how do satellitite adjust course

Why do satellites stay on course?

The main part of the reason that satellites stay on course is the same as the reason that artillery shells stay on course: we very carefully put them into courses that they are naturally inclined to stay on once they are on, making allowances for gravity, the curvature of the Earth, and the rotation of the Earth.

What is the direction of acceleration of a satellite in space?

The velocity of the satellite would be directed tangent to the circle at every point along its path. The acceleration of the satellite would be directed towards the center of the circle - towards the central body that it is orbiting.

How do I get a satellite into an elliptical orbit?

Start by slowing down the satellite at the starting position A. It will now start to drop down, into an elliptical orbit, and if allowed to do so will come back up again to the same height, almost a day later.

How do elliptical paths affect the speed of a satellite?

In the case of elliptical paths, there is a component of force in the same direction as (or opposite direction as) the motion of the object. As discussed in Lesson 1, such a component of force can cause the satellite to either speed up or slow down in addition to changing directions.

Do satellites have to adjust their orbit?

Throughout their lifetime, GOES satellites have to be moved three or four times to keep them in place. NASA's low Earth orbit satellites adjust their inclination every year or two to maintain a Sun-synchronous orbit. Satellites in a low Earth orbit are also pulled out of their orbit by drag from the atmosphere.

How does a satellite change orbit?

If we want to move a spacecraft to a higher orbit, we have to increase the semimajor axis (adding energy to the orbit) by increasing velocity. On the other hand, to move the spacecraft to a lower orbit, we decrease the semimajor axis (and the energy) by decreasing the velocity.

How do spacecraft change direction in space?

Rockets propel themselves using fuel that generates high-pressure gas. The movement of the exhaust gases away from the rocket body pushes the rocket in the forward direction, since the force exerted by the exhaust gas has an equal reaction in the opposite direction.

How does a satellite rotate around the Earth?

How Do Satellites Orbit Earth? Most satellites are launched into space on rockets. A satellite orbits Earth when its speed is balanced by the pull of Earth's gravity. Without this balance, the satellite would fly in a straight line off into space or fall back to Earth.

How do satellites orient themselves?

The orbits are tilted to the earth's equator by 55 degrees to ensure coverage of polar regions. Powered by solar cells, the satellites continuously orient themselves to point their solar panels toward the sun and their antenna toward the earth.

Do satellites move fast or slow?

Presently circling the Earth at an average altitude of 216 mi (348 km) and at a speed of 17,200 mi (27,700 km) per hour, it completes 15.7 orbits per day and it can appear to move as fast as a high-flying jet airliner, sometimes taking about four to five minutes to cross the sky.

How do satellites navigate?

Satellite Navigation is based on a global network of satellites that transmit radio signals from medium earth orbit. Users of Satellite Navigation are most familiar with the 31 Global Positioning System (GPS) satellites developed and operated by the United States.

How do spaceships move in space if there is no matter?

The simple act of accelerating something in a particular direction (the rifle bullet or hot gases from a rocket exhaust) creates an equal force acting in the opposite direction (Newton's 3rd law). This reaction is what propels a spaceship upwards or through space, regardless of the presence of ground or atmosphere.

How do astronauts determine which direction is up?

Using the defined coordinate frame, a spacecraft must be able to both determine and control its orientation. Instead of a compass, spacecraft sensors use the sun and stars to determine the craft's orientation relative to the coordinate frame.

Do all satellites go in the same direction?

Usually satellites orbit in the direction of Earth's rotation, but there are some satellites that travel in the opposite direction. Certain satellites, such as specific weather satellites, even manage to "hover" above one specific area on Earth's surface by rotating over the equator and orbiting once a day.

Do all satellites move at the same speed?

A: No, satellites that orbit at different altitudes have different speeds. Satellites that are further away actually travel slower. The International Space Station has a Low Earth Orbit, about 400 kilometers (250 miles) above the earth's surface.

Why does the space station not fall down?

Gravity—combined with the satellite's momentum from its launch into space—cause the satellite to go into orbit above Earth, instead of falling back down to the ground.

What is L&I?

Lodging and Institution (and MDU) systems, including hotels, hospitals, apartment buildings, and other managed properties in which a single antenna serves an entire building.

Which courses and certifications are covered by the Online L&I program?

MDU, SMATV, D2 Advantage, and DRE (non-managed system version). These are delivered by SatProf on behalf of SBCA.

I am starting from scratch and I want to get certified by SBCA for SMATV, general (non-DTV) MDU, or DTV D2A. What do I do?

Go to www.sbca.org, click on the Certification, and then the Commercial link. Scroll down to the appropriate certification and click the Learn More button. The order link is on this page.

My online course has expired but I haven not finished it, or I want to review it

General Students: Online course modules are open for 120 days after you are enrolled. Under certain special circumstances, we may be able to give you a one-time extension of your access for a short time so you can finish. Just write to us at [email protected]. The best solution is to subscribe to the Resources and Maintenance Subscription.

How do I get my certificate?

Log into your account at training.sbca.org, select 'My Training' and 'Results'. If unsure contact: [email protected]

How long is my certification good for?

