Most small asteroids have an angular momentum (at least
I am not aware of one that doesn't). The instantaneous
rotation axis goes through the center of gravity, but
moves along an irregular cone. The intersection of this
cone with the surface of the asteroid is an irregular
closed line separating an area of potential lower angular
momentum from an area of a higher angular momentum.
Because of the law of conservation of angular momentum
the instantaneous axis of rotation is constrained to
follow the boundary between these two areas. The resulting
motion is called tumbling. When there is an impact on the
asteroid, the angular momentum may change by increasing or
decreasing. As a result the two areas will change accordingly.
It may ocurr that the impacts may be of such a type that the
areas of potentially greater or smaller angular momentum
become so small as to be negligible. When that happens
(which probability in my opinion is astronomically sic.
small) the asteroid no linger tumbles, but rotates about a
constant axis. To continue to rotate, all subsequent
impacts would have to be in the 'equatorial' plane and
at right angles to the axis of rotation.
Now about the mystery. The asteroid Eros does mot tumble.
It rotates. My conclusion is that the phenomenon that
caused it to rotate is of relatively recent origin, say
a few hundred million years, and has not been impacted
since. How and why did it acquire this motion. It has
been suggested that solar radiation may over millions
of years produce such an effect. If true, then why do
the other asteroids still tumble?
A secondary question relates to this: Why did the
investigators of the Near probe of Eros decide to take
the risky maneuvre to try to land the probe at the
equatorial region? It would have been so much simpler
to land more slowly at either polar area without worrying
about the timing of the landing to avoid the probe from
being hit by the rotating body?
.
Re: Axis of rotation ... think it would help a lot if I had some visualisation of the physical ... the concepts of angular momentum and angular velocity, ... the direction of the axis.... remain the same - in other words, the axis of rotation always passes ... (sci.physics)
Re: Does the earth slow down? ... >> I recently read that the Earth spins faster on it's axis during the ... > Conservation of angular momentum is the key. ... > shift the mass around (for example, ... the velocity of rotation... (sci.physics)
Re: Does the earth slow down? ... Conservation of angular momentum is the key. ... shift the mass around (for example, ... distance of the mass from the axis of rotation), ... to conserve angular momentum, the velocity of rotation... (sci.physics)
Re: origin of inertia ... > There is no conservation of the total angular momentum... A torque is a force and a force ...Gravity is exerting a force upon me. ... accelerating each particle toward the center of the axis of rotation.... (sci.physics)
Re: Terraforming Venus will be easier ... we can figure out how much of an asteroid must be flashed away in ... million tons with a specific density of 2.8 metric tons per ...Venus rate of rotation is; ... (sci.physics)
