out? There are worse things in space after all.

Scenario 2: A female crewmember is about to give birth to twin baby girls, but in this case it is another spacecraft without provisions for gravity as it coasts a year and a half to mars.

For the sake of discussion, this ship is fully radiation shielded, the only challenge now lies with... how in the world do you deliver twins in zero g?!

This will get messy folks... please stay appropriate as the thread will get closed otherwise.

Edited October 15, 2019 by Spacescifi

[kerbiloid]

2 hours ago, Spacescifi said:

for 6 months or longer?

2 hours ago, Spacescifi said:

A female crewmember is about to give birth to twin baby girls

Usually it takes about nine...
A saga of space Siebenmonatskinder? Or she was launched pregnant because nobody noticed, lol?

***

In a rotating 10 ft cylinder a human would feel and look like a natural aeolipile:

Spoiler

yes, with same jets

 

Edited October 15, 2019 by kerbiloid

[Spacescifi]

12 minutes ago, kerbiloid said:

Usually it takes about nine...
A saga of space Siebenmonatskinder? Or she was launched pregnant because nobody noticed, lol?

***

In a rotating 10 ft cylinder a human would feel and look like a natural aeolipile:

  Reveal hidden contents

yes, with same jets

 

 

Pregnant launch. One and a half years of coasting to Mars.

 

[kerbiloid]

2 minutes ago, Spacescifi said:

One and a half years of coasting to Mars.

Coasting to Mars takes 6...8 months.

[Codraroll]

On 10/14/2019 at 9:00 PM, Spacescifi said:

Two scenarios here:

[snip]

And for the record:

1. What kind of rocket are you thinking of here? 30 people in a ship with a diameter of only three meters? It would have to be a rather long tube, and the people would constantly walk into each other because the distance from head to floor is shorter than the distance from head to celing, or the distance from waist to wall, by a pretty considerable margin. How would you even duck out of somebody's way? Taking a step to the side wouldn't move your head away from the centerline of the ship. Heck, with a diameter that small, and rotary gravity, people's heads would constantly experience negative Gs because most people are more than 1.5 meters tall. So yeah, you're effectively stuffing a lot of people into a tiny corridor, and one would think the technology required for a spaceship to sustain 30 people on a long-term voyage to Mars would also produce rockets with slightly less cramped living quarters.
2. Messy situation. If the woman was already pregnant when the ship launched, the fetuses probably wouldn't survive the launch itself. If she got herself pregnant during the voyage, there's effectively no good way for it to end. It's an ethics question first and foremost, not a science question.

[snip]

Edited October 16, 2019 by Vanamonde

[KSK]

You do know that babies don't drop out under gravity right? Provided that your crewmember has something to brace against, I don't see an unassisted delivery being any more problematic than usual, although yes, keeping the various fluids contained might be more challenging. Check that - unsure if getting rid of amniotic fluid once her waters have broken would be an issue but suction devices exist for various medical and dental procedures so I imagine something could be worked out.

If an intervention is required (breech birth or whatever), that could get tricky in zero-g but tricky in the sense of 'executing a complex task in freefall' rather than freefall making the condition requiring intervention any more complex.

Edit:  As for your first question, I would say no. The angular velocity you'd need to spin that 10 foot tube up to, to simulate 1g, would be high, most probably too high for comfort. If you want to play around with suitable values, have a look at SpinCalc. I'm sure other such calculators exist too.

 

Edited October 15, 2019 by KSK

[Shpaget]

10 ft diameter = 3 m, meaning that most adults would have their head "above" axis of rotation. So their heads would fall upwards while the rest of the body downwards. This is beyond just disorienting. Forget about moving around in that environment. Lying down on the floor may be tolerable if keep very still.

Check this Tom Scott's video on what happens when you try to move around in rotating environment.

And that room is 22 ft (6,7 m) in diameter, Tom is not standing perpendicular to the wall (it's actually closer to parallel), not spinning nearly at 1g etc.

10 ft diameter for 1g gravity simulation is not nearly enough. Coriolis will make you suffer. 

[Rakaydos]

7 hours ago, kerbiloid said:

Coasting to Mars takes 6...8 months.

