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Expert: Mars Astronauts Would Lose Teeth
Ant wrote to us with a story on Discovery about the long term consequences of manned and "womanned" missions to Mars - lots of research about bone-weakening effects of zero G environments, with tooth loss high on the list.
I say we get all the astronauts to smile for a group picture when they land on mars.
URL is wroing... Real URL is:
a rs teeth.html
http://dsc.discovery.com/news/briefs/20010827/m
Do people read the bit which says "Check URLS" anymore?
Talez
Well most space food is in a paste or freeze dried format to boost nutrient intake anyway so it wouldnt matter.
One would thing the issues with blood polling and muscular atrophy may be more succint on long missions like this, there is a dange that muscles can atrophy very badly with long term exposure to low or zero gravity, this coupled with bone fatigue might mean that an astronaut arriving back on earth after his long trip might just collapse when he is exposed to the earths gravity.
Astronaut pancake anyone ?
I refuse to argue with Anonymous Cowards - if you want a discussion get an account....
It looks like the story link doesn't work. At least it didn't work for me. Here is the one that worked for me.
http://dsc.discovery.com/news/briefs/20010827/mars teeth.html
--Got Lists? | Top 95 Star Wars Line
(just joking, its a fine state, I lived through High School there)
What, me worry?
The discovery page seems dead. But, going out on a limb -- from what I've read, it seems to take about 6 months to get to mars. There have been more than a few people who've lasted this long in space, and they seemed to have nice smiles when they returned.
Once on mars, the effects should be mitigated by the gravitational field - right? How much less is mars' gravity compared to earth?
Realizing that doing something like this would increase the cost by, well, a lot, couldn't the astronauts accelerate at around .5 to 1 G for half the trip (creating gravity), then reverse the spaceship and decelerate (yes, I can't spell, but neither can the Slashdot staff some days).
You'd need more fuel for this, of course. But it could reduce the problems of microgravity.
Of course, I could be wrong.
52 Weeks, 52 Religions with John Hummel
That's right. Go into space, become old and degrepit. Die young, with no teeth.
I'd have to say that NASA will need a more effective marketing campeign.
NASA: So, you want to be an astronaut?
John DOe: I realize I don't have to worry about the space shuttle blowing up, but I don't want to die young, with no teeth either...
--Got Lists? | Top 95 Star Wars Line
He probably doesn't have any teeth left anyway.
--
"Karma can only be portioned out by the cosmos." - Homer Simpson [1F10]
However, as others have pointed out, simply spinning the ship is by far the easiest and simplest way to get around this issue.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
What if they just created artificial gravity via centripetal force by simply rotating the craft about its axis on the way to Mars? I don't know the physics involved here, maybe it's just not possible to create enough gravity that way unless you have a spacecraft with a really big radius, such as the space station in 2001.
I'm sure that more-informed minds then mine have already considered this simple idea, I'm just wondering why it's not feasible.
If the manned Mars spacecraft wasn't big enough to create sufficient gravity that way, maybe they could just hire really fat astronauts, in order to make the most of the limited gravity. just kidding...
OtakuBooty.com: Smart, funny, sexy nerds.
The Discovery article states "...in both older women and weightless astronauts, the bone-repair mechanisms in the body shut down." Are there any doctors out there that can explain (in detail) what happens to the body in low gravity that causes bones to atrophy?
So much for the standard picture of the intrepid space explorer! I doubt Doc Smith would have sold so many books if his main character in the Lensman series was named Kimball "Gums" Kinnison.
And the brethren went away edified.
As good as this parallel is, there is a substantial inversion going on nowadays. In the old days of exploring, most of the crew were essentially thugs, biomass to keep the ship/sled/canoes going. All the *truly* intellegent people, ignoring the single great explorer on each of these expeditions (grudgingly giving them the benefit of a clue) stayed at home, and didn't have these problems with their fingers rotting off and discovering that fruits really are good for you in moderation. Nowadays we send our absolute best and brightest (or at least the best and brightest we can muster). These folks are precisely the people that wanted to keep their teeth and other extremities in the first place.
Besides, in the olden days of exploration, most people didn't even start with teeth and all their fingers...
But how are you going to open bottles and tighten bolts on your way home? Teeth are much more mass/fuel effecient than spanners will ever be...
Oh, I'm sorry, I thought this was a Russian mission at first. Teaches me to not read the article...
