Diacria quadrangle
Encyclopedia
The Diacria quadrangle
is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey
(USGS) Astrogeology Research Program
. The quadrangle is located in the northwestern portion of Mars’ western hemisphere and covers 180° to 240° east longitude (120° to 180° west longitude) and 30° to 65° north latitude. The quadrangle uses a Lambert conformal conic projection
at a nominal scale of 1:5,000,000 (1:5M). The Diacria quadrangle is also referred to as MC-2 (Mars Chart-2).
The southern and northern borders of the Diacria quadrangle 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). The quadrangle covers an approximate area of 4.9 million square km, or a little over 3% of Mars’ surface area. The Phoenix Lander’s landing site (68.22° N, 234.25° E) lies about 186 km north of the northeastern quarter of the Diacria quadrangle. The landscape viewed by the Phoenix lander is probably representative of a large portion of the terrain in the northern Diacria quadrangle.
located at 48° N and 190° E on Mars. The feature was named by Greek astronomer E. M. Antoniadi in 1930 after a highland area in northern Attica
, Greece. The name was approved by the International Astronomical Union
(IAU) in 1958.
volcanic plateau. Topographic, volcanic, and tectonic features associated with the large volcanoes Olympus Mons
(south of map area) and Alba Mons (east of map area) characterize the southeastern and east central portions of the quadrangle.
The northern and western areas of the quadrangle lie in the northern lowland plains of Mars and cover portions of Amazonis Planitia
(in the south), Arcadia Planitia
(west central) and Vastitas Borealis
(in the north). The large crater Milankovič (118.4 km in diameter) is located in the north central portion of the quadrangle at 54.7° N, 213.3° E.
Elevation data from the Mars Orbital Laser Altimeter (MOLA) instrument on the Mars Global Surveyor
spacecraft shows that the regional terrain slopes gently downward to the northwest, with the highest elevation about 3.5 km (3,500 m) above datum (Mars “sea level”) on the western flank of the Alba Mons volcano in the southeastern portion of the quadrangle. The lowest points in the quadrangle are about 4.5 km below datum (-4,500 m) in Vastitas Borealis in the northwest corner. The regional relief is thus about 8 km, but at a local scale, slopes are very shallow; the portion of Amazonis Planitia in the south central part of the quadrangle contains some of the flattest terrain on the entire planet.
Unlike some other places visited on Mars with landers (Viking
and Pathfinder
), nearly all the rocks near Phoenix are small. For about as far as the camera can see, the land is flat, but shaped into polygons between 2–3 meters in diameter and is bounded by troughs that are 20 cm to 50 cm deep. These shapes are due to ice in the soil expanding and contracting due to major temperature changes. The microscope showed that the soil on top of the polygons is composed of flat particles (probably a type of clay) and rounded particles. Also, unlike other places visited on Mars, the site has no ripples or dunes. Ice is present a few inches below the surface in the middle of the polygons, and along its edges, the ice is at least 8 inches deep. When the ice is exposed to the Martian atmosphere it slowly sublimates. Some dust devil
s were observed.
The western flank of the volcano also contains some NW-SE trending graben
s (Cyane Fossae
). An image from High Resolution Imaging Science Experiment (HiRISE
) on the Mars Reconnaissance Orbiter
(MRO) beautifully shows a line of rimless pit craters in Cyane Fossae. The pits may have formed by the collapse of surface materials into open fractures created as magma intruded the subsurface rock to form dikes
.
troughs (Acheron Fossae
). The troughs are grabens, structures formed when the crust moves downward between two faults. Graben
s form in areas where the crust has undergone extensional stress. The Acheron Fossae region is partially covered by volcanic deposits from Alba Mons in the east, geologically young basalt
ic lava flows or sediments in the west and southeast, and the jumbled, furrowed terrain of Lycus Sulci in the south.
base. This feature, called the Olympus Mons aureole, consists of several large lobes and has a distinctive corrugated or grooved surface texture. East of Olympus Mons, the aureole is partially covered by lava flows, but where it is exposed it goes by different names (Gigas Sulci
, for example).The origin of the aureole remains debated, but it was likely formed by huge landslides or gravity-driven thrust sheets
that sloughed off the edges of the Olympus Mons shield.
