The title refers to the Valles Marineris (Mariner Valleys) canyon system on Mars, the largest in the Solar System. It stretches across nearly a quarter of the planet, roughly 3870 km (2400 miles) in length, spans 600 km (370 miles) at its widest and goes down 9.3 km (5.8 miles) at its deepest. The system was named after the 1971 Mariner 9 Mars orbiter.