clipka <ano### [at] anonymousorg> wrote:
> I think it all depends on whether you want hollywood-style space
> fighters -- that for some obscure reason are constantly firing their
> main engines anyway, and for much more obvious reasons may need to turn
> quickly -- or a real-world spaceship.
>
> A real-world spaceship will only occasionally fire /any/ engines of
> notable power at all, drifting unaccelerated most of the time, with
> plenty of time to change its attitude -- which is done mostly for
> thermal management (attitude towards the sun), scientific reasons
> (attitude towards a point of interest, though usually scientific
> instruments on a manned spacecraft will have their own degrees of
> freedom to track a POI), or to prepare for the occasional major course
> correction. To save weight there will only be a single set of engines
> for such corrections, mounted so that the array points away from the
> center of mass, usually at what is perceived as the rear end of the
> ship. Attitude changes will be done without haste, allowing for better
> fine-tuning as well as preventing any nausea-inducing effects (any that
> go significantly beyond the nausea-inducing effect of zero-g anyway).
> Actual course corrections /will/ involve notable g forces, but
> acceleration will be linear. No attitude changes will be made during
> such acceleration burns whatsoever, except possibly to actively
> stabilize the attitude(*). Any course correction procedure asking for a
> deliberate change in attitude during the acceleration burn would
> demonstrably be a waste of propellant.
>
> Docking is another matter; there, attitude is mostly kept unchanged and
> maneuvering thrusters are used for acceleration in arbitrary directions.
> But even then, such changes will be kept minute, to both keep relative
> speed low and -- again -- prevent additional nausea.
>
> For anyone interested in real-spaceflight mechanics, Kerbal Space
> Program is a highly recommended piece of software.
>
>
> (* Spacecraft with continuous-thrust engines like ion drives are an
> exception, but their thrust-to-weight ratio is extremely low anyway, so
> there's not much acceleration going on that could potentially induce
> nausea.)

I don't know that it's the acceleration that's causing the nausia in the MF
example above, as much as it's the dissonance between the physically percieved
motion of the ship and the motion as relayed to the brain by the eyes.

Like when you stand on a bridge, watching the water flow benieth you, and you
get the feeling that the bridge is moving the opposite direction, except in that
case, your standing still, while on the Falcon, you'd actually be in motion, but
not in the way your eyes tell you.

For the actual physics, I'll have to trust the experts.

Regards,
A.D.B.

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Am 17.01.2016 um 07:23 schrieb Anthony D. Baye:

> I don't know that it's the acceleration that's causing the nausia in the MF
> example above, as much as it's the dissonance between the physically percieved
> motion of the ship and the motion as relayed to the brain by the eyes.

Not exactly -- it's not so much a dissonance in perceived motion as it
is a dissonance in perceived acceleration (primarily in the absence or
direction thereof) and/or perceived change in attitude. Your eyes
constitute your only sense that can perceive motion, so there cannot be
any dissonance in that, whereas acceleration and changes in attitude are
detected by both your eyes and your vestibular system (a part of the
inner ear).

> Like when you stand on a bridge, watching the water flow benieth you, and you
> get the feeling that the bridge is moving the opposite direction, except in that
> case, your standing still, while on the Falcon, you'd actually be in motion, but
> not in the way your eyes tell you.

But that just causes a weird feeling, not nausea. Your eyes may be at
dissonance with reason, but reason is presumably the highest-level
function of the brain, whereas nausea is among the most fundamental
functions, that there is no such thing as nausea from a dissonance
between perception and reason.


> For the actual physics, I'll have to trust the experts.

And who would that be?

I would have serious doubts about the "expert" status of anyone claiming
that real-world space pilots "want to turn gradually, not make a right
angle and fly off in a new direction instantly". It is certainly
well-advised to avoid excessive g forces, and there may be reasons to
avoid fast changes in attitude in preparation for a turn, but barring
that, there are in fact at least two compelling reasons to make any
actual changes in trajectory pretty sharp: (1) There is (almost) always
a single ideal point in time where the change in trajectory is least
expensive in terms of propellant use; and (2) computing the parameters
for an engine burn required to transit from one particular trajectory to
another is quite easy for sufficiently short burn times, but gets more
complicated the longer the burn takes.

