Tuesday, September 10, 2013

Small Pale Red Planet Issue 1 Phase 13


Cebrenia Region




Topographical Map of The Cebrenia Region showing landing site of Viking 2 Lander

The southern and northern borders of the Cebrenia Region are approximately 3,065 km (1,905 mi) and 1,500 km (930 mi) wide, respectively. The north to south distance is about 2,050 km (1,270 mi).



Image of The Cebrenia Region

The Region's prominent features are the large Craters Mie and Stokes, a Volcano, Hecates Tholus, and a group of mountains, Phlegra Montes. This area is a flat, smooth plain for the most part, so the relatively large craters Mie and Stokes really stand out. The Galaxias Region has an area of chaos, where the ground seems to have collapsed.

NASA's Viking Mission to Mars was composed of two spacecraft, Viking 1 and Viking 2, each consisting of an orbiter and a lander. The primary mission objectives were to obtain high resolution images of the Martian surface, characterize the structure and composition of the atmosphere and surface, and search for evidence of life.  Viking 2’s orbiter was inserted into a Mars orbit on August 7, 1976 . Imaging of candidate sites was begun and the landing site was selected based on these pictures and the images returned by the Viking 1 Orbiter.  The lander separated from the orbiter on September 3, 1976 at 22:37:50 UTC and landed in Utopia Planitia in the Cebrenia Region.

The Surface of Utopia Planitia

Normal operations called for the structure connecting the orbiter and lander (the bioshield) to be ejected after separation, but because of problems with the separation the bioshield it was left attached to the orbiter. The orbit inclination was raised to 75 degrees on 30 September 1976 Viking 2 landed about 200 km west of the crater Mie. Its landing coordinates were 48° N and 226° W.

What would it look like walking around the landing site: The sky would be a light pink. The dirt would also appear pink. The surface would be uneven; the soil would be formed into troughs. Large rocks would be spread about. Most of the rocks are similar in size. Many of the rocks would have small holes or bubbles on their surfaces caused by gas escaping after the rocks came to the surface. Some boulders would show erosion due to the wind. Many rocks would appear to be perched, as if wind removed much of the soil at their bases. In the winter snow or frost would cover most of the ground. There would be many small sand dunes that are still active. The wind speed would typically be 7 meters per second (16 miles per hour).


Viking 2 Lander Image

The soil resembled those produced from the weathering of basaltic lavas. The tested soil contained abundant silicon and iron, along with significant amounts of magnesium, aluminum, sulfur, calcium, and titanium. trace elements, strontium and yttrium were detected. The amount of potassium was 5 times lower than the average for the Earth's crust. Some chemicals in the soil contained sulfur and chlorine that were like typical compounds remaining after the evaporation of sea water.


Photo from Viking Lander 2 shows late-winter frost on the ground on Mars around the lander.

The view is southeast over the top of Lander 2,  shows patches of frost around dark rocks. The surface is reddish-brown; the dark rocks vary in size from 10 centimeters (four inches) to 76 centimeters (30 inches) in diameter. This picture was obtained September 25, 1977. The frost deposits were detected for the first time 12 Martian days (sols) earlier in a black-and-white image. Color differences between the white frost and the reddish soil confirm that we are observing frost.

Viking 2 Lander Video

Search for Life:  Viking did three experiments to look for life. The results were surprising and interesting. Most scientists now believe that the data were due to inorganic chemical reactions of the soil, although a few scientists still believe the results were due to living reactions. No organic chemicals were found in the soil. However, dry areas of Antarctica do not have detectable organic compounds either, but they have organisms living in the rocks. Mars has almost no ozone layer, like the Earth, so UV light sterilizes the surface and produces highly reactive chemicals such as peroxides that would oxidize any organic chemicals.  Research, published in the Journal of Geophysical Research in September 2010, proposed that organic compounds were actually present in the soil analyzed by both Viking 1 and 2.

Just to the east at 48°N and 140°E is the large impact crater Mie.


The Crater Mie Floor


The Crater Mie Floor in color

Impressive research, reported in the journal Science in September 2009, has showed that some new craters on Mars show exposed, pure, water ice. After a time, the ice disappears, evaporating (sublimation) into the atmosphere. The ice is only a few feet deep. The ice was confirmed with the Compact Imaging Spectrometer (CRISM)] on board the Mars Reconnaissance Orbiter (MRO). The ice was found in a total of 5 locations. Three of the locations are in the Cebrenia Region.  Impact craters generally have a rim with ejecta around them, in contrast volcanic craters, which usually do not have a rim or ejecta deposits. Sometimes craters will display layers. Since the collision that produces a crater is like a powerful explosion, rocks from deep underground are tossed onto the surface. Therefore, craters can show us what lies deep under the surface.

