Hellas Quadrangle - Hellas Basin

Hellas Basin

The Hellas quadrangle contains part of the Hellas Basin, the largest known impact crater on the surface of Mars and the second largest in the solar system. The depth of the crater is 7152 m (23,000 ft) below the standard topographic datum of Mars. The basin is located in the southern highlands of Mars and is thought to have been formed about 3.9 billion years ago, during the Late Heavy Bombardment. Studies suggest that when an impact created the Hellas Basin, the entire surface of Mars was heated hundreds of degrees, 70 meters of molted rock fell on the planet, and an atmosphere of gaseous rock was formed. This rock atmosphere was 10 times as thick as the Earth's atmosphere. In a few days, the rock would have condensed out and covered the whole planet with an additional 10 m of molten rock. In the Northwest portion of Hellas Planitia is a strange type of surface called complex banded terrain or taffy-pull terrain. Its process of formation is still largely unknown, although it appears to be due to erosion of hard and soft sediment along with ductile deformation. Ductile deformation results from layers undergoing strain.

Early in the planet's history, it is believed that a giant lake existed in the Hellas Basin. Possible shorelines have been discovered. Glacial features (terminal moraines, drumlins, and eskers) have been found that may have been formed when the water froze.

• Hellas Basin Area topography. Crater depth is 7152 m (23,000 ft) below the standard topographic datum of Mars.

• Hellas Basin with graph showing the great depth of the crater. It is the deepest crater on Mars and has the highest surface pressure: 1155 Pa (11.55 mbar, 0.17 psi, or 0.01 atm).

• Twisted Ground in Hellas, as seen by HiRISE. This is one more example of how difficult it would be to walk on Mars.