Olympus Mons and hence lead to the low gradients on the surface of the planet. Olympus Mons is an unlikely landing location for automated space probes in the near future. The high elevations preclude parachute-assisted landings because the atmosphere is insufficiently dense to slow the spacecraft down. Moreover, Olympus Mons stands in one of the dustiest regions of Mars. A mantle of fine dust obscures the underlying bedrock, possibly making rock samples hard to come by and likely posing a significant obstacle for rovers. Olympus Mons is the result of many thousands of highly fluid, basaltic lava flows that poured from volcanic
Arsia Mons the three Tharsis Montes volcanoes, it is the only major Tharsis volcano south of the equator. The volcano is in diameter, almost high (more than higher than the surrounding plains), and the summit caldera is 110 km (72 miles) wide. It experiences atmospheric pressure lower than 107 pascals at the summit. Excluding Olympus Mons, it is the largest known volcano in terms of volume. Arsia Mons has 30 times the volume of Mauna Loa in Hawaii, the largest volcano on the Earth. The caldera of Arsia Mons was formed when the mountain collapsed in on itself after its reservoir of