(Erebus Mountains). The region contains hundreds of clustered to isolated hillocks that stand 500 to 1,000 m above the surrounding plains. The presence of numerous partly filled “ghost” craters in the area indicates that the hills represent the high-standing remnants of ancient highland crust that was inundated by lava flows and (possibly) alluvial sediments from Tharsis in the southeast and the Elysium
volcanic province to the west.
Medium resolution Mariner 9
and Viking
spacecraft images from the 1970s show that large portions of Arcadia Planitia have an overall mottled (blotchy light and dark) appearance. At higher resolution, landforms commonly consist of lobate flow fronts; small channel segments; wrinkle ridges
; pedestal craters; and low, isolated volcano-like hills with summit craters. MOLA images reveal numerous large, shallowly buried craters, suggesting that an old cratered surface lies under a layer of younger material.
At the resolution of the Mars Orbital Camera (MOC) on the Mars Global Surveyor spacecraft (around several m per pixel), much of the northern plains has a distinctly stippled, pitted texture that causes the ground to resemble the surface of a basketball or orange rind. This texture is likely caused by a mantle of ice and dust covering the landscape. The small hollows and pits formed as the ice evaporated (sublimed).
The geologic history and origin of the northern plains are complex and still poorly understood. Many of the landforms resemble periglacial
features seen on Earth, such as moraines, ice-wedged polygons
, and pingo
s. Arcadia Planitia and Vastitas Borealis likely consist of a hodgepodge of old lava flows, ice-related features, and reworked sediments of diverse origin. Some theorize that the northern plains were once covered by oceans or large lakes.
) onboard the Mars Reconnaissance Orbiter
(MRO). The ice was found in a total of 5 locations. One of the locations (Site 5) is in the Diacria quadrangle at about 46° N, 182° E (Arcadia Planitia).
This discovery is significant because it shows the presence of subsurface ice at latitudes further south than expected and proves that future colonists on Mars will be able to obtain water from a wide variety of locations. The ice can be dug up, melted, and then taken apart to provide fresh oxygen
and hydrogen
for rocket fuel. Hydrogen is the powerful fuel used by the space shuttle
main engines
show dark streaks on steep slopes, such as crater
walls. It seems that the youngest streaks are dark and they become lighter with age. Often they begin as a small narrow spot then widen and extend downhill for hundreds of meters. Several ideas have been advanced to explain the streaks. Some involve water
, or even the growth of organisms
. The streaks appear in areas covered with dust. Much of the Martian surface is covered with dust because at more or less regular intervals dust settles out of the atmosphere covering everything. We know a lot about this dust because the solar panels of Mars rover
s get covered with dust. The power of the Rovers has been saved many times by the wind, in the form of dust devils that have cleared the panels and boosted the power. So we know that dust falls from the atmosphere frequently.
It is most generally accepted that the streaks represent avalanches of dust. Streaks appear in areas covered with dust. When a thin layer of dust is removed, the underlying surface appears dark. Much of the Martian surface is covered with dust. Dust storm
s are frequent, especially when the spring season begins in the southern hemisphere. At that time, Mars is 40% closer to the sun. The orbit of Mars is much more elliptical then the Earth's. That is the difference between the farthest point from the sun and the closest point to the sun is very great for Mars, but only slight for the Earth. Also, every few years, the entire planet is engulfed in a global dust storm. When NASA's Mariner 9
craft arrived there, nothing could be seen through the dust storm. Other global dust storms have also been observed, since that time. Dark streaks can be seen in some of the images below.
(TES) on the Mars Global Surveyor spacecraft has allowed planetary scientists to estimate the amount of dust cover for broad swaths of the planet. In general, the Diacria quadrangle is extremely dusty, particularly in Arcadia Planitia and the region around the flank of Alba Mons and the Olympus Mons aureole in the southeastern portion of the quadrangle. A few large patches of relatively low dust cover occur in Amazonis Planitia and in the northwest corner of the quadrangle.