The Kufra Crater Floor, as seen by HiRISE has pits that are thought to be caused by escaping water. This crater is right on the western border of the Cebrenia Region at 41°N.


Kufra Crater floor, as seen by HiRISE. Pits are thought to be caused by escaping water.

Hrad Valles is an ancient outflow channel in the Cebrenia quadrangle of Mars, located at 38.7° north latitude and 224.7° west longitude. It is 825 km in length and was named for the word for "Mars" in Armenian.


Hrad Valles may have been formed when the large Elysium Mons volcanic complex melted ground ice, as seen by THEMIS.

When hot subsurface molten rock comes close to  ice, large amounts of liquid water and mud may have formed. Hrad Valles in the Cebrenia Region is close to Hecates Tholus (the northern-most of the Elysium Volcanoes), and may have supplied water to create the channel.  Hrad Valles originates from the volcano region near the southern border of the Cebrenia Region and appears to end near the Kumara Crater at 43°N and 129°E.

Chincoteague Crater is an impact crater in the Cebrenia quadrangle of Mars, located at 41.5° N and 236.0° W. It is 37.0 km in diameter.  It is located just to the west of Hrad Valles.


Close up of Chincoteague Crater, as seen by HiRISE. Note the gullies and associated landforms.


Apsus Vallis, as seen by THEMIS.

Apsus Vallis is near the Elysium volcanic system; it may have been partially formed by the action of lava.  Apsus Vallis is a channel in the Cebrenia Region of Mars, located at 35.1° north latitude and 225° west longitude. It is 120 km long and was named after a classical river in ancient Macedonia, the present-day Seman River.  Apsus Vallis is a small channel  originating from the western edge of the volcano region in the south and lies west of  Hrad Valles.

Just to the west and northwest of the foothills leading to Hecates Tholus lies the Galaxias Chaos complex.  Chaos terrain on Mars is distinctive; nothing on Earth compares to it. Chaos terrain generally consists of irregular groups of large blocks, some tens of kilometers across and a hundred or more meters high. The tilted and flat topped blocks form depressions hundreds of meters deep.


Galaxias Chaos by CTX

A chaotic region can be recognized by a rat's nest of mesas, buttes, and hills, chopped through with valleys which in places look almost patterned. Some parts of this chaotic area have not collapsed completely—they are still formed into large mesas, so they may still contain water ice. Chaos regions formed long ago.  In the Galaxias Region  the ground seems to have collapsed. Such land forms on Mars are called "Chaos terrain." Galaxias Chaos is different from many other chaotic regions. It does not have associated outflow channels, and it does not display a great elevation difference between it and the surrounding land area, as most of the other chaos regions. Research  published in 2010, suggests that the Galaxias Chaos is the site of a volcanic flow that buried an ice-rich layer, called the Vastitas Borealis Formation (VBF).


Galaxias Chaos as seen by HiRISE.

It is generally believed that the VBF is a residue from water-rich materials deposited by large floods. The VBF may have been of varied thickness and may have contained varied amounts of ice. In the thin atmosphere of Mars, this layer would have slowly disappeared by sublimation (changing from a solid directly to a gas).



Galaxias Chaos in the Infrared

Since some areas would have sublimated more than others, the upper lava cap would not be supported evenly and would crack. Cracks/troughs may have begun from sublimation and shrinkage along the edges of the lava cap. Stress from the undermining of the cap edge would have made cracks in the cap. Places with cracks would undergo more sublimation, then the cracks would widen and form the blocky terrain characteristic of regions of chaos.



Next we come to the foothills region leading to the volcano Hecates Tholus located in the southern center of the region.  Hecates Tholus is a Martian volcano, notable for results from the European Space Agency's Mars Express mission which indicate a major eruption took place 350 million years ago. The eruption created a caldera 10 km in diameter.  It has been suggested that glacial deposits later partly filled the caldera and an adjacent depression. Crater counts indicate this happened as recently as 5 to 20 million years ago. So this is a recent event on the geological time scale.


Hecates Tholus, as seen by Mars Global Surveyor.

However climate models show that ice is not stable at Hecates Tholus today, pointing to climate change since the glaciers were active. It has been shown that the age of the glaciers correspond to a period of increased obliquity of Mars' rotational axis. The volcano is at location 32.12°N 150.24°E, in the Cebrenia Region, and has a diameter of 182 km. It is the northernmost of the Elysium volcanoes; the others are Elysium Mons and Albor Tholus both in the Elysium Region.


Topographical map of Hecates Tholus 

Large amounts of water ice are believed to be present under the surface of Mars. Some channels lie near volcanic areas. When hot subsurface molten rock comes close to this ice, large amounts of liquid water and mud may have been formed.