Cheap flight on a wrong way Cycler. (mars-> earth cycler takes about 6 years to get back around to mars. Same for a Earth-> mars cycler going back to earth)

[kerbiloid]

7 hours ago, Codraroll said:

diameter of only three meters? It would have to be a rather long tube, and the people would constantly walk into each other because the distance from head to floor is shorter than the distance from head to celing

While agreed with the other part of the answer, 3 m cylinder = 2 x 2 m corridor inside (Almaz) or a chain of 2 x 2 x 2 cubicles (MOL). And ~50 cm between the corridor and the hull for a crawlway.

6 hours ago, KSK said:

You do know that babies don't drop out under gravity right?

Depends on the nurse's dexterity.

That's like basketball but without dribbling. Usually without.

4 hours ago, Shpaget said:

10 ft diameter = 3 m, meaning that most adults would have their head "above" axis of rotation.

They can lie on the floor. On mats.
Buckets can stay vertical, btw. This helps, too.

27 minutes ago, Rakaydos said:

Cheap flight on a wrong way Cycler. (mars-> earth cycler takes about 6 years to get back around to mars. Same for a Earth-> mars cycler going back to earth)

Of course, ion engines allow a million year trip, too, but the Hohmann transfer takes 6..8 months.

Edited October 15, 2019 by kerbiloid

[sevenperforce]

Foetuses do not drop solely due to gravity, but their weight is critical to stimulating contractions. nethersl birth would require induction. But of course no one would ever, ever countenance the slightest chance of pregnancy (at any stage) on orbit.

Obligatory:

Spoiler

 

[Spacescifi]

7 hours ago, Shpaget said:

10 ft diameter = 3 m, meaning that most adults would have their head "above" axis of rotation. So their heads would fall upwards while the rest of the body downwards. This is beyond just disorienting. Forget about moving around in that environment. Lying down on the floor may be tolerable if keep very still.

Check this Tom Scott's video on what happens when you try to move around in rotating environment.

And that room is 22 ft (6,7 m) in diameter, Tom is not standing perpendicular to the wall (it's actually closer to parallel), not spinning nearly at 1g etc.

10 ft diameter for 1g gravity simulation is not nearly enough. Coriolis will make you suffer. 

 

Possible solution.... get only short astronaut crew 4 ft and greater but not at 5 feet.

 

[kerbiloid]

Or optimize an astronaut's height with surgery.
Attach second pair of arms instead of legs.

Edited October 15, 2019 by kerbiloid

[Rakaydos]

1 hour ago, kerbiloid said:

Or optimize an astronaut's height with surgery.
Attach second pair of arms instead of legs.

https://www.amazon.com/Falling-Free-Vorkosigan-McMaster-Bujold-ebook/dp/B005SHX1CE

[Shpaget]

A little bit more down to Earth novel:

https://www.amazon.com/Rood-Joshua-Klein/dp/1434844005

[Spacescifi]

 

Meanwhile an Arnold Schwartzaneggar type Commander astronaut is calling the other astronauts not real men/women as they lay down in the 1g 10 ft diameter cylinder. He walks around and toughs it out a few hours a day, gradually increasing the length over time as he grows accustomed to it.

Meanwhile the the other 29 astronauts crawl around the cylinder like the 'babies' they are... according to the Commander anyway LOL.

Granted the other astronauts would also be laughing at Commander toughguy when he upchucks his lunch trying to adjust to the differential gravity.

Edited October 15, 2019 by Spacescifi
Upchuck

[Vanamonde]

Some comments have been removed. Folks, no one is forcing you to read any threads here. If you don't like the subject of one, just skip to the next one. 

[Codraroll]

On 10/15/2019 at 10:03 PM, Spacescifi said:

 

Meanwhile an Arnold Schwartzaneggar type Commander astronaut is calling the other astronauts not real men/women as they lay down in the 1g 10 ft diameter cylinder. He walks around and toughs it out a few hours a day, gradually increasing the length over time as he grows accustomed to it.

Meanwhile the the other 29 astronauts crawl around the cylinder like the 'babies' they are... according to the Commander anyway LOL.

Granted the other astronauts would also be laughing at Commander toughguy when he upchucks his lunch trying to adjust to the differential gravity.

