Astronaut Scott Kelly on the devastating effects of a year in space

[Winston]

NASA astronaut Scott Kelly spent a year in space. His recollections of this unprecedented test of human endurance, and the physical toll it took, raise questions about the likelihood of future travel to Mars.

Edited extract from "Endurance: A Year in Space, A Lifetime of Discovery" by Scott Kelly, to be published on October 19, 2107

https://www.theage.com.au/good-week...fects-of-a-year-in-space-20170922-gyn9iw.html

 

[soopirV]

NASA astronaut Scott Kelly spent a year in space. His recollections of this unprecedented test of human endurance, and the physical toll it took, raise questions about the likelihood of future travel to Mars.

Edited extract from "Endurance: A Year in Space, A Lifetime of Discovery" by Scott Kelly, to be published on October 19, 2107

https://www.theage.com.au/good-week...fects-of-a-year-in-space-20170922-gyn9iw.html

That's a fascinating read, thanks for sharing!

 

[RocKiteman]

I agree - THANKS for sharing!

I DO NOT want to seem flippant when I make this comment, but it seems to me that the solution to this problem is well illustrated by the U.S.S. DISCOVERY from 2001: A Space Odyssey. Namely, SOME FORM of rotation to simulate gravity.

Due to the engineering required to design a system for this, I do not know if a rotating internal centrifuge, a rotating external centrifuge, or just spinning the entire spacecraft in some fashion will be the method used. But travelling on interplanetary missions without some form of simulated gravity seems out of the question.

 

[Peartree]

I agree - THANKS for sharing!

I DO NOT want to seem flippant when I make this comment, but it seems to me that the solution to this problem is well illustrated by the U.S.S. DISCOVERY from 2001: A Space Odyssey. Namely, SOME FORM of rotation to simulate gravity.

Due to the engineering required to design a system for this, I do not know if a rotating internal centrifuge, a rotating external centrifuge, or just spinning the entire spacecraft in some fashion will be the method used. But travelling on interplanetary missions without some form of simulated gravity seems out of the question.

I don't recall the exact figures, but I vaguely recall seeing why it was clearly NOT trivial to do such a thing. It had to do with the size of the rotating structure that was needed to a) provide sufficient habitable space, b) rotational forces wouldn't be unpleasant or deadly to the astronauts, and c) large enough so that the forces of rotation were not too great for the normal strength of materials to make such a structure physically possible. In the end, the structure necessary was staggeringly large and far surpassed anything we have ever even considered constructing in space. That, in turn, made it prohibitively difficult/expensive to propel such a large structure/mass through space.

 

[Dugway]

This link is an ad for a book and most of it describes how he was doing 48 HOURS after returning home. Astronauts that spend even a couple months in space face similar challenges for a number of days after returning. In an interview with Kelly from last month:

Do you think humans can last long enough in space to get to Mars?

Yes. It will take something like 200 days to get there, then you spend a year on the surface, then it’s 200 days to get back. I think we can do that. The real challenge is going to be when you want to keep people in space for a couple of years...

https://www.wired.com/story/astronaut-scott-kelly-explains-how-the-iss-is-like-harris-county-jail/

 

[RocKiteman]

I don't recall the exact figures, but I vaguely recall seeing why it was clearly NOT trivial to do such a thing.

I was NOT trying to suggest it was otherwise....

 

[Peartree]

This link is an ad for a book and most of it describes how he was doing 48 HOURS after returning home. Astronauts that spend even a couple months in space face similar challenges for a number of days after returning. In an interview with Kelly from last month:

Do you think humans can last long enough in space to get to Mars?

Yes. It will take something like 200 days to get there, then you spend a year on the surface, then it’s 200 days to get back. I think we can do that. The real challenge is going to be when you want to keep people in space for a couple of years...

https://www.wired.com/story/astronaut-scott-kelly-explains-how-the-iss-is-like-harris-county-jail/

Isn't 200 days there, 200 days back, and a year on the surface still more than two years? I guess the assumption is that the year on Mars at 1/3 gravity will be better than weightlessness in space. The problem is that we really have no idea whether that's true or not.

 

[Peartree]

I was NOT trying to suggest it was otherwise....

Sorry, I didn't mean to suggest that you did. I was just emphasizing that it isn't as easy as it sounds. I've heard people say, "Well, just make a spinning thingy like in the movies and make "artificial gravity." It sounds simple, but we're not even remotely close to being able to do that yet.

 

[dhbarr]

Great discussion, makes me wonder how much more gravity one gets on the Tharsis volcanoes vs., say, one of the poles.

 

[RocKiteman]

Sorry, I didn't mean to nsuggest that you did..

No problemo. I just seem to have a talent for wording things the wrong way...《grin》

I've heard people say, "Well, just make a spinning thingy like in the movies and make "artificial gravity." It sounds simple, but we're not even remotely close to being able to do that yet.