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clipka <ano### [at] anonymousorg> wrote:
> Am 17.01.2016 um 07:23 schrieb Anthony D. Baye:
>
> > I don't know that it's the acceleration that's causing the nausia in the MF
> > example above, as much as it's the dissonance between the physically percieved
> > motion of the ship and the motion as relayed to the brain by the eyes.
>
> Not exactly -- it's not so much a dissonance in perceived motion as it
> is a dissonance in perceived acceleration (primarily in the absence or
> direction thereof) and/or perceived change in attitude. Your eyes
> constitute your only sense that can perceive motion, so there cannot be
> any dissonance in that, whereas acceleration and changes in attitude are
> detected by both your eyes and your vestibular system (a part of the
> inner ear).
>
> > Like when you stand on a bridge, watching the water flow benieth you, and you
> > get the feeling that the bridge is moving the opposite direction, except in that
> > case, your standing still, while on the Falcon, you'd actually be in motion, but
> > not in the way your eyes tell you.
>
> But that just causes a weird feeling, not nausea. Your eyes may be at
> dissonance with reason, but reason is presumably the highest-level
> function of the brain, whereas nausea is among the most fundamental
> functions, that there is no such thing as nausea from a dissonance
> between perception and reason.
>
>
> > For the actual physics, I'll have to trust the experts.
>
> And who would that be?
>
> I would have serious doubts about the "expert" status of anyone claiming
> that real-world space pilots "want to turn gradually, not make a right
> angle and fly off in a new direction instantly". It is certainly
> well-advised to avoid excessive g forces, and there may be reasons to
> avoid fast changes in attitude in preparation for a turn, but barring
> that, there are in fact at least two compelling reasons to make any
> actual changes in trajectory pretty sharp: (1) There is (almost) always
> a single ideal point in time where the change in trajectory is least
> expensive in terms of propellant use; and (2) computing the parameters
> for an engine burn required to transit from one particular trajectory to
> another is quite easy for sufficiently short burn times, but gets more
> complicated the longer the burn takes.

I was not claiming to have expert information on the issue.  I was simply
stating that I was not the person who would know.  What came before was simply
my perception, based more on intuition than anything else.

my apologies for my unscientific input.

Regards,
A.D.B.

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Am 17.01.2016 um 21:33 schrieb Anthony D. Baye:
> clipka <ano### [at] anonymousorg> wrote:

>>> For the actual physics, I'll have to trust the experts.
>>
>> And who would that be?
...
> I was not claiming to have expert information on the issue.  I was simply
> stating that I was not the person who would know.  What came before was simply
> my perception, based more on intuition than anything else.
> 
> my apologies for my unscientific input.

If anyone has to apologize it's me. I was under the wrong impression
that by "the experts" you meant someone who had backed your earlier ideas.

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> But that just causes a weird feeling, not nausea. Your eyes may be at
> dissonance with reason, but reason is presumably the highest-level
> function of the brain, whereas nausea is among the most fundamental
> functions, that there is no such thing as nausea from a dissonance
> between perception and reason.

Can't they just train the astronauts to not suffer from this type of 
nausea as much? Or at least have it impact their functionality less. 
Being able to launch with slightly less fuel requried seems quite a 
strong goal to me.

IIRC from a course at University on flight mechanics, there is some 
empirical function that estimates a "comfort" level for a human in a 
flying craft. It was some weighted combination of linear and rotational 
accelerations in the various axes. Presumably the people determining 
these sorts of things have access to such requirements, and it's then an 
optimisation problem to use the minimum amount of fuel for a given level 
of "comfort" for the pilots.