Buvinda Vallis

Buvinda Vallis, as seen by THEMIS. Buvinda Vallis is associated with Hecates Tholus; it lies just east of Hecates Tholus. Located at 33.4 N and 208.1 W. it is 119.6 km long. It was named after a classical river in Hibernia and the present Boyne River, Ireland.

To the east of Hecates Tholus  begins the Phlegra Montes It is a system of mountains in the Cebrenia Region of Mars, located at 40.4 degrees north latitude and 163.71 degrees east longitude.  Material moving down slope in Phlegra Montes, was seen by HiRISE.  The movement is probably aided by water/ice.



The Phlegra Montes

Leaving the Phlegra Montes we move to the northeast and come to Stokes Crater.  It is located at  55.9°N 188.8°W and is 66 kilometers in diameter.


Possible Phyllosilicates in Stokes Crater


Megabreccia in the Central Uplift of Stokes Crater

Large craters like Stokes will invariably have a central structural uplift, which form mountain peaks in or near the center of the crater. The Northern plains are largely covered by lavas and sediments, but craters such as Stokes allow us to observe the otherwise buried bedrock, exposed within its central uplift.  The first sub image shows a wide variety of colors and textures in a jumbled, fragmental pattern, i.e. "megabreccia." In the stereo anaglyph we can see that many of the fragmental blocks "stick out," indicating that they are more resistant to erosion than the the surrounding finer-grained material between the blocks. There is also an abundance of dark sand dunes and other smaller Aeolian (wind-driven) bed forms on top of the area of exposed bedrock.  Megabreccia, consisting of very large fragments of pre-existing bedrock, is created by energetic processes, but especially by impact events on Mars. Although megabreccia deposits can coat central uplifts, it may not have been the Stokes impact that made this megabreccia.


Megabreccia in craters

Going southeast through the Arcadia Planitia which extends back into the Diacria Region.  We cross the southeast Corner of the Cebrenia Region at 30°N and 180°E and enter the Amazonis Region.

Wednesday, September 4, 2013

Small Pale Red Planet Issue 1 Phase 12


Casius Region




Topographical Map for the Casius Region

The southern and northern borders of the Casius Region are approximately 3,065 km and 1,500 km wide, respectively. The north to south distance is about 2,050 km. (slightly less than the length of Greenland.



Image of Casius Region

The high latitude Casius Region bears several features that are believed to indicate the presence of ground ice.  Patterned ground is one such feature. Usually, polygonal shapes are found pole ward of 55 degrees latitude. Other features associated with ground ice are Scalloped Topography, Ring Mold Craters, and Concentric Crater Fill.



Ring Mold Craters

Ring Mold Craters look like the ring molds used in baking. They are believed to be caused by an impact into ice. The ice is covered by a layer of debris. They are found in parts of Mars that have buried ice. Laboratory experiments confirm that impacts into ice result in a "ring mold shape." They may be an easy way for future colonists of Mars to find water ice.


The Nilosyrtis Mensae Channel

Nilosyrtis Mensae like several other features, sits in more than one Region. Part of Nilosyrtis Mensae is in the Ismenius Lacus Region, the rest is in Casius Region.  So leaving the Protonilus Mensae we enter the Nilosyrtis Mensae just east of the border of the Casius Region  then leaving the Ismenius Lacus Region in the Nilosyrtis Mensae we enter the Casius Region while following the shoreline of  the Dichotomy on Mars.   It is centered on the coordinates of 36.87° N and 67.9° E. Its western and eastern longitudes are 51.1° E and 74.4° E. North and south latitudes are 36.87° N and 29.61° N. Its name was adapted by the IAU in 1973. It was named after a classical albedo feature, and it is 705 km (438 mi) across.


Ridges in surface of Nilosyrtis Mensae

The surface of Nilosyrtis Mensae is classified as fretted terrain. This terrain contains cliffs, mesas, and wide flat valleys. Surface features are believed to have been caused by debris-covered glaciers. 

South of this area in the southwest corner of the Casius Region is the last part of  Terra Sabaea that we see.  Going from from south to north at about 30-33 Degrees North, Huo Hsing Vallis empties into the Nilosyrtis Mensae.


Huo Hsing Vallis

Huo Hsing Vallis is an ancient river valley that originates south in the Uplands of the  Syrtis Major  Region of Mars at 30.5° North latitude and 293.4° West longitude. It is about 318 km long and was named after the word for "Mars" in Chinese. It goes through the Terra Sabaea in the Casius Region and emptied into the Nilosyrtis Mensae. 

