How do you calculate gravity gradient?
The most frequently used and intuitive component is the vertical gravity gradient, Gzz, which represents the rate of change of vertical gravity (gz) with height (z). It can be deduced by differencing the value of gravity at two points separated by a small vertical distance, l, and dividing by this distance.
How can the gravity gradient be used to stabilize a spacecraft?
Gravity-gradient stabilization (a.k.a. “tidal stabilization”) is a method of stabilizing artificial satellites or space tethers in a fixed orientation using only the orbited body’s mass distribution and gravitational field.
How does gravity gradient stabilization work?
The gravity gradient (GG) principle operates in such a manner that restoring torques on an Earth orbiting satellite will rotate the satellite toward a position in which the axis of minimum inertia is aligned with the local vertical. An excellent example of this principle is the Moon.
What is the gravity gradient torque?
The gravity gradient torque is the main perturbation of the attitude motion. The oblateness of the Earth makes a contribution to the gravity gradient torque, which is approximately 5 orders of magnitude less than the main term on the geosynchronous orbit (Kumar, 2008).
What is a Gravimeter used for?
The gravimeter measures the shape of seawater-filled cavities at the edge of some major fast-moving glaciers. Data about the amount of water under ice fills in a crucial gap in knowledge related to calving and melting of glaciers.
How do Gradiometers work?
This device consists of two magnetometers placed in series (i.e., one above the other). The result coming from the device is the difference in magnetic flux at that point in space, in other words, the result is the difference between what each of the magnetometers detects.
How does spin stabilization work?
With spin stabilization, the entire spacecraft rotates around its own vertical axis, spinning like a top. This keeps the spacecraft’s orientation in space under control. The advantage of spin stabilization is that it is a very simple way to keep the spacecraft pointed in a certain direction.
What is gravitational potential gradient?
The gravitational potential gradient is defined as the rate of change of gravitational potential with distance in the field. This is equal to the gravitational field intensity (g = EG) at that point. Put simply it is the rate at which the field changes as the distance from the mass producing the field changes.
How many types of gravimeters are there?
There are two types of gravimeters: absolute and relative. Absolute gravimeters measure the local gravity in absolute units (Gal). Absolute gravimeters are compact (Autograv CG-5 model) and used in the field. They work by directly measuring the acceleration of a mass during freefall in a vacuum.
What is the difference between gradiometer and magnetometer?
The gradiometer is a magnetometer which measures the change in the magnetic field (the gradient of the field). Compared to a magnetometer this increases the measurement accuracy and the sensitivity to regional changes of the Earth’s magnetic field. Both measuring systems can also be used on the water.
Which one is the three-axis stabilization?
Three-axis stabilization is an alternative method of spacecraft attitude control in which the spacecraft is held fixed in the desired orientation without any rotation. One method is to use small thrusters to continually nudge the spacecraft back and forth within a deadband of allowed attitude error.
How is gravity gradient stabilization used in space?
Gravity-gradient stabilization. Gravity-gradient stabilization (a.k.a. “tidal stabilization”) is a method of stabilizing artificial satellites or space tethers in a fixed orientation using only the orbited body’s mass distribution and gravitational field.
How does gravity affect the orientation of a spacecraft?
The idea is to use the Earth ‘s gravitational field and tidal forces to keep the spacecraft aligned in the desired orientation. The gravity of the Earth decreases according to the inverse-square law, and by extending the long axis perpendicular to the orbit, the “lower” part of the orbiting structure will be more attracted to the Earth.
How does the gravity of the Earth decrease?
The gravity of the Earth decreases according to the inverse-square law, and by extending the long axis perpendicular to the orbit, the “lower” part of the orbiting structure will be more attracted to the Earth. The effect is that the satellite will tend to align its axis of minimum moment of inertia vertically.