Saturday, February 15, 2014

Small Pale Red Planet Issue 6 Phase 7


The Mare Tyrrhenum Region




Topographical Map of the Mare Tyrrhenum Region

The Mare Tyrrhenum Region covers the area from 225° to 270° west longitude and 0° to 30° south latitude on Mars. Schiaparelli named the area after Earth's Tyrrhenian Sea, which lies between Italy and Sicily.  The region was subsequently renamed to Mare Tyrrhena after spacecraft photos revealed that it is an old, cratered plain rather than a sea. It contains the large volcano Tyrrhenus Mons, one of the oldest, and perhaps the most complex volcanoes on Mars. Mare Tyrrhenum's largest crater is Herschel. Licus Vallis and the Ausonia Montes are other major features in the region.



Image of the Mare Tyrrhenum Region

The Mare  Tyrrhenum Region of Mars has heavily cratered highlands that dominate the Mare Tyrrhenum Region. The central part is marked by a large shield volcano, Tyrrhena Patera (Tyrrhenus Mons), and associated ridged plains of Hesperia Planum that probably are made up of basaltic lava flows.

In the Mare Tyrrhenum Region the Tyrrhena Terra covers the western third of the Region:


Location Tyrrhena Terra Area

The 1000 × 2000 km area region of Tyrrhena Terra (outlined by the white box in the inset) sits between two regions of low altitude – Hellas Planitia and Isidis Planitia – in Mars' southern hemisphere, as shown in this global topography map. Hydrated minerals were found in 175 locations associated with impact craters in Tyrrhena Terra, such as inside the walls of craters, along crater rims, or in material excavated by impacts. Analysis suggests that these minerals were formed in the presence of water that persisted at depth for an extended period of time.



Excavating Water-Rich Rocks

The large 25 km-diameter crater in the foreground of this High Resolution Stereo Camera (HRSC) perspective view has excavated rocks which have been altered by groundwater in the crust before the impact occurred. Using OMEGA (Visible and Infrared Mineralogical Mapping Spectrometer) on ESA's Mars Express and CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) on NASA's Mars Reconnaissance Orbiter (MRO), scientists have identified hydrated minerals in the central mound of the crater, on the crater walls and on the large ejecta blanket around the crater.



Light Outcrop on Crater Floor

This observation shows part of the floor of a large impact crater in the southern highlands, north of the giant Hellas impact basin. Most of the crater floor is dark, with abundant small ripples of wind-blown material. However, a pit in the floor of the crater has exposed light-toned, fractured rock.  The light-toned material appears fractured at several different scales. These fractures are called joints, and result from stresses on the rock after its formation.  Joints are similar to faults, but have undergone virtually no displacement. With careful analysis, joints can provide insight into the forces that have affected a unit of rock, and thus into its geologic history. The fractures appear dark; this may be due to trapping of dark, wind-blown sand in the crack, to precipitation of different minerals along the fracture, or both.  Note: This crater lies in Tyrrhena Terra to the south of Oenotria Scopulus, a scopulus (pl. scopuli) being a lobate or irregular scarp.


Tyrrhena Terra in the Mare Tyrrhenum Region

Next we come to the Cerberus Dorsa located at two locations- at 9 and 11.5°S both are ridges leading into the central region of the Mare Tyrrhenum Region.  Cerberus  in Greek and Roman mythology, is a multi-headed (usually three-headed) dog, or "hellhound"  which guards the entrance of Hades,  Therefore it is a classical name for these features.



Lobate Ejecta Blanket of Large Crater in Cerberus Dorsa

Next we come to Tivoli Crater is located at 101°E 14°S.


Tivoli Crater

It is 33 kilometers in diameter and is named after a town in Grenada.  It is located on the eastern edge of the Tyrrhena Terra.


The  Tyrrhenus Labryithus is located almost directly to the south at 101.6°E 17°S


Tyrrhenus Labryithus

As you can see Tyrrhenus Labyrinthus is a type of Chaos terrain. It is 102.68 kilometers in diameter and is named after a classical albedo feature.


The next feature of interest is Rayadurg Crater located at 102.5°E 18.5°S.


Possible Olivine-Rich Bedrock in Rayadurg Crater

Rayadurg Crater is 22 kilometers in diameter and is named after an India place name.


The next crater to the southwest is Kamativi Crater.  Kamativi Crater is centered at 100°E 21.5 S. 


Dark Cones in Kamativi Crater

Kamativi Crater is 59 kilometers in diameter and is named after Zimbabwe place name.


South southeast of Kamativi Crater is the Ausonia Montes  located at 25.42° south latitude an 99.04° east longitude.


