Difference between revisions of "What Mars Actually Looks Like!"

Latest revision as of 17:01, 13 October 2024

Article written by Jim Secosky. Jim is a retired science teacher who has used the Hubble Space Telescope, the Mars Global Surveyor, and HiRISE.

Almost all of the sites that we have landed on Mars with spacecraft have been to the most drab and boring places on the planet. This was done to ensure a safe landing. This article will display many of the more exciting landscapes using HiRISE images. HiRISE images can show detail down to the size of a small kitchen table. With HiRISE we frequently even see spacecraft that have landed on the surface. Many of the scenes shown here are about one would see at the height of a helicopter. Most of the HiRISE images here were obtained through the HiWish program, a program where anyone could suggest places to be imaged with HiRISE. To obtain the images, I studied wide angle CTX images to find sites that could contain interesting features. I was lucky that many of my suggestions were photographed, and I was able to gather them together for this article.

Viking 1

Rocks and dunes, as seen from Viking 1 Holes were dug by the digging tool. Part of the meteorology boom is visible.

Viking 1 was the first successful spacecraft to land on Mars. It landed on July 20, 1976 at 22.27 N and 47.95 W (312.05 E). July 20th was also the date when we first landed on the moon in 1969.

Viking 2

View from Viking 2

Viking 2 landed on September 3, 1976 at 47.64 N and 275.71 W (84.29 E).

Mars Pathfinder

Wide view from Mars pathfinder, showing Sojourner Rover

The Mars Pathfinder landed on July 4, 1997 at 19 degrees 7’ 48” in Ares Vallis.

Spirit Rover

The Spirit Rover landed on January 4, 2004 at 14.5684 S and 175.472636 E (184.527364 W).

Bonneville crater from Spirit Rover Columbia Hills are in the right in the distance. Spirit eventually drove to the Columbia Hills.
Wide view with Husband Hill in the distance to which Spirit eventually drove to. Solar panels are visible.
Wide view from Spirit Rover Solar panels are visible.

Opportunity Rover

The Opportunity Rover landed on January 25, 2004 at 1.9462 S and 354.4734 E (5.5268 W).

Wide view from Opportunity showing heat shield to the left and circular impact crater on the right
Wide view of Perserverance Valley taken with Opportunity Rover High points visible on the rim of Endeavour Crater include "Winnemucca" on the left and "Cape Tribulation" on the right. Winnemucca is part of the "Cape Byron" portion of the crater rim. The horizon at far right extends across the floor of Endeavour Crater, which is about 14 miles (22 kilometers) in diameter.
Wide view from top of the "Cape Tribulation" segment of the rim of Endeavour Crater.

Phoenix

Wide view from Phoenix lander Solar panels are visible.

Phoenix landed in the far North of Mars on May 25, 2008 at 68.22 N and 125.7 W (234.3 E) in Vastitas Borealis.

Curiosity Rover

Early view from Curiosity Mount Sharp is in the distance. The shadow of Rover is visible. Mount Sharp at a height of about 3.4 miles is taller than Mt. Whitney in California.

The Curiosity Rover landed on August 6, 2012 at Gale Crater in Aeolis Palus at 4.5895 S and 137.4417 E (222.5583 W). By this time scientists were able to be more precise with their landings, so Curiosity has been able to get views of Mars that are pretty exciting.

Slip Face on Downwind Side of 'Namib' Sand Dune on Mars, as seen by Curiosity Dune stands about 13 feet (4 meters) high. Picture taken with Navcam.
This evenly layered rock photographed by the Mast Camera (Mastcam) on NASA's Curiosity Mars Rover shows a pattern typical of a lake-floor sedimentary deposit not far from where flowing water entered a lake.
View from the "Kimberley" formation on Mars taken by NASA's Curiosity rover.
View from Mastcam on Curiosity showing sloping buttes and layered outcrops on lower Mount Sharp Location is within the "Murray Buttes" region on lower Mount Sharp.
360-degree panorama of a location called "Teal Ridge"
Close view of layers of ancient sediment on a boulder-sized rock called "Strathdon," as seen by the Mars Hand Lens Imager (MAHLI) camera on the end of the robotic arm on NASA's Curiosity rover.

What follows are a few pictures of the many different scenes that we have studied with powerful cameras on board the Mars Reconnaissance Orbiter that has been going around Mars for over 10 years.

Dunes

The Martian surface displays many beautiful dark dunes. For many years, scientists thought dark dunes were composed of the grains of sand from the volcanic rock basalt; this was confirmed by rovers on the surface.^[1] The dunes are covered by a seasonal carbon dioxide frost that forms in early autumn and remains until late spring.

The presence of dunes on Mars and the observations that they do change is clear proof that there is air on Mars. However, we must remember that its atmosphere is only about 1 % as dense as the Earth's. Hence, a wind speed of a 60-mph storm on Mars would feel more like 6 mph (9.6 km/hr).^[2]

                             Colorful dunes in the Mare Tyrrhenum quadrangle^[5]

Dunes processed in the rgb color system
Wide view of dune field in Ismenius Lacus quadrangle
Defrosting dunes in Mare Boreum quadrangle
Color view of dunes defrosting Ice is in the toughs of the polygons.
Wide view of dune field
Close view of dunes
Close view of dunes
Falling dunes These “falling dunes” are a type of topographically-controlled sand dune that formed when down-slope winds were focused by local topography. The dunes point to the lowest areas--in this photo that is toward the top.

                                 Dunes  This image was named picture of the day for July 25, 2021

Dunes of various shapes are common on Mars, especially on the floors of craters. Sand gets into craters and then the winds are not strong enough to get it over the rim. '

Wide view of crater showing ridges and various shaped sand dunes on floor. Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
Close view of various shaped dunes Picture is about 1 km across. Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
Close view of various shaped dunes Picture is about 1 km across. Some dunes would be called star dunes. Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
Close view of various shaped dunes Picture is about 1 km across. Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
Close view of various shaped dunes Picture is about 1 km across. Some dunes would be called star dunes. Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
Close view of various shaped dunes Picture is about 1 km across. Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.

Layers

Many places on Mars show rocks arranged in layers. Volcanoes, wind, or water can produce layers.^[6] Layers can be hardened by the action of groundwater.

Layers and fault in Firsoff Crater in Oxia Palus quadrangle, as seen by HiRISE under HiWish program

Layers some with overhang. This image was named HiRISE picture of the day
Layers and layered mounds. Each layer records some sort of change and water may have been involved.
Layers Dark parts are basalt sand that has settled on horizonal surfaces.
Close, color view of layers. Light brown is from dust falling from sky. Dark parts are basalt sand that has settled on horizonal surfaces.
Layers in Crommelin Crater
Layers in Danielson Crater in Oxia Palus quadrangle
Color image of layers on the floor of Danielson Crater taken under the HiWish program

Faults in Danielson Crater, as seen by HiRISE under HiWish program
Faults and layers in Danielson Crater, as seen by HiRISE under HiWish program
Wide view of layers in Danielson Crater, as seen by HiRISE under HiWish program. Image was named HiRISE picture of the day.
Close view of top of image of Danielson Crater, as seen by HiRISE (ESP_071634_1880).
Close view of top of image of Danielson. Arrows indicate parts that are enlarged.
Layers in Danielson Crater with enlargements of some spots (indicated with arrows).
Layers in Danielson Crater with enlargements of some spots (indicated with arrows).
Layers in Danielson Crater, as seen by HiRISE under HiWish program.