Many areas on Mars, including the Diacria quadrangle, experience the passage of giant dust devils
. When a dust devil goes by it blows away the coating of dust and exposes the underlying dark surface. Dust devils have been seen from the ground and high overhead from orbit. They have even blown the dust off of the solar panels of the two Rovers on Mars, thereby greatly extending their lives. The twin Rovers were designed to last for 3 months, instead they both lasted more than six years, and one is still going. The pattern of the tracks have been shown to change every few months.
Quadrangle (geography)
In geology or geography, the word "quadrangle" usually refers to a United States Geological Survey 7.5-minute quadrangle map, which are usually named after a local physiographic feature. The shorthand "quad" is also used, especially with the name of the map; for example, "the Ranger Creek, Texas...
is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
(USGS) Astrogeology Research Program
Astrogeology Research Program
The USGS Astrogeology Science Center has a rich history of participation in space exploration efforts and planetary mapping, starting in 1963 when the Flagstaff Science Center was established by Gene Shoemaker to provide lunar geologic mapping and assist in training astronauts destined for the...
. The quadrangle is located in the northwestern portion of Mars’ western hemisphere and covers 180° to 240° east longitude (120° to 180° west longitude) and 30° to 65° north latitude. The quadrangle uses a Lambert conformal conic projection
Lambert conformal conic projection
A Lambert conformal conic projection is a conic map projection, which is often used for aeronautical charts. In essence, the projection superimposes a cone over the sphere of the Earth, with two reference parallels secant to the globe and intersecting it. This minimizes distortion from projecting...
at a nominal scale of 1:5,000,000 (1:5M). The Diacria quadrangle is also referred to as MC-2 (Mars Chart-2).
The southern and northern borders of the Diacria quadrangle 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). The quadrangle covers an approximate area of 4.9 million square km, or a little over 3% of Mars’ surface area. The Phoenix Lander’s landing site (68.22° N, 234.25° E) lies about 186 km north of the northeastern quarter of the Diacria quadrangle. The landscape viewed by the Phoenix lander is probably representative of a large portion of the terrain in the northern Diacria quadrangle.
Origin of name
Diacria is the name of a telescopic albedo featureClassical albedo features on Mars
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. The most popular system of...
located at 48° N and 190° E on Mars. The feature was named by Greek astronomer E. M. Antoniadi in 1930 after a highland area in northern Attica
Attica
Attica is a historical region of Greece, containing Athens, the current capital of Greece. The historical region is centered on the Attic peninsula, which projects into the Aegean Sea...
, Greece. The name was approved by the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
(IAU) in 1958.
Physiography and geology
The Diacria quadrangle is located at the northwestern edge of the TharsisTharsis
The Tharsis region on Mars is a vast volcanic plateau centered near the equator in Mars’ western hemisphere. The region is home to the largest volcanoes in the Solar System, including the three enormous shield volcanoes Arsia Mons, Pavonis Mons, and Ascraeus Mons, which are collectively known as...
volcanic plateau. Topographic, volcanic, and tectonic features associated with the large volcanoes Olympus Mons
Olympus Mons
Olympus Mons is a large volcanic mountain on the planet Mars. At a height of almost , it is one of the tallest mountains in the Solar System, three times as tall as Mount Everest and more than twice the height of Mauna Kea the tallest mountain on Earth. Olympus Mons is the youngest of the large...
(south of map area) and Alba Mons (east of map area) characterize the southeastern and east central portions of the quadrangle.
The northern and western areas of the quadrangle lie in the northern lowland plains of Mars and cover portions of Amazonis Planitia
Amazonis Planitia
Amazonis Planitia is one of the smoothest plains on Mars. It is located between the Tharsis and Elysium volcanic provinces to the west of Olympus Mons in the Valles Marineris region of the Memnonia quadrangle, centered at...