If they switch the minty-fresh taste of colgate, their teeth will stay strong, white, and clean.
Donate background CPU time to fight cancer.
Because the Moon, in some ways, is actually not closer to us at all, and there are a lot more things worth having on Mars when we get there.
Firstly, Mars has a day almost identical in length to Earth's. Why is this so important? Because it means you might be able to grow plants there by the natural light. Growing plants under artificial light is very inefficient - the only ones that we can afford to do so for are kind of illegal in many places :) You can't grow plants by natural light on the moon because the two-week night would kill most plants (let alone the problems of your greenhouse heating up to boiling point during the two-week day).
Secondly, Mars has almost certainly got a lot more water available than the Moon does. The moon has virtually no water available. You can't have a colony without a water supply :)
Thirdly, just because Mars is further away doesn't mean it's more difficult to get stuff to and from it. The travel time is an important issue for humans, but for cargo it often doesn't matter, and for cargo it takes *less* fuel to land stuff on Mars because you can use the Martian atmosphere to slow down when you get there, unlike the moon where you have to use more fuel slowing down. Going the other way, it's easier to get stuff off the Moon than Mars (because the moon has less gravity), but you can make rocket fuel for your rocket a lot more easily on Mars than you can on the Moon (because if you have water, you can use electrolysis to get hydrogen and oxygen - instant rocket fuel).
Finally, if you're going to run a self-sustaining colony which pays its own way, to pay for imports from Earth you need something you can export back. From what we know about the composition of the moon, we're fairly sure that there's not much there of value (except for Helium-3, which is a fuel that might be used in fusion power plants in the future but is very difficult to extract), but on Mars there's a distinct possibility of finding high-grade deposits of gold, platinum, and other commercially valuable metals. In addition, if we ever mine the asteroids (many of which are virtually pure precious metal and are thus incredibly valuable), it's much easier to supply the miners with food and supplies from Mars than from the Earth or Moon.
In any case, we're not really trying to colonize either yet. As to the interest in exploring Mars, we've been to the Moon and have a fairly good idea of what it's like. Mars is the next step along the line.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
Just this morning I was reading issue 2303 of New Scientist and read an article that states that research has shown that the activity of standing on a vibrating platform moving at 30 hertz for 20 minutes a day has induced sheep to gain 35 % more bone mass within a year.
Trials have been started on elderly female patients with osteporosis and seem to be showing positive results.
Of course, 0G could make it difficult to stand *on* a vibrating platform, but these experiments must be able to teach reserachers something about ways to combat the problems. If tiny, high frequency strains can help improve bone growth then there must be other ways to induce those strains within a 0G environment.
A little planning goes a long way...
To give you some idea of how far we are from this. If you could afford the fuel to do 0.5 G to half way and then flip to slow down, the whole trip takes only 2.4 days at Martian closest approach. Ramp it up to 1 G and you get things down to 1.7 days.
Simulated gravity could be made this way but no engine design has fuel sufficiently light to make this even remotely possible with current technology.
As far as spinning. Acceleration = Radius * (angular frequency)^2. To get a good one G in a ship with a 5 meter radius, you'd have to spin it at 1.4 revolutions per second. Okay so make the ship bigger and aim for less gravity? 20 meters for 0.5 G still carries a rate of 0.49 rev. per sec. Spinning isn't generally a simple answer unless you are planning something that is monumentally huge. A station 2 km across can get to 0.5 G with one revolution about every 14 seconds. (If you feel like making the stretch to call that simple.)
Someone might point out that without air resistance or other interactions, getting and keeping a spin isn't the problem it would normally be. This is true, but if the object is small you get all kinds of wierd effects caused by the gradients in force. For instance a 1m tall person standing in that 5 m ship at 1G would have only 80% of the gravity at his feet acting on his head.
I will concede that getting such a ship spinning takes not unreasonable amounts of energy (considerably less than would presumably be spent getting it to Mars at a reasonable speed, and not a problem if you start the spin while in Earth orbit and fuel is plentiful), but then you pretty much have to go in a straight line along the axis, because you've just made the largest gyroscope man's ever seen, and turning the thing would be a bitch.
Some of the other problems would include getting in and out of such a ship (think floating through a hatch on the axis and then somehow matching rotation). Also anything on the outer wall would want horribly much to fly off. Large stresses would be involved in getting it spinning and holding it there. And last but not least on my short list, is that any propulsion system would carry both mass and angular momentum away from the ship affecting the rate of rotation.
