I hope they keep the lid very well sealed :-)

Rxke · 2014-07-02 23:53:20

Long duration experiment on ISS with fruitflies!

http://www.space.com/26411-fruit-flies- … video.html

-Fruit flies, all genetically identical, so that makes for solid science.

-they live generations in a very short time, so we will be able to see a lot: inherited degeneration, adaptations etc. etc.

-The kicker: they will have a 1 g centrifuge to allow a subset of flies to live in 1 g!

JoshNH4H · 2014-07-03 12:11:58

I'd like to see a centrifuge operating at, say, 40% of a g too. Why wasn't that included?

GW Johnson · 2014-07-03 16:05:43

"Why wasn't that (a centrifuge at fractional gee) included?"

Because no one at NASA wants to, or will ever, admit that not doing fractional gee studies in LEO was a major mistake in judgement and management.

Further proof they really have no intentions (yet) of flying humans to Mars. Or anywhere else beyond cis-lunar space.

GW

JoshNH4H · 2014-07-03 17:30:44

On the other hand, it shouldn't be too big challenge to only spin the centrifuge at about 60% of the speed to generate Martian gravity instead of terran

idiom · 2014-07-03 18:05:38

Maybe they are scared of the result?

What if 0.8 G turns out to be just as bad as 0 G?

Better not to know. Science is dumb. And scary.

Rxke · 2014-07-04 07:00:31

JoshNH4H wrote:

I'd like to see a centrifuge operating at, say, 40% of a g too. Why wasn't that included?

hoping that will be its extended mission, no?
i mean, it would be a pity if they didn't keep using it after the planned tests were done.

JoshNH4H · 2014-07-04 09:36:44

Perhaps we should contact the research team and see!

SpaceNut · 2014-07-04 19:56:28

How do you strap a fruit fly down to feel the 1 g as when they are flying they will see none of it.....

JoshNH4H · 2014-07-04 21:12:49

Presumably the air will be moving at the same speed as the walls, and thus anything moving the same speed as the air (flies will, more or less) will also feel gravitational force

Rxke · 2014-07-05 01:18:28

SpaceNut wrote:

How do you strap a fruit fly down to feel the 1 g as when they are flying they will see none of it.....

My mind just melted trying to figure that out

Josh's answer made it even worse, I tried imagining flying in such an environment... Those poor flies won't know what happens to them, center or outer circumference of centrifuge will have different pseudogravity, wow, try to fly in that kind of environment....

GW Johnson · 2014-07-05 17:32:58

Aw, it's not hard to figure out. With spin gravity, the centrepital acceleration is a force field dependent only on radius R from the spin center. What that means is there is a significant gee gradient with R, directly proportional to spin rate, which is the only difference between what happens in a smallish centrifuge versus what we experience down here. Down here, R is measured in 1000's of km and spin rate is a very, very small number, so we are unaware of the (otherwise inherent) gradient.

With small medical centrifuges, the gee gradient is considerable, so the fruit flies may well be confused by it. So would people, so the Kibo centrifuge module for ISS that was cancelled might not be the best design. At this point, who knows? There is precisely zero experience with it.

But! We know that untrained civilians can tolerate 3, at most 4, rpm for a spin rate. Using that 4 rpm figure, the radius R for 1 full gee is 56 m. That has a fairly-low gee gradient, too!

That's too big a radius to spin a ship about its long axis for anything but a gigantic nuclear explosion-propulsion colonization ship. But it is quite reasonable for a slender baton configuration spun end-over-end. That's a configuration seen as extremely stable in every Friday night football game all across America (baton twirlers throwing spinning batons high in the air), in spite of the fact that NASA has never looked at it.

That implies a ship design around 120 m long with a departure weight around 300 to 900 tons. Big, but definitely not "Battlestar Galactica".

Your habitat is at one end, your engines at the other, and the "structure" in between is your propellant tankage, which you have to carry anyway. How simple is that concept? Why in the hell would we ever need either a truss (massive inert weight gain) or a cable-connected structure (multiple single-point failure modes)? Those are all that NASA ever looked at.

GW

NC Martian · 2015-02-24 22:22:20

" Study of the flies will give researchers more understanding on how long-duration spaceflight will effect
humans. "

Yes.

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#1 2014-07-02 23:53:20

I hope they keep the lid very well sealed :-)

#2 2014-07-03 12:11:58

Re: I hope they keep the lid very well sealed :-)

#3 2014-07-03 16:05:43

Re: I hope they keep the lid very well sealed :-)

#4 2014-07-03 17:30:44

Re: I hope they keep the lid very well sealed :-)

#5 2014-07-03 18:05:38

Re: I hope they keep the lid very well sealed :-)

#6 2014-07-04 07:00:31

Re: I hope they keep the lid very well sealed :-)

#7 2014-07-04 09:36:44

Re: I hope they keep the lid very well sealed :-)

#8 2014-07-04 19:56:28

Re: I hope they keep the lid very well sealed :-)

#9 2014-07-04 21:12:49

Re: I hope they keep the lid very well sealed :-)

#10 2014-07-05 01:18:28

Re: I hope they keep the lid very well sealed :-)

#11 2014-07-05 17:32:58

Re: I hope they keep the lid very well sealed :-)

#12 2015-02-24 22:22:20

Re: I hope they keep the lid very well sealed :-)

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