(in the south), Arcadia Planitia
Arcadia Planitia
Arcadia Planitia is a smooth plain with fresh lava flows and Amazonian volcanic flows on Mars. It was named by Giovanni Schiaparelli in 1882 after the Arcadia region of ancient Greece....
(west central) and Vastitas Borealis
Vastitas Borealis
Vastitas Borealis is the largest lowland region of Mars. It is in the northerly latitudes of the planet and encircles the northern polar region. Vastitas Borealis is often simply referred to as the Northern plains or Northern lowlands of Mars. The plains lie 4–5 km below the mean radius of...
(in the north). The large crater Milankovič (118.4 km in diameter) is located in the north central portion of the quadrangle at 54.7° N, 213.3° E.
Elevation data from the Mars Orbital Laser Altimeter (MOLA) instrument on the Mars Global Surveyor
Mars Global Surveyor
The Mars Global Surveyor was a US spacecraft developed by NASA's Jet Propulsion Laboratory and launched November 1996. It began the United States's return to Mars after a 10-year absence. It completed its primary mission in January 2001 and was in its third extended mission phase when, on 2...
spacecraft shows that the regional terrain slopes gently downward to the northwest, with the highest elevation about 3.5 km (3,500 m) above datum (Mars “sea level”) on the western flank of the Alba Mons volcano in the southeastern portion of the quadrangle. The lowest points in the quadrangle are about 4.5 km below datum (-4,500 m) in Vastitas Borealis in the northwest corner. The regional relief is thus about 8 km, but at a local scale, slopes are very shallow; the portion of Amazonis Planitia in the south central part of the quadrangle contains some of the flattest terrain on the entire planet.
What does the surface look like
Viking program
The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...
and Pathfinder
Mars Pathfinder
Mars Pathfinder was an American spacecraft that landed a base station with roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight wheeled robotic rover named Sojourner.Launched on December 4, 1996 by NASA aboard a Delta II booster a...
), nearly all the rocks near Phoenix are small. For about as far as the camera can see, the land is flat, but shaped into polygons between 2–3 meters in diameter and is bounded by troughs that are 20 cm to 50 cm deep. These shapes are due to ice in the soil expanding and contracting due to major temperature changes. The microscope showed that the soil on top of the polygons is composed of flat particles (probably a type of clay) and rounded particles. Also, unlike other places visited on Mars, the site has no ripples or dunes. Ice is present a few inches below the surface in the middle of the polygons, and along its edges, the ice is at least 8 inches deep. When the ice is exposed to the Martian atmosphere it slowly sublimates. Some dust devil
Dust devil
A dust devil is a strong, well-formed, and relatively long-lived whirlwind, ranging from small to large . The primary vertical motion is upward...
s were observed.
Western flank of Alba Mons
The western flank of the Alba Mons volcano makes up the eastern and southeastern edge of the quadrangle. In terms of area, Alba Mons (formerly, Alba Patera) is the largest volcanic feature on Mars. The flank has a very low slope (l° or less) and is characterized by lava flows and an outwardly radiating array of ridges and channels. Some of the channels have a drainage pattern that resembles that formed by rain water on the slopes of terrestrial volcanoes. However, many other channels on the flanks of Alba Mons were clearly formed by flowing lava.The western flank of the volcano also contains some NW-SE trending graben
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....
s (Cyane Fossae
Cyane Fossae
Cyane Fossae is a trough in the Diacria quadrangle of Mars. Its location is centered at 32.57° north latitude and 120.17° west longitude. It is long and was named after a classical albedo feature name....
). An image from High Resolution Imaging Science Experiment (HiRISE
HiRISE
High Resolution Imaging Science Experiment is a camera on board the Mars Reconnaissance Orbiter. The 65 kg , $40 million instrument was built under the direction of the University of Arizona's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corp....
) on the Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...
(MRO) beautifully shows a line of rimless pit craters in Cyane Fossae. The pits may have formed by the collapse of surface materials into open fractures created as magma intruded the subsurface rock to form dikes
Dike (geology)
A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...
