How does IBEX communicate with Earth?
IBEX will complete one orbit every five to eight days, depending on conditions at launch. During each orbit, there is a period of time when the spacecraft is within the Earth’s magnetosphere. Since that is not the best time for making observations, the spacecraft uses that time to communicate with Earth. It uses antennae that are attached to the outside of the spacecraft to send radio signals to receivers on Earth. Due to the rotation of the Earth each day, the IBEX team needs a global network of receivers so that no matter how the satellite and Earth are lined up, there is a receiver available to accept the signal. IBEX is never further away from Earth than the Moon, so it takes a second or less for signals to travel between IBEX and Earth. However, IBEX communications are slow. Communication from the satellite to the ground is only 320,000 bits of information per second, and from the ground to the satellite is only 2,000 bits per second. Compare this to a typical home cable modem con
