[removed]

One common issue with most astronauts in zero g is that they tend to lose or lessen their sense of smell and taste. This causes them to crave spicier food more while on the ISS than when on Earth.

Here's an article about the topic

In summary, with blood and fluids not being pulled down by gravity, your head tends to be more full of fluids than normal, and it feels like a mild cold congestion all the time. This doesn't seriously impact your digestion or anything, but is just a minor annoyance. Keeping morale high on stressful missions is important, so having good spicy food in space is still important.

>with blood and fluids not being pulled down by gravity, your head tends to be more full of fluids than normal, and it feels like a mild cold congestion all the time.

I'd be interested in knowing what is the minimum G you need to avoid this. Creating 1G in space via spinning is very problematic, but making .05G would be easy. Would it help?

This issue isn't fully understood, and would be tough to reproduce outside of space flight. From reports I've read it takes up to a full 24 hours of being in zero G before the effect kicks in. That would be too long to simulate in most experiments on Earth ( such as on parabolic flights which give zero G in bursts of like 30 seconds). Personally I doubt you would need a full 1 G to mitigate this smell and taste issue, but realistically if you were going to use rotational simulated gravity, you would want something closer to a full 1G for the other benefits (such as keeping up bone density and muscle mass).

Wouldn't patients lying flat in bed all day experience a similar issue?

[removed]

We just don't know. There are no facilities that can produce extended hypogravity to study those longer-term effects. Honestly I think that would be as good a reason as any to construct a spin-gravity space station capable of up to 1 g: Conduct a study to see how much gravity is required for humans to stay healthy. Because if we are going to make permanent settlements on the Moon or on Mars, I think we should probably figure out beforehand if a third or a sixth of Earth's gravity is enough for humans.

[removed]

Longest stay on the moon was 75 hours, anybody know if they mentioned their sinus clearing during that time?

Ever wondered why airline meals seem to taste bland? Ask an airline meal chef about loss of taste on passenger flights. I'm sure it's not the same issue as spaceflight but a long haul flight also affects your sense of taste and smell. A good thing when you consider all the farts unleashed during those flights too.

That's a great question - our gut is a super interesting system, and microgravity does affect it in some ways, though obviously it still works up there.

One thing that's important to note is that your intestines are long, and honestly kind of all over the place. We're talking around 7 meters (20+ ft), going down, sideways, and sometimes up. Between that and the fact that we digest laying down a lot of the time, one realises that gravity pushing that food down isn't really the main driving force. What does most of that job is layers of smooth muscle, that contracts and pushes things along without you even being conscious of it. So the fact that things float up there is not a huge deal.

But lack of gravity does tend to do things to fluids, however. With gravity, they typically settle pretty well, with gases coming back up and separating from the liquids pretty cleanly. Since liquids also become floaty blobs in space, that stops being the case. This means that our usual ways of expelling gases - burping and farting - may stop just expelling gases. Notably, burps often come up with what feel like acid reflux, and, well, one shouldn't trust a fart in space (Google Apollo 10 floating turd for an interesting tidbit).

Another thing of note is that for many astronauts, arrival in space can be accompanied by space sickness, usually nausea, vomiting and a generally upset tummy. This is a digestive issue too, but one mainly caused by the sensory adjustment to space.

Only very slightly. I read a study on this, and they found that the effect is almost too small to measure, affecting only odors that were barely perceptible in the first place.

This might be because it's nearly impossible for a person to be truly flat and immobile for long enough. They'll turn their head, lift it sightly from the pillow, etc., and even small shifts like that would affect fluid movements.

The amount of nausea and accompanied actually being sick is is officially known as space adaptation syndrome , but is unofficially measured on a scale known as the Garn Scale. The units range from 0 to 1 "Garn", where 1 Garn is as sick as an astronaut could possibly get.

The name comes from Republican Senator Jake Garn, the first sitting member of congress to go to space. He flew on STS-51-D as a payload specialist and as a subject on an experiment regarding space adaptation syndrome, and he didn't disappoint: he was so ill throughout the 167 hours of his mission that, ever since, astronauts coined the Garn Scale after him!

