Stop 5 at Hellas

Colorized shaded-relief perspective view of Tyrrhena Patera, Mars
Image: Color-coded elevation draped over perspective shaded-relief imagery from the Mars Orbiter Laser Altimeter
Location: Southern highlands near Hesperia Planum northeast of the Hellas impact structure; view is to the west
Scale: Area encompassing Tyrrhena is > 300 kilometers; Vertical exaggeration is 10 X

The image above is a perspective view of Tyrrhena Patera. As explained in stop 4, a "patera" is a term used to describe a volcano on Mars. Tyrrhena, along with Hadriaca Patera, are among the oldest central vent volcanoes on Mars and the only large volcanoes located in the southern hemipshere of Mars. These two volcanoes are near one another in the southern highlands northeast of the Hellas impact structure. They are both low-relief, areally extensive features with summit calderas and radial channels and ridges along their flanks. Low-relief volcanoes on Earth are typically associated with effusive volcanic styles where flows are very fluid and explosive eruptions with billowing ash is not expected.

Volcanoes are found on all the rocky planets of the solar system and even on the satellites of some outer gaseous planets. Their occurrence throughout the solar system stresses the importance of volcanism in the creation and evolution of planets. Planets are born hot and continue to produce heat, albeit at a declined rate over time. Volcanism allows the internal heat of the planet to be released to the surface, which is then radiated out to space. Although the association of volcanoes and their destructive effects upon human activity is what garners attention, they are simply part of the natural evolution of a planet and by studying their eruptive styles, features, and flow materials we can learn a great deal about the planet's interior.

Channel and mesa surfaces along the flanks of Tyrrhena Patera
Image: Portion of THEMIS visible spectrum image V26032003
Location: Along the northern flank of Tyrrhena Patera
Scale: Image width (excluding black no-data areas) is approximately 20.8 kilometers

Like Hadriaca Patera, the flanks of Tyrrhena have very well-defined channels.

See stop 4 for a more complete description of the formation of channels on the patera

The image on the left taken by the Thermal Emission Imaging System (THEMIS) camera in the visible wavelength range shows a small portion of the channeled flanks on Tyrrhena Patera. The areas between the channels are in the form of flat mesa-like ("tabletop") surfaces that have not been modified. Together with Hadriaca Patera, planetary scientists at PSI are now studying these surfaces to understand the timing and deposition of volcanic materials at Tyrrhena Patera.

See stop 4 for a more complete description of the technique used to study these surfaces