Glaciers

There are large areas on Mars that contain what is thought to be ice moving under a cover of debris. A few meters of debris can preserve ice for long periods of time.^[7]

Several types of landforms have been identified as probably dirt and rock debris covering huge deposits of ice.^[8] ^[9] ^[10] ^[11] Concentric crater fill (CCF) contains dozens to hundreds of concentric ridges that are caused by the movements of sometimes hundreds of meter thick accumulations of ice in craters.^[12] ^[13] Lineated valley fill (LVF) are lines of ridges in valleys.^[14] ^[15] ^[16] These lines may have developed as other glaciers moved down valleys. Some of these glaciers seem to come from material sitting around mesas and buttes.^[17] Lobate debris aprons (LDA) is the name given to these glaciers. All of these features that are believed to contain large amounts of ice are found in the mid-latitudes in both the Northern and Southern hemispheres.^[18] ^[19] ^[20]

Glacier leaving a valley in the Ismenius Lacus quadrangle
Concentric crater fill The concentric lines are formed from ice moving away from the crater walls. This crater is mostly full of ice.
Wide view of concentric crater fill in crater in Casius quadrangle

Mesa with Lobate Debris Aprons (LDA) Orbiting radars have detected ice in LDA’s under a thin cover of debris.

Lobate Debris Aprons (LDA) around a mound

Labeled view of Lineated Valley Flow and glacier

Lineated Valley Flow in valley
Lineated Valley Flow, as seen by HiRISE under the HiWish program
Lineated valley fill in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris. Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
Close view of lineated valley fill (LVF) in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris. Picture is about 1 km wide. Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
Close view of lineated valley fill (LVF) in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris. Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
Close view of lineated valley fill (LVF) in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris. Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
Lineated valley fill in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris. Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
Close view of lineated valley fill (LVF) in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris. Picture is about 1 km wide. Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.

Gullies

Martian gullies are networks of narrow channels and their associated downslope deposits, found on steep slopes. A high concentration occurs near 40 degrees north and south of the equator. Usually, each gully has an alcove at its head, a fan-shaped apron at its base, and a channel linking the two.^[21] They are believed to be relatively young because they have few, if any craters. They were believed to be caused by recent running water, but with more observations other ideas emerged. In summary of our present understanding of gullies it can be said: A number of studies have demonstrated that gullies are being modified on present day Mars. ^[22] ^[23] ^[24] ^[25] Today, liquid water cannot exist on the Red planet because the both the pressure and the temperature are too low. Researchers have proposed other mechanisms that could account for gully formation without liquid water.^[26] Most involve dry ice (solid carbon dioxide) accumulating during cold seasons and then changing to a gas in the spring. The gas coming off could start material moving down slopes. The gas mixed with sand and other debris could act like water to erode channels. Also, pieces of dry ice could easily side down due to the lubricating effect of gas coming off the dry ice.

Channels on sand dunes, as seen by HiRISE. Arrows show chunks of ice that moved down to enlarge gullies.

However, one wonders if these processes could account for the formation of all the gullies. Maybe, liquid water was sometimes necessary, especially to move large boulders. A study of over 700 sites, published in 2022 in Icarus, concluded that liquid water would not have been needed. During the duration of the study many large boulders were moved—one being 5 meters across. Many types of changes were seen in gullies. Some channels were extended, new channels were formed, and other channels were filled with new debris.^[27] ^[28] Perhaps, some water was involved in the past, but all the gullies seen today could have been made without water.

Gullies with alcove, channel, and apron labeled
Gullies in Argyre quadrangle Curved channels were thought to need running water to form.
Color view of Gullies, as seen by HiRISE under HiWish program
Gullies in Phaethontis quadrangle Ridges at the end of the gullies may be the remains of old glaciers.^[29]
Close view of gully in crater, as seen by HiRISE

Gullies on crater wall The bright apron is a bit unusual.
Gully on crater wall The bright apron is a bit unusual.
Wide view of gullies
Close view of gully alcoves Picture is about 1 km across.
Close view of gully alcoves Picture is about 1 km across.
Close view of gully channels Picture is about 1 km across.

Channels

There are thousands of channels that were probably caused by running water in the past on Mars. Some are large; some are tiny.^[30] ^[31] ^[32] ^[33] ^[34]

Small branched channel
Channel in the Sinus Sabaeus quadrangle
Streamlined forms in wide channel These were shaped by running water.^[35]
An oxbow means that water flowed long enough to make a meander before the stream made a shortcut across the meanders.

Inverted relief

Some places on Mars show inverted relief. In these locations, a stream bed may be a raised feature, instead of a valley. Inverted former stream channels may be caused by the deposition of large rocks, cementation, or maybe by lava moving down the channel. In either case later erosion would erode the surrounding land and leave the old channel as a raised ridge because the ridge would be more resistant to erosion. The image below, taken with HiRISE show curved ridges that are old channels that have become inverted. They have the shape of streams but are above ground.^[36]

Possible inverted streams, as seen by HiRISE under HiWish program

Inverted stream, a stream bed has been filled with hard materials that did not erode away like the surroundings

Troughs

The great weight of several huge volcanoes on Mars has stretched the crust and made it break into cracks called, “troughs” or “fossae.” Some of them show evidence that lava and/or water have come out of them in the past. They can be very long.^[37] ^[38] ^[39]

Troughs in the Elysium Planitia
Troughs in Amenthes quadrangle
Pits and troughs Troughs seem to start with lines of pits. Layers and dark slope streaks are also visible.
Troughs in the Cebrenia quadrangle, as seen by HiRISE under HiWish program

Craters

Most of the surface of Mars is over a billion years old. Because Mars has not had active plate tectonics for a very long time (if it ever had active plate tectonics), impact craters stay for a long time. So, impact craters are a major surface feature. There is a rich variety of craters on the planet.^[40] ^[41] We have found that Mars is hit by 200 impacts/year.^[42] ^[43] ^[44]

Young crater with bright ejecta in the Phoenicis Lacus quadrangle as seen by HiRISE under HiWish program The impact reached down to a layer that is light-toned. That light-toned material was then deposited on a dark surface.

