Landing on Mars

GW Johnson · 2012-07-12 08:06:17

Here's a question for those of you who know more about microgravity disease than I do.

Consider: a 6 month tour on the space station is followed by a 3-4 gee re-entry (very few minutes) and permanent 1-gee upon landing. They have to be carried. Cannot even sit up. And that's with daily vigorous exercise in zero gee on the station.

It takes 6-8.5 months to fly to Mars one way. Say we design for no more than 3-4 gees during entry. Again, a very few minutes' exposure. What makes anyone believe these astronauts will be able to sit up or stand in 0.38 gee any better than they do in 1 gee? Especially when we have zero real experience on which to base this judgement?

Would it not be far more prudent to just plan on providing spin artificial gravity at near 1 gee during the trip, and have them arrive physically fit?

Am I missing something here?

GW

RobS · 2012-07-12 08:15:10

I think that is exactly Zubrin's argument. I'd spin to 0.38 gee so they get used to Martian gravity. I suspect it takes a while to adjust your reflexes. You can't drink a cup of coffee the same way or sip soup the same way; you might spill them. You can't turn corners while walking the same way; your forward momentum is the same but your friction on the floor is 0.38 as much (because it's a function of weight). You can't throw an item of clothing across the room the same way. If you play any games that involve throwing (velcro darts would be fun, for example) they'd function differently.

louis · 2012-07-12 09:44:44

Well the effects of zero G seem to be wrapped up in a good deal of secrecy. A lot of people I have read suggest that physical ability recovers very well, within 24 hours, although the immune system is affected for a lot longer.

I am not sure spin G is necessarily a good idea as it's going to throw up a lot of technical problems in my view.

I would prefer gravitational research to form part of the (say 10 year) development programme. So maybe after 3 or 4 years we would be flying people in zero G for several months and then maybe putting them on the Moon to see how they function. I think we should know after 6 years whether or not it is feasible for people to work on Mars after a zero G flight.

Rxke · 2012-07-12 13:21:23

... And if it's not?

re: lots of technical problems, maybe so, but it would also *solve* a lot of problems, no suffering zero-g toilets to for months, for starters. The ability to take a shower, et c....

RobS · 2012-07-12 13:28:01

I'm not sure Zubrin's proposal even creates very many technical problems, either. He suggests attaching the hab to the empty third stage by a long tether, so the rotations per minute would be low and coriolis wouldn't be a problem. Mid course corrections would be timed carefully and made using a series of small bursts during the few seconds the engines are pointing the right way.

louis · 2012-07-12 18:50:19

Rxke wrote:

... And if it's not?
re: lots of technical problems, maybe so, but it would also *solve* a lot of problems, no suffering zero-g toilets to for months, for starters. The ability to take a shower, et c....

What if it goes wrong? You're going to have a lot of astronauts breathing sh*t 50 million miles from home...will you have back up? Or are you going to assume it will be failsafe. If failsafe it will probably take years of development and cost huge amounts.

RobS · 2012-07-12 20:23:03

You'll have to have backup because you'll be in zero gee part of the time anyway. But a simple cable is pretty fail safe.

GW Johnson · 2012-07-12 22:51:46

I think the two cable-connected bodies spinning about a common center of gravity will indeed work as artificial gravity. With a long tether, it is easy to provide up to (or exceeding) one full gee at very low rpm, and that's a good thing.

On the other hand, I really do not believe you can do course correction burns on a tether system, no matter how carefully you might time them. The system is far too structurally compliant. Any disturbance whatsoever (even people moving around inside) induces oscillations, which can very easily amplify, as I see no possibility of intrinsic damping in such a system. At the very least, you have to de-spin and disassemble/re-dock for every maneuver.

The spinning "stiff" object has the advantage hands-down over any tether system, on a safety basis alone. No assembly/disassembly required. Just thruster burns. And it doesn't have to be a 3:1 L/D (for stability) object spinning about its long axis (the usual assumption leading to "battlestar galactica" designs). It can be a simple slender baton spinning end-over-end. That's stable, too. And very easy to spin-up or de-spin. For any maneuvers. Any time you want.

