Surface Features on Mars

Dr. Joshua BandfieldMars Space Flight FacilityArizona State University

Mars has Many Types of Surface Features

• Craters

• Volcanic Features

• Channels

• Layers

• Wind Features

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Choosing a Research Topic

• The features to be studied need to be a good size for study with THEMIS data– 100’s of kilometers is too big, 10 meters is too small

• A single THEMIS image should capture the feature– We can’t do studies that require taking many images– We can use other images taken already, however

• THEMIS needs to be the correct type of data to use to lead to a conclusion– Sizes, shapes, textures

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Choosing a Research Topic• There are other types of data are available that

will help solve the problem

• Other THEMIS images already collected can be used to help answer the question

• Higher and lower resolution images available from other spacecraft can help as well

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Impact Craters

• Craters on Mars have a number of important features:– Ejecta

– Density (how many on a surface)

– Morphology (shape)

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Crater Ejecta

• Ejecta are the materials that get thrown out of a crater when a meteorite hits the surface– Sometimes the ejecta

will look rougher than the surrounding terrain

Crater in Elysium Planitia 18N, 136ECrater in Elysium Planitia 18N, 136E

All THEMIS visible imagesAll THEMIS visible imagesare ~18 km acrossare ~18 km across

Most THEMIS images are Most THEMIS images are taken during the afternoon taken during the afternoon and the sun is shining from and the sun is shining from the left side of the imagethe left side of the image

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Rampart Craters

• Rampart craters have distinct ejecta that look like it flowed across the surface– This is probably due to

ice or liquid water present in the subsurface when the crater formed

Rampart Crater in AcidaliaPlanitia 28N, 319E7

Modified Craters

• Craters can be eroded by wind and water or flooded with lava

Ares Vallis 16N, 330EAres Vallis 16N, 330EOrcus Patera 16N, 183EOrcus Patera 16N, 183E

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Crater Density

• The relative age of the surface of Mars can be determined by figuring out the crater density (the number of craters on a surface)– Young surfaces will have few

craters– Old surfaces will have many craters

Kasei VallisKasei Vallis25N, 287E25N, 287E

OlderSurface

YoungerSurface

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Crater Morphology• The morphology (shape) of a

crater will look different based on how old and how large the crater is– Large craters have central

peaks or rings and slumping walls

– Old craters are eroded and have ‘softer’ features

Central Peak

Slumps

Arabia Terra 18N, 6EArabia Terra 18N, 6E10

THEMIS and Craters

• THEMIS is good for observing crater shapes and sizes for smaller craters– This is good to see how craters are shaped

and how they are modified

• Crater densities can be used to date the relative ages of surfaces– If the ages are very different!

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Volcanic Features

• We see evidence for lots of volcanoes and lava flows on Mars– Olympus Mons

(shown in the picture) is a shield volcano the size of the state of Arizona!

Olympus Mons 18N, 230E (Wide Angle)Olympus Mons 18N, 230E (Wide Angle)12

Lava Flows

• There are many lava flows on Mars of all ages– These are similar to lava flows

that we see in places like Hawaii, but can be much larger!

Daedalia PlanumDaedalia Planum-26N, 232E-26N, 232E13

Volcanoes• Mars has many volcanoes

that are usually one of three types:– Shield volcanoes (these can

be huge!!)– Cones– Patera

Biblis Patera 2N, 237EBiblis Patera 2N, 237E

Apollinaris Patera -10N, 174EApollinaris Patera -10N, 174E(Wide Angle, ~100 km across)(Wide Angle, ~100 km across)

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Cones

• These are small, steep sided volcanoes– Only ~100 m across

Isidis Planitia 12N, 90EIsidis Planitia 12N, 90E

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THEMIS and Volcanoes

• THEMIS can observe the shape of smaller volcanoes– This can determine the type of volcano

• Different lava flows can be mapped– The relative dates of the flows can often be

determined from the image

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Channels

• Channels on Mars can be large or small– Outflow channels were

formed by massive floods in the past

– Valley networks were formed by trickles of water in the past

Valley Networks on Alba PateraValley Networks on Alba Patera44N, 242E44N, 242E17

Channels• Outflow channels on Mars

were formed by catastrophic floods– The water came from

underground

Outflow Channels in Elysium PlanitiaOutflow Channels in Elysium Planitia22N, 126E 22N, 126E

Ares and Tiu Valles 15N, 330EAres and Tiu Valles 15N, 330E(Wide Angle, ~1500 km across)(Wide Angle, ~1500 km across)

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Gullies

Formed recently by liquid water!

