The Martian

To solve this problem, Watney needs to know the size and direction of the dust storm. He decides that he is going to take the rover around the nearby area and leave a solar cell behind every 40 kilometers. He will also leave one of the cameras that he salvaged from the spare EVA suit with each solar cell. The next day, he will travel around and collect them all, using their respective wattages to tell how deep into the storm they are and where the storm is the thickest. Then he can begin to figure out how to navigate around it while staying on track to get to the Ares 4 MAV in time.

When he collects the solar cells, he realizes that his optimal path to avoid the storm is southeast—but this will take him off his path and cause him to miss his scheduled arrival date at the Ares 4 MAV, which is sol 494. However, because the Hermes flyby is actually scheduled for sol 549, he still has a margin of time. He travels 540 kilometers due south and evades the storm. The power regeneration on the solar cells is now at 100%, and he can travel directly to the Schiaparelli Crater, where the Ares 4 MAV is located.