I would rather see us deliver close to one full gee so we know for sure the astronauts will be physically fit on arrival. We have no data (none!!) to suggest they will be fit spending the trip at 0.38 gee. One can always put a lab space at the 0.38 gee level of a spinning design to practice skills for Mars, while spending off-hours and scheduled rest periods at one full gee for health.

As for habitat volume required, that issue is actually related to gee levels and health, too. The only partial-gravity data we have is surrogate bed rest data, and it is a stretch beyond any credibility to infer from that what level of gee is therapeutic. What is certain (the ONLY thing that is certain!!) from those bed rest studies is that enforced immobility will cause disease, even in a 1 gee gravity field. That is a supremely-important result.

Therefore, there must be room inside the spacecraft to move around all day long, and to exercise. Two guys riding in a Dragon cannot do that, 1-gee tether rig or no. You just gotta have a gym. Zubrin is just plain wrong about going to Mars in a small capsule. They won't survive the whole trip, not unless you fly very, very fast (like 1-2 months one-way).

Most of our knowledge about handling water and wastewater, plus the effects of free convection effects in ventilation and fresh-air maintenance, was derived down here at 1 gee. The smart thing to do would be to take advantage of that, and simply design for pretty close to 1 gee. We already know how to handle zero-gee for "short" periods, when maneuvering, or docking, etc. But there's no need to endure that (or try to compensate for it) for long periods. Just spin the ship head-over-heels, with the habitat at one end.

It's a very fuzzy limit, but most of the aeromedical experiences we have gained over about the last half century would suggest most folks can withstand 2 to 4 rpm spin rates pretty much indefinitely. At 4 rpm, the 1 gee radius is but 56 meters. If we were to assemble the transit vehicle in LEO from docked modules, it's pretty hard to imagine such a ship under 100 m long, don't you think? Even if only two guys go.

That's not 2 guys in a Dragon on a Falcon-Heavy, by any means. But it's still something we could build, and right now, too. I think most of these direct-launch/direct-landing minimalist designs are just not realistic, because they're just not survivable scenarios for the people.

GW

louis · 2012-07-13 02:31:28

This is an interesting summation for people who are interested:

http://science.nasa.gov/science-news/sc … st02aug_1/

It seems to me as mentioned before that there is a lot of secrecy about the real effects of zero G and our ability to counteract those effects.

I had not come across the vacuum chamber device before - sounds interesting.

I would have thought as well that in terms of bone loss space medicine might potentially help a lot. Also, presumably, in terms of crew selection you would be looking for people with very dense bones and you would build up their bones on Earth before launch.

Does anyone know if any work was done with weights on the Moon?

GW Johnson · 2012-07-13 15:12:42

Louis:

As far as I remember, the only weights the lunar astronauts lifted on the moon were those 100 kg suits.

Lower body negative pressure temporarily relieves the upper body and face swelling that is typical of zero-gee body fluid redistribution. It's no real solution to anything.

The only real "secrecy" is that no one at NASA (or ESA or any of the rest) wants to admit that there is no solution to extended living in zero gee. Artificial gravity is absolutely required beyond about a year or so for sure, and beyond about 6 months, with some serious but recoverable effects. That's why ISS crews are changed out at no more than about 6-7 months. Didn't you notice that?

The other "secret" is that "they" completely failed to find out how much gee is therapeutic, after all these decades doing stuff in LEO. In other words, "they" didn't do their damned jobs for all those tax dollars we spent. "They" (all the government space agencies) do not want you to know that. The favorite-contractor corporations get tarred with the same brush: they also did nothing, choosing instead just to profit from the status quo.

The original NASA Mars mission was on the books for the 1980's. We could have sent them back then, but in 20-20 hindsight, that crew would most likely have died from microgravity disease or solar flare radiation. We actually knew how to handle all of those things by the mid 1990's, roughly.

The only remaining problem is a practical Mars lander - as evidenced by the technological troubles the JPL guys are encountering putting ever more massive rovers on the surface. You have to do something different from Viking 1/2 by the time you exceed around a landed ton or so.

