Dr. David Yellin is a geologist who, like many others, got stuck on Mars due to the early discharge of the space cannon. After his arrival in the ill-fated first capsule, Yellin, together with Major Greg Duprey and Richard Sherman, went out to explore the mines. It turned bad when Duprey and Sherman got stuck in the mines near Syrtis Major at 10°N 71°E after a cave-in while searching for iron ore for Andrew Carnegie.