The more I think about it, the worse of an idea the 1g 10 ft diameter cylinder becomes. How would two people standing upright pass each other if one was going from one end of the ship to the other? One of them would have to walk up the wall relative to the other and crouch down, as there would only be five feet from the floor to the centerline at any point. Stepping out of the way while standing up is not possible, as everybody's torso would always be in the center of the tube. This, of course, ignores how incredibly uncomfortable it would be to walk around with your head experiencing constant negative Gs and the dizziness of the Coriolis force. This calculator cites some sources that say 10 RPM is more than even seasoned pilots can adapt to within a reasonable time frame, and your ship is doing 24.4 RPM.

But that assumes walking up the wall is even possible. You can't dedicate the entire spacecraft interior to be a floor. Presumably, all sorts of instruments, controls, screens, etc. would line the walls of the tube (just see the ISS), so you can't just put your foot anywhere. By the way, due to the aforementioned issues with standing up, and a lack of space for anything that pokes into the tube, the only feasible position for working with any of these would be lying down next to them, which is not a comfortable position to hold for any length of time even if you're not spinning around once every 2.45 seconds.

Then there's the storage compartments. For reasons mentioned above, they would have to be recessed in the floor. And since the spacecraft spins so quickly, the gravity at the bottom of these storage compartments would be quite a bit stronger than on their surface, so working inside them would be a royal pain. Half a meter down, you're at 1.3g already. Solar panels or radiators (30 people generate three kilowatts of power even at light activity, so you'll have quite a bit of waste heat to get rid of) sticking out five meters beyond that would experience 4.5g at their tips. It would make EVAs difficult, to say the least.

And of course, space. Space for 30 people in a 10 ft wide tube, with provisions to last for half a year. Using the ISS as a very rough comparison, that one contains a pressurised volume of 900 m³ and has provisions for six crew for ... I can't find any sources on the fly, so let's say three months. Your ship has five times as many crew and they're up there for twice as long, but let's say they're all Commander Toughguys and live twice as cramped as the ISS crew does, cancelling out that last doubling. So a pressurized volume five times that of ISS, or around 4500 m³ would be required. Let's say 4000, because it makes calculations easier. Now, we've already assumed storage compartments to be half a meter deep, so let's say you have a pressurized radius of 2 meters.

4000 m³ / (pi * 2 m *2 m) gives a necessary tube length of (1000/pi) meters, or 318.3 meters. 1043 footsies if you want to stay Imperial. You can find contrived reasons for halving that number, and maybe halving it again, but your ship would still have proportions like a toothpick. This is just the crew and pressurized storage compartments, remember; presumably you've got a power plant and a propulsion system as well.

The point I'm trying to make is, 10 ft is ludicrously small. Both for the size of the crew, the magnitude of gravity you're looking for, and for the technological advancement required to make it a reality in the first place. If you can outfit a ship for 30 people for six months, and mount a nuclear engine at its back, you can easily build it with a bigger diameter. Building it 4 meters wide and 300 meters long would be vastly more difficult than, say, 10 meters wide and 50 meters long (which gives the same volume). With the ship's floor once again being half a meter from the hull (at a radius of 4.5 meters), you can do 1G with a spin rate of 14 RPM, which is still a lot more than what is comfortable, but enough for a semi-realistic Commander Toughguy to overcome while his crew does not. And you can have upright workstations, and all the storage in zero G in the middle of the ship. Scaling up the radius makes everything more practical overall.

[RCgothic]

We have rockets that can put:

Dragon, 13ft

Orion, 16ft

Skylab, 23ft.

When starship is operational, it will be 30ft. Why exactly are you limiting to 10ft?

Even so, simulating 1g with roll would be horrific. You'd be much better off spinning up in pitch or yaw for a long cylinder. Better still, tethering two craft together and spinning around the mutual barycentre.

The centre of mass of a human male is approx 0.56 the ratio of height. For a 6ft male, the centre of mass would be within 2ft of the roll axis and the top of the head would be in negative g. I have no idea how you sum that lot to 1g total, but I suspect it requires a rotation *much* faster than the 24.4 RPM Codraroll calculated above.

 

[RCgothic]

Ok, I'll bite, using my best Googlefu and an estimate for head length:

The average human is 67kg. Average height 1.67m. The cylinder is 1.52m radius.

Let's break the body down into 3 regions of roughly uniform mass distribution.