GW

louis · 2012-07-14 06:53:32

GW Johnson wrote:

Louis:
As far as I remember, the only weights the lunar astronauts lifted on the moon were those 100 kg suits.
Lower body negative pressure temporarily relieves the upper body and face swelling that is typical of zero-gee body fluid redistribution. It's no real solution to anything.
The only real "secrecy" is that no one at NASA (or ESA or any of the rest) wants to admit that there is no solution to extended living in zero gee. Artificial gravity is absolutely required beyond about a year or so for sure, and beyond about 6 months, with some serious but recoverable effects. That's why ISS crews are changed out at no more than about 6-7 months. Didn't you notice that?
The other "secret" is that "they" completely failed to find out how much gee is therapeutic, after all these decades doing stuff in LEO. In other words, "they" didn't do their damned jobs for all those tax dollars we spent. "They" (all the government space agencies) do not want you to know that. The favorite-contractor corporations get tarred with the same brush: they also did nothing, choosing instead just to profit from the status quo.
The original NASA Mars mission was on the books for the 1980's. We could have sent them back then, but in 20-20 hindsight, that crew would most likely have died from microgravity disease or solar flare radiation. We actually knew how to handle all of those things by the mid 1990's, roughly.
The only remaining problem is a practical Mars lander - as evidenced by the technological troubles the JPL guys are encountering putting ever more massive rovers on the surface. You have to do something different from Viking 1/2 by the time you exceed around a landed ton or so.
GW

I am probably on a hiding to nothing given your expert knowledge GW, but here goes...

http://en.wikipedia.org/wiki/Valeri_Pol … sonal_life

Valeri spent 437 days in zero G. That's more than the time required to be in Zero G for a Mars programme. He appears to have recovered his health (still alive after nearly three decades).

Can we not improve on the technology and medicine of 1988?

Clearly we wouldn't send someone to Mars without first testing the ability of crews to survive this gruelling regime. I think if we could do a moon landing (after 6 monhts in zero G) followed by a year's stay on the Moon, after which we have another 6 months zero G before returning to Earth then we would be ready to go.

In a ten year Mars programme, you might run with Yrs 1-4 long term space flights and Yrs. 3-7 lunar simulations of Mars trip looking to give the project the green light in Yr. 7.

Clearly this approach means that the landing has to be automated I think. We might also want to look at robotic hands to help the crew weakened by months of zero G. But essentially it would be a case of 48 hours rest on landing before beginning exercises to adapt to the .38 G.

RobS · 2012-07-14 07:45:00

One problem with using the moon to practice for Mars is that you have to spend billions to develop the equipment to land there, and then you have the political fight over maintaining a presence on the moon versus making one or two brief visits. I suppose Musk could do both, but NASA clearly can't.

GW Johnson · 2012-07-14 13:02:46

I think my point is that we don’t need to “practice” for Mars (or anywhere else). We already know what we need to know.

We could have gone to Mars successfully about 20 years ago. Everything we needed to know about, was known then. Including radiation and microgravity effects. The only real limitation persisting to this very day is an effective Mars lander in the 10-100 ton dead-head payload class.

That’s about a 5 year technology development and demonstration. We already know what to do, we just haven’t done it. Mostly because of “not invented here” problems at NASA.

Microgravity is a simple problem to solve. Beyond roughly about 14 months, it becomes increasingly and essentially permanently irreversible to expose yourself to zero gee. It’s demonstrably bad enough at 6 months, that’s why ISS crews are changed out at 6-7 month intervals.

Exercise regimens make no real difference at that 12-14 month length of exposure. We already know that. There is no credible data whatsoever (!!!!) to suggest that 0.38 gee on Mars is any way therapeutic. The round-trip Mars mission is about 24 to 28 months long. So, there is NO solution space for traveling to Mars in zero-gee.

You can completely forget that concept. That way lies a dead crew.

So, spin the damned ship for artificial gee. Simple as that.