[removed]

[removed]

Having good spicy food in space would unlock the final achievement in my life.

[removed]

[removed]

[removed]

What about the Moon? Did astronauts there experienced such symptoms or not?

The problem with aircraft is that the cabin air is very dry, (bleed air from the engines that has been run through airconditioning packs and is at least partly recycled). This dries out the mucous membranes in the nose, which in turn dulls your sense of smell.

Your sense of taste isn't standalone - it depends heavily on your sense of smell. So with that missing/impaired, food will taste bland or even entirely different to how it does on the ground.

Come to think of it, this may also be a factor in the ISS as well as the congestion problems they have. It would be interesting to know if they have humidifiers on board up there.

::Edit:: Yes they do, sort of! it's the Temperature and Humidity Control (THC) subsystem of the Environmental Control and Life Support System (ECLSS).

> ...gravity pushing that food down isn't really the main driving force. What does most of that job is layers of smooth muscle, that contracts and pushes things along without you even being conscious of it.

For anyone who wants to know more, this process is known as peristalsis.

Certain neurological conditions (e.g. Paralytic Ileus) can impact it and the results of this certainly prove that gravity doesn't play much of a part in the movement of food through the gut.

yeah, that's what happened in Skylab1.
The spider food got loose that the crew said F!-that, let it burn up in re-entry!

[removed]

If they did, it was probably due to the exposure to 0G for a few days before even getting there. The moon has gravity so we could assume that would prevent such things from occurring. A question this brings me to is how long does it take to fully regain those senses? Would the short time on the moon under some amount of gravity bring the senses right back or does it take time? On top of that, was this an effect we even understood when we were still putting people on the moon or was that too short of a time to really observe this?

[removed]

I recently attended a presentation by Tim Peake (a UK astronaut) and, as well as the more commonly known issue of reduced sense of taste and smell, the other issue with eating in space is that you quickly feel full as gravity isn't pulling the food down to the bottom of the stomach so triggers the 'full' feeling and you have to get used to ignoring it.

Surprisingly though, you don't need gravity for your body to pull food down to your stomach when you swallow it.

Saw a video a while ago where an astronaut talks about the hassle of doing your business in space. Apparently you have to be really aware of your bowels because gravity isn't pulling on the waste and you don't get that feeling of "it's time to go" as strongly.

More generally, just knowing what I know about how the body works. Digestion is just a bunch of muscly tube shoving nutrients around. It's not as gravity dependent as you'd think. Might make your guts feel funky but doesn't affect a whole lot.

[removed]

That's what I wonder if anyone did any research while they were on the surface of the Moon or were they just too busy keeping astronauts alive :)

0.1 G would cause dirt and water to go down to the floor. That might make cleaning easier.

I’d guess they were quite focused on the mission, but there could have been observations made about this issue regardless.

[removed]

That’s because the esophagus uses a snake like motion to pull food down to your stomach. This is so the chance of the food going to the lungs is lessened.

[removed]

Not the digestive system, but I was pretty shocked when our Dutch astronaut Andre Kuipers told that because of the lack of gravity you have a permanent feeling of a heavy cold with mucus flying free in your cavities.

I thought do you even feel good up there?

[removed]

On the bright side he says he would do it again because it was his dream to go to space

Has any airline ever tried a humidifier? Seems too simple to not have thought of.

[removed]

[removed]

The corrosion was my thought as well. The other reasons make sense to me as well. And go figure the private flights have figured it out haha.

[removed]

[removed]

[removed]

The gravity exerted on astronauts in the ISS is about 90% of what it exerts to a human at sea level. Being in orbit, the ISS and the astronauts in it are always falling.

Your question isn’t about the lack of gravity, rather it is asking about how the digestive system works in freefall.

[removed]

[removed]

[removed]

Reading up on how quadriplegics cope with a lack of body movement while still eating whole foods is quite interesting.

[removed]