Okay, so I've sat down and done the calculations. Sustained acceleration isn't likely to work any time soon. Rotation is technically possible, but certainly not easy given the kind of speed needed and presents serious technical issues to deal with the stresses, manuevering, getting in and out of the ship, etc.
Good luck NASA, I hope you figure something out in my lifetime.
That's right, it's a feature. The space is inserted in the displayed text, but not in the href= attribute of the HTML <a> tag. The space is inserted to prevent long "words" that can't be wrapped by all browsers from messing up the site format.
now we need to go OSS in diesel cars
Well, I don't remember much about frequency from my physics lessons at school, but I thought I should just confirm that the article states 30 hertz. They also describe the movement as imperceptible:
"The researchers have found that when sheep are made to stand on a platform vibrating at an imperceptible 30 hertz for 20 minutes a day, their legs gained 35 per cent more bone mass within a year", oh, it also mentions that the information comes from Nature vol 412, p 603.
I must admit that the story mostly stood out in my mind because I had a great image of sheep being made to stand on a vibrating platform that made them wobble around and lose their balance - but then I was on the tram to work so my mind was wandering!
A little planning goes a long way...
This is the major hazard of space colonization. You have to get money from it, if you want to pay it with corporate money. And you suggest raw materials!!! I firmly believe transport costs of pure platinum from Mars would be high enough to make extraction from sea water look dirt cheap. Recycling is another thing that will not let the prices go that high. Extraction of gold from used electronics will be cheaper than importing the stuff from Mars.
Information would be cheap to transport, so prodicung it on other planets would be better. For geological/planetological research, every planet will have it's own colony, if robots are not considered better.
However, I think Moon would be the prime place for some sciences: Astronomers would love the continuous two-week data set. Radio interference from Earth would be no problem on the backside of Moon. No atmosphere means all wavelengths (IR to gamma-rays) can be studied from the Moon. Lower gravity means that the telescopes can be made larger. Some deep craters near the Lunar poles are in permanent shadow, so they would be excellent places for far infrared astronomy, where detectors must be at milliKelvin temperatures. To have a 10-K heat sink nearby will make things very easy.
Hazardous biotech research could also be done and safely tested on the Moon. It would be much harder to kill billions of people by stupid accidents.
Another possibility of the Moon is to use coilgun-like launchers that would use solar power to accelerate the cargo. This would eliminate the need for chemical propellant and rockets. Estimated launch price: less than one dollar per kilogram! As launching from Earth will never be able to compete with this, manufacturing satellites etc. could be an interesting option.
If I remember my biology classes correctly, teeth already are regarded as an evolutionary relic by some biologists, so they are bound to disappear anyway some time 'soon' (on the evolutionary timescale, that is).
What's more: *of course* humanity will adopt to living in space, they will look different from the people living on earth, that's the whole point in evolution, isn't it?
That this might bear some problems for the first spacefarers has already been a topic in SF literature, e.g. in C.M. Kornbluth's story "The Altar at Midnight".
tom
--
"Just believe everything I tell you, and it will all be very, very simple."
And while we keep waiting to see some toothless astronauts, the brainless bureaucrates keep us tight to earth...
Also Mars has that giant alien machine underground that heats up the frozen ice core and releases oxygen into the environment within a matter of minutes to create an instant earth-like atmosphere. Does the moon? No way. So we got that going for us.
"Tommyknockers, Tommyknockers, knockin' at my door..."
It would give them plenty of exercise to the teeth and jaw muscles, and might well be popular (most astronauts are American now and so presumably like chewing the cud).
OTOH the gum might also come in handy for fixing things in the ship and or holding things down in zero g
think of the sponsorship deals... the Wrigley's Orbiter etc
I know some tooth-impaired good ol' boys who would be excellent candidates for the Mars program. Far from pretty boys, they would not mind at all losing their remaining teeth.
NASA should also contact Shane McGowan [formerly of The Pogues] if anyone can find him.
In thpace ... no one can hear you thcream.
Sorry, I left out a "k". I meant to say 3500kHz, not 3500Hz. And I know that figure is right because I read it off the screen when my wife had a scan last night. :-)
These machines have come a long way since when I briefly did some work with them 11 or so years ago. (I never got to operate the machines, of course. I just developed film. This was in the days before ultrasound and CT scan machines had photo printers hooked up to them. I digress.)