The Ausonia Montes

Ausonia Montes is a mountainous area  in the southwest corner of the Mare Tyrrhenum Region  of Mars. It is 158 kilometers (98 mi) across and was named after a classic albedo feature.


Going southwest of Ausonia Montes you drop off in Savich Crater centered at 96° E 27°S.



Fractured Terrain in Savich Crater

Savich Crater is 188 kilometers in  diameter is named for the Russian astronomer Alexei Nikolaevich Savich (1810 or 1811-1883).


Savich Crater and Vicinity

On the southeastern border of the Mare Tyrrhenum Region we have the northern part of the Hadriaca Patera a small volcano

Sample of Hadriaca Patera

It is located at the 90°-94°E to 28.5°S  the northern part of the volcano comes right over the border into the Mare Tyrrhenum Region from Region from the south.  It is located southeast of Savich Crater.


Location of Northern Part of Hadriaca Patera (in brown)

From here we begin to travel back up into the central area of the Mare Tyrrhenum Region. The first large crater we come to east of the Ausonia Montes is Bombala Crater centered at 106°E 28°S.



Thousands of small craters within the Bombala Crater

Bombala Crater is 38 kilometers in diameter and is named after a Australia (New S. Wales) place name.

East of Bombala Crater the Hesperia Dorsa is  a ridge that goes to the northeast.  It begins north of a small unnamed crater at about 109.5°E 28°S.


View of Hesperia Dorsa by Themis

Hesperia Dorsa is a long ridge going from the south to northeast past Kinkora Crater.  Then at about 112°E 22°S it branches out into a group of ridges going northwest and northeast one of which is the Tyrrhena Dorsa.


The next prominent feature is Kinkora Crater centered at 112.5°E 25°S.


Western Rim of Kinkora Crater

Kinkora Crater is a crater in the Mare Tyrrhenum Region of Mars. It is 54.3 km in diameter and was named by the International Astronomical Union's Working Group for Planetary System Nomenclature (IAU/WGPSN) in 1991, after the town of Kinkora, Prince Edward Island, Canada.


The Hesperia Planum  covers the central part of the Mare Tyrrhenum Region.  The Hesperia Planum is a broad lava plain in the southern highlands of the planet Mars. The plain is notable for its moderate number of impact craters and abundant wrinkle ridges. It is also the location of the ancient volcano Tyrrhena Mons (Tyrrhena Patera). The Hesperian time period on Mars is named after Hesperia Planum.




Planum (pl. plana) is Latin for plateau or high plain. It is a descriptor term used in planetary geology for a relatively smooth, elevated terrain on another planet or moon.


The Hesperia Planum Area

The Hesperia Planum is located along the broad northeastern rim of the giant Hellas impact basin and is centered at lat. 22.3°S, long. 110°E in the Mare Tyrrhenum Region (MC-22). It has a maximum width of 1700 km (1056 mi) and covers an area of about 2 million km2 (772000 sq. mi).


Northwest of Kinkora Crater is Trinidad Crater centered at 109.5°E 23.5°S.


Central Peak of Trinidad Crater

Trinidad Crater is approximately 28 kilometers in diameter. It is named after a Peru place name.


Next we come to one of the most important features in the Mare Tyrrhenum Region the Tyrrhenum Mons (also known as the Tyrrhena Patera).  Tyrrhenum Mons, formerly Tyrrhena Mons or Tyrrhena Patera, is a large volcano in the Mare Tyrrhenum quadrangle of Mars, located at 21.36° south latitude and 105.5° east longitude. The name "Tyrrhena Patera" now refers only to the central depression, a volcanic crater or caldera. It was named after a classical albedo feature


Pit crater chains and concentric features around Tyrrhenum Mons, as seen by HiRISE

Pit chains are found at the summit of Tyrrhenus Mons. They are formed by collapse of material into underground voids. Since they form chains and concentric fractures that are aligned, they are probably caused by extension of the surface. Volcanic processes made the crust pull apart. Voids were formed, then material fell into them, leaving holes. It is one of the oldest volcanoes on Mars. As a consequence of its old age, Tyrrhenum Mons has many radiating gullies on its slopes.


Lave flow, as seen by THEMIS. Note the shape of the edges

When it was formed, magma may have gone through frozen ground and then erupted as easily eroded ash, instead of lava flows.