I’d suggest a 1 gee design, simply because there is no credible data whatsoever (again !!!!) to suggest that anything less is therapeutic. That’s no more than 4 rpm for no less than a 56 m radius. Basic physics. Radius times square of angular velocity equals radial (inward) acceleration.

But no “Battlestar Galactica” is required, nor is any Rube Goldberg cable tether system required. Build your ship as a slender baton from simple docked modules in LEO, and spin it end over end. Nothing hard about that at all. Something 5 m wide at 20:1 L/D is 100 m long. Stack it up in parallel to achieve 10 m wide at L/D = 20:1. 200 m long, that’s a 100 m radius at about 2 rpm on the outbound leg.

5 m wide fits or replaces a lot of the existing payload fairings we already have. Modules can ride up “naked” on existing launchers in the 20-25 ton class, or two at once on a Falcon-Heavy, very soon.

What is so hard about that?

For the lander, you just need to use low levels of retro thrust during entry to end the hypersonics at an acceptably high altitude, and perhaps low levels of retro thrust with a chute (if you choose to use one), then finally high levels of retro thrust for the final touchdown.

Take a good look at Spacex’s Dragon with the Super Draco’s installed. That’s a small 2-3 ton dead-head payload one-way (only !!) lander right there. Retro thrust is exactly what they’re doing.

Retro plume instability is solved by cant angle. Theirs (Spacex) is 45 degrees, but you don’t need that much. They did that to avoid firing a rocket plume through a hole in a heat shield. But, if you seal the engine compartment behind the heatshield to prevent throughflow, you actually can have a hole in a heatshield. Throughflow is death (Columbia 2003). No throughflow is a static gas column, the best insulator we know. We already did this ca. 1970 with Gemini-B for the MOL test flight.

Radiation is not a problem if you use a “real” habitat module for the interplanetary transits. 20 cm of water (or wastewater) stops solar flares. End of problem. You have to have water and wastewater tanks anyway. So position them as radiation shielding. At least around the flight deck as your radiation shelter.

The cosmic ray stuff at 60 REM/yr max is very close to our current “acceptable limit” for astronauts of 50 REM/yr, even in a peak radiation year. The min exposure is 24 REM/yr. Varies sinusoidally with time during the sunspot cycle. There is a career limit, which is violated in a second flight to Mars, if conducted in a peak radiation year.

All these things have been known since about 1990 or so. As I said, we could have gone to Mars about 20 years ago.

GW

louis · 2012-07-14 14:33:07

RobS wrote:

One problem with using the moon to practice for Mars is that you have to spend billions to develop the equipment to land there, and then you have the political fight over maintaining a presence on the moon versus making one or two brief visits. I suppose Musk could do both, but NASA clearly can't.

I think for this purpose you can follow the Apollo template more or less.

GW Johnson · 2012-07-14 14:50:28

I just posted the atmospheric entry model I am going to use, all updated and checked out, over at "exrocketman". Anybody with access to a spreadsheet program can do this. The dynamics portion is OK as it is, and was since 1956.

For the heating effects, I updated this to an integrated total instead of the crude closed-form estimate, and I corrected the convective stagnation-point heat flux correlation from something published recently that was in error. I still have no radiation heating model, but if you triple the convective values, you should be "in the ballpark".

GW

http://exrocketman.blogspot.com see article dated 7-14-12

louis · 2012-07-14 14:52:07

GW Johnson wrote:

I think my point is that we don’t need to “practice” for Mars (or anywhere else). We already know what we need to know.
We could have gone to Mars successfully about 20 years ago. Everything we needed to know about, was known then. Including radiation and microgravity effects. The only real limitation persisting to this very day is an effective Mars lander in the 10-100 ton dead-head payload class.
That’s about a 5 year technology development and demonstration. We already know what to do, we just haven’t done it. Mostly because of “not invented here” problems at NASA.
Microgravity is a simple problem to solve. Beyond roughly about 14 months, it becomes increasingly and essentially permanently irreversible to expose yourself to zero gee. It’s demonstrably bad enough at 6 months, that’s why ISS crews are changed out at 6-7 month intervals.
Exercise regimens make no real difference at that 12-14 month length of exposure. We already know that. There is no credible data whatsoever (!!!!) to suggest that 0.38 gee on Mars is any way therapeutic. The round-trip Mars mission is about 24 to 28 months long. So, there is NO solution space for traveling to Mars in zero-gee.
You can completely forget that concept. That way lies a dead crew.
So, spin the damned ship for artificial gee. Simple as that.
I’d suggest a 1 gee design, simply because there is no credible data whatsoever (again !!!!) to suggest that anything less is therapeutic. That’s no more than 4 rpm for no less than a 56 m radius. Basic physics. Radius times square of angular velocity equals radial (inward) acceleration.
But no “Battlestar Galactica” is required, nor is any Rube Goldberg cable tether system required. Build your ship as a slender baton from simple docked modules in LEO, and spin it end over end. Nothing hard about that at all. Something 5 m wide at 20:1 L/D is 100 m long. Stack it up in parallel to achieve 10 m wide at L/D = 20:1. 200 m long, that’s a 100 m radius at about 2 rpm on the outbound leg.
5 m wide fits or replaces a lot of the existing payload fairings we already have. Modules can ride up “naked” on existing launchers in the 20-25 ton class, or two at once on a Falcon-Heavy, very soon.
What is so hard about that?
For the lander, you just need to use low levels of retro thrust during entry to end the hypersonics at an acceptably high altitude, and perhaps low levels of retro thrust with a chute (if you choose to use one), then finally high levels of retro thrust for the final touchdown.
Take a good look at Spacex’s Dragon with the Super Draco’s installed. That’s a small 2-3 ton dead-head payload one-way (only !!) lander right there. Retro thrust is exactly what they’re doing.
Retro plume instability is solved by cant angle. Theirs (Spacex) is 45 degrees, but you don’t need that much. They did that to avoid firing a rocket plume through a hole in a heat shield. But, if you seal the engine compartment behind the heatshield to prevent throughflow, you actually can have a hole in a heatshield. Throughflow is death (Columbia 2003). No throughflow is a static gas column, the best insulator we know. We already did this ca. 1970 with Gemini-B for the MOL test flight.
Radiation is not a problem if you use a “real” habitat module for the interplanetary transits. 20 cm of water (or wastewater) stops solar flares. End of problem. You have to have water and wastewater tanks anyway. So position them as radiation shielding. At least around the flight deck as your radiation shelter.
The cosmic ray stuff at 60 REM/yr max is very close to our current “acceptable limit” for astronauts of 50 REM/yr, even in a peak radiation year. The min exposure is 24 REM/yr. Varies sinusoidally with time during the sunspot cycle. There is a career limit, which is violated in a second flight to Mars, if conducted in a peak radiation year.
All these things have been known since about 1990 or so. As I said, we could have gone to Mars about 20 years ago.
GW

If it's simple to solve zero G then of course I am in favour - but they said the Space Shuttle was a simple business! We've never actually tried doing it and I imagine there must be some issues to do with mass distribution.

I guess I'd be happier if I'd ever heard Elon Musk mention it as part of his solution.

Regarding the therapeutic nature of 0.38 G, don't you think with properly distributed lead weights we can certainly reverse bone loss?

GW Johnson · 2012-07-14 16:46:37

Louis:

"Regarding the therapeutic nature of 0.38 G, don't you think with properly distributed lead weights we can certainly reverse bone loss?"

Nope. I don't. There are no credible data to support that notion, widespread as it seems to be.

GW

RobS · 2012-07-14 21:03:17

Of course, there is also no data to the contrary, since we can't do experiments in partial gee that last more than about 30 seconds!

louis · 2012-07-15 07:16:17

RobS wrote:

Of course, there is also no data to the contrary, since we can't do experiments in partial gee that last more than about 30 seconds!

Quite. But there is good evidence that stressing exercises in zero G can retard bone loss and keep up muscle strength, so it is a reasonable hypothesis I think that using weight attachments on the limbs head and torso on the Moon or Mars would have an even greater effect.