This is a fairly young crater as it still shows ejecta, layers, and a rim.
Group of secondary craters These are formed from material that is blasted way up in the air from the impact.^[45]
Secondry craters, as seen by HiRISE under HiWish program These were made from material thrown in the air by primary impact of large body nearby.
Group of secondary craters They are small and the same age. They formed from material that was blasted way up in the air from an impact.
Crater containing gullies and depressions The curved depressions are formed when the ground loses ice. Gullies may be due to water or dry ice moving down the walls.
Crater with pits and holes on floor The shapes on the floor occurred when ice left the ground.
Close view of pits on floor of crater A box shows the size of a football field. Note: This is an enlargement of the previous image of a crater.
Layered mound in crater Layers represent material that once covered a wide area. Mound was shaped by winds.^[46]
Layered feature in crater in Casius quadrangle These layered features are quite common in some regions of Mars.
Wide view of ring-mold crater on the floor of a larger crater
Close view of ring-mold craters (indicated with arrows) Surface between the ring-mold craters is covered with brain terrain.
New, small crater We have detected many new craters on Mars that have impacted the planet since good cameras have orbited the planet. To see before and after photos of a new impact go to https://static.uahirise.org/images/2020/details/cut/ESP_062948_2175.gif
Exposed ice in small craters The fresh ice had almost disappeared when the second picture was taken. This set of images is good evidence that ice lies under a thin layer of debris.
Pedestal crater The surface was protected from erosion by the ejecta. In the past all the surrounding ground was at the level of the pedestal. Most of the loss is thought to be from the loss of ice.^[47] ^[48]
Pedestal crater with a butterfly shape. this may have formed from a low angle impact.
Crater with light streak Streaks associated with craters are quite common on Mars because there is a great deal of fine dust that can be blown around.

Scientists love to study central peaks of craters because they contain samples of material from deep under a surface. Durning an impact, the ground is pushed down. It then rebounds and brings up rocks from deep underground.^[49]

Central peak of an impact crater, as seen by HiRISE Colors show different minerals--some used to be deep underground.

Scalloped Terrain

Scalloped topography is common in the mid-latitudes of Mars, between 45° and 60° north and south. It is especially prominent in the region of Utopia Planitia.^[50] ^[51] Such topography consists of shallow, rimless depressions with scalloped edges, commonly referred to as "scalloped depressions" or simply "scallops". Scalloped depressions can be isolated or clustered and sometimes seem to coalesce. The usual scalloped depression displays a gentle equator-facing slope and a steeper pole-facing scarp.^[52] ^[53] ^[54] Scalloped topography may be of great importance for future colonization of Mars because it may point to deposits of pure ice.^[55] ^[56]

Scalloped terrain in Casius quadrangle
Scalloped terrain in Utopia Planitia in the Casius quadrangle
Scalloped terrain in Utopia Planitia

Brain Terrain

Brain terrain is a region of maze-like ridges 3–5 meters high. A person could wander between these ridges like a rat in a maze. Some ridges may consist of an ice core, so they may be sources of water for future colonists.^[57]

Labeled picture of open and closed brain terrain in the Ismenius Lacus quadrangle Closed-cell brain terrain may still contain an ice core.^[58]
Wide view of brain terrain in the Ismenius Lacus quadrangle
Brain terrain forming in Ismenius Lacus quadrangle

Ribbed terrain

Ribbed terrain forms as ice leaves the ground along cracks in a process called " sublimation." Much of the ground is ice so that when the ice disappears the ground collapses.^[59]

Ribbed terrain

Ribbed terrain The box is the size of a football field

Linear Ridge Networks

Close view of ridge network, as seen by HiRISE under HiWish program

This terrain appears over much of the planet. However, there is a heavy concentration of these features, also called irregular polygonal ridge networks, in the Nili Fossae region.^[60] These networks consist of groups of narrow ridges that often meet at close to right angles. We are not sure of how it originated.^[61] They may have been caused by fluids moving into cracks that were created by impacts. The fluids then became hard and erosion resistant.^[62] ^[63] ^[64] ^[65] ^[66] ^[67] ^[68] We are not totally sure of the exact ways these ridges were created. Over 14,000 people from around the world helped map them, so that scientists could better understand them. Some ridges contain clays, so water may have been involved in their formation because clays need water to form.^[69] ^[70]

Wide view of linear ridge network Location is Casius quadrangle.
Close view of linear ridge network Location is Casius quadrangle.
Ridge network in Amazonis quadrangle
Ridge network in Mare Tyrrhenum quadrangle
Close view of ridge network
Ridges, this picture was named HiRISE picture of the day on March 29, 2024.
Close view of ridges This picture was named HiRISE picture of the day on March 29, 2024.

Yardangs

Yardangs form from fine-grained material. They are shaped by the wind and show the direction of the prevailing winds. Much of this fine-grained material probably has its origin in the many large volcanoes on the planet. Yardangs are especially common in what's called the "Medusae Fossae Formation." This formation is found in the Amazonis quadrangle and near the equator.^[71] Because they exhibit very few impact craters they are believed to be relatively young.^[72]

Yardangs
Yardangs in Amazonis quadrangle
Wide view of yardangs in Amazonis quadrangle
Close, color view of yardangs in Amazonis quadrangle
Wide view of yardangs in Arabia quadrangle
Close view of yardangs, these features are shaped by the wind.

Dust Devil Tracks

Dust devil tracks can be very beautiful. They are made by giant dust devils removing bright colored dust from the Martian surface; consequently exposing a dark layer.^[73] Dust devils on Mars have been photographed both from the ground and from orbit. They have even blown dust off the solar panels of two Rovers on Mars, thereby greatly extending their useful lifetime.^[74] The dust devils can be 650 meters high and 50 meters across.^[75] The pattern of the tracks has been shown to change every few months.^[76]

Dust devils are common.^[77] One team of researchers have calculated that on average 1 dust devil happens every sol (day on Mars) for each square kilometer.^[78] ^[79] In the first 216 Martian days (Sols), the Perseverance Rover in Jezero Crater found that at least four dust devils passed Perseverance on a typical Martian day and that more than one per hour passes by during a peak hourlong period just after noon.^[80] ^[81] ^[82] Perseverance Rover recorded a tall dust devil in the distance on Aug. 30, 2023. Scientists calculated that the dust devil was about 2.5 miles (4 kilometers) away and was moving east to west at about 12 mph (19 kph). Its width was about 200 feet (60 meters). Even though only the bottom 387 feet (118 meters) of the devil was visible in the camera frame, scientists estimated its total height at about 1.2 miles (2 kilometers) using the dust devil's shadow.^[83]

Dust devil as seen by Perseverance rover It is 5 times taller than the Empire State Building
Dust Devil Tracks
Dust devil tracks in Hellas quadrangle Dark material is visible in the troughs of polygons.

