What is orbit precession?

Precession refers to a change in the direction of the axis of a rotating object. The major axis of each planet’s elliptical orbit also precesses within its orbital plane, in response to perturbations in the form of the changing gravitational forces exerted by other planets.

Is a satellite in orbit balanced?

When a satellite is in orbit, it has a perfect balance between its momentum and Earth’s gravity. But finding this balance is sort of tricky. Gravity is stronger the closer you are to Earth. And satellites that orbit close to Earth must travel at very high speeds to stay in orbit.

Why do satellites precess?

Nodal precession is the precession of the orbital plane of a satellite around the rotational axis of an astronomical body such as Earth. However, most bodies rotate, which causes an equatorial bulge. This bulge creates a gravitational effect that causes orbits to precess around the rotational axis of the primary body.

Do satellites stay in orbit forever?

The orbit will tend to shift over time but it will stay orbiting the Earth in the same way that the Moon still orbits the Earth after millions of years. But usually we don’t want them to stay in a particular orbit forever. A satellite has a useful lifetime of between 5 and 15 years depending on the satellite.

What causes precession?

Precession is caused by the gravitational influence of the Sun and the Moon acting on Earth’s equatorial bulge.

What is free precession?

Torque-free precession implies that no external moment (torque) is applied to the body. In torque-free precession, the angular momentum is a constant, but the angular velocity vector changes orientation with time.

Can the earth fall out of orbit?

Thanks to gravity, the earth does fall. It is actually in a constant state of falling since it is in orbit around the sun. This gravitational pull that the sun has on the earth is useful since it stops earth from catapulting into space.

What is the J2 effect?

The term J2 comes from an infinite series mathematical equation that describes the perturbational effects of oblation on the gravity of a planet. The two main orbital elements affected by J2 Perturbations are the Right Ascension of the Ascending Node (Ω) and the Argument of Perigee (ω).

What is the main cause of precession?

Do satellites need fuel?

Satellites are able to orbit around the planet because they are locked into speeds that are fast enough to defeat the downward pull of gravity. Satellites do carry their own fuel supply, but unlike how a car uses gas, it is not needed to maintain speed for orbit.

How is the precession of a satellite calculated?

For a satellite in a prograde orbit around Earth, the precession is westward (nodal regression), that is, the node and satellite move in opposite directions. A good approximation of the precession rate is ω is the angular velocity of the satellite’s motion (2 π radians divided by its period in seconds),

What makes a satellite orbit a SYN Synchronous orbit?

To achieve a syn-synchronous orbit, the orbital plane is inclined slightly away from a true north-south track to introduce a slow precession in the orbital plane, roughly one degree per day. This precession ensures that the equatorial crossing times of the satellites, in terms of the local solar time, remain nearly constant throughout the year.

How does the orbit of a satellite affect coverage?

At this altitude, you can get true global coverage if the scan swath of the satellite’s instrumenation is about 3000 km. The orbit, however, can be improved if the orbital plane is inclined slightly away from a true N-S orbit. In this case, the asymmetric gravitational pull of the Earth introduces a slow precession in the orbital plane.

How does the nodal precession affect the orbit?

Nodal precession. For a typical prograde orbit around Earth (that is, in the direction of primary body’s rotation), the longitude of the ascending node decreases, that is the node precesses westward. If the orbit is retrograde, this increases the longitude of the ascending node, that is the node precesses eastward.