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>> But that just causes a weird feeling, not nausea. Your eyes may be at
>> dissonance with reason, but reason is presumably the highest-level
>> function of the brain, whereas nausea is among the most fundamental
>> functions, that there is no such thing as nausea from a dissonance
>> between perception and reason.
>
> Can't they just train the astronauts to not suffer from this type of
> nausea as much? Or at least have it impact their functionality less.
> Being able to launch with slightly less fuel requried seems quite a
> strong goal to me.

Not really.  It actually comes from the cerebellum and is pretty much a 
reflex.  Your eyes and inner ear disagree, and ever since we were 
dinosaurs, that could only mean one thing "Oh! crap, I've been 
poisoned!" and the reflex is to evacuate the toxin, by sweating and/or 
vomitting.

They teach astronauts to try to compensate for it, but it's not always 
easy, and it used to be easier just to screen them before sending them 
to outer space.  There's one (whose name escapes me at the moment) who 
had to have one of his ear nerves completely severed, making him deaf on 
that side at the same time, to resolve the issue.


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>> Can't they just train the astronauts to not suffer from this type of
>> nausea as much? Or at least have it impact their functionality less.
>> Being able to launch with slightly less fuel requried seems quite a
>> strong goal to me.
>
> Not really.  It actually comes from the cerebellum and is pretty much a
> reflex.  Your eyes and inner ear disagree, and ever since we were
> dinosaurs, that could only mean one thing "Oh! crap, I've been
> poisoned!" and the reflex is to evacuate the toxin, by sweating and/or
> vomitting.

Didn't they try various things like projecting an image onto the inner 
walls that was in sync with the actual movement. Saying that, some 
people still feel ill with the VR kit, and that's only just their head 
moving! The same inputs seem to affect different people by vastly 
different amounts.

> They teach astronauts to try to compensate for it, but it's not always
> easy, and it used to be easier just to screen them before sending them
> to outer space.  There's one (whose name escapes me at the moment) who
> had to have one of his ear nerves completely severed, making him deaf on
> that side at the same time, to resolve the issue.

Now we're talking. Sorry, we need to save 5 kg of fuel, and we can't 
have you puking each time we turn (although if you could just aim your 
puke along this axis and open the window...) so we have to take your 
inner ear out :-)

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Am 19.01.2016 um 08:43 schrieb scott:

>> They teach astronauts to try to compensate for it, but it's not always
>> easy, and it used to be easier just to screen them before sending them
>> to outer space.  There's one (whose name escapes me at the moment) who
>> had to have one of his ear nerves completely severed, making him deaf on
>> that side at the same time, to resolve the issue.
> 
> Now we're talking. Sorry, we need to save 5 kg of fuel, and we can't
> have you puking each time we turn (although if you could just aim your
> puke along this axis and open the window...) so we have to take your
> inner ear out :-)

I suspect it was more like, "Sorry, we need you to /not/ constantly puke
/all/ the time you'll be in /zero-g/, so..."

Also, I somehow suspect that this is an urban legend, where someone got
the following facts wrong:


- Alan Shepard was diagnosed with Meniere's disease during his training
for the Gemini project.

- Meniere's disease does indeed lead to false sensations of rotating,
which in turn is prone to induce nausea.

- In those days, Meniere's disease was indeed typically treated by
neurectomy, i.e. nerve cutting.

BUT:

- Meniere's disease would induce nausea regardless of g forces or
attitude changes involved. I would even reckon that the human brain
might adapt over time.

- Besides inducing nausea, false sensations of rotating would really
mess up your ability to safely pilot an aircraft (and, by extension, at
least from the reasoning of that time, a spacecraft), which would have
been much more of a concern for the Gemini 3 mission. So Alan Shepard
did not undergo treatment to prevent constant puking (because hey, that
was expected to be part of the deal for /anyone/) but to restore his
ability to properly judge changes (or absence thereof) in his
spacecraft's attitude.