Dark Slope Streaks

Dark slope streaks are avalanche-like features common on dust-covered slopes, especially in the equatorial regions.^[84] These streaks have never been observed on the Earth.^[85] They form in relatively steep terrain, such as along cliffs and crater walls.^[86] The darkest streaks are only about 10% darker than their surroundings. The streaks seem much darker because of contrast enhancement in the image processing.^[87]

Dry ice accumulates just under the surface during cold Martian nights and then changes to a gas in the morning. That gas creates enough wind to disturb dust particles and send them down steep slopes. As the bright dust slides down it reveals the underlying dark volcanic rocks. This process was discovered by measuring temperatures in the area. At the recorded temperatures, carbon dioxide from the air should have frozen on the surface, but it was not visible. It was concluded that the dry ice was forming just under the surface rather than on top..^[88] ^[89]

Dark slope streaks in trough Layers are also visible in the image.
Close view of dark slope streaks
New dark slope streak that was triggered by an impact

Lava

Large areas of Mars are covered with lava flows.^[90] ^[91] ^[92] ^[93] Lava flows can also move around an create what appear to be layers, especially if it fluid like water. Basalt flows can often be that way.^[94]

Lava flows in Phoenicis Lacus quadrangle
Rafts of lava in Amazonis quadrangle
”Rootless cones” caused by lava flowing over ice-rich ground in Elysium quadrangle

Mud Volcanoes

Mud volcanoes are very common in the Mare Acidalium quadrangle. Because they bring up mud from underground, they may hold evidence of life.^[95] Being underground the mud was protected from radiation on the surface. Methane has been detected on Mars; methane may be produced by certain bacteria. Some scientists speculate that methane may come from mud volcanoes.^[96]

Mud volcanoes in Mare Acidalium quadrangle

Close view of mud volcano, as seen by HiRISE

Close view of mud volcano, as seen by HiRISE. Picture is about 1 km across. This mud volcano has a different color than the surroundings because it consists of material brought up from depth. These structures may be useful to explore for reamins of past life since they contain samples that would have been protected from the strong radiation at the surface.

Mud volcanoes

Rootless cones

Rootless Cones are believed to be caused by lava flowing over ice or ground containing ice.^[97] ^[98] Heat from the lava causes the ice to quickly change to steam which blows out a ring or cone. Some of the forms do not have the shape of rings or cones because maybe the lava moved too quickly; thereby not allowing a complete cone shape to form.

Rootless cones formed when lava flowed over ice or ice-rich ground. The sharp bend in the line of cones may have been caused by the lava changing direction.

Close view of rootless cones, as seen by HiRISE under the HiWish program

Wide view of field of rootless cones in Elysium quadrangle

Honeycomb Terrain

Honeycomb terrain in Hellas quadrangle

Honeycomb terrain is found on parts of the floor of Hellas Planitia. It may be due to rising bodies of ice followed by erosion.^[99] ^[100] ^[101]

Fractured Surface and Blocks

Rock breaking up into cube-shaped blocks

In many places on Mars bedrock breaks up into large blocks. Sometimes the blocks form what look like perfect cubes. Although one may think these shapes had to be made by intelligent aliens, this is a natural process. The salt you put on your food also breaks up into cubes. Check your salt out with a magnifying glass.

Tilted blocks as seen by HiRISE under HiWish program These blockls were formed horizonality, but have been tilted. Perhaps ice left the ground on one side.

Tilted blocks It is as if something pushed up from under the ground.

Fractured Ground

Some places on Mars break up with large fractures that create a terrain with mesas and valleys. Some of these can be quite pretty.

Wide view of fractured ground
Close view of fractured ground

Dipping layers

Groups of layers that are tilted are common in some areas of Mars. They represent material that once covered a wide area.^[102] ^[103] The layers may be related to changes in the climate in the past. They may have been shaped by the wind.

Wide view of layered features in Hellas quadrangle
Close view of layered features in Hellas quadrangle Each layer may represent a change in the climate.
Tilted layers in Ismenius Lacus These sets of layers can often be seen leaning against slopes.

Wide view of dipping layers, as seen by HiRISE under the HiWish program. The dark strip is where a computer problem is preventing the gathering of data.
Group of dipping layers. Each layer represents a change in the Martian climate.
Remaining parts of a group of dipping layers. Erosion has removed most of the material.
Close view of dipping layers that show the thin nature of the layers.

Boulders

Much of the surface of Mars is covered with hard, basalt volcanic rock. When the rock breaks down it often forms large boulders the size of houses.

Fractures with boulders in low areas in Elysium quadrangle Box shows size of football field.
Color view of boulders
Close view of dunes showing boulders with arrows If you click on image to enlarge, you can see the tracks left by the boulders as they traveled down the dune.
Boulder and boulder tracks, as seen by HiRISE under HiWish program The arrow shows a boulder that has made a track in the sand as it rolled down dune.
Boulders and tracks, as seen by HiRISE under HiWish program The arrows show a boulders that have produced a track by rolling down dune.

Hollows

Some places on Mars have surfaces that are covered with hollows. Sometimes they form large holes, sometimes curved canyons. They can be pretty and would be fun to explore on foot in the future. This terrain may have developed from what has been called ribbed terrain. Either way, these scenes were caused as ice left the ground.

Wide view of hollows in ground, probably from ice leaving the ground
Close color view of hollows in ground, probably from ice leaving the ground
Hollows in ground, probably from ice leaving the ground Location is Hellas Montes Region.
Close view of hollows. Narrow ridges were made when hollows kept expanding.
Close, color view of hollows. The HiView program was used in the rgb color scheme.

Mesas

Many, large areas of Mars have eroded such that there are many mesas. Some show layers. Mesas show how the kind of material that covered a wide area. Mesas are what are left after the ground is mostly eroded.

Mesa with box showing size of football field
Layered mesa with box showing size of football field
Mesa that is 14 km or 8.7 miles around the outside

Landslides

Mars shows various mass movements like landslides. There are many steep slopes for material to move down, especially in craters and canyons.

Landslide
Landslide
Landslide

Latitude Dependent Mantle

Latitude Dependent Mantle is very common in certain latitudes.^[104] It often appears as a smooth covering. A certain percentage of it consists of ice. It may be a major source of water for future colonists because it has a widespread distribution. Sometimes mantle displays layers because it was deposited at different times. It can be as thick as 90 meters.^[105] ^[106]

Comparison of terrain with and without a covering of mantle
Mantle, as seen by HiRISE under HiWish program
Close view that displays the thickness of the mantle, as seen by HiRISE under HiWish program
Mantle layers with layers

Exhumed craters

Exhumed craters seem to be in the process of being uncovered.^[107] ^[108] The surface of Mars is very old. Places have been covered, uncovered, and covered again by sediments. The pictures below show a crater that is being exposed by erosion. When a crater forms, it will destroy what's under it. In the example below, only part of the crater is visible. Had the crater been created after the layered feature, it would have removed part of the feature and we would see the entire crater.

Wide view of exhumed craters, as seen by HiRISE under HiWish program
Close view of exhumed crater This crater is and was under a set of dipping layers.

Swiss Cheese Terrain

Parts of Mare Australe show pits that make the surface look like Swiss cheese.^[109] ^[110] ^[111] ^[112] These pits are in a 1-10 meter thick layer of dry ice that lies on a much larger water ice cap. These circular pits have steep walls that work to focus sunlight, thereby increasing erosion. For a pit to develop, a steep wall of about 10 cm and a length of over 5 meters in necessary.^[113]

Swiss Cheese Terrain near South Pole, as seen by HiRISE
Changes in Swiss Cheese Terrain from August 2009 to January 2019

wiss Cheese Terrain August 2009
Swiss Cheese Terrain January 2019

Ice Cap Layers

The northern ice cap of Mars displays many layers of ice that accumulated when the climate changed. These are visible when there is a canyon in the ice. The climate of Mars changes greatly due to the large changes in the tilt of Mars. Mars does not have a large moon to stabilize its' tilt.