SpaceNut · 2012-07-15 09:46:05

Wow research of iss bone lose experiments and exercise was not all that hard and it brought back these cases...
ISS Experiment Finds Osteoporosis Drugs Counteract Bone Loss have confirmed that osteoporosis drugs can actively prevent osteoporosis-like symptoms that astronauts suffer on long-term missions.

The research on ISS crew began in 2009, with the weekly oral administration of 70 mg of alendronate (Fosamax), a counter biphosphonate, to five astronauts. The subjects, including astronauts Koichi Wakata and Soichi Noguchi, started by taking three doses before going to the ISS. Some astronauts also received a single 4 mg intravenous zolendronic acid dose 45 days before the flight. The astronauts’ bone mass was then monitored and the results were finally compared with those of 14 astronauts who had not taken Fosamax.
The results showed a significant difference between the two groups of astronauts. The average bone density loss for the astronauts who did not take Fosamax was 7% in the femur and 5% in the hip bone. In contrast, the five astronauts on the counter biphosphonate, had an average loss of 1% in the femur and, surprisingly, a 3% increase in the hip bone, with very low Calcium level in their urine. However, it was noted that the drug’s effectiveness was reduced the longer it was taken.

Bone Loss & Exercise

To help prevent bone loss, it is best that you work out daily and strength-train a few days a week. The University of Arizona College of Public Health recommends 30 minutes of weight bearing exercise per day for the best results.

ISS Experiments by Expedition

GW Johnson · 2012-07-15 14:03:02

Go look at this news article, and you will understand what I said in other posts about bloated contractors and bloated government agencies. You have to read between the lines, though. Not even the reporters who wrote the article truly understand why this happened. Or what it really means.

http://www.msnbc.msn.com/id/3033063/ns/ … nce-space/

It’s very sad these ex-shuttle folks are caught in the middle. But, working in defense contracting, in a second/third tier vendor, I never had a $100K/yr job, either. Not like those NASA folks. Although I did make a comfortable salary, not seen by me again since the defense plant where I worked got closed by corporate politics-for-profit, and in egregious error at that.

Teaching college is far less than half of that salary. Teaching high school is less than a quarter. I’ve done both, since the defense jobs ended in these parts. But, we’re still alive. We might even get to retire in 5 years or so, no thanks to the defense industry, but due to our own efforts, and no small measure of good luck.

There has to be a coordinated plan for space exploration, and the necessary oversight to prevent contractor and agency bloat. The US Congress provided neither, not in 50 years. What a bunch of incompetents and malfeasants!

THAT is why the NASA we have today is not the NASA of 1959.

THAT is why the NASA of today cannot send men to Mars, even though the knowledge and most of the technology to do so, existed as far back as about 1990.

THAT is why it appears a private outfit like Spacex seems more likely to go to Mars, if anybody ever goes at all. Very sad, that outcome. Especially since it is the role of government to explore, and business to exploit, not the other way round.

THAT is why I say the things I say.

GW

louis · 2012-07-15 14:28:40

GW Johnson wrote:

Go look at this news article, and you will understand what I said in other posts about bloated contractors and bloated government agencies. You have to read between the lines, though. Not even the reporters who wrote the article truly understand why this happened. Or what it really means.
http://www.msnbc.msn.com/id/3033063/ns/ … nce-space/
It’s very sad these ex-shuttle folks are caught in the middle. But, working in defense contracting, in a second/third tier vendor, I never had a $100K/yr job, either. Not like those NASA folks. Although I did make a comfortable salary, not seen by me again since the defense plant where I worked got closed by corporate politics-for-profit, and in egregious error at that.
Teaching college is far less than half of that salary. Teaching high school is less than a quarter. I’ve done both, since the defense jobs ended in these parts. But, we’re still alive. We might even get to retire in 5 years or so, no thanks to the defense industry, but due to our own efforts, and no small measure of good luck.
There has to be a coordinated plan for space exploration, and the necessary oversight to prevent contractor and agency bloat. The US Congress provided neither, not in 50 years. What a bunch of incompetents and malfeasants!
THAT is why the NASA we have today is not the NASA of 1959.
THAT is why the NASA of today cannot send men to Mars, even though the knowledge and most of the technology to do so, existed as far back as about 1990.
THAT is why it appears a private outfit like Spacex seems more likely to go to Mars, if anybody ever goes at all. Very sad, that outcome. Especially since it is the role of government to explore, and business to exploit, not the other way round.
THAT is why I say the things I say.
GW

Interesting points!

