Initializing System Sandbox…
On Earth, navigation coordinates like GPS (latitude and longitude) assume a stationary reference plane. In interplanetary space, there is no stationary ground.
When transmitting between Earth and Mars, radio photons take up to 22 minutes to traverse millions of kilometers. During that transit window, both planets hurtle tens of thousands of kilometers along their heliocentric orbits. Aiming directly at where the target appears in the sky guarantees pointing at empty space.