.
Acheron Fossae
Near the southeast corner of the quadrangle (37° N, 225° E) lies a southward sloping, semicircular block of ancient, heavily cratered, highland crust that is dissected by numerous, arcuateArcuate
Arcuate can refer to:* Arcuate delta, a type of river delta* Arcuate fasciculus* Arcuate line * Arcuate artery* Arcuate nucleus* Arcuate nucleus * Internal arcuate fibers of the brain...
troughs (Acheron Fossae
Acheron Fossae
Acheron Fossae is a trough in the Diacria quadrangle of Mars. Its location is centered at 37.67° north latitude and 135.87° west longitude. It is 718 km long and is named after a classical albedo feature at 35°N, 140°W ....
). The troughs are grabens, structures formed when the crust moves downward between two faults. Graben
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....
s form in areas where the crust has undergone extensional stress. The Acheron Fossae region is partially covered by volcanic deposits from Alba Mons in the east, geologically young basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic lava flows or sediments in the west and southeast, and the jumbled, furrowed terrain of Lycus Sulci in the south.
Lycus Sulci (Olympus Mons Aureole)
Lycus Sulci (24.6° N, 219° E) is the name applied to the northwestern portion of a larger terrain feature that partially encircles Olympus Mons and extends up to 750 km from the giant shield volcano’sShield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...
base. This feature, called the Olympus Mons aureole, consists of several large lobes and has a distinctive corrugated or grooved surface texture. East of Olympus Mons, the aureole is partially covered by lava flows, but where it is exposed it goes by different names (Gigas Sulci
Gigas Sulci
Gigas Sulci is an area of subparallel furrows and ridges in the Tharsis quadrangle of Mars, located at . It is 398 km across and was named after a classical albedo feature name....
, for example).The origin of the aureole remains debated, but it was likely formed by huge landslides or gravity-driven thrust sheets
Thrust fault
A thrust fault is a type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata. They are often recognized because they place older rocks above younger...
that sloughed off the edges of the Olympus Mons shield.
Erebus Montes
Westward from Lycus Sulci, across the flat plains of Amazonis Planitia, lies an elongated region of knobby terrain called Erebus MontesErebus Montes
Erebus Montes is a group of mountains in the Diacria quadrangle of Mars, located at 35.69 ° North and 185.0 ° West. It is 785 km across and was named after an albedo feature at 26N, 182W....
(Erebus Mountains). The region contains hundreds of clustered to isolated hillocks that stand 500 to 1,000 m above the surrounding plains. The presence of numerous partly filled “ghost” craters in the area indicates that the hills represent the high-standing remnants of ancient highland crust that was inundated by lava flows and (possibly) alluvial sediments from Tharsis in the southeast and the Elysium
Elysium Planitia
Elysium Planitia is the second largest volcanic region on Mars, after Tharsis Montes. It is centered at . It includes volcanoes, from north to south, Hecates Tholus, Elysium Mons and Albor Tholus. Another large volcano, Apollinaris Mons, lies south of the others. Besides having large volcanoes,...
volcanic province to the west.
Arcadia Planitia and Southern Vastitas Borealis
North and east of the Erebus Montes are low-lying plains that characterize a large part of the Diacria Quadrangle and of the Martian northern hemisphere in general.Medium resolution Mariner 9
Mariner 9
Mariner 9 was a NASA space orbiter that helped in the exploration of Mars and was part of the Mariner program. Mariner 9 was launched toward Mars on May 30, 1971 from Cape Canaveral Air Force Station and reached the planet on November 13 of the same year, becoming the first spacecraft to orbit...
and Viking
Viking program
The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...
spacecraft images from the 1970s show that large portions of Arcadia Planitia have an overall mottled (blotchy light and dark) appearance. At higher resolution, landforms commonly consist of lobate flow fronts; small channel segments; wrinkle ridges
Wrinkle-ridge
A wrinkle ridge is a type of feature commonly found on lunar maria. These features are low, sinuous ridges formed on the mare surface that can extend for up to several hundred kilometers. Wrinkle ridges are tectonic features created when the basaltic lava first cooled and contracted...
