When the Galaxy 4 communications satellite went off course in 1998, it shut down National Public Radio and 80 percent of the United States' 50 million pagers, and other communications systems. Satellites are either GEOs, parked in the geosynchronous orbit more than 22,000 miles over the equator, or they are LEOs, satellites at varying altitudes in different orbital patterns. Their shapes and sizes depend on their missions. Unlike airplanes, which must be aerodynamic to remain airborne, satellites operate in a vacuum. A satellite in orbit may be the nearest thing to a perpetual-motion machine, because it is in a constant state of free fall.
Gravity works equally well on both.
Satellites assume two general shapes, boxlike and cylindrical, depending on the method required to keep them pointed in the right direction. Axis-stabilized satellites are the ones that look like boxes, which contain the central bus, and have exterior winglike projections for solar panels, which provide electricity. Spin-stabilized satellites maintain the right direction by spinning around an imaginary longitudinal axis, and are thus cylindrical. Instead of wings, the solar cells are mounted on a thin sheet surrounding the bus. On both types, the central bus holds the electronics and a battery to operate when the satellite is blocked from the sun by the Earth.