Water, Water, Everywhere?

Anuradha Koratkar,

Susan Hoban,

Albert Hill, and

Brendan Shaughnessy

Water is the driver of Nature. - Leonardo da Vinci

Let us brainstorm the importance of water to life

1.

2.

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6.

Water is a necessity for every form of life known

Does anyone have any other suggestion?

Use the chat to respond, or *6 on your telephone

Importance of water to life

• Water to drink; we need to stay hydrated to remain alive; we are 55 – 75% water!

• Solar energy converted by plants; water is the catalyst that helps plants grow.

• Water vapor in the atmosphere traps radiation and warms up the Earth.

• Earth’s oceans affect climate and store heat.

Importance of water in space exploration

• Water to drink.

• Water to grow plants.

• Water can be broken apart to make air (oxygen) and rocket fuel (oxygen + hydrogen).

• Water for protection.

• Water is heavy, too expensive to carry.

Where can we find water?

Water in the solar system - Comets

• Detected in comet’s tails.

• Up to 80% can be water ice.

• Indications that water once flowed on the surface.

• Much of the water may exist as subsurface ice.

Water in the solar system - Mars

Water in the solar system - Mars

• Polar ice caps are mostly frozen carbon di-oxide and trace amounts of water.

Water in the solar system – Europa and Ganymede

• Cracked surface with many fissures

• There may actually be a liquid ocean under the ice!

Europa

Ganymede

Why is water unusual?

• Earth is the only known location in the solar system where liquid water exists.

• All three states of water are found on Earth.

• Solid form, ice, is less dense than the liquid form.

Water in the Earth-Moon System

• Comets and asteroids may have provided all the water on Earth.

• The Earth and Moon are about the same distance from the Sun.

• The Earth has plenty of evidence for water in all states.

• We do not see such evidence on the Moon.

Why is water not abundant on the Moon? 1.

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Temperature and distance

• Temperature of a planet depends on– Distance from

the Sun– The greenhouse

effect

Mercury

Venus

Earth

Mars Jupiter

SaturnUranus

Neptune

Pluto

Phase diagrams

Pressure

Temperature

1 atm

Phase Diagram for Water

1 atm

Liquid

Gas

Solid

Pressure

Temperature (C)0 100

T

C

Facts about the Moon• The temperature on the Moon is expected to

be -20 degrees C because of its distance from the Sun.

• A “day” on the Moon is 14 Earth days

– The recorded temperatures are -233 degrees C (night-time) and 123 degrees C (day-time)

– Gas can be heated to high temperatures

• The Moon is smaller than the Earth.

– One-sixth the gravity so gas can escape

– Moon has no atmosphere

Poll Question

What can you say about water if we put all these facts

together?

Can there be ice on the Moon?

• Comets and asteroids could have left water on the Moon – just like on Earth

• Effects of temperature and pressure implies water sublimates in sunlight and drifts off into space.

• But the Moon has deep cold craters where sunlight cannot reach!– Water may exist in such places as frozen

ice

There are many craters near the poles that are permanently shadowed

South Pole North Pole

What is the evidence for ice on the Moon?

• Lunar Prospector shows enhancement of H, indicating possible presence of ice

What is the evidence for ice on the Moon?

Lunar Prospector and Clementine:

• Signs of ice in shadowed craters near the moon's poles--perhaps as much as a cubic kilometer.

• Radio and optical observations of crash site show no water.

• There is NO conclusive evidence.

The search for ice on the Moon• Search permanently shadowed

craters at the Moon's poles

• Detect ice crystals in lunar soil

• Map the temperature of the Moon

• Search for regions that could have hydrogen-bearing compounds like water

If you have any questions let us discuss them on the discussion listserv. Flavio will send everyone a link in case you are not

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For those of you working on earning two credits, there is homework. Flavio will send you a message with a link to it.Please send it in by 21st Nov. 2006

See you at the next session which will be Radiation: Can’t live with it, can’t live

without it!