"...just make a spinning thingy..." :lol:

 

[hornet driver]

In practical terms the rotating space station makes little sense--in today's terms. If you choose to be in a 1 g environment and be comfortable(no nausea, side effects, or adaptations) The station needs to be -at minimum--about 750 ft in radius. That's almost 2 revolutions per minute at a speed of around 105 mph. 1 rotation per minute makes the ring 2900+ ft in radius at 209 mph. And to get really comfortable at 1/2 rotation per minute the darn thing needs to be 11,735 ft in radius and rotating at 418 mph! On top of that the whole thing needs to be balanced! That includes the folks on board moving around. Technically it's well within our grasp but financially and just from a practical point of view it's a pipe dream! It would have to be a robust /heavy structure. Just rotating it to those speeds would put tremendous stress on the structure--although this could be done slowly.Plus the whole thing will want to fly apart. A ring solves this problem somewhat from a structural point of view A spoked structure,( no ring) presents it's own set of problems and minimizes usable space. The simple task of lofting all this weight into space at several hundreds of thousands of dollars/lbs and then assembly makes it a fantasy! Once you did get it built , just maneuvering the giant gyroscope would be interesting at best. Having tethered habitats has it's own set of problems on top of the ones already mentioned. Yea, I guess until we learn to manipulate gravity or at best design a ship that can accelerate at somewhere near 1 g( by the way, you have to decelerate at 1 g when you get where your going) we are stuck with what we have. But, it's cool to think about!

 

[Bat-mite]

I used to think of the problem with low gravity as simply being that you lose muscle mass by not having to resist gravity externally. But then I learned that your internal organs also rise up inside your chest cavity, your excrement doesn't naturally descend to your rectum, your blood circulation is affected, and the list goes on and on. Our bodies were designed to need gravity. It will be quite a challenge to overcome that, but perhaps not impossible.

 

[rcktnut]

I'm sure as far as a trip to Mars goes, lack of or reduced gravity is the least of worries. Lots of other "nasties" to consider. IMO Mars is possible, other than that nowhere else to go. No need for artificial gravity. I think we should spend more time and money taking care of our earth rather than trying to leave it.

 

[Winston]

My view - send robotic probes everywhere and especially places where life might exist (liquid water) for the same total cost as perhaps one interplanetary manned program. Once something very promising is found send a sample and return mission - the 2020 Mars lander will collect and encapsulate such samples for a possible future pickup and return mission. Once those samples show some positive indications and IF robotics have not by that time via AI and robotics advances provided adequate capabilities, send humans.

Spaceflight osteopenia

https://en.wikipedia.org/wiki/Spaceflight_osteopenia

Bone remodels in response to stress in order to maintain constant strain energy per bone mass throughout.[3] To do this, it grows more dense in areas experiencing high stress, while resorbing density in areas experiencing low stress. On Mars, where gravity is about one-third that of earth, the gravitational forces acting on astronauts' bodies would be much lower, causing bones to decrease in mass and density.[4]

Average bone loss of 1-2% was recorded in astronauts on Mir each month.[1] This is in comparison to 1–1.5% bone loss in the elderly per year, and 2–3% in postmenopausal women.

Preventing Bone Loss in Space Flight

https://www.nasa.gov/mission_pages/station/research/benefits/bone_loss.html

Radiation Remains a Problem for Any Mission to Mars
Engineers have yet to find ways to protect astronauts from cosmic rays and solar radiation

https://www.smithsonianmag.com/science-nature/radiation-remains-problem-any-mission-mars-180959092/

Manned vs. Unmanned Space Exploration (Part 1)

https://phys.org/news/2005-11-unmanned-space-exploration.html

Manned vs. Unmanned Space Exploration (Part 2)

https://phys.org/news/2005-11-unmanned-space-exploration_1.html

 

[jderimig]

In practical terms the rotating space station makes little sense--in today's terms. If you choose to be in a 1 g environment and be comfortable(no nausea, side effects, or adaptations) The station needs to be -at minimum--about 750 ft in radius.

The whole station doesn't need to rotate, only the astronaut probably just during sleeping hours. Think outside the box.

 

[burkefj]

I'm more concerned with long term exposure to cosmic radiation for that long a time, it is not very feasable to shield against that, our atmosphere does a pretty good job.

 

[gjxj]

I don't recall the exact figures, but I vaguely recall seeing why it was clearly NOT trivial to do such a thing. It had to do with the size of the rotating structure that was needed to a) provide sufficient habitable space, b) rotational forces wouldn't be unpleasant or deadly to the astronauts, and c) large enough so that the forces of rotation were not too great for the normal strength of materials ...

maybe you don't need to simulate full earth gravity. Even say 10% might alleviate many of the issues.

 

[hornet driver]

maybe you don't need to simulate full earth gravity. Even say 10% might alleviate many of the issues.

The number NASA uses is .85g as a target. Not sure where I got that number from, it was a study I read somewhere.I remember thinking why not just go for 1g.

 

[mrichhcirm]

Im probably way oversimplifying but here goes:
Two spacecraft of approximately equal mass, connevted by a tether. They will revolve around each other with the rotational axis somewhere near the middle of their tether. Not as spacious as the giant wheel station, but serviceable.

 

[hornet driver]

The tether idea solves the problem of induced gravity. On the other hand it introduces a bunch of others. The combined unit must be balanced. You have to be able to maneuver the combined unit. Each unit must be self sufficient and independent of the other. the tether has to hold the weight of both modules! It becomes more of a problem looking for answers than an answer to the problems.