Layers exposed in ice cap in Mare Boreum quadrangle
Layers exposed in ice cap in Mare Boreum quadrangle
Layers in northern ice cap Some of the layers are at different angles because erosion took away some layers to the right.
Layers in northern ice cap This photo was named picture of the day for January 21, 2019.
Layers in northern ice cap

Spiders

The official name for spiders is "araneiforms."As the temperature goes up in the spring, pressurized carbon dioxide gas and dark dust are released from under slabs of ice.^[114] This results in the appearance of dark plumes that are often blown in one direction by local winds. This dust darkens channels under the ice and forms dark shapes that resemble spiders.^[115] ^[116] ^[117] ^[118] This process was demonstrated in laboratory simulations involving slabs of dry ice placed on glass spheres of different sizes.^[119] ^[120] ^[121]

Spiders and plumes, as seen by HiRISE under HiWish program
Close view of spiders

Polygonal Patterned Ground

Many surfaces on Mars display “polygonal patterned ground.” The polygons can be of different shapes and sizes. They are believed to be caused by ice in the ground.^[122] Like permafrost regions on Earth, this permanently frozen water is still active.

With the changing seasons, alternate cooling and warming causes the ice-cemented soil to contract and expand. With the right conditions, cracks are made into the hard frozen ground releasing the stresses caused by contraction. Over long periods of cyclic cracking, a honeycomb-like polygonal pattern arises.^[123]

The patterns formed may yet be another marker for underground ice that could be used by future colonists. Before we land crews on Mars, we may very well have detailed maps for where the colonists can obtain water.

Wide view of large and small polygons
Close, color view of polygons Note: this is an enlargement of the previous wide view image.
High center polygons

Wide view of crater floor that is covered with polygons Low places still contain frost. Image taken with HiRISE under HiWish program.
Enlarged view of polygons from previous image. Dark line is a defect in processing.
Enlarged view of polygons from a previous image that shows polygons of varying sizes. Dark lines are defects in processing.

Notes about pictures

Most pictures from spacecraft have some sort of enhancement. For many views of Mars there is not much contrast, so the contrast is enhanced in a process known as stretching. In that process the darkest parts are set to black while the lightest parts are set to be white. The colors for HiRISE images are different than the human eye would see. HiRISE only sees in only 3 colors and sometimes infrared is used rather than red.^[124] ^[125] Displaying colors in this way allows us to better identify rocks and minerals. HiRISE images are about 5 km wide with a 1 km wide band in the center that is in color.^[126]

HiRISE image with pink color representing chloride salt.

    Wide view of layers in Danielson Crater  The center band is in color.

References

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External links

Layered Sediments in Hellas Planitia

Changes in dust devil tracks

before and after pictures of a new impact

Looking for Slope Streaks-old and new pictures of streaks]

Seeing the wonders of Mars with HiRISE under the HiWish program

The strange beauty of Mars with HiRISE and HiWish

0:25 / 0:48 Zooming in on Mars with HiRISE images from HiWish program

Features of Mars with HiRISE under HiWish program Shows nearly all major features discovered on Mars. This would be good for teachers covering Mars.

A trip to Mars with Hubble, Viking, and HiRISE

Mars through HiRISE under the HiWish program

Beautiful Mars as seen by HiRISE under HiWish program

HiRISE images from HiWish Program

Martian Ice - Jim Secosky - 16th Annual International Mars Society Convention
Martian Geology - Jim Secosky - 16th Annual International Mars Society Convention
Walks on Mars - Jim Secosky - 16th Annual International Mars Society Convention
https://www.youtube.com/watch?v=kpnTh3qlObk[T. Gordon Wasilewski - Water on Mars - 20th Annual International Mars Society Convention] Describes how to get water from ice in the ground
Jeffrey Plaut - Subsurface Ice - 21st Annual International Mars Society Convention

Flying around Candor Chasma at an altitude of 100 meters

Flight over Mars using HiRISE images--very beautiful

HiRISE images of polar regions with narriation

HiRISE images of beautiful scenes

Flyover of many parts of Mars using HiRISE images--Very nice

Pictures from HiRISE and from Curiosity

[1] Lorenz, R. and J. Zimbelman. 2014. Dune Worlds How Windblown Sand Shapes Planetary Landscapes. Springer. NY.

[2] ttps://www.space.com/30663-the-martian-dust-storms-a-breeze.html

[3] ttps://www.uahirise.org/ESP_057071_1890

[4] ttps://www.uahirise.org/ESP_057071_1890

[5] ttps://www.uahirise.org/ESP_057071_1890

[6] url=http://hirise.lpl.arizona.edu?PSP_008437_1750 |title=HiRISE | High Resolution Imaging Science Experiment |publisher=Hirise.lpl.arizona.edu?psp_008437_1750

[7] Head, J. W.; et al. (2006). "Extensive valley glacier deposits in the northern mid-latitudes of Mars: Evidence for Late Amazonian obliquity-driven climate change". Earth and Planetary Science Letters. 241 (3): 663–671.

[8] Head, J. and D. Marchant. 2006. Evidence for global-scale northern mid-latitude glaciation in the Amazonian period of Mars: Debris-covered glacial and valley glacial deposits in the 30 - 50 N latitude band. Lunar. Planet. Sci. 37. Abstract 1127

[9] Head, J. and D. Marchant. 2006. Modifications of the walls of a Noachian crater in Northern Arabia Terra (24 E, 39 N) during northern mid-latitude Amazonian glacial epochs on Mars: Nature and evolution of Lobate Debris Aprons and their relationships to lineated valley fill and glacial systems. Lunar. Planet. Sci. 37. Abstract 1128

[10] Head, J., et al. 2006. Extensive valley glacier deposits in the northern mid-latitudes of Mars: Evidence for the late Amazonian obliquity-driven climate change. Earth Planet. Sci. Lett. 241. 663-671

[11] Head, J., et al. 2006. Modification if the dichotomy boundary on Mars by Amazonian mid-latitude regional glaciation. Geophys. Res Lett. 33

[12] Garvin, J. et al. 2002. Lunar Planet. Sci: 33. Abstract # 1255.

[13] ttp://photojournal.jpl.nasa.gov/catalog/PIA09662

[14] Carr, M. 2006. The Surface of Mars. Cambridge University Press. ISBN|978-0-521-87201-0

[15] Squyres, S. 1978. Martian fretted terrain: Flow of erosional debris. Icarus: 34. 600-613.

