What is the communications delay between Earth and Mars?
We communicate with the Pathfinder lander using radio waves, which travel at a speed of 2.9979245x108meters per second. During the July 4 landing Mars and Earth were 192 million Km apart. At that distance it took 10 minutes and 39 seconds for the radio signal to travel in one direction. Because of their orbits, Mars and Earth are moving farther apart. As of November 6 Mars is approximately 291 million Km from Earth. At that distance it now takes 16 minutes and 10 seconds for the signals to travel in one direction. On May 13, 1998 Earth and Mars will be in conjunction (opposite sides of the sun) at a distance of 2.49 AU (1 AU is defined as 1.4956×1011 meters). At that distance it will take 20 minutes and 42 seconds for a radio signal to reach Mars. On June 22, 1998 Earth and Mars will be their farthest apart at 2.52 AU. At that distance it will take 20 minutes and 57 seconds for a radio signal from Earth to reach mars. It is these time delays which makes it impossible to communicate wit
