Behaviour of Gyro in space compared to on Earth / in gravity

In summary, the difference between a gyroscope free floating in space and one on Earth is the absence of twisting forces in space. In space, there is only one force acting on the gyroscope, while on Earth there are two forces (gravity and the table) creating torque. If a constant force is applied in space, the gyroscope will precess, but it will stop once the force is removed. This is different from Earth where the force of gravity is constant, allowing the gyroscope to continuously precess.
  • #1
mike walker
2
0
My question is about a toy gyroscope free floating in space far away from any gravitational field. I want to know why it does not precess in response to external force?

On Earth the torque on a tabletop gyroscope comes from (i) the table pushing up, and (ii) the gyroscope's inertia resisting the push around it's centre of mass - causing spin. In space it's the same - except that instead of a table we use an astronaut's finger to push rather than gravity. Yet in space, the gyro will not precess as it does on Earth.

DETAILS:

What is the difference between applying 1g of tilting force to a gryoscope here on Earth (gravity) and doing the same thing a gyroscope floating in space by pushing it with a finger.

Here on Earth a tabletop gyroscope will precess due to the Earth's gravitational pull applying a tilting force around the centre of mass. However, in space, a tilting force applied to one end of the axis does not precess the gyroscope. it will maintain its orientation while accelerating with the force without tipping, pitching or precession.

Why do they behave differently? The inputs are the same.

In both cases torque is applied to the gyroscope. On Earth by gravity accelerating the table upwards (against freefall). If the force from the table is not aligned with the centre of mass of the gyroscope this will cause torque. In space the astronaut's finger pushes one end of gyroscope, if finger is not aligned with the gyroscopes centre of mass it will cause a torque.

So if the force and the resulting torque are the same in space and on Earth why are the results so different? Why does the space gyroscope maintain orientation without precession?

In summary, can anyone explain why a free floating gyro in space does not precess in response to external force applied at one end of the axis.
 
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  • #2
On the table gravity and table continuously exert forces, which result in a sustained torque on a tilted gyro. When pushed around in space, the gyro floats away from the finger and the torque disappears. To have a comparable situation the astronaut would have to continuously accelerate the gyro at 1g, with an off center force.
 
  • #3
A torque applied to a gyro in space has the exact same affect as a torque applied to a gyro on Earth.

If there's a difference, it has to be because the astronaut isn't actually applying a torque to the gyro, even though he's applying a force to it. I have a hard time imagining he wouldn't apply at least some torque to the gyro, though.

However, even if he is applying a torque, precession will only occur as long as the force is applied. It stops as soon as the gyro leaves the astronaut's finger.

On Earth, the force of gravity is constant, so you never see the gyro stop precessing.
 
  • #4
Many thanks for clarifying that. A couple of articles I read said the gyro in space would not precess - that's what confused me.

For example I read this:

"In the weightless environment of the space shuttle, a spinning toy gyroscope was recorded on videotape. The gyro spun around an axis that kept pointing toward the same distant star. Even when an astronaut pushed on the gyroscope, it stubbornly maintained the orientation of its axis as it flew across the cabin. In the absence of twisting forces, a gyroscope 's axis will always point in whatever direction it was pointing when you started it spinning."

http://isaac.exploratorium.edu/~pauld/exnet/gyroscopes.htm

That article says that the difference in space is that there are no twisting forces. It says that on Earth there are two forces - the table pushing the axle up, and gravity pulling the gyroscope down - and this creates torque. Whereas in space there is only one force - so no torque. I don't have a physics background but I think that is nonsense. In space there is still torque if the astronaut maintains the force - i.e. accelerates. From what you say, if the Astronaut maintained the force then the gyro would precess while the force is being applied. That makes a lot more sense so I pretty much understand it now.
 
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  • #5


The key difference between the behavior of a gyro in space and on Earth is the presence of a gravitational field. On Earth, the force of gravity causes the table to push up on the gyro, creating a torque that causes precession. In space, there is no gravitational field to provide this force, so the gyro does not experience the same torque that it would on Earth. Additionally, in space, there is no fixed point of reference for the gyro to precess around, as there is on Earth with the force of gravity. Without this fixed point, the gyro is able to maintain its orientation without precession, even when an external force is applied.

Furthermore, the gyro in space is not subject to the same frictional forces as it would be on Earth, which can also impact its behavior. In a microgravity environment, the gyro's axis can spin freely without the resistance of air or other surfaces, allowing it to maintain its orientation without precession.

In essence, the absence of a gravitational field and the presence of a frictionless environment are the main factors that contribute to the difference in behavior of a gyro in space compared to on Earth. It is important to note that this behavior is not unique to gyroscopes, but is a fundamental principle of objects in a microgravity environment.
 

1. How does gyro behavior differ between space and Earth?

The behavior of a gyro in space is significantly different from its behavior on Earth due to the absence of gravity. In space, there is no force acting on the gyro to keep it aligned with a specific direction, so it will continue to spin in its original orientation, even if the spacecraft is rotating or moving.

2. How does the lack of gravity affect a gyro's stability in space?

In space, a gyro's stability is greatly affected by the lack of gravity. Without the force of gravity pulling the gyro towards a fixed point, it will continue to spin in its original direction, making it difficult to stabilize and control the spacecraft. Special mechanisms and control systems must be in place to maintain the gyro's stability in space.

3. Does a gyro behave differently in different levels of gravity?

Yes, a gyro's behavior is greatly affected by the level of gravity it is experiencing. In lower levels of gravity, such as on the Moon or in orbit, a gyro will spin at a slower rate and require less force to move or control. In higher levels of gravity, such as on Earth, a gyro will spin at a faster rate and require more force to move or control.

4. How does a gyro's behavior in space impact spacecraft navigation?

The behavior of a gyro in space greatly impacts spacecraft navigation. Gyros are used to measure and maintain the orientation and stability of a spacecraft, and without the force of gravity to keep them aligned, they can easily become disoriented. This can make it challenging for spacecraft to accurately navigate and maintain their intended trajectory.

5. Are there any special considerations for using gyros in space compared to on Earth?

Yes, there are several special considerations for using gyros in space compared to on Earth. In space, gyros must be carefully designed and calibrated to function in a zero-gravity environment. They must also be shielded from external forces, such as solar wind or radiation, which can interfere with their accuracy and performance. Additionally, backup systems and redundancy measures are often put in place to ensure the safe navigation of spacecraft in case of gyro failure.

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