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@@ Line 96: / Line 96: @@
                                    Dunes  This image was named picture of the day for July 25, 2021
+Dunes of various shapes are common on Mars, especially on the floors of craters.  Sand gets into craters and then the winds are not strong enough to get it over the rim.  '
+<gallery class="center"  widths="380px" heights="360px">
+File:ESP 082974 1685ridge and star shaped dunes 01.jpg|Wide view of crater showing ridges and various shaped sand dunes on floor.  Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
+File:ESP 082974 1685ridge and star shaped dunes 02.jpg|Close view of various shaped dunes  Picture is about 1 km across.  Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
+File:ESP 082974 1685 star shaped dunes 03.jpg|Close view of various shaped dunes  Picture is about 1 km across.  Some dunes would be called star dunes.  Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
+File:ESP 082974 1685ridge and star shaped dunes 04.jpg|Close view of various shaped dunes  Picture is about 1 km across.  Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
+File:ESP 082974 1685 star shaped dunes 03.jpg|Close view of various shaped dunes  Picture is about 1 km across.  Some dunes would be called star dunes.  Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
+File:ESP 082974 1685star shaped dunes 05.jpg|Close view of various shaped dunes  Picture is about 1 km across.  Image is from Sinus Sabaeus quadrangle and was taken with HiRISE.
+</gallery>
 ==Layers==
@@ Line 106: / Line 123: @@
 <gallery class="center"  widths="380px" heights="360px">
+File:Layers some with overhang ESP 26270 1820.jpg|Layers some with overhang.  This image was named HiRISE picture of the day
+File:Layers and layered mounds ESP 26270 1820.jpg|Layers and layered mounds.  Each layer records some sort of change and water may have been involved.
+File:Layered area with faults ESP 26270 1820.jpg|Layers  Dark parts are basalt sand that has settled on horizonal surfaces.
+File:Color view of layers 26270 1820.jpg|Close, color view of layers.  Light brown is from dust falling from sky.  Dark parts are basalt sand that has settled on horizonal surfaces.
 File:Wikiesp 035896 1845crommelinbutte.jpg|thumb|300px|left|Layers in Crommelin Crater
 File:544858 1885topcloselayers5.jpg|thumb|300px|center|Layers in Danielson Crater in Oxia Palus quadrangle
@@ Line 112: / Line 134: @@
 </gallery>
 [[File:60331 1880widelayersdark.jpg|600pxr|Layers on the floor of Danielson Crater taken under the [[HiWish program]]  Box shows size of a football field.]]
+<gallery class="center" widths="190px" heights="180px" >
+File:Layers in Danielson Crater, as seen by HiRISE under HiWish program 01.jpg|Faults in Danielson Crater, as seen by HiRISE under HiWish program
+File:Close view of layers in Danielson Crater, as seen by HiRISE under HiWish program 10.jpg|Faults and layers in Danielson Crater, as seen by HiRISE under HiWish program
+File:Layers in Danielson Crater, as seen by HiRISE under HiWish program 02.jpg|Wide view of layers in Danielson Crater, as seen by HiRISE under HiWish program.  Image was named HiRISE picture of the day.
+File:Layers in Danielson Crater, as seen by HiRISE under HiWish program 03.jpg|Close view of top of image of Danielson Crater, as seen by HiRISE (ESP_071634_1880).
+File:Layers in Danielson Crater, as seen by HiRISE under HiWish program 08.jpg|Close view of top of image of Danielson.  Arrows indicate parts that are enlarged.
+File:Layers in Danielson Crater, as seen by HiRISE under HiWish program 04.jpg|Layers in Danielson Crater with enlargements of some spots (indicated with arrows).
+File:Layers in Danielson Crater, as seen by HiRISE under HiWish program 06.jpg|Layers in Danielson Crater with enlargements of some spots (indicated with arrows).
+File:Close view of layers in Danielson Crater, as seen by HiRISE under HiWish program 07.jpg|Layers in Danielson Crater, as seen by HiRISE under HiWish program.
+</gallery>
 ==Glaciers==
@@ Line 137: / Line 173: @@
 File:53630 2195lvf.jpg|Lineated Valley Flow, as seen by HiRISE under the HiWish program
+File:ESP 084607 2210lvf 01.jpg|Lineated valley fill in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris.  Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
+File:ESP 084607 2210lvf 02.jpg|Close view of lineated valley fill (LVF) in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris.  Picture is about 1 km wide.  Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
+File:ESP 084607 2210lvf 03.jpg|Close view of lineated valley fill (LVF) in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris. Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
+File:ESP 084607 2210lvf 04.jpg|Close view of lineated valley fill (LVF) in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris. Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
+File:ESP 084607 2210lvf 05.jpg|Lineated valley fill in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris.  Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
+File:ESP 084607 2210lvf 06.jpg|Close view of lineated valley fill (LVF) in valley, as seen by HiRISE under HiWish program. Linear valley flow is ice covered by debris.  Picture is about 1 km wide.  Lineated valley fill is generally considered to be and example of a glacier, as it involves the movement of ice.
 </gallery>
 ==Gullies==
-[[Martian gullies]] are networks of narrow channels and their associated downslope  deposits, found on steep slopes.  A high concentration occurs near 40 degrees north and south of the equator.   Usually, each gully has an ''alcove'' at its head, a fan-shaped ''apron'' at its base, and a ''channel'' linking the two.<ref name="Malin, M. 2000">Malin, M., Edgett, K.  2000.  Evidence for recent groundwater seepage and surface runoff on Mars. Science 288, 2330–2335.</ref> They are believed to be relatively young because they have few, if any craters.   They were believed to be caused by recent running water, but with more observations other ideas emerged.  In summary of our present understanding of gullies it can be said:  A number of studies have demonstrated that gullies are being modified on present day Mars. <ref>C.M. Dundas, A.S. McEwen, S. Diniega, C.J. Hansen, S. Byrne, J.N. McElwaine.  The formation of gullies on Mars today.  Geol. Soc. London Spec. Publ., 467 (2019), pp. 67-94, 10.1144/SP467.5</ref> <ref>C.M. Dundas, S. Diniega, C.J. Hansen, S. Byrne, A.S. McEwen.  Seasonal activity and morphological changes in Martian gullies.  Icarus, 220 (2012), pp. 124-143, 10.1016/j.icarus.2012.04.005 </ref> <ref>.M. Dundas, S. Diniega, A.S. McEwen.  Long-term monitoring of Martian gully formation and evolution with MRO/HiRISE.  Icarus, 251 (2015), pp. 244-263, 10.1016/j.icarus.2014.05.013</ref> <ref>J. Raack, S.J. Conway, T. Heyer, V.T. Bickel, M. Philippe, H. Hiesinger, A. Johnsson, M. Massé.  Present-day gully activity in Sisyphi Cavi, Mars - flow-like features and block movements.  