- The nerve-cutting procedure to manage Meniere's disease would
apparently only involve the portion of the ear nerve responsible for
relaying orientation and acceleration information, while leaving hearing
intact.

- Meniere's disease does involve impaired hearing anyway.

- Ultimately, Alan Shepard did /not/ have any of his ear nerves cut, and
instead underwent a brand new and entirely different procedure, to be
fitted with a so-called endolymphatic shunt to drain excess fluid from
his inner ear.

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>>> Can't they just train the astronauts to not suffer from this type of
>>> nausea as much? Or at least have it impact their functionality less.
>>> Being able to launch with slightly less fuel requried seems quite a
>>> strong goal to me.
>>
>> Not really.  It actually comes from the cerebellum and is pretty much a
>> reflex.  Your eyes and inner ear disagree, and ever since we were
>> dinosaurs, that could only mean one thing "Oh! crap, I've been
>> poisoned!" and the reflex is to evacuate the toxin, by sweating and/or
>> vomitting.
>
> Didn't they try various things like projecting an image onto the inner
> walls that was in sync with the actual movement. Saying that, some
> people still feel ill with the VR kit, and that's only just their head
> moving! The same inputs seem to affect different people by vastly
> different amounts.
>

Possible.  however, our inner ear has been used to gravity for millions 
of years.  it's not always obvious what it feels in micro-gravity,  and 
sometimes, both ears apparently feel different, as my ex-girlfriend told 
me after flying on the "vomit-comet" once.  so you can't really project 
something diffferent for each astronaut, even less for each eye of the 
same astronaut.

>> They teach astronauts to try to compensate for it, but it's not always
>> easy, and it used to be easier just to screen them before sending them
>> to outer space.  There's one (whose name escapes me at the moment) who
>> had to have one of his ear nerves completely severed, making him deaf on
>> that side at the same time, to resolve the issue.
>
> Now we're talking. Sorry, we need to save 5 kg of fuel, and we can't
> have you puking each time we turn (although if you could just aim your
> puke along this axis and open the window...) so we have to take your
> inner ear out :-)
>
We'd also save space and weight if we simply cut your legs off.  You 
don't need them any way, while you're up there.

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> Am 19.01.2016 um 08:43 schrieb scott:
>
>>> They teach astronauts to try to compensate for it, but it's not always
>>> easy, and it used to be easier just to screen them before sending them
>>> to outer space.  There's one (whose name escapes me at the moment) who
>>> had to have one of his ear nerves completely severed, making him deaf on
>>> that side at the same time, to resolve the issue.
>>
>> Now we're talking. Sorry, we need to save 5 kg of fuel, and we can't
>> have you puking each time we turn (although if you could just aim your
>> puke along this axis and open the window...) so we have to take your
>> inner ear out :-)
>
> I suspect it was more like, "Sorry, we need you to /not/ constantly puke
> /all/ the time you'll be in /zero-g/, so..."
>
> Also, I somehow suspect that this is an urban legend, where someone got
> the following facts wrong:
>
>
> - Alan Shepard was diagnosed with Meniere's disease during his training
> for the Gemini project.
>
> - Meniere's disease does indeed lead to false sensations of rotating,
> which in turn is prone to induce nausea.
>
> - In those days, Meniere's disease was indeed typically treated by
> neurectomy, i.e. nerve cutting.
>

IT's still part of the protocol, but not the first step.


> BUT:
>
> - Meniere's disease would induce nausea regardless of g forces or
> attitude changes involved. I would even reckon that the human brain
> might adapt over time.
>
> - Besides inducing nausea, false sensations of rotating would really
> mess up your ability to safely pilot an aircraft (and, by extension, at
> least from the reasoning of that time, a spacecraft), which would have
> been much more of a concern for the Gemini 3 mission.

When my wife gets her vertigo attacks, she had difficulty piloting her 
bed!  She definitely wouldn't be able to pilot a spaceship.

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