How are satellites launched?The trick when launching a satellite is to get it high enough to do its job without losing the capsule to outer space. It's a delicate balance of push and pull, accomplished by the inertia of the moving object and the Earth's gravity. If you launch a satellite at 17,000 mph, the forward momentum will balance gravity, and it will circle the earth. On the other hand, if the satellite is launched faster then 23,500 mph, it will leave the gravitational pull of the Earth. Why does a satellite stay in orbit? Due to the balance of two factors:
To illustrate this principle, attach a small weight or a ball to a string and swing it around in a circle. If the string were to break, the ball would fly off in a straight line but because it is tethered (like gravity tethers a satellite), it orbits you.  Imagine that you could climb an imaginary mountain whose summit pokes above the Earth's atmosphere (It would be about ten times higher than Mt. Everest). If you threw a baseball from the mountain top, it would fall to the ground in a curving path. Two motions act upon it: trying to go in a straight line and falling toward Earth. The faster you throw the ball, the farther it will go before it hits the ground. If you could throw the ball at a speed of 17,000 mph, the ball wouldn't reach the ground. It would circle the Earth in a curved path; it would be in orbit. (It would be traveling at 5 miles per second and take about ten minutes to cross the United States.) This is the speed needed to put satellites into orbit, which is why the Space Shuttle and other satellites require such powerful boosters.
Updated February 15, 2002. Copyright 1998, Gulf of Maine Aquarium. Please email comments or questions to Space@octopus.gma.org |