Icarus, 350 (2020), 10.1016/j.icarus.2020.113899. article #113899</Ref>  Today, liquid water cannot exist on the Red planet because the both the pressure and the temperature are too low.  Researchers have proposed other mechanisms that could account for gully formation without liquid water.<ref>S.J. Conway, T. de Haas, T.N. Harrison.  Martian gullies: a comprehensive review of observations, mechanisms and insights from Earth analogues.  Geol. Soc. London Spec. Publ., 467 (2019), pp. 7-66, 10.1144/SP467.14</ref>   Most involve dry ice (solid carbon dioxide) accumulating during cold seasons and then changing to a gas in the spring.  The gas coming off could start material moving down slopes.  The gas mixed with sand and other debris could act like water to erode channels.  Also, pieces of dry ice could easily side down due to the lubricating effect of gas coming off the dry ice.  However, one wonders if these processes could account for the formation of all the gullies.  Maybe, liquid water was sometimes necessary, especially to move large boulders.  A study of over 700 sites, published in 2022 in Icarus, concluded that liquid water would not have been needed.  During the duration of the study many large boulders were moved—one being 5 meters across.  Many types of changes were seen in gullies.  Some channels were extended, new channels were formed, and other channels were filled with new debris.<ref> Dundas, C., et al.  2022.  Martian gully activity and the gully sediment transport system.  Icarus.  (in press) </ref>  <ref>https://www.sciencedirect.com/science/article/pii/S0019103522002408#bb0145</ref>   Perhaps, some water was involved in the past, but all the gullies seen today could have been made without water.
+[[Martian gullies]] are networks of narrow channels and their associated downslope  deposits, found on steep slopes.  A high concentration occurs near 40 degrees north and south of the equator.   Usually, each gully has an ''alcove'' at its head, a fan-shaped ''apron'' at its base, and a ''channel'' linking the two.<ref name="Malin, M. 2000">Malin, M., Edgett, K.  2000.  Evidence for recent groundwater seepage and surface runoff on Mars. Science 288, 2330–2335.</ref> They are believed to be relatively young because they have few, if any craters.   They were believed to be caused by recent running water, but with more observations other ideas emerged.  In summary of our present understanding of gullies it can be said:  A number of studies have demonstrated that gullies are being modified on present day Mars. <ref>C.M. Dundas, A.S. McEwen, S. Diniega, C.J. Hansen, S. Byrne, J.N. McElwaine.  The formation of gullies on Mars today.  Geol. Soc. London Spec. Publ., 467 (2019), pp. 67-94, 10.1144/SP467.5</ref> <ref>C.M. Dundas, S. Diniega, C.J. Hansen, S. Byrne, A.S. McEwen.  Seasonal activity and morphological changes in Martian gullies.  Icarus, 220 (2012), pp. 124-143, 10.1016/j.icarus.2012.04.005 </ref> <ref>.M. Dundas, S. Diniega, A.S. McEwen.  Long-term monitoring of Martian gully formation and evolution with MRO/HiRISE.  Icarus, 251 (2015), pp. 244-263, 10.1016/j.icarus.2014.05.013</ref> <ref>J. Raack, S.J. Conway, T. Heyer, V.T. Bickel, M. Philippe, H. Hiesinger, A. Johnsson, M. Massé.  Present-day gully activity in Sisyphi Cavi, Mars - flow-like features and block movements.  Icarus, 350 (2020), 10.1016/j.icarus.2020.113899. article #113899</Ref>  Today, liquid water cannot exist on the Red planet because the both the pressure and the temperature are too low.  Researchers have proposed other mechanisms that could account for gully formation without liquid water.<ref>S.J. Conway, T. de Haas, T.N. Harrison.  Martian gullies: a comprehensive review of observations, mechanisms and insights from Earth analogues.  Geol. Soc. London Spec. Publ., 467 (2019), pp. 7-66, 10.1144/SP467.14</ref>   Most involve dry ice (solid carbon dioxide) accumulating during cold seasons and then changing to a gas in the spring.  The gas coming off could start material moving down slopes.  The gas mixed with sand and other debris could act like water to erode channels.  Also, pieces of dry ice could easily side down due to the lubricating effect of gas coming off the dry ice.
+<gallery class="center"  widths="380px" heights="360px">
+File:Channels on Southern Sand Dunes with ice blocks visible ESP 079809 1325.jpg|Channels on sand dunes, as seen by HiRISE.  Arrows show chunks of ice that moved down to enlarge gullies.
+</gallery>
+However, one wonders if these processes could account for the formation of all the gullies.  Maybe, liquid water was sometimes necessary, especially to move large boulders.  A study of over 700 sites, published in 2022 in Icarus, concluded that liquid water would not have been needed.  During the duration of the study many large boulders were moved—one being 5 meters across.  Many types of changes were seen in gullies.  Some channels were extended, new channels were formed, and other channels were filled with new debris.<ref> Dundas, C., et al.  2022.  Martian gully activity and the gully sediment transport system.  Icarus.  (in press) </ref>  <ref>https://www.sciencedirect.com/science/article/pii/S0019103522002408#bb0145</ref>   Perhaps, some water was involved in the past, but all the gullies seen today could have been made without water.
 <gallery class="center"  widths="380px" heights="360px">
@@ Line 149: / Line 198: @@
 File:57707 1410gullycolorwide.jpg|Color view of Gullies, as seen by HiRISE under HiWish program
 File:Gullies near Newton Crater2185.jpg|Gullies  in Phaethontis quadrangle  Ridges at the end of the gullies may be the remains of old glaciers.<ref>https://www.uahirise.org/ESP_057450_1410</ref>
+File:Close view of gully.jpg|Close view of gully in crater, as seen by HiRISE
+</gallery>
+<gallery class="center"  widths="380px" heights="360px">
+File:Close view of gullies ESP 080430 2310 01.jpg|Gullies on crater wall  The bright apron is a bit unusual.
+File:Close view of gullies ESP 080430 2310 02.jpg|Gully on crater wall  The bright apron is a bit unusual.
+File:ESP 084659 1355 gullies cropped 01.jpg|Wide view of gullies
+File:ESP 084659 1355 gullies cropped 02.jpg|Close view of gully alcoves  Picture is about 1 km across.
+File:ESP 084659 1355 gullies cropped 03.jpg|Close view of gully alcoves  Picture is about 1 km across.
+File:ESP 084659 1355 gullies cropped 04.jpg|Close view of gully channels  Picture is about 1 km across.
 </gallery>
@@ Line 203: / Line 263: @@
 File:26079secondaries.jpg|Group of secondary craters   These are formed from material that is blasted way up in the air from the impact.<ref>https://www.uahirise.org/hipod/ESP_046876_1465</ref>
+File:Secondary craters ESP 081458 1425.jpg|Secondry craters, as seen by HiRISE under HiWish program  These were made from material thrown in the air by primary impact of large body nearby.
 File:ESP 046876 1465secondarycraters.jpg|Group of secondary craters  They are small and the same age.  They formed from material that was blasted way up in the air from an impact.
@@ Line 288: / Line 349: @@