North of the Nilosyrtis Mensae located near the western border of the Casius region at about 42° North is Renaudot Crater.


Dunes and Bedrock in Renaudot Crater

Concentric Crater Fill:  Concentric crater fill is when the floor of a crater is mostly covered with a large number of parallel ridges. They are thought to result from a glacial type of movement. Sometimes boulders are found on concentric crater fill; it is believed they fall off the crater wall,  then were transported away from the wall with the movement of the glacier.

Going north from Renaudot Crater to about 50°N. 35°E we come to the Pyramus Fossae.


Possible Duricrust in Pyramus Fossae

Duricrust is a hard layer on or near the surface of soil. Duricrusts can range in thickness from a few millimeters or centimeters to several meters.  It is typically formed by the accumulation of soluble minerals deposited by mineral-bearing waters that move upward, downward, or laterally by capillary action, commonly assisted in arid settings by evaporation.  Minerals often found in duricrust include silica, iron, calcium, and gypsum.  Duricrust is often studied during missions to Mars because it may help prove the planet once had more water. Duricrust was found on Mars at the Viking 2 landing site, and a similar structure, nicknamed "Snow Queen," was found under the Phoenix landing site. Phoenix's duricrust was later confirmed to be water-based.

Going east from there we come to Utopia Planitia.  The Utopia Planitia (Latin: "Nowhere Plain") is the largest recognized impact basin on Mars and in the solar system with an estimated diameter of 3300 km,  is the Martian area where the Viking 2 lander touched down and began exploring on September 3, 1976 in the Cebrenia Region.  The Utopia region is located in both the Casius  Region and the Cebrenia Region of Mars to the east.  Many rocks in Utopia Planitia appear perched, as if wind removed much of the soil at their bases. A hard surface crust is formed by solutions of minerals moving up through soil and evaporating at the surface. Some areas of the surface exhibit what is called "scalloped topography," a surface that seems to have been carved out by an ice cream scoop. This surface is thought to have formed by the degradation of an ice-rich permafrost.

Utopia Planitia Area

Utopia Rupes is south of Utopia Planitia  in the central are of the Region at  about 40-44°N.


Polygons and Pits in Utopia Rupes

South of Utopia Rupes we come to the Astapus Colles:


Astapus Colles mounds and knobs, as seen by HiRISE. Scale bar is 500 meters long.

Astapus Colles :  is a group of hills in the Casius Region of Mars, located at 35.5 North and 272.3 West. It is 580 km across named after an albedo feature. 

The classical albedo features of Mars are the light and dark features that can be seen on the planet Mars through an Earth-based telescope. Before the age of space probes, several astronomers created maps of Mars on which they gave names to the features they could see based on albedo features. The most popular system of nomenclature was devised by Giovanni Schiaparelli, who used names from classical antiquity. Today, the improved understanding of Mars enabled by space probes has rendered many of the classical names obsolete for the purposes of cartography; however, some of the old names are still used to describe geographical features on the planet.

East of  Astapus Colles is Adamas Labyrinthus located at about 35°N.


In the Adamas Labyrinthus area we come to abrupt landscape changes.  

A review of existing images of Mars reveals a diverse landscape. In some instances, such as around volcanoes and in valleys, a casual glance suggests the features are much like those here on Earth. Closer inspection, however, often confirms differences in scale and or subtle characteristics relative to their more familiar terrestrial counterparts.  These same images also reveal a Mars that is often very different form the Earth. Some locations are marked by huge jumbles of blocks forming chaotic terrain, whereas others are buried beneath blankets of dust.

Just North of Adamas Labyrinthus is Nier Crater.


Gullies in the walls of Nier Crater

To the north east on the Region border is Vivero Crater.  Located at about 49°North.



The Central Peak in Vivero Crater

The high-velocity collision of interplanetary objects (mostly asteroids, also comets) with the surface of Mars creates primary impact craters. The primary impacts may eject significant numbers of rocks at high velocity which fall back to make secondary craters. The study of craters is important for many reasons, such as understanding cratering mechanics, attempts to estimate the ages of terrains or processes, understanding properties of the target material such as presence of ground ice, and understanding landscape evolution (since we have some understanding of the morphology of pristine craters). The study of small craters (< 10 m diameter) can provide information about atmospheric density, and perhaps how it has varied over time. Not all craters are of impact origin—craters can also form from volcanism or ground collapse.

Next we come to Bacolor Crater right in the southeast corner of the Casius Region.


Bacolor Crater Ejecta, as seen by HiRISE. Scale bar is 1000 meters long.

Bacolor Crater: is a crater located at 33 North and 241.4 West. It is 20.8 km in diameter and was named after a town in the Philippines.