You can work it out from the knowledge that the average speed of sound in soft tissue is 1540m/s. A 3500kHz frequency gives you a wavelength of 1540/3.5e6 metres or 0.4mm, which is the sort of resolution that you need for diagnostic purposes. Diagnostic imaging devices can use different frequencies, of course. Typical range is 1-15 MHz.
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I know that we all think that a spinning spacecraft is a wonderful idea, but it's a bit much.
:-P
What about just a single chamber, perhaps along the lines of living quarters, that spun, much like the old amusement park rides?
A certain amount of exposure to ~1g per day should be enough to ward off the deterioration of bone mass, and it would be cheaper than engineering an entire spaceship to spin fast enough to induce gravity.
Of course, I'm certainly missing the key detail of this spinning chamber most likely staying in place while the rest of the ship spins, but I leave the tough work to the NASA engineers
Raptor
"Procrastination is great. It gives me a lot more time to do things that I'm never going to do."
I would give my eye teeth for a trip to Mars, and so would any NASA astronaut.
Clear the technological hurdles -- if the bone loss problem isn't solved by then, well, screw it. Take volunteers.
So will this work for me? Could I make a vibrating platform and become more caveman like?
... well ... kind of dumb ... but I still want to try it!
The possibilities are
Just Flat panel displays that look and feel like windows, showing a static view from the axis or some such.
**>>BELCH
Okay, but do you have any particular reason to believe this, or is it just a tenet of your faith? If you consider that fuel can be made relatively cheaply from local ingredients (just react some H_2 with the atmosphere, really) and that transport time isn't important for cargo, it might not be too expensive at all. Strap a booster onto your block-o-platinum and loft into Martian orbit (low gravity, so lots easier than for Earth). Fire up an ion/magsail/Vasimir/whatever engine and two years later you're aerobreaking into Earth orbit.
By far the largest cost to mining on Mars is going to be transporting and supporting the human miners -- which, sadly, makes robots a promising alternative. It'll be interesting to see which gets there first, robots sophisticated enough for autonomous mining operations, or launch costs low enough to realistically support human extraterrestrial colonization.
Quantum mechanics: the dreams that stuff is made of.
So what about when they get back to Earth?
You mean they're supposed to come back?
-- dR.fuZZo
This dragon keeps coming up as one of the major reasons not to explore the solar system, and it's one of the easiest to put to bed. All you have to do is attach the spacecraft to its spent upper stage with a long tether, and spin the whole system like a baton. You can get modest gravities with reasonable (on the order of a hundred or so feet, depending on the mass of the upper stage and the spaceship) tether lengths and angular velocities. The nice thing is that even if the tether were to break, the only thing you'd be losing would be a useless hunk o' metal. The astronauts would of course be less comfortable, but the mission could be accomplished.
If you're interested in this sort of thing, Robert Zubrin's "The Case for Mars" (http://www.marssociety.org has a copy for you) details things like navigation and maneuvering on a rotating platform.
Why yes, I AM a rocket scientist!
Okay, but do you have any particular reason to believe this, or is it just a tenet of your faith? If you consider that fuel can be made relatively cheaply from local ingredients (just react some H_2 with the atmosphere, really) and that transport time isn't important for cargo, it might not be too expensive at all. Strap a booster onto your block-o-platinum and loft into Martian orbit (low gravity, so lots easier than for Earth).
You still have to loft the cargo out of the Martian gravity well, and cancel the (very large) gravitational potential energy difference between Mars's orbit and Earth's. This will be about as expensive as launching something into space from Earth - not cheap. Your fuel isn't free. It costs time and effort (read: money) to manufacture, even on Mars.
There's also no reason to believe that mining on Mars will be cheaper than mining on earth even if you *don't* transport the cargo anywhere. Why would we magically find rich veins of platinum on Mars? It has roughly earth-like composition.
If you're going to mine anything, then near-earth asteroids are your best bet, and even then, I'm skeptical of asteroid mining being worth the cost. Asteroid composition varies widely enough that you can find ones that are very rich in metal ore.
IMO, mining the moon for raw mass is probably the most practical operation that will go on in space. To build a space colony, you need a lot of mass just for radiation shielding. Moon dirt works well for that, and is a lot cheaper to loft than material from Earth. If you're building a spinning structure that has mostly tensile forces, then you can get structural material from the moon too (fiberglass cables).