 File:46269 1770ridges2.jpg|Close view of ridge network
+File:Ridges in ESP 074906 2160.jpg|Ridges, this picture was named HiRISE picture of the day on March 29, 2024.
+File:ESP 074906 2160-2ridgesclose.jpg|Close view of ridges  This picture was named HiRISE picture of the day on March 29, 2024.
 </gallery>
@@ Line 299: / Line 363: @@
 File:ESP 045831 1750yardangswide.jpg|Wide view of yardangs in Amazonis quadrangle
 File:ESP 045831 1750yardangscolor.jpg|Close, color view of yardangs in Amazonis quadrangle
+File:Wide view of field of yardings.jpg|Wide view of yardangs in Arabia quadrangle
+File:ESP 061610 1895yardangsclose.jpg|Close view of yardangs, these features are shaped by the wind.
 </gallery>
@@ Line 309: / Line 374: @@
 <ref>https://www.science.org/doi/10.1126/sciadv.abn3783</ref> <ref> Newman, C., et al.  2022.  The dynamic atmospheric and aeolian environment of Jezero crater, Mars.  Science Advances.  Vol. 8.  Number 21</ref>  Perseverance Rover recorded a tall dust devil in the distance on Aug. 30, 2023.
 Scientists calculated that the dust devil was about 2.5 miles (4 kilometers) away and was moving east to west at  about 12 mph (19 kph). Its width was about 200 feet (60 meters). Even though only the bottom 387 feet (118 meters) of the devil was visible in the camera frame, scientists estimated its total  height at about 1.2 miles (2 kilometers)  using the dust devil's shadow.<ref>https://www.jpl.nasa.gov/images/pia26074-martian-whirlwind-takes-the-thorofare</ref>
-[[File:PIA26074-MarsPerseveranceRover-Whirlwind-20230830.gif|thumb|center|300px|Dust devil as seen by Perseverance rover It is 5 times taller than the Empire State Building
-[[File:dust_devils.gif|thumb|right|300px|Dust devils photographed by Mars Rover Spirit]]
 <gallery class="center"  widths="380px" heights="360px">
+File:PIA26074-MarsPerseveranceRover-Whirlwind-20230830.gif|Dust devil as seen by Perseverance rover It is 5 times taller than the Empire State Building
 File:ESP 036297 2370devils.jpg|Dust Devil Tracks
 File:ESP 048078 1160devils.jpg|Dust devil tracks in Hellas quadrangle   Dark material is visible in the troughs of polygons.
@@ Line 351: / Line 413: @@
 [[File:61584 2300mudvolcano.jpg|thumb|300px|right|Close view of mud volcano, as seen by HiRISE]]
+[[File:84807 2225conecolor 01.jpg|thumb|300px|center|Close view of mud volcano, as seen by HiRISE.  Picture is about 1 km across.  This mud volcano has a different color than the surroundings because it consists of material brought up from depth.  These structures may be useful to explore for reamins of past life since they contain samples that would have been protected from the strong radiation at the surface.]]
 [[File:53381 2265mud.jpg|thumb|300px|center|Mud volcanoes]]
@@ Line 380: / Line 443: @@
 <br clear=all>
+<gallery class="center"  widths="380px" heights="360px">
+File:Tilted blocks 82243 1765 01.jpg|Tilted blocks as seen by HiRISE under HiWish program  These blockls were formed horizonality, but have been tilted.  Perhaps ice left the ground on one side.
+</gallery>
+<gallery class="center" widths="190px" heights="180px">
+File:Tilted blocks 82360 1925.jpg|Tilted blocks  It is as if something pushed up from under the ground.
+</gallery>
 ==Fractured Ground==
@@ Line 397: / Line 469: @@
 File:50793 1365layers2.jpg|Close view of layered features in Hellas quadrangle   Each layer may represent a change in the climate.
 File:ESP 035801 2210pyramidsismenius.jpg|Tilted layers in Ismenius Lacus   These sets of layers can often be seen leaning against slopes.
+</gallery>
+<gallery class="center"  widths="380px" heights="360px">
+File:Dipping layers in HiRISE image ESP 080402 2240 01.jpg| Wide view of dipping layers, as seen by HiRISE under the HiWish program.  The dark strip is where a computer problem is preventing the gathering of data.
+File:Dipping layers in HiRISE image ESP 080402 2240 02.jpg|Group of dipping layers.  Each layer represents a change in the Martian climate.
+File:Dipping layers in HiRISE image ESP 080402 2240 03.jpg|Remaining parts of a group of dipping layers.  Erosion has removed most of the material.
+File:Dipping layers in HiRISE image ESP 080402 2240 05.jpg|Close view of dipping layers that show the thin nature of the layers.
 </gallery>
@@ Line 420: / Line 504: @@
 File:ESP 043688 2245closecolor.jpg|Close color view  of hollows in ground, probably from ice leaving the ground
 File:ESP 026042 1470hollows.jpg| Hollows in ground, probably from ice leaving the ground   Location is Hellas Montes Region.
+File:Close view of hollows created when ice left the ground. 03.jpg|Close view of hollows.  Narrow ridges were made when hollows kept expanding.
+File:Close view of hollows created when ice left the ground.jpg|Close, color view of hollows.  The HiView program was used in the rgb color scheme.
 </gallery>
@@ Line 445: / Line 533: @@
 ==Latitude Dependent Mantle==
-Latitude Dependent Mantle is very common in certain latitudes.<ref>Kreslavsky, M., J. Head, J. 2002. Mars: Nature and evolution of young, latitude-dependent water-ice-rich mantle. Geophys. Res. Lett. 29, doi:10.1029/ 2002GL015392.</ref>    It often appears as a smooth covering.  A certain percentage of it consists of ice.  It may be a major source of water for future colonists because it has a widespread distribution.  Sometimes mantle displays layers because it was deposited at different times.
+Latitude Dependent Mantle is very common in certain latitudes.<ref>Kreslavsky, M., J. Head, J. 2002. Mars: Nature and evolution of young, latitude-dependent water-ice-rich mantle. Geophys. Res. Lett. 29, doi:10.1029/ 2002GL015392.</ref>    It often appears as a smooth covering.  A certain percentage of it consists of ice.  It may be a major source of water for future colonists because it has a widespread distribution.  Sometimes mantle displays layers because it was deposited at different times.  It can be as thick as 90 meters.<ref>https://www-sciencedirect-com.wikipedialibrary.idm.oclc.org/science/article/pii/S0019103520305091</ref> <ref>Berman, D., et al.  2021.  Ice-rich landforms of the southern mid-latitudes of Mars: A case study in Nereidum Monte.  Icarus.  Icarus.  Volume 355.  114170</ref>
 <gallery class="center"  widths="380px" heights="360px">

Difference between revisions of "What Mars Actually Looks Like!"

Latest revision as of 17:01, 13 October 2024

Contents

Viking 1

Viking 2

Mars Pathfinder

Spirit Rover

Opportunity Rover

Phoenix

Curiosity Rover

Dunes

Layers

Glaciers

Gullies

Channels

Inverted relief

Troughs

Craters

Scalloped Terrain

Brain Terrain

Ribbed terrain

Linear Ridge Networks

Yardangs

Dust Devil Tracks

Dark Slope Streaks

Lava

Mud Volcanoes

Rootless cones

Honeycomb Terrain

Fractured Surface and Blocks

Fractured Ground

Dipping layers

Boulders

Hollows

Mesas

Landslides

Latitude Dependent Mantle

Exhumed craters

Swiss Cheese Terrain

Ice Cap Layers

Spiders

Polygonal Patterned Ground

Notes about pictures

References

See Also

Further reading

External links

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