Question

With reference to Low Earth Orbits (LEO), consider the following statements:

Which of the statements given above is/are correct?

• A. Only 1
• B. Only 2
• C. Both 1 and 2
• D. None of the above

Answer 1

The correct option is A Only 1

There are two disadvantages to Low Earth Orbits (LEOs). The first is that there is still some atmospheric drag. Even though the amount of atmosphere is far too little to breathe, there is enough to place a small amount of drag on the satellite or other object. As a result, over time these objects slow down and their orbits slowly decay. Simply put, the satellite or spacecraft slows down and this allows the influence of gravity to pull the object towards the Earth.
The second disadvantage has to do with how quickly a satellite in LEO goes around the Earth. As you can imagine, a satellite travelling 18,000 miles per hour or faster does not spend very long over any one part of the Earth at a given time. So what happens if we want a satellite to spend all of its time over just one part of the Earth? For instance, a weather satellite wouldn’t be very effective for us in North America if it didn’t have a long dwell time over us. (Dwell time = the time a satellite sits over one part of the globe.) Also, a communications satellite wouldn’t work very well for us in North America if it spent most of its time over Africa or Asia.