Hale Crater -35N, 324E Hale Crater -35N, 324E

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Chaos Terrain• Chaos terrain is often at the

head of the outflow channels where the ground collapsed

Aureum Chaos -3N, 331E Aureum Chaos -3N, 331E

Wide Angle (~500 km across)Wide Angle (~500 km across)2N, 340E 2N, 340E

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THEMIS and Channels

• THEMIS can observe many water related surface features– The size and shape of valley networks– The flood size can be estimated from chaos

terrain and outflow channels– Where gullies occur and their size and shape

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Layers• There are many kinds of

layered rocks on Mars– We don’t know how all of

them formed

Candor Chasma -7N, 290E Candor Chasma -7N, 290E

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Finely Layered Deposits

Layers in Becquerel CraterLayers in Becquerel Crater22N, 353E 22N, 353E

• Formed by ash from volcanoes or by sediments deposited in water

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Polar Layered Deposits

• Alternating layers of water ice and dust

• These layers record Mars’ climate history

South Pole Layered Deposits -82N, 306E 23

THEMIS and Layers

• THEMIS can determine the size of some layered deposits

• The thickness and number of layers can be determined from images

• The shape of the layers can sometimes help find out how they formed

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Wind Features

• Mars is an aeolian (wind driven) planet– Wind Erosion– Dunes– Wind streaks– Dust devils– Dust mantled surfaces

Wind Eroded FeaturesWind Eroded Featuresin Tharsis -5N, 200Ein Tharsis -5N, 200E

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Dunes

• Dunes are wind blown piles of sand– Sand dunes on Mars are

often dark because they are made of basaltic sand

Sand Dunes in Kaiser CraterSand Dunes in Kaiser Crater-47N, 19E-47N, 19E27

Wind Streaks

• Wind streaks form behind topographic features (such as crater rims)– Dust can be deposited or

scoured in a wind streak

Syrtis Major 0N, 72ESyrtis Major 0N, 72E28

Dust Devils• Dust devils pick dust up in to the atmosphere

– They can act like vacuum cleaners and leave dust-free tracks behind them

Dust Devil Tracks Dust Devil Tracks in Argyre Planitiain Argyre Planitia-47N, 318E-47N, 318E29

Martian Dust• Mars’ atmosphere is always dusty

– Sometimes there are dust storms that cover the entire planet!

• Many surfaces are covered with a mantle of dust

Dust Storm NearMars’ North Pole

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THEMIS and Wind Features

• THEMIS can use wind features to determine wind directions on the surface of Mars

• Images can tell whether a surface is sandy, rocky, or dusty

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Polar Caps• Mars’ polar caps are made of solid CO2

(dry ice) and water ice

Mars’ North PoleMars’ North Pole Mars’ South PoleMars’ South Pole32

Polar Caps• There are many strange

landforms in the Martian poles

Swiss Cheese TerrainSwiss Cheese TerrainMars’ South PoleMars’ South Pole33

Valles MarinerisValles Marineris

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Valles Marineris

• The Grand Canyon of Mars– Large enough

to stretch across the entire United States!

– Landslides, dunes, layers

Coprates Chasma Coprates Chasma -15N, 302E-15N, 302E

Melas ChasmaMelas Chasma-9N, 282E-9N, 282E

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Mars Maps• Zoom in to see details

• Also see: http://pubs.usgs.gov/imap/i2782/i2782_sh1.pdf

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The Martian Dichotomy

• Mars has a northern hemisphere with few craters (the northern lowlands)

• The southern hemisphere is older and heavily cratered (the southern highlands)

• Nobody really knows how this dichotomy formed!

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Mars’ Dichotomy

• The global dichotomy can be seen in the global elevation map

DichotomyBoundary

Cratered Highlands

Northern Lowlands

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Tharsis

• Tharsis is a huge (1/3 of the planet) volcanic region on Mars

• There are many lava flows and shield volcanoes

Ascraeus Mons

Pavonis Mons

Arsia Mons

Alba Patera

Olympus Mons

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