I don't think there's any doubt at all about what Musk's objective is and Space X, with all the orbital missions, is simply a vehicle to establishing humanity on Mars, which Musk rightly sees as an event on a par with the discovery of fire or the neolithic revolution. So I am sure it will happen because, as you say, it is possible.

I've nothing against the NASA salaries, but a lot against the prioritisation and the way they let scientific objectives dominate over what one might call "cultural" objectives (i.e. establishing humanity on the Moon and on Mars).

louis · 2012-07-15 14:31:39

SpaceNut wrote:

Wow research of iss bone lose experiments and exercise was not all that hard and it brought back these cases...
ISS Experiment Finds Osteoporosis Drugs Counteract Bone Loss have confirmed that osteoporosis drugs can actively prevent osteoporosis-like symptoms that astronauts suffer on long-term missions.
The research on ISS crew began in 2009, with the weekly oral administration of 70 mg of alendronate (Fosamax), a counter biphosphonate, to five astronauts. The subjects, including astronauts Koichi Wakata and Soichi Noguchi, started by taking three doses before going to the ISS. Some astronauts also received a single 4 mg intravenous zolendronic acid dose 45 days before the flight. The astronauts’ bone mass was then monitored and the results were finally compared with those of 14 astronauts who had not taken Fosamax.
The results showed a significant difference between the two groups of astronauts. The average bone density loss for the astronauts who did not take Fosamax was 7% in the femur and 5% in the hip bone. In contrast, the five astronauts on the counter biphosphonate, had an average loss of 1% in the femur and, surprisingly, a 3% increase in the hip bone, with very low Calcium level in their urine. However, it was noted that the drug’s effectiveness was reduced the longer it was taken.

Bone Loss & Exercise
To help prevent bone loss, it is best that you work out daily and strength-train a few days a week. The University of Arizona College of Public Health recommends 30 minutes of weight bearing exercise per day for the best results.

ISS Experiments by Expedition

Thanks for that interesting info. It seems that the issue of bone loss has been tamed if not entirely overcome. Of course there are other health effects of microgravity but I think they are all probably manageable.

I myself see dangers in getting diverted into artificial G technology if we have addressed the health effects.

Impaler · 2012-07-16 02:22:43

Be vary wary on that Bone-lose study. First off the problem is BONE STRENGTH not density, for a long time people assumed low density and high fracture risk were synonymous and just simple cause and effect. Thus the focus on drugs that in a rather crude and unnatural way increase density by directly interfering with the bodies bone mineral breakdown. But Bone is (thank goodness) not just a lump of Chalk, its a complex lattice structure and its strength is nearly ALL is it's complex protein-mineral micro-structure.

Thus it should really come as no big shock that this artificial interruption in the normal bone cycle actually weakens the bones rather then strengthens it. Their is in fact a BIG fall-out and liability here in drugs that were advertized to 'fix osteoporosis' but which did no such thing because the erroneous conflation of bone density and bone strength.

The Drug in this ISS study (Fosamax) is exactly the drug that has now been massively discredited by findings of higher rates of crippling Femur fractures when taken for long periods, and it's now recommended that only people suffering severe osteoporosis be put on the drug and even then only for short periods. Astronauts might be such a group ware the benefits outweigh the risks but its FAR from proven.

http://articles.mercola.com/sites/artic … tures.aspx

We are basically still at square-1 when it comes to drug-based solutions to the bone lose problem in Space, if anything I expect that we will find non-drug control methods like diet, exercise and various mechanical vibrations/stresses and particularly the selection of the best 'bone retaining' astronauts selected from ISS stays (like anything we would expect some individuals to be genetically more resistant) as the best solution for assembling a longer duration crew that must live in zero-g. This is not to say artificial gravity is wrong/bad/stupid, just that drugs are not the silver bullet some claim they are.