Legs are approximately 35% of body mass (21.7kg) and are on average 45% of total height (0.75m). Their average radial position is 1.15m. They contribute 24.9w2 to force.

Head and neck is roughly 8% of body weight (5kg). They're about 30cm long. That puts the average radial position bang on the spacecraft axis. It contributes nothing.

Trunk and arms is the remainder. 35.3kg and 62cm long. The average radial position is 0.46m from the axis. They contribute 16.4w2 to force.

The total force due to centripetal acceleration is therefore 41.3w2.

1g on 67kg is 657N = 41.3w2

15.9 = w2

w = 4 radians per second = 94rpm.

Incidentally your toes would be experiencing approx 2.47g.

Edited October 17, 2019 by RCgothic

[kerbiloid]

5 hours ago, Codraroll said:

How would two people standing upright pass each other if one was going from one end of the ship to the other?

They have a whole lot of place.

Spoiler

This habitat is same high as the 2x2 corridor and twice narrower.
They just should be lying on the floor mats rather than sitting to keep the head at the same side from the rotation axis.

Also, you can easily pack 12 persons in a 2.3 x 2.3 x 2.3m cubicle, and they would still have place to sleep, eat, and play.

Spoiler

A pair of 3-storey bunk beds at the opposite walls, 60 cm wide.
The upper and the middle beds are for sleeping, 50 cm of vertical space, enough to turn around.

The lower bed is for sitting. So, every bed contains 2 persons sleeping on the upper and the middle beds, and 4 sitting side-by-side (0.5 m per each) on the lower bed. So, 6 in total.
They sleep in 3 shifts by two (8 h x 3 = 24 h).

2 triple beds = 12 persons in the cubicle.

A tabletop board as a table to eat or play, put on the bed handles when needed in the passway (1 m wide) between the beds.
Two bed-long chest under the lower bed., for goods

(No, not necessary a prison. A nuke shelter as well.)

As we can see, this room nicely matches 1.875 x 1.875 corridor in a 2.5 m cylinder in KSP geometry.

(Certainly, they need a restroom and a place to have a walk, and they can do this in shifts).

Of course, officially the spacemen in the 3 m diameter cylinder (2 x 2 corridor) still need the sanitary 28 m³ of empty space, so 7 m of this corridor per human minus the cabin and lab space.

4 hours ago, RCgothic said:

Even so, simulating 1g with roll would be horrific. You'd be much better off spinning up in pitch or yaw for a long cylinder.

The 3 m cylinders with the crew will be quickly rolling along a huge rotating drum.
They will be rolling so fast that will produce 1 g inside.

Also, may be launch them down from a hill in an O'Neil cylinder.

3 hours ago, RCgothic said:

The average human is 67kg.

What a light human. Usually they arre ~95 kg like Kerbals (together with suits) or ~150 kg together with seats.
Naked and hungry weight less, of course.

3 hours ago, RCgothic said:

Let's break the body down into 3 regions of roughly uniform mass distribution.

I like your style, dude...

3 hours ago, RCgothic said:

Legs are approximately 35% of body mass (21.7kg)

And can be used for aspic. Anyway they don't need them in zero-G. So, both mass economy and nutrition.

Edited October 17, 2019 by kerbiloid

[Spacescifi]

6 hours ago, Codraroll said:

The more I think about it, the worse of an idea the 1g 10 ft diameter cylinder becomes. How would two people standing upright pass each other if one was going from one end of the ship to the other? One of them would have to walk up the wall relative to the other and crouch down, as there would only be five feet from the floor to the centerline at any point. Stepping out of the way while standing up is not possible, as everybody's torso would always be in the center of the tube. This, of course, ignores how incredibly uncomfortable it would be to walk around with your head experiencing constant negative Gs and the dizziness of the Coriolis force. This calculator cites some sources that say 10 RPM is more than even seasoned pilots can adapt to within a reasonable time frame, and your ship is doing 24.4 RPM.

But that assumes walking up the wall is even possible. You can't dedicate the entire spacecraft interior to be a floor. Presumably, all sorts of instruments, controls, screens, etc. would line the walls of the tube (just see the ISS), so you can't just put your foot anywhere. By the way, due to the aforementioned issues with standing up, and a lack of space for anything that pokes into the tube, the only feasible position for working with any of these would be lying down next to them, which is not a comfortable position to hold for any length of time even if you're not spinning around once every 2.45 seconds.

