Imagine this scenario: You are tasked with shooting an arrow and hitting a target the size of a quarter. This in itself is a pretty difficult task that requires immense accuracy. Now, the quarter-sized target that you are tasked with hitting is sitting in Times Square, New York, and you are standing in Los Angeles. This is the example that Jill Seubert uses to contextualize her job as a deep space navigator. Seubert is in charge of steering spacecraft from the moment they separate away from the launch vehicle until they reach their final destination. She has the opportunity to adjust the course of the spacecraft (the arrow in the analogy) only a couple of times along its trajectory. But in order to make the necessary adjustments, she must know the exact location of the spacecraft at any given moment in time.