; pedestal craters; and low, isolated volcano-like hills with summit craters. MOLA images reveal numerous large, shallowly buried craters, suggesting that an old cratered surface lies under a layer of younger material.
At the resolution of the Mars Orbital Camera (MOC) on the Mars Global Surveyor spacecraft (around several m per pixel), much of the northern plains has a distinctly stippled, pitted texture that causes the ground to resemble the surface of a basketball or orange rind. This texture is likely caused by a mantle of ice and dust covering the landscape. The small hollows and pits formed as the ice evaporated (sublimed).
The geologic history and origin of the northern plains are complex and still poorly understood. Many of the landforms resemble periglacial
Periglacial
Periglacial is an adjective originally referring to places in the edges of glacial areas, but it has later been widely used in geomorphology to describe any place where geomorphic processes related to freezing of water occur...
features seen on Earth, such as moraines, ice-wedged polygons
Ice wedge
An ice wedge is a crack in the ground formed by a narrow or thin piece of ice that measures up to 3-4 metres wide at ground level and extends downwards into the ground up to several metres. During the winter months, the water in the ground freezes and expands...
, and pingo
Pingo
A pingo, also called a hydrolaccolith, is a mound of earth-covered ice found in the Arctic and subarctic that can reach up to in height and up to in diameter. The term originated as the Inuvialuktun word for a small hill. A pingo is a periglacial landform, which is defined as a nonglacial...
s. Arcadia Planitia and Vastitas Borealis likely consist of a hodgepodge of old lava flows, ice-related features, and reworked sediments of diverse origin. Some theorize that the northern plains were once covered by oceans or large lakes.
Ice exposed in new craters
A study reported in the journal Science in September 2009, shows that some newly formed craters have excavated clean, water ice from just below the surface in five locations on Mars. After a short time, the ice disappears, subliming into the atmosphere. The ice is only a few feet deep. The ice was confirmed with the Compact Imaging Spectrometer (CRISMCRISM
The Compact Reconnaissance Imaging Spectrometer for Mars is a visible-infrared spectrometer aboard the Mars Reconnaissance Orbiter searching for mineralogic indications of past water on Mars. The CRISM instrument team comprises scientists from over ten universities and led by principal...
) onboard the Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...
(MRO). The ice was found in a total of 5 locations. One of the locations (Site 5) is in the Diacria quadrangle at about 46° N, 182° E (Arcadia Planitia).
This discovery is significant because it shows the presence of subsurface ice at latitudes further south than expected and proves that future colonists on Mars will be able to obtain water from a wide variety of locations. The ice can be dug up, melted, and then taken apart to provide fresh oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
for rocket fuel. Hydrogen is the powerful fuel used by the space shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
main engines
Dark slope streaks
Many places on MarsMars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
show dark streaks on steep slopes, such as crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
walls. It seems that the youngest streaks are dark and they become lighter with age. Often they begin as a small narrow spot then widen and extend downhill for hundreds of meters. Several ideas have been advanced to explain the streaks. Some involve water
Water on Mars
Water on Mars is a psychedelic rock and electronic music group from Quebec City, Québec, Canada. The music trio is led by Philippe Navarro, guitarist, vocalist, arranger, producer, principal lyricist, and music composer....
, or even the growth of organisms
Life on Mars
Scientists have long speculated about the possibility of life on Mars owing to the planet's proximity and similarity to Earth. Fictional Martians have been a recurring feature of popular entertainment of the 20th and 21st centuries, but it remains an open question whether life currently exists on...
. The streaks appear in areas covered with dust. Much of the Martian surface is covered with dust because at more or less regular intervals dust settles out of the atmosphere covering everything. We know a lot about this dust because the solar panels of Mars rover
Mars Rover
A Mars rover is an automated motor vehicle which propels itself across the surface of the planet Mars after landing.Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to...
s get covered with dust. The power of the Rovers has been saved many times by the wind, in the form of dust devils that have cleared the panels and boosted the power. So we know that dust falls from the atmosphere frequently.