Then there's the storage compartments. For reasons mentioned above, they would have to be recessed in the floor. And since the spacecraft spins so quickly, the gravity at the bottom of these storage compartments would be quite a bit stronger than on their surface, so working inside them would be a royal pain. Half a meter down, you're at 1.3g already. Solar panels or radiators (30 people generate three kilowatts of power even at light activity, so you'll have quite a bit of waste heat to get rid of) sticking out five meters beyond that would experience 4.5g at their tips. It would make EVAs difficult, to say the least.

And of course, space. Space for 30 people in a 10 ft wide tube, with provisions to last for half a year. Using the ISS as a very rough comparison, that one contains a pressurised volume of 900 m³ and has provisions for six crew for ... I can't find any sources on the fly, so let's say three months. Your ship has five times as many crew and they're up there for twice as long, but let's say they're all Commander Toughguys and live twice as cramped as the ISS crew does, cancelling out that last doubling. So a pressurized volume five times that of ISS, or around 4500 m³ would be required. Let's say 4000, because it makes calculations easier. Now, we've already assumed storage compartments to be half a meter deep, so let's say you have a pressurized radius of 2 meters.

4000 m³ / (pi * 2 m *2 m) gives a necessary tube length of (1000/pi) meters, or 318.3 meters. 1043 footsies if you want to stay Imperial. You can find contrived reasons for halving that number, and maybe halving it again, but your ship would still have proportions like a toothpick. This is just the crew and pressurized storage compartments, remember; presumably you've got a power plant and a propulsion system as well.

The point I'm trying to make is, 10 ft is ludicrously small. Both for the size of the crew, the magnitude of gravity you're looking for, and for the technological advancement required to make it a reality in the first place. If you can outfit a ship for 30 people for six months, and mount a nuclear engine at its back, you can easily build it with a bigger diameter. Building it 4 meters wide and 300 meters long would be vastly more difficult than, say, 10 meters wide and 50 meters long (which gives the same volume). With the ship's floor once again being half a meter from the hull (at a radius of 4.5 meters), you can do 1G with a spin rate of 14 RPM, which is still a lot more than what is comfortable, but enough for a semi-realistic Commander Toughguy to overcome while his crew does not. And you can have upright workstations, and all the storage in zero G in the middle of the ship. Scaling up the radius makes everything more practical overall.

 

Thank you for the thorough analysis. I never considered the g-forces radial gravity would have on the sidewalls. They would likely need to be built extra strong to not break the ship apart under it's own weight.

5 hours ago, RCgothic said:

We have rockets that can put:

Dragon, 13ft

Orion, 16ft

Skylab, 23ft.

When starship is operational, it will be 30ft. Why exactly are you limiting to 10ft?

Even so, simulating 1g with roll would be horrific. You'd be much better off spinning up in pitch or yaw for a long cylinder. Better still, tethering two craft together and spinning around the mutual barycentre.

The centre of mass of a human male is approx 0.56 the ratio of height. For a 6ft male, the centre of mass would be within 2ft of the roll axis and the top of the head would be in negative g. I have no idea how you sum that lot to 1g total, but I suspect it requires a rotation *much* faster than the 24.4 RPM Codraroll calculated above.

 

It is always interesting how reality is often different and more awesome than what we see in scifi. I like it!

Yeah, it would be better do pitch based spinning as it is cheaper to strengthen the rear and front of the vessel than it is to reinforce all the sidewalls. Likely less weight that way too. Would make for some odd deck arrangements though, since the middle of the ship would be zero g.

Who knew? Tumbling rotation is cheaper and less wear and tear on a ship's hull compared to radial rotation.

Unless the structure is huuuge. But that is not ideal for a rocketship.

Gravity is an ironic thing. It's one pf those things where scaling up is actually good for structural integrity, even though getting stuff off a planet to simulate gravity via rotation is made difficult because of gravity in the first place.

 

I am at the point where I finally realize that tumble rotating rocketships are overall superior to radial rorating rings or saucers, unless you scale up by a whole lot.

Even then a rocket shape is still likely superior. As it generates less drag leaving the atmosphere and won't necessarily require orbital assembly via multiple launches.

Edited October 17, 2019 by Spacescifi