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All those microgravity-induced health problems and risks go away if you supply spin gravity. Period.
The only question is how much spin gravity is enough? We evolved at 1 gee, that is what our bodies were made for, but some lower number may be adequate. That question was never answered with real partial-gravity experiments. Which is now so very clearly the stupid research shortfall that it appears to be.
So, until it is answered, you provide 1 gee or pretty close to it. The gravity you get depends upon the spin radius and the square of the spin speed: a = R w^2. For convenience: gee = (R/56 m)(spin rate/4 rpm)^2.
There's a max spin rate you can use, for long term exposures, and it is a lot slower than what can be used in short-term exposures, such as carnival rides. The value is fuzzy, not very well-researched, but appears to be in the 3-4 rpm range range, maybe closer to 4 than 3 rpm, but who really knows?
In any event, if you take 4 rpm as max spin rate, then for 1 full gee, your spin radius is 56 m. Period. That plus the pre-conceived notion that only rifle-bullet spin can be used, led to the perception that we would have to build "Battlestar Galacticas" if we were going to include spin gravity, and nobody could afford that. Which in turn is why spin gravity was never researched - circular as that thinking is.
There is one other spin mode that nobody thinks about: baton spin (end-over-end). It is also stable, and if you only build the baton, you don't have to build a huge massive thing. The downside is very little volume at the ends where the full gravity exists. There is decreasing partial gravity toward zero at the spin center. It might or might not serve as a spaceship design, but it would certainly serve as an easy-to-build, relatively-cheap space station for researching partial gravity effects in orbit.
Think about it: 6 modules docked together end to end, each one 5 m diameter and 20 m long. That's a 120 m long baton. Spun up to about 4 rpm, the spin radius is 60 m to the outer end. The two end modules are pretty close to 1 gee at the ends and 2/3 gee near the docking collars, with maybe about 250-300 cu.m habitable internal volume each. The other 4 modules are the same sizes, with around 2/3 to 1/3 gee in the outer pair, and 1/3 to near 0 in the inner pair. Each cylindrical module could have perhaps 8 or 9 decks in it.
It wouldn't take all that long to see who stayed healthier in which modules.
GW
Last edited by GW Johnson (2024-03-05 11:39:48)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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Scientists Reveal How Many People You'd Need to Colonize Mars
As few as 22 people could sustain a colony of pioneers long enough to establish a human presence on Mars.
That's the conclusion of a new study by a team of researchers in the US that used modeling and simulation to work out the minimum initial population size for a successful Mars colony that goes on to thrive.
That's a lot lower than a previous estimate of 110 people. The more the merrier, perhaps, though the travel bill for a trip to the Red Planet would skyrocket with every extra mouth to feed.
https://www.nature.com/articles/s41598-020-66740-0https://arxiv.org/abs/2308.05916
"Beyond mining a few basic minerals and water, the colonizers will be dependent on Earth resupply and replenishment of necessities via technological means, i.e., splitting Martian water into oxygen for breathing and hydrogen for fuel," the researchers write.
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For SpaceNut re #252
Your links to articles about proposals for settlement of Mars (as opposed to just a visit) reminded me of OldFart1939's entire topic devoted to planning for an expedition.
I am suggesting as a first Starship Mission to the Red Planet Mars and having a crew composition of 17 astronauts
This is based on the "Triad concept," and a somewhat military style organization. There will be a relatively loose hierarchical structure, but there needs to be a leadership pyramid established before anyone sets foot inside a Starship.
Triads: Three astronauts with a particular set of skills assigned to complete a certain set of tasks; particularly important for working outside in the hazardous desert-like environment. It's not possible to find a single individual who has all the necessary skills that will be utilized when the skill set required is enormous. There also needs to be inspection of work done by at least a second individual when so much is "on the line." Medical skills are also sometimes requiring a second or third set of skilled hands.
