Dr. Amy J. Williams
Geobiologist, University of California, Davis
Curiosity Rover Science Team Member

Earth and Mars are both rocky planets and are the same age (4.6 billion years old).
Although they started the same way, the two
2 have evolved into very different worlds…

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• What types of geologic evidence would you look for to prove there was water on
Mars in the past?
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Satellite Observations Ground Level Observations
Mars Reconnaissance Orbiter
– HiRISE camera
Mars Curiosity Rover 8

Evidence for Water on Mars -
Satellite Observations
Geomorphology –
The study of landforms and the processes that make them
1. Inverted Paleochannels
2. Alluvial Fans
3. Deltas
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Inverted Paleochannels
(from erosion around preserved stream channels)
Gale Crater, Mars Utah
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Alluvial Fans
(water spreads out on a plain, depositing sediment)
Holden Crater, Mars China
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Deltas
(sediment depositing in large bodies of water)
Eberwalde delta, Mars Louisiana deltas
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Group Discussion –
Which of these lines of evidence is most convincing of water on
Mars? Why?
1. Inverted Paleochannels
2. Alluvial Fans
3. Deltas
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1
3
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Evidence for Water on Mars -
Ground Level Observations
Spirit and
Opportunity
2003
Sojourner
1996
Curiosity
2012 15

Evidence for Water on Mars -
Ground Level Observations
Sedimentology -
The study of sediments and the processes that control their deposition.
1.
Hematite “Blueberries” / Concretions
2. Gypsum Veins
3. Conglomerate Rocks
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Hematite ‘Blueberries’ – concretions formed by iron interacting with groundwater
Meridiani Planum Utah
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Meridiani Planum Utah
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Gypsum – formed from flowing water
NASA/JPL-Caltech/Cornell/ASU
“There was a fracture in a rock, water flowed through it, gypsum was precipitated from the

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Mars Earth
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Group Discussion –
Which of these lines of evidence is most convincing of water on
Mars? Why?
1.
Hematite “Blueberries” / Concretions
2. Gypsum Veins
3. Conglomerate Rocks
1 3
2
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• Average temperature is -65 °F
• At the poles in winter it’s -200°F
NASA/AP
• The 2008 Phoenix
Lander found water ice under the polar surface and water droplets formed on the lander 24
NASA/JPL-Caltech/University of Arizona/Max Planck Institute

• Spring and summer flows form on crater walls
• Thought to be ground ice that melts in the spring
NASA/JPL-Caltech/Univ. of Arizona
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• Mars once had a thicker atmosphere to retain water vapor, but it’s been mostly blown away by solar winds and large impacts.
26 universetoday.com

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On Earth, where there is water, there is life…
Mars Exploration Rover Mission Goal: Follow the Water
Viking
Pathfinder
Phoenix
MER
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Mars Curiosity Rover Goal:
Search for a Habitable Environment
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HUMMOCKY
PLAINS
BEDDED
FRACTURED UNIT
Bradbury
Landing
Yellowknife
Bay
Rover Tracks
Curiosity
CRATERED
UNIT
NASA/JPL-Caltech/Univ. of Arizona
Curiosity and its tracks captured by
HiRISE on the Mars Reconnaissance Orbiter
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Heading into Yellowknife Bay
NASA/JPL-Caltech/MSSS
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NASA/JPL-Caltech/MSSS
“Shaler” rocks just outside Yellowknife Bay show inclined,

ChemCam Remote
Micro-Imager
NASA/JPL-Caltech/LANL/CNES/IRAP/IAS/
LPGN/CNRS/LGLyon/Planet-Terre
Sheepbed rocks contain 1 to 5-mm fractures filled with calcium sulfate minerals that precipitated from
33 fluids at low to moderate temperatures

NASA/JPL-Caltech/MSSS
Sheepbed rocks also contain many spherules suggesting that water percolated though pores 34

Arm deployed at John Klein
NASA/JPL-Caltech/D. Bouic
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NASA/JPL-
Caltech/LANL/CNES/IRAP/IAS/LPGN
NASA/JPL-Caltech/MSSS
The first drill hole on Mars!
NASA/JPL-Caltech/MSSS
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An Ancient Habitable Environment at Yellowknife Bay
• The regional geology and fine-grained rock suggest that the
John Klein site was at the end of an ancient river system or within an intermittently wet lake bed
• The mineralogy indicates sustained interaction with liquid water that was not too acidic or alkaline, and low salinity.
• Key chemical ingredients for life are present, such as carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur
• The presence of minerals in various states of oxidation would provide a source of energy for primitive organisms
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NASA/JPL-Caltech/MSSS

NASA/JPL-Caltech/Univ. of Arizona
Dingo Gap
Yellowknife
Bay
Curiosity’s traverse to the Kimberley, via waypoints Darwin and Cooperstown
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(Murray Buttes)
The Kimberley
(Yellowknife Bay)
NASA/JPL-Caltech/Univ. of Arizona
Curiosity’s ultimate goal is to explore the lower reaches of the 5-km high Mt. Sharp
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Atmospheric Gas
Abundances
Measured by SAM
NASA/JPL-Caltech/Goddard
Sulfate Unit (8 km)
Clay Unit (6 km)
Hematite Ridge (5 km)
Paintbrush Unit (2 km)
(distance from Murray Buttes)
NASA/JPL-Caltech/MSSS
Curiosity’s Extended Mission will explore Mt. Sharp, with an emphasis on understanding the subset of habitable
40 environments that preserve organic carbon.

Reflection:
Which piece of evidence for water on
Mars would you share in your classroom?
[Learning Goal, Assessment, Activity]
1
Orbital Data
1. Inverted Paleochannels
2. Alluvial Fans
3. Deltas
2 4
Ground Data
4. Hematite “Blueberries”
5. Gypsum Veins
6. Conglomerate Rocks
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3
5
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Questions?
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NASA/JPL-Caltech/MSSS