Mars, on the other hand, has little that would be worth transporting back to Earth. In pretty much all cases, you'd be better off mining or manufacturing it on earth and avoiding transport costs.
OTOH, Mars is a great site for colonizing and possibly terraforming, once there are enough settlers willing to pay out of pocket for the trip.
It's certainly good to identify such problems and prepare for the ahead of time, but I'm not that worried about this. Science/Medicine are making good progress on preventing problems once they know about them (while IMO progress isn't as hot in the whole fixing-existing-problems domain). This feels like a readily-understandable problem.
By the time we're ready (socially, financially and technologically) to make trips to Mars with such frequency that this is a serious problem, I feel confident that a supplemental drug and/or exercise regimen and/or artificial environment will be available to prevent this problem.
are you serious about those dreams? Because I have them too... not every day or week, but regularly enough.
Or just a roataing section.
Not too difficult, and very plausable. The problem is that it doesn't fit with NASA's current spend very very little methodilogy. anything that we sent do mars with people in it had better be the most expensive and over-engineered mechanical marvel the human race has ever created. The problem is that we're trying to get there in a volkswagon bug instead of a Lincoln navigator. and we really need to be bringing the Lincoln.
Do not look at laser with remaining good eye.
You state early on that mining Mars or asteroids is unlikely to be profitable, and then state that the moon is better because space colonies need radiation shielding, which can be gotten relatively cheaply by using lunar regolith. Nowhere do you state why people would want to build space colonies, rather than lunar or martian colonies. I'd be curious to know why people would rather build space colonies (which are more difficult to construct and supply) than planetside colonies.
They might not be built at all. I'm postulating that they will be, which leads to my conclusion about profitable space industries. If you assume no large space structures will be built, then I doubt that any space industries will be profitable.
The most immediate use for space stations and space colonies is as way-stations to lunar colonies and for interplanetary craft. This assumes that lunar colonies will be constructed. If we have no need for substantial interplanetary travel or colonization, then there is no need for space stations.
The safest method of building and supplying a moon base or moon colony would be to have two fairly large space stations, orbiting the moon and the earth, with solar-powered ion drive shuttles carrying cargo between them. Build the first station in Earth orbit, and use it as a testbed to work out all of the problems with building space stations and more-or-less self-sufficient environments. Build a second station in Earth orbit, and use ion drives to move it to lunar orbit. Then set up the supply line. Travel time for the ion shuttles is a few months, but they're in a constant stream and unmanned, so this isn't a problem. You now have a conveyer belt carrying food and supplies to the lunar-orbit station, and carrying waste back.
Send construction materials along this pipe, and you can build a lunar colony. Send food and supplies, making sure to keep a month or two of surplus dirt-side on the moon and/or in the lunar station, and your lunar colony can handle just about any disaster without a big, fast, expensive rescue ship being needed.
The earth-orbit station is an ideal launch station for ion-drive probes to other parts of the solar system. The lunar-orbit station is an excellent site to manage construction of other space stations or large craft from (lunar material would be sent to a nearby construction site). This is where you'd likely build a Mars-colonizing ship. The ship would have to be big, carrying all of the equipment needed for a self-sufficient Mars colony base, and would become Mars's orbiting station.
All of this presupposes a desire to build lunar or Martian colonies. Given that desire, this is probably the easiest, cheapest, and safest way of doing it. Without that desire, there's no real reason to go into space at all.
Wait, I'm missing something here. What's the difference between acceleration and delta v? I seem to remember that acceleration = change in velocity. What gives?
Acceleration is the instantaneous change in velocity (derivative of velocity) at any given time. Delta-v is the integral of acceleration over time (actually of the magnitude of acceleration). For a ship accelerating in one direction outside a gravity well, it will be the total change in velocity (v_end - v_start).
Acceleration is how fast you can change your speed, and delta-v is the total amount you can change your speed by.
What exact amplitude do they call "imperceptible"?
A few mm? A few um? A few nm?
--Blair
"Gotta love those irreproducible results."
No...there is definitely water ice on Mars (check the polar ice caps). There may be ice on the Moon; the last probe to check came up about as inconclusive as whether there was life in that Martian meteorite.
But there is oxygen on the Moon, and hydrogen from the solar wind if nothing else. Add in electricity (solar panels - at the poles, where they could always be in sun - anyone?), and...