Does weightlessness affect foot sensitivity?

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The astronauts returning on Space Shuttle Atlantis will have a special task ahead. Wilfrid Laurier University, Professor Stephen Perry is a researcher keen to quantify the influence of space travel on foot sensitivity. Specially trained researchers will systematically tickle the feet of the astronauts in a scientific experiment . Perry cites foot sole sensation as a critical factor in balance control and wants to determine whether weightlessness improves equilibrium. As we know Prof. Perry has already developed a special shoe that alerts seniors when they are listing too much, reducing fall-related injuries.

 

Dear All
The astronauts are not weightless at all.
Remember the earth has a gravitational effect on the moon.

Hoiw they become weightless is to travel to about 240-280Km above earth and then travel at 23000 Km/Hr.
At this height and speed gravity will attract you to earth at 4.1 metres/ second
at this speed the earth's curvature is falling away relative to the space craft at 4.1 metres a second and thus the astronauts stay stationary.
They are not weightless.

There was a study done in 2004 that compared midaged people who ran and those who did not. They compared the nerve conductions of all nerves to the lower limbs.
They found that those who ran had a 50msec slower conduction pattern comared to those who did not run.

Diabetics with peripheral neuropathy do not fall in great numbers because they have no skin sensation..or do they?

The main receptors are the type 3 and 4 that stop you falling and they are in the joints, tendons, ligaments and joint capsule not skin.
Regardsto all
Sunny here
musmed

 

I know this is just a detail, but have you seen the astronauts floating around outside the shuttle? How do they do that?

Cheers

 

Dear Frederick
As I wrote, they are stationary relative to their tangential position from earth, and thus they appear to float as if weightless.
Hopes this helps
musmed

 

Well, I don't just think they are appearing weightless, they are weightless. They are not massless, but certainly weightless.

Another way to view this is that they are falling towards the earth, making them as weightless as a free falling skydiver, but because of their high orbital velocity, they fall around the earth continuously.

Cheers

 

Dear George
Of course they are not weightless. If they are falling towards earth as they are, they must not be weightless as they have mass.
Because everything else that is there, ie spaceship, other people etc, are all travelling at a specific speed and height so as to match the earths changing horizon they appear stationary and thys appear weightless.

Just pretend we keep the same velocity of 23000km/hr and change orbit to 500km from 230-430Km from earth, what will happen to these astronauts?
do they go up or down inside the craft?
Regards
Paul C musmed

 

You are confusing weight with mass. That's the distinction you are missing. You should look in any high school physics book for the definitions.

Cheers

 

Ok dear
Their orbit velocity and height is selected so that the earth's curvature changes matches the speed they fall towards earth under gravity. That is 4.1meters a second and thus they remain relatively stationary but not weightless.

Regards
to all
amen
musmed
qed

 

On the surface of the Earth, the weight W of an object is related to its mass m by
W=mg
where g is the acceleration due to the Earth's gravity, equal to about 9.81 m s−2. An object's weight depends on its environment, while its mass does not: an object with a mass of 50 kilograms weighs 491 newtons on the surface of the Earth; on the surface of the Moon, the same object still has a mass of 50 kilograms but weighs only 81.5 newtons.
ref: Google

We usually like to learn, but sometimes don't want to be taught.

Cheers

 

The term "weightlessness" is, unfortunately, a misnomer since even out in space, there is gravitational acceleration. The more accepted scientific term for the diminished acceleration of gravity in space is "microgravity" or "micro-g environment". In earth orbit, such as in the International Space Station, there is still gravitational acceleration from the earth acting not only on the space station but also the astronauts inside the space station. However, since they are all basically falling toward the earth along an orbital path that is a constant distance from the earth, the effect is what we often call "weightlessness". Other forms of "weightlessness" can occur while occupants of an airplanes are accelerated toward the earth (i.e. NASA's Vomit Comet) or if space travelers were able to travel enormous distances away from any stars/planets of significant mass (not done yet by humans).

In his General Theory of Relativity, Albert Einstein contemplated a Thought Experiment using the example of an individual experiencing gravitational acceleration here on earth and of an individual also being accelerated upward in an container (e.g. elevator) where the occupant would not know if they were moving or not moving relative to a reference frame. Einstein was said to consider his General Theory of Relativity to be the greatest scientific accomplishment of his lifetime.

Great discussion.

 

Yes, well, not quite. "micro g" "xero g" "weightlessness" are commonly interchanged. Going to the moon the astronauts were subject to some gravitational acceleration, as they were not equidistant from all sources of gravity. This would be a "micro g" state. In weightless orbit, falling through a vacuum, true xero g or weightless conditions exist. Although many different sources of gravitational acceleration are acting on the astronauts, they effectively cancel each other out with the constant acceleration of falling in orbit, making for a weightless condition.

Einstein thought that gravity was not really centred in body mass, but curved space. Not really applicable to feet.

Yes, an old tickle for dusty neurons.

Cheers

 

And one of my favorite responses to my patients who are interested in how my business is doing and have a sense of humor....as long as there is obesity and gravity, I will be doing very good business as a podiatrist.:drinks

 

aye matey, and dressy shoes help too!

Cheers

 

Biomechanical analysis of running in weightlessness on a treadmill equipped with a subject loading system.
Gosseye TP, Willems PA, Heglund NC.
Eur J Appl Physiol. 2010 Jun 27. [Epub ahead of print]