Determining a spacecraft's velocity in the vastness of space presents unique challenges due to the absence of familiar reference points like trees or air. Unlike on Earth where speedometers and GPS provide straightforward measurements, astronauts rely on physics principles. Velocity, defined as speed in a specific direction, is crucial for precise navigation, especially for missions like reaching Mars or lunar landings. Two primary methods are employed: the Doppler effect, which analyzes shifts in transmitted and reflected radio waves to measure speed relative to an observer, and inertial measurement, which tracks acceleration over time to calculate changes in velocity. Both methods have limitations, with Doppler requiring line-of-sight and inertial measurement accumulating errors, necessitating periodic recalibration.