Tyrrhenum Mons (0r Tyrrhena Patera)

Tyrrhenum Mons lies on the northeast edge of the Hellas impact basin. It numbers among a handful of similar low volcanic structures (originally called paterae, after the Latin word for dish) in the cratered highlands next to Hellas.  The others are Hadriaca Patera (also on the northeast) and Amphitrites, Peneus, and Pityusa (all on the southwest of Hellas). Tyrrhenum and its neighbors also show a different volcanic style than later volcanoes such as Olympus Mons and the others in Tharsis and Elysium. Tyrrhenum's low slopes, wide structure, and heavily scored flanks suggest that it is made of easily eroded materials. Scientists call such volcanic debris "pyroclastic," from the Greek meaning fire-broken.


Tyrrhena Mons in Color

Keeping a low profile- Tyrrhena Mons is one of a handful of low-elevation, easily eroded volcanoes that lie next to the Hellas impact basin. Among the oldest known volcanoes on Mars, Tyrrhena shows marked differences from large and lofty volcanoes such as Olympus Mons. It's not even 2 km high compared to Olympus' more than 20 km, and instead of being made from flows of hard, basaltic lava, Tyrrhena was built from numerous explosive eruptions that spewed mostly cinders and ash. This view looks north from an altitude of about 20 kilometers (12 miles); no vertical exaggeration.



This observation covers a small part of the plains surrounding the volcano Tyrrhena Patera.

Most of this area is covered by a thick layer of "mantling" material which hides the underlying rocks. Infrared data from the Mars Odyssey spacecraft suggested that this area is rockier than most of the region.  The center of the image is at full resolution, but the outer edges have averaged each group of 4 x 4 pixels. This reduces the amount of data that needs to be returned to Earth and helps ascertain how much resolution is actually needed to study this kind of terrain.  This observation confirms that the area is unusually rocky, with some bare patches of ancient shattered rock exposed at the surface. This image is also a good example of how the HiRISE team samples unknown terrain.


Going straight through the Tyrrhenum Mons is the Tyrrhena Fossae.  From about 105°to 108°E and 20.5°-24°S moving from the southeast to the northeast.



The channel feature in this VIS image is part of Tyrrhena Fossae, is a large depression that dissects Tyrrhena Mons.


Tyrrhena Fossae

Fossa on Mars are large troughs (long narrow depressions) are called fossae in the geographical language used for Mars. Troughs form when the crust is stretched until it breaks. The stretching can be due to the large weight of a nearby volcano. A trough often has two breaks with a middle section moving down, leaving steep cliffs along the sides; such a trough is called a graben. Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because they may be reservoirs of water.


To the east of Tyrrhenum Mons we return to the Hesperia Dorsa and to the Tyrrhena Dorsa which is a ridge that branches off to the southeast.


Crossing Wrinkle Ridges in Tyrrhena Dorsa

Just northeast of where the Dorsum split up is Khurli Crater at 113°E 21.5°S.


Location of Khurli Crater and Vicinity as seen by Themis

Khurli Crater is 8.9 kilometers in diameter and is named after a Pakistan place name.


Suata Crater is located directly north or the Tyrrhenum Mons area at 107°E 19°S.


Location  of Suata Crater and Vicinity as seen by Themis

Suata Crater is 24.3 kilometers in  diameter and is named after A Venezuela place name.


Once again we come to is the Cerberus Dorsa which runs from a confluence with the Tyrrhena Fossae north to northwest. Starting at about 20°S and then going to the northeast to 12°S. in a long curve.  In the north central part of the Region we come to Tinto Valles a runoff channel that leads into Palos Crater.  It is located at 111.5 E and begins at about 5.5°S. going northward.


Tinto Valles

Tinto Valles ins 146.5 kilometers in length and is named after the Río Tinto (Spanish, red river) is a river in southwestern Spain that originates in the Sierra Morena mountains of Andalusia.

The Tinto Valles then flows into the Palos Crater centered at 110.5°E 2.5°S.



Floor of Palos Crater

This image shows a portion of the floor in Palos Crater. The floor appears bumpy with high-standing layered knobs. Most of the terrain on the floor is weathering into meter-size polygonal blocks. The circular structures in the image, many of which are filled with darker Aeolian material, are eroded impact craters.  Palos Crater is breached in the south by the 146.5 kilometers-long Tinto Vallis. Water transported along Tinto Vallis could have could have collected into Palos Crater to form a lake that later drained to the north. Sediments carried by Tinto Vallis would have also been deposited within Palos Crater so the layered unit we see along the floor today could represent these fluvial sediments.  Palos Crater is 55 kilometers in diameter and is named after a Spanish place name.  Palos Crater in turn opens into the Amenthes Planun.


In the Mare Tyrrhenum Region we encounter the southern part of the Amenthes Planum. From  about  105°E  to 112°E with a penetration as far south as 2.5°S along the Equator.