At a minimum will also need to learn of a way to actually medically scan and determine the TRUE strength of a persons bones (non destructively of course) and and move away from false proxies like density.

As usually it will be ground based research that helps us in Space via 'trickle up' rather then space-tech 'trickle down', NASA would probably love to do this kind of research both to protect the astronauts and to give them a really big 'useful science' feather in it's cap that it can point too every time someone says NASA is a waste of money. But the test population they have to work on is just pathetically small it would take a decade to accumulate a marginally meaningful clinical study, ware as ground based research has access to millions of test subjects, and DEEP pockets of funding to conduct such studies. Thus the ground will always innovate drugs faster then Space can, and space will always be a receiver of drug discoveries rather then a creator of them.

Last edited by Impaler (2012-07-16 02:29:03)

louis · 2012-07-16 06:05:04

Impaler wrote:

Be vary wary on that Bone-lose study. First off the problem is BONE STRENGTH not density, for a long time people assumed low density and high fracture risk were synonymous and just simple cause and effect. Thus the focus on drugs that in a rather crude and unnatural way increase density by directly interfering with the bodies bone mineral breakdown. But Bone is (thank goodness) not just a lump of Chalk, its a complex lattice structure and its strength is nearly ALL is it's complex protein-mineral micro-structure.
Thus it should really come as no big shock that this artificial interruption in the normal bone cycle actually weakens the bones rather then strengthens it. Their is in fact a BIG fall-out and liability here in drugs that were advertized to 'fix osteoporosis' but which did no such thing because the erroneous conflation of bone density and bone strength.
The Drug in this ISS study (Fosamax) is exactly the drug that has now been massively discredited by findings of higher rates of crippling Femur fractures when taken for long periods, and it's now recommended that only people suffering severe osteoporosis be put on the drug and even then only for short periods. Astronauts might be such a group ware the benefits outweigh the risks but its FAR from proven.
http://articles.mercola.com/sites/artic … tures.aspx
We are basically still at square-1 when it comes to drug-based solutions to the bone lose problem in Space, if anything I expect that we will find non-drug control methods like diet, exercise and various mechanical vibrations/stresses and particularly the selection of the best 'bone retaining' astronauts selected from ISS stays (like anything we would expect some individuals to be genetically more resistant) as the best solution for assembling a longer duration crew that must live in zero-g. This is not to say artificial gravity is wrong/bad/stupid, just that drugs are not the silver bullet some claim they are.
At a minimum will also need to learn of a way to actually medically scan and determine the TRUE strength of a persons bones (non destructively of course) and and move away from false proxies like density.
As usually it will be ground based research that helps us in Space via 'trickle up' rather then space-tech 'trickle down', NASA would probably love to do this kind of research both to protect the astronauts and to give them a really big 'useful science' feather in it's cap that it can point too every time someone says NASA is a waste of money. But the test population they have to work on is just pathetically small it would take a decade to accumulate a marginally meaningful clinical study, ware as ground based research has access to millions of test subjects, and DEEP pockets of funding to conduct such studies. Thus the ground will always innovate drugs faster then Space can, and space will always be a receiver of drug discoveries rather then a creator of them.

Thanks Impaler for that very useful clarification/update.

It seems like we are perhaps not so much further along the line.

I too was thinking that selection of crew is important. But the problem there I guess is that you run up against the safe lifetime limits on radiation exposure among astronauts.

Some people do have big strong bones - my legs just sink like a stone in the water (except for the very salty Med). I suspect the big boned tend not to be chosen as fighter pilots and the like, the sort of people who provide the astronaut intake. Perhaps we should widen the search for people who are on the small side in terms of height but big boned - think more of a weightlifter's body.

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