It is most generally accepted that the streaks represent avalanches of dust. Streaks appear in areas covered with dust. When a thin layer of dust is removed, the underlying surface appears dark. Much of the Martian surface is covered with dust. Dust storm
Dust storm
A dust / sand storm is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Particles are transported by saltation and suspension, causing soil to move from one place and deposition...
s are frequent, especially when the spring season begins in the southern hemisphere. At that time, Mars is 40% closer to the sun. The orbit of Mars is much more elliptical then the Earth's. That is the difference between the farthest point from the sun and the closest point to the sun is very great for Mars, but only slight for the Earth. Also, every few years, the entire planet is engulfed in a global dust storm. When NASA's Mariner 9
Mariner 9
Mariner 9 was a NASA space orbiter that helped in the exploration of Mars and was part of the Mariner program. Mariner 9 was launched toward Mars on May 30, 1971 from Cape Canaveral Air Force Station and reached the planet on November 13 of the same year, becoming the first spacecraft to orbit...
craft arrived there, nothing could be seen through the dust storm. Other global dust storms have also been observed, since that time. Dark streaks can be seen in some of the images below.
Dust and dust devil tracks
Large portions of the martian surface are blanketed with bright reddish-ochre dust. The dust particles are typically less than 40 micrometres in size and are composed of iron oxide minerals. Data from the Thermal Emission SpectrometerThermal Emission Spectrometer
The Thermal Emission Spectrometer is an instrument on board Mars Global Surveyor. TES collects two types of data, hyperspectral thermal infrared data from 6 to 50 micrometers and bolometric visible-NIR measurements...
(TES) on the Mars Global Surveyor spacecraft has allowed planetary scientists to estimate the amount of dust cover for broad swaths of the planet. In general, the Diacria quadrangle is extremely dusty, particularly in Arcadia Planitia and the region around the flank of Alba Mons and the Olympus Mons aureole in the southeastern portion of the quadrangle. A few large patches of relatively low dust cover occur in Amazonis Planitia and in the northwest corner of the quadrangle.
Many areas on Mars, including the Diacria quadrangle, experience the passage of giant dust devils
Dust Devils
Dust Devils is an independently published role-playing game set in the Old West, written by Matt Snyder. It was voted the 2002 Indie RPG of the Year; it also won the Best Synergy of Game and Rules category, as well as placing in the Best Production and Most Innovative Game categories.The game uses...
. When a dust devil goes by it blows away the coating of dust and exposes the underlying dark surface. Dust devils have been seen from the ground and high overhead from orbit. They have even blown the dust off of the solar panels of the two Rovers on Mars, thereby greatly extending their lives. The twin Rovers were designed to last for 3 months, instead they both lasted more than six years, and one is still going. The pattern of the tracks have been shown to change every few months.
See also
- Water on MarsWater on MarsWater on Mars is a psychedelic rock and electronic music group from Quebec City, Québec, Canada. The music trio is led by Philippe Navarro, guitarist, vocalist, arranger, producer, principal lyricist, and music composer....
- Dark slope streak
- Dust Devil TracksDust Devil TracksMany areas on Mars experience the passage of giant dust devils. A thin coating of fine bright dust covers most of the Martian surface. When a dust devil goes by it blows away the coating and exposes the underlying dark surface, which within a few weeks assumes its former bright colour, either from...
- Fossa (geology)Fossa (geology)Fossa is a term used in planetary geology to describe a long, narrow depression on the surface of an extraterrestrial body, such as a planet or moon...
- Volcanism on MarsVolcanism on MarsVolcanic activity, or volcanism, has played a significant role in the geologic evolution of Mars. Scientists have known since the Mariner 9 mission in 1972 that volcanic features cover large portions of the Martian surface. These features include extensive lava flows, vast volcanic plains, and the...
- Phoenix Lander