.Wrinkle Ridge in Amenthes Planum -Lat: 0.8°S  Long: 106.5°



Valley and Crater Rim in Amenthes Planum -Lat: 3.2°S Long: 110.7°

Amenthes Planum is a plateau on Mars named after the Egyptian god of the dead and has a diameter of 960 kilometers.


Between 115-116°E on the Equator there is the southern half of Escalante Crater.



Escalante Crater

Escalante Crater is an impact crater located in the Mare Tyrrhenum and  Amenthes Regions of Mars. It is 79.3 km (49.3 mi) in diameter, and was named after the Mexican astronomer (c. 1930) F. Escalante.

Going south of there we come to the Tagus Valles at about 114.5°E 6°S.



Tagus Valles

In the ancient cratered southern highlands of Mars, the faint traces of a wet past are seen in the form of channels (lower center), fluidized debris around craters (bottom right) and blocks of eroded sediments (top left). Volcanic activity may have deposited the fine dusting of dark material visible in the top left. The image was taken by the High Resolution Stereo Camera on ESA’s Mars Express on 15 January 2013 (orbit 11504), with a ground resolution of approximately 22 m per pixel. The image center lies at about 4°S / 114°E, part of the Tagus Valles in an unnamed region north of Hesperia Planum.


Loon Crater puts us back into central Hesperia Planum again at 114.5°E 18.5°S. just north of the ridges of the Hesperia Dorsa to the southeast.


Loon Crater

Loon Crater is 7.6 kilometers in diameter and is named  after a Canada (Ontario) place name.


Going towards the southeastern corner of the Mare Tyrrhenum Region we enter the Terra Cimmeria  which occupies the eastern part of the Region.  Centered at 128°E 21°S is Müller Crater.



Location of Müller Crater

Müller Crater is 129 kilometers in diameter and is named after Hermann Joseph Muller (or H. J. Muller) (December 21, 1890 – April 5, 1967)who was an American geneticist, educator, and Nobel laureate best known for his work on the physiological and genetic effects of radiation (X-ray mutagenesis) as well as his outspoken political beliefs. Muller frequently warned of the long-term dangers of radioactive fallout from nuclear war and nuclear testing, helping to raise public awareness in this area.


Going further north the  next crater we come to is Herschel Crater centered at 130°E 15°S.


Dunes in Herschel Crater

Herschel Crater  is a large crater on Mars. It is named after the eighteenth century astronomer William Herschel.  Herschel Crater is 300 kilometers wide, it is so large that it is properly considered an impact basin. It is located in the cratered highlands of the Martian southern hemisphere, at 15°S, 130°E. Its floor was discovered by the Mars Global Surveyor spacecraft to contain fields of dark sand dunes.


Animation of Dunes in Herschel Crater using HiRISE  DTM



Rippling Dune Front in Herschel Crater

A rippled dune front in Herschel Crater on Mars moved an average of about two meters (about two yards) between March 3, 2007 and December 1, 2010, as seen in this image from NASA's Mars Reconnaissance Orbiter.  The pattern of ripples on the dune surface was changed completely between the two different images. Herschel Crater is located just south of the equator in the cratered highlands.  This is one of several sites where the orbiter has observed shifting sand dunes and ripples. Previously, scientists thought sand on Mars was mostly immobile. It took the mission's High Resolution Imaging Science Experiment (HiRISE) to take sharp enough images to finally see the movement.  While dust is easily blown around the Red Planet, its thin atmosphere means that strong winds are required to move grains of sand.



Dark Dunes in Herschel Crater  HiRISE DTM  128°E 14.S

The eastern part of the Mare Tyrrhenum Region is covered by an area known as Terra Cimmeria.  Terra Cimmeria is a large Martian region, centered at  Coordinates: 34.7°S 145°E and covering 5,400 km (3,400 mi) at its broadest extent. It covers latitudes 15 N to 75 S and longitudes 170 to 260 W. Terra Cimmeria is one part of the heavily cratered, southern highland region of the planet. The Spirit rover landed near the area (see next Phase).  A high altitude visual phenomena, probably a condensation cloud, was seen above this region in late March 2012. NASA tried to observe it with some of its Mars orbiters, including the THEMIS instrument on the 2001 Mars Odyssey spacecraft and MARCI on the Mars Reconnaissance Orbiter.