What have I planned as the necessary sets of skills"
Leadership: A group commander and an assistant commander; both with great communications skills and abilities to do lots of data management. They will be tasked with work assignments and difference resolution. There needs to be a final authority when differences of opinion arise between crew members.
Geologist triad: They will be tasked with collection of samples and determination of WHERE to put the permanent habitation modules. Do studies of weight bearing capabilities of potential landing sites and layout of the landing complex. Search for water.
Construction and maintenance triads; there will be 2 of these because they will be the most important set of tasks needed to keep everyone else alive. Maintain the rovers, Set up a solar farm or a nuclear reactor system.
Scientist triad: a good biologist and microscropist to examine samples looking for signs of life, past and present; a chemist with skills in elemental analysis to determine the contents of various samples returned by the geologist triad. A molecular biologist with instrumentation skills (polarimetry, gas chromatography, HPLC, and other skills needed to analyze samples for signs of life).
Medical triad: One Surgeon, one GP, cross trained as a dentist, and one nurse with Nurse Practitioner certification.
OK, this is my baseline for a crewed mission.
Last edited by Oldfart1939 (2021-04-26 10:09:18)
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Microgravity Associated Bone Loss-A (MABL-A)
https://www.nasa.gov/mission/station/re … /?#id=8870
Role of Mesenchymal Stem Cells in Microgravity Induced Bone Loss
Mouse Habitat Experiment
https://spaceflight101.com/iss/mouse-ha … xperiment/
The Japanese Mouse Habitat Experiment in some ways is similar to the U.S.-led Rodent Habitat set up on the Space Station in 2014, however, there are a number of significant differences including the use of artificial gravity and the accommodation of one mouse per cage for individual studies of behavioral changes.
another Soviet / USSR / Russia record feat achieved by cooperation on the ISS
expected to also be the first person to reach 1000 days in space
'Oleg Kononenko'
He smashed the world record by spending 878 days in space. His body is likely not the same
https://www.trentonian.ca/news/oleg-kononenko-space
Last edited by Mars_B4_Moon (2024-04-13 02:43:56)
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There's a whole lot more to microgravity diseases than just bone loss and muscle weakening from lack of use. That's all that was expected back in the Mercury/Gemini/Apollo days.
We have since found that there is damage to the eyes, there is damage to the immune system, there is damage to the chromosomes (although how much is microgravity and how much is radiation exposure is arguable), and there is damage to the heart and circulatory system. All of these are "for sure" now.
There is as yet no end in sight to this list. As the years go by, we keep finding more and more things in the body that zero gee damages. That trend suggests we do not yet know all the risks.
Each and every one of those things, and a lot of other practical issues about living in space (like how to take a bath, or how to use a familiar toilet, or how to cook on a stovetop), are solved if you add in artificial gravity (as spin). Gees ~ (spin radius/56 m)*(spin rate/4 rpm)^2. There is a max spin rate for long-term exposures: about 3-4 rpm. And THAT means you must use a spin radius equal to or exceeding 56 m! Cable-connected modules, and building Battlestar-Galacticas, are not the only ways to do that, by the way! Although some never bother to think outside those 2 boxes.
The radiation threat is NOT the cosmic ray bugaboo that so many claim! If you hear somebody still claiming that, know that it is BS. Period! At least in the inner solar system, the real lethal threat is big solar flares. The data that we have suggests that 25 g/cm^2 of low molecular weight shielding material would protect well enough, against even a really big solar flare like the 1972 event that occurred between two Apollo missions. Had a crew been out there during that event, they would have died within less than 10 hours, and it is a very ugly death.
Living space is a problem, ask anybody who ever served time in solitary confinement. But it's not just a volume per person. You have different needs at different times.
Sometimes you need to be with other people, sometimes you need to get completely away from other people, and there's a spectrum all in between those two extremes. Shipboard conditions and facilities are a guide to this, but they are simply not "right" for a spacecraft.
