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M Looking for LifeAdapted from “Destination Mars” NASA JSC

Brian Grigsby

School of Earth and Space ExplorationASU Mars Education

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Wall Street Journal

August 3, 2007In a Strange Universe, We Stick to Search

For Familiar Life

“Would we recognize (life) if we ever did chance upon alien life?...It is clear that nothing would be more tragic in the American exploration of space than to encounter alien life without recognizing it.”

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MWorking with data…Working with data…

What is life?How do we define it?

Where can life survive?How does this affect our search for life?

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MActivity ObjectivesActivity Objectives

Students will: • Form an operational definition of life• Conduct a simulated experiment with soil samples• State relationships between the soil samples using

their operational definition of life• Make an inference about the possibility of life on

Mars based upon data obtained

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MNational Science Standards (K-4)National Science Standards (K-4)

• As a result of their activities in grades K-4, all students should develop an understanding of:– CONTENT STANDARD A:

• Abilities necessary to do scientific inquiry

• Understanding about scientific inquiry

– CONTENT STANDARD C:• The characteristics of organisms

• Life cycles of organisms

• Organisms and environments

– CONTENT STANDARD G:• Science as a human endeavor

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MNational Science Standards (5-8)National Science Standards (5-8)

• As a result of their activities in grades 5-8, all students should develop an understanding of:– CONTENT STANDARD A:

• Properties and changes of properties in matter

– CONTENT STANDARD B:• Properties of objects and materials

– CONTENT STANDARD C:• Structure and function in living systems • Diversity and adaptations of organisms

– CONTENT STANDARD G:• Science as a human endeavor

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MNational Science Standards (9-12)National Science Standards (9-12)

• As a result of their activities in grades 9-12, all students should develop an understanding of:

– CONTENT STANDARD A:• Abilities necessary to do scientific inquiry

• Understanding about scientific inquiry

– CONTENT STANDARD B:• Structure of atoms

• Structure and properties of matter

• Chemical reactions

• Interactions of energy and matter

– CONTENT STANDARD C:• The cell

• Molecular basis of heredity

• Biological evolution

• Interdependence of organisms

• Matter, energy, and organization in living systems

• Behavior of organisms

– CONTENT STANDARD G:• Science as a human endeavor

• Nature of scientific knowledge

• Historical perspectives

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Characterize the Geology

Determine if Life Ever Arose on Mars

Characterize the Climate

Prepare for Human Exploration

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When?Where?Form?

Amount?

MARS SCIENCE STRATEGY:Follow the Water!

MARS SCIENCE STRATEGY:Follow the Water!Common

Thread

LIFE

CLIMATE

GEOLOGY

HUMAN

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M1970’s—Viking Landers1970’s—Viking Landers

• Science instruments: – Biology instrument, gas chromatograph/mass

spectrometer, X-ray fluorescence spectrometer, seismometer, meteorology instrument, stereo color cameras, physical and magnetic properties of soil, aerodynamic properties and composition of Martian atmosphere with changes in altitude

• Results: Inconclusive

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MFast forward 30 years…2007Fast forward 30 years…2007

• Phoenix Mars Lander• Launch date: August 2007• Landing: May 2008• Science Instruments:

– Surface Stereo Imager (SSI) – Robotic Arm (RA) – Microscopy, Electrochemistry, and

Conductivity Analyzer (MECA) – Robotic Arm Camera (RAC) – Thermal and Evolved Gas

Analyzer (TEGA) – Mars Descent Imager (MARDI) – Meteorological Station (MET)

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MPhoenix Lander: Science ObjectivesPhoenix Lander: Science Objectives

• Study the history of the ice as written into the soils.

• Understand the geomorphology through imaging.

• Study the weather throughout the northern summer.

• Evaluate if the martian soils can potentially support life.

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MActivity focus points:Activity focus points:

Evaluate if the martian soils can potentially support life.

On Earth, energy, liquid water, and carbon material are the basic ingredients needed by all life.

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M Evaluate if the martian soils can potentially support life.

Ultraviolet radiation, oxidants, and other poisons would make the soil uninhabitable.

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MBackground InformationBackground Information

• We usually recognize something as being alive or not alive.

• But the signs of life or previous life are not easy to determine.

• Scientists must establish criteria to work with in their research.

• How then, do we identify/define life?Can you identify the living things in this

picture?

Yeast

Sand

Sugar

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MDefinition of LifeDefinition of Life

• Consider a bear and a chair:

– Both have legs, but only one can move on its own

– The other would need a motor to get around

– Indicators for life:• Locomotion, respiration, etc.

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• Another example would be a tree and a light pole

– We know that a light pole can not reproduce, it is made by humans.

– But a tree produces seeds, that may produce more trees

– The tree also takes in nutrients and gives off gasses and grows.

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MSubtle, but fundamental signs of life:Subtle, but fundamental signs of life:

• Metabolic processes that show chemical exchanges which may be detected in some sort of respiration or exchange of gases or solid materials

• Some type of reproduction, replication or cell division• Growth• Reaction to stimuli

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MOperational Definition of Life Part 1 (5 min)Operational Definition of Life Part 1 (5 min)

• Using the “Fundamental Criteria for Life Chart”, come up with characteristics that make an individual item alive or not alive.

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MIts Alive! Part 2Its Alive! Part 2

• Objective– You will examine 3 different soil samples and look for

signs of life based on the criteria from Part 1.

• Materials– Soil samples

– Warm/hot water

– Magnifying lens

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MProcedure (teams of 3)Procedure (teams of 3)

1. Each team has been given a set of soil samples, but no one knows if there is anything alive in them.

2. Using the craft sticks, place a couple of scoops into the paper cup

3. From the sample in the cup, place a small amount onto a flat white surface and observe with a hand lens, then record your data on Data Chart I.

4. Make careful observations and check for indications of living material in them, based on your criteria from Part A.

5. Observe all 3 samples6. You can smell and touch the samples but do not

taste them.7. Once you have observed the samples, place a

small amount of water into the paper cup, just covering the sample.

8. Record any changes in the sample on Data Chart II

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MAnalysis / conclusionAnalysis / conclusion

• Which samples showed indication of activity?• Does that mean there is life in those samples?• Are there other explanations for activity in those

samples?

• By applying the fundamental criteria for indicating life we developed, which sample contained life?

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MSample contentsSample contents

• Sample A: Soil and Sugar• Sample B: Soil, Sugar and Yeast• Sample C: Soil Sugar and Alka-Seltzer

•Sample A: Physical Reaction (sugar Dissolves in the sample)

•Sample B and C: Chemical reaction

•Sample B sustains long-term activity

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• Are there other tests that would detect life in Sample B?– (there might be microbes in the soil that would grow on a

culture medium)

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MExtensionsExtensions

• Have students answer the following question:

–What do you think alien life would look like?