Gullies in Craters in Terra Cimmeria

Terra Cimmeria is the location of gullies that may be due to recent flowing water.   Gullies occur on steep slopes, especially on the walls of craters.  Moreover, they lie on top of sand dunes which themselves are considered to be quite young. Usually, each gully has an alcove, channel, and apron. Some studies have found that gullies occur on slopes that face all directions, others have found that the greater number of gullies are found on pole ward facing slopes, especially from 30-44° S.  Although many ideas have been put forward to explain them,  the most popular involve liquid water coming from an aquifer, from melting at the base of old glaciers, or from the melting of ice in the ground when the climate was warmer. Because of the good possibility that liquid water was involved with their formation and that they could be very young, scientists are excited. Maybe the gullies are where we should go to find life.  There are three theories concerning their origin:  The first is that most of the gully alcove heads occur at the same level, just as one would expect of an aquifer. Various measurements and calculations show that liquid water could exist in aquifers at the usual depths where gullies begin.  The second  theory,  is much of the surface of Mars is covered by a thick smooth mantle that is thought to be a mixture of ice and dust. This ice-rich mantle, a few yards thick, smoothens the land, but in places it has a bumpy texture, resembling the surface of a basketball. The mantle may be like a glacier and under certain conditions the ice that is mixed in the mantle could melt and flow down the slopes and make gullies.  The third theory  might be possible since climate changes may be enough to simply allow ice in the ground to melt and thus form the gullies. During a warmer climate, the first few meters of ground could thaw and produce a "debris flow" similar to those on the dry and cold Greenland east coast.


Well Preserved Crater in Terra Cimmeria  HiRISE DTM 32°S 140.7°E.


Magnetic Stripes and Plate Tectonics:

The Mars Global Surveyor (MGS) discovered magnetic stripes in the crust of Mars, especially in the Phaethontis and Eridania quadrangles (Terra Cimmeria and Terra Sirenum). The magnetometer on MGS discovered 100 km (62 mi) wide stripes of magnetized crust running roughly parallel for up to 2,000 kilometers (1,200 mi). These stripes alternate in polarity with the north magnetic pole of one pointing up from the surface and the north magnetic pole of the next pointing down.

Bedrock in Terra Cimmeria

When similar magnetic stripes were discovered on Earth in the 1960s, they were taken as evidence of plate tectonics. Researchers believe these magnetic stripes on Mars are evidence for an short, early period of plate tectonic activity. When the rocks became solid they retained the magnetism that existed at the time. A magnetic field of a planet is believed to be caused by fluid motions under the surface (called a Planet‘s dynamo). However, there are some differences, between the magnetic stripes on Earth and those on Mars. The Martian stripes are wider, much more strongly magnetized, and do not appear to spread out from a middle crustal spreading zone. Because the area containing the magnetic stripes is about 4 billion years old, it is believed that the global magnetic field probably lasted for only the first few hundred million years of Mars' life, when the temperature of the molten iron in the planet's core might have been high enough to mix it into a magnetic dynamo.


Magnetic Fields of Earth and Mars

This is an artist's concept comparing the present day magnetic fields on Earth and Mars. Earth's magnetic field is generated by an active dynamo -- a hot core of molten metal. The magnetic field surrounds Earth and is considered global (left image). The various Martian magnetic fields do not encompass the entire planet and are local (right image). The Martian dynamo is extinct, and its magnetic fields are "fossil" remnants of its ancient, global magnetic field.  Billions of years ago when the planets of our solar system were still young, Mars was a very different world. Liquid water flowed in long rivers that emptied into lakes and shallow seas. A thick atmosphere blanketed the planet and kept it warm. In this cozy environment, living microbes probably found a home, starting Mars down the path toward becoming a second life-filled planet next door to our own.  When Mars lost it’s Magnetic field it could no longer maintain an atmosphere- it was ripped away by the Sun’s solar wind leaving only a remnant behind -what we see now.


To the northeast of Herschel Crater in the northeast corner of the Mare Tyrrhenum Region we come to Knobel Crater centered at 133.5°E 6.5°S.


Knobel Crater

Knobel Crater is 128.6 kilometers in diameter and is named after Edward Ball Knobel (21 October 1841 – 25 July 1930) who was an English businessman and amateur astronomer. He was born in London, England.


The next feature we come to is a valley called Licus Vallis that stretches into the next geographical Region to the north of the Mare Tyrrhenum Region. The Vallis starts at 127°E 4.5°S.


The Licus Vallis Channels

The Licus Vallis valley network on Mars. White arrows indicate one of the newly discovered dry river channels.  Licus Vallis is an ancient river valley in the Mare Tyrrhenum Region of Mars. It is 219.1 km (136.1 mi) long and was named after an ancient name for the  modern Lech River in Germany and Austria

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