On a ship, you can go out on deck and feel the sun and the wind on your face. You cannot do that on a spacecraft, so you will need more spaces and facilities than a ship has. You can't do that "go out on deck" thing on a submarine, but not everybody can be a submariner.
Real life is complicated and messy.
GW
Last edited by GW Johnson (2024-04-13 12:52:09)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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There's a whole lot more to microgravity diseases than just bone loss and muscle weakening from lack of use. That's all that was expected back in the Mercury/Gemini/Apollo days.
We have since found that there is damage to the eyes, there is damage to the immune system, there is damage to the chromosomes (although how much is microgravity and how much is radiation exposure is arguable), and there is damage to the heart and circulatory system. All of these are "for sure" now.
There is as yet no end in sight to this list. As the years go by, we keep finding more and more things in the body that zero gee damages. That trend suggests we do not yet know all the risks.
Each and every one of those things, and a lot of other practical issues about living in space (like how to take a bath, or how to use a familiar toilet, or how to cook on a stovetop), are solved if you add in artificial gravity (as spin). Gees ~ (spin radius/56 m)*(spin rate/4 rpm)^2. There is a max spin rate for long-term exposures: about 3-4 rpm. And THAT means you must use a spin radius equal to or exceeding 56 m! Cable-connected modules, and building Battlestar-Galacticas, are not the only ways to do that, by the way! Although some never bother to think outside those 2 boxes.
The radiation threat is NOT the cosmic ray bugaboo that so many claim! If you hear somebody still claiming that, know that it is BS. Period! At least in the inner solar system, the real lethal threat is big solar flares. The data that we have suggests that 25 g/cm^2 of low molecular weight shielding material would protect well enough, against even a really big solar flare like the 1972 event that occurred between two Apollo missions. Had a crew been out there during that event, they would have died within less than 10 hours, and it is a very ugly death.
Living space is a problem, ask anybody who ever served time in solitary confinement. But it's not just a volume per person. You have different needs at different times.
Sometimes you need to be with other people, sometimes you need to get completely away from other people, and there's a spectrum all in between those two extremes. Shipboard conditions and facilities are a guide to this, but they are simply not "right" for a spacecraft.
On a ship, you can go out on deck and feel the sun and the wind on your face. You cannot do that on a spacecraft, so you will need more spaces and facilities than a ship has. You can't do that "go out on deck" thing on a submarine, but not everybody can be a submariner.
Real life is complicated and messy.
GW
Thanks for that. This video shows why it is important to have some form of artificial gravity for a 6 month flight to Mars:
NASA astronaut shows how hard walking is after return from International Space Station (ISS).
https://www.youtube.com/watch?v=BVHqnXjhuN8
This video shows some proposed means of doing it:
Artificial Gravity is Critical for Mars Exploration & Beyond - SpaceX Starship can make this happen!
https://m.youtube.com/watch?v=he2thPRcpQc
About the radiation shielding issue, 25 g/cm^2 is probably doable for a small habitat for, say, a four astronaut exploration team. But it would require a huge additional mass for a passenger cabin the size of the Starships carrying 100 Mars colonists with 1,000 cubic meters volume.
To estimate it for the Starship, approximate the Starship passenger cabin as a 10m*10m*10m cube. Then that’s 6*10*10 = 600 square meters. An areal density for the shielding of 25 g/cm^2 equals 250 kg/m^2. So a total of 150,000 kg, 150 tons. This is about the mass of the entire payload capacity of the Starship.
For an exhaustive look at the problems of zero gravity and space radiation on long space missions see this book by Dennis Chamberland, a Ph.D scientist who worked 30 years in the biology division for NASA:
Departing Earth Forever: Book One - Warning and Promise: The Manual for Today's Colonists Preparing to Launch to Mars and our Moon Kindle Edition.
https://www.amazon.com/Departing-Earth- … 949&sr=8-1
Bob Clark
Last edited by RGClark (2024-04-19 05:54:46)
Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):
“Anything worth doing is worth doing for a billion dollars.”
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