SBCA Fundamentals and L&I certifications are good for two years. The expiration date will appear on your certificate.

What is the difference between the certification exam and the recertification exam?

They are the same. The certification course in the learning system contains the exam for each topic, and serves for both initial certification and recertification.

What frequency does a GPS satellite have?

GPS satellites also have Rb clocks on them, which have a transition frequency of 6.8 GHz. They are designed to have the same output frequency as the Cs clocks. We get our crystals from the same company that make Swatch watches. You can get crystals with a fractional frequency stability of parts in 10^14 at 1 second.

How is time determined in clocks?

You compare that signal to other clocks. In many clock systems, the time is determined by integrating the frequency of that output. It's not the output of a single clock — it's something you do after you've gotten the signal from your clock, with an external measurement system.

Is GPS in LEO?

But GPS satellites are not in LEO. They're halfway to geosynchronous (at an altitude of ~20,000km) and the kinematic dilation is about 7 microseconds. The gravitational term is about 45 microseconds/day fast. ——. The adjustment is made in the oscillators in the clocks.

What forces disturb the orientation of the satellite?

Tidal and other force may disturb the orientation of the satellite and thrusters are needed to maintain the general orientation but the principle condition is to keep the same face towards the earth throughout the orbit. The same applies to the moon. It is a projectile that is trying to go in a straight line.

Why is the satellite flying straight?

In reality the satellite is flying straight because it was launched forward, and it is constantly falling towards the Earth, but its forward speed exactly offsets the pull of gravity.

How does an object of significant length rotate?

When an object of significant length is placed into orbit, the side closer to the center of gravity receives somewhat more "pull" than the far end, and it rotates around its own center of mass. This eventually damps rotation to match the orbital duration. This can, however, take years to accomplish.

Why do vehicles need attitude control?

Vehicles need to have some kind of active attitude control system so they can keep themselves properly oriented. If that attitude control relies on fuel, the depletion of the fuel tanks marks the end of the vehicle's useful life.

What happens if a projectile is fired in space?

If the same projectile is fired in space with enough force that it falls to earth at the same rate as the earth is falling away, it will never fall to earth and will be "in orbit". Providing it has been given no initial spin then it will always keep the same face towards the earth throughout its orbit.

How to keep antenna pointed at Earth?

The best way to keep an antenna always pointed at Earth, if you can manage it, is to stick a large weight at the tip of your antenna . The weight will receive more pull, and naturally keep the antenna pointed at that direction.

Does tidal stress affect the orientation of an object?

Keep in mind that the object rotates on its center of mass. The center of gravitic force, however, may not be on the center of mass, and so tidal stress will slowly alter the orientation of the object. In earth orbit, this is complicated by the tidal stress of the moon, as well.

Where does the acceleration of a satellite go?

The acceleration of the satellite would be directed towards the center of the circle - towards the central body that it is orbiting. And this acceleration is caused by a net force that is directed inwards in the same direction as the acceleration.

What is the principle of satellites?

The fundamental principle to be understood concerning satellites is that a satellite is a project ile. That is to say, a satellite is an object upon which the only force is gravity. Once launched into orbit, the only force governing the motion of a satellite is the force of gravity. Newton was the first to theorize that a projectile launched ...

How would gravity pull a projectile downward?

Consider a projectile launched horizontally from the top of the legendary Newton's Mountain - at a location high above the influence of air drag. As the projectile moves horizontally in a direction tangent to the earth, the force of gravity would pull it downward.

How far does a projectile have to travel to orbit the Earth?

For a projectile to orbit the earth, it must travel horizontally a distance of 8000 meters for every 5 meters of vertical fall. It so happens that the vertical distance that a horizontally launched projectile would fall in its first second is approximately 5 meters (0.5*g*t 2 ).

How far does a projectile drop?

As the projectile travels tangentially a distance of 8000 meters in 1 second, it will drop approximately 5 meters towards the earth. Yet, the projectile will remain the same distance above the earth due to the fact that the earth curves at the same rate that the projectile falls.

What are Kepler's three laws?

Kepler's Three Laws. Circular Motion Principles for Satellites. Mathematics of Satellite Motion. Weightlessness in Orbit. Energy Relationships for Satellites. A satellite is any object that is orbiting the earth, sun or other massive body. Satellites can be categorized as natural satellites or man-made satellites.

What direction does an inward force move a satellite?

One might think that an inward force would move a satellite right into the center of the circle ; but that's only the case if the satellite were in a rest position. Being that the satellite is already in motion in a tangential direction, the inward force merely turn from its straight-line tangential direction.

How high will the satellite be at its apogee?

Now boost the speed up so that half a day later, the satellite will be higher up (at its apogee) at the geostationary height (35786km) and at the wanted orbit longitude position.

How long do satellites stay in orbit?

Satellites are launched and put into their intended orbit longitude positions, where they normally stay for many years. As time passes and needs change, it can be helpful to move satellites to new orbit longitude positions. During a satellite's lifetime, typically 15 years, it may be moved perhaps a couple of times.