How does an earth made satellite orbit our planet. Also How do we make this happen so accurately?

Question

I am interested in this subject and cant find much information on it. Anybody have a link to a good place for info(better yet maybe a youtube video or something) That describes how this is all works.How did we figure this out? If it was just theory until fact how did the theorists calculate this?

I am not an Einstein here so i need simple people explanations hehe.

Answer 1

actually, it is just the pull of gravity. With enough horizontal velocity, the satellite does not drop towards Earth, but actually fly loops around the planet, being held by gravity just like a rubber band.

It was also Isaac Newton, who did not only discover how gravity works outside Earth, based on measurements by astronomers of the orbits of planets, but he also suggested a thought experiment: A cannon on top of a high tower, outside the atmosphere fires cannon balls with different velocities. The more velocity you give the cannon ball, the further it will fly. At one point, the cannon ball will fly halfway around a spherical Earth before hitting ground again. If you now fire a cannon ball with slightly more velocity, it will never hit the planet at all, orbiting it forever. With much more velocity, it will even be able to leave the gravity field of Earth.

So, that is all magic behind a orbit - plain Newtonian gravity. well, not quite. In reality there are many aspects of gravity, which still are researched, for example, in a few months, the fish-shaped satellite GOCE will be launched from a Russian spaceport to make a more precise map of Earths gravity field.  

Answer 2

I think that the gravity on Earth decreases as we go on very high elevations (above the mesosphere), and that there are certain areas that can sustain an object in orbit, in which the gravity (pulling down on the satellite) equals the normal force (pulling the satellite up). This can be seen on the Asteroid Belt.

We can make this happen by calculating the speed and the forces that will act on the satellite, and trying to find a location suitable for the satellite to sustain an orbit.

Answer 3

By rotating around our planet at a speed of 8 km/s or 28,800 km/h and at an altitude of about 400 km. The centrifugal force cause by the rotation of the satellite around the Earth counteracts the pull of the Earth's gravity!

Answer 4

Well i think what is happening is its between two atmospheres which has a gravitational pull which is pulling it up and down due to the spot that it is at. I don't know if this is right but i hope that it does help a bit

also you might want to look into nasa.com which might describe it better

Answer 5

It's just the balance between gravity and momentum.  The cannonball thought-experiment is very good, and is reproduced in all the orbital mechanics textbooks.  As the cannonball proceeds partway around the Earth in each successively more powerful shot, you have to keep in mind how the direction of gravity changes as it acts on the ball.  "Down" is forever changing as the cannonball flies.

Looking at the problem from the side, imagining the Earth's circle marked off as in hours on a clock face and the cannon firing clockwise from 12 o'clock, a weak cannon may only land its cannonball at 1 o'clock.  And the curvature of the clock-Earth (and of the cannonball's path) may not be very visible at that scale.

But if you have a cannon that can fire to 3 o'clock, you can see that "down" with respect to 3 o'clock -- if you defined it as "toward the center of the clock" is actually now pulling toward the left: from the 3 o'clock edge to the center.  And so forth up until, say, 10 o'clock.  If you fire a cannonball all the way around clockwise from 12 o'clock to 10 o'clock, the direction of "down" has changed almost in a complete circle along the path of the cannonball.  And if you measure the distance between the cannonball and the edge of the clock (surface of the Earth) at each point along the way, you'll find it is declining appropriately as Newton predicts.

So then the trick is to fire it with such force that it doesn't ever hit the ground; it will keep circling in that path forever, following a circular path as its momentum (tendency to keep going in a straight line) is perfectly balanced by the circularly-changing force of gravity at every point along its path.

Celestial mechanics is a very old science.  My collectable textbooks on the subject go back to the 1910s with full mathematical rigor.  The computations arose because, at heart, they are very simple and involve only two forces:  momentum and gravity.  We've known about those for hundreds of years and been able to reason about them mathematically.  So it was only a matter of time before someone put those two concepts together and realized it explained and predicted how we observe objects in the sky to move.

How do we achieve this so accurately?  In a word: engineering.

We first have to guide rockets accurately.  If everything on them works properly (and sometimes, sadly, it doesn't and the satellite gets put into "hydrosynchronous" orbit -- i.e., the ocean), then we can very accurately detect the movements of launch vehicles as they ascend and apply corrective steering actions to them.

Then we have to measure satellite paths accurately.  There are a number of mathematical ways to use radar and visual sightings of an orbiting spacecraft to describe its orbit very accurately.

Then, after the satellite is in orbit, we have to be able to adjust its orbit by adding or subtracting momentum.  That's done by a combination of onboard guidance devices to measure acceleration and orientation, and small rocket motors of varying designs.  Sometimes a very small nudge here and there is all it takes.  We can adjust velocities in very small increments, such as tenths or hundredths of meters per second; and we can measure orientation (for aligning the engines to our desired direction) to tenths and hundredths of a degree on small spacecraft, and thousandths of a degree on larger ones like the space shuttle.