Where can we find water?
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.
The Cosmic Abundance of Elements
H2O NH3 CH4
Water, Ammonia, Methane
CO2 CO N2
Ignore inert gases
He, Ne, Ar
Water phase diagram
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.
• 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
Water in the solar system - Mars
• Indications that water once flowed on the surface.
• Much of the water may exist as subsurface ice.
Water in the solar system - Comets
• Detected in
comet’s tails.
• Up to 80% can
be water ice.
Comet Borrelly
Deep Space 1
Comet Wild 2
Stardust
Deep Impact-July 2006
Then there’s Ceres…
• Ceres (largest
asteroid)
discovered in
1801.
• Average density
of the asteroids
~5g/ml
• Ceres density
~2.1 g/ml
• Comets avg.
density ~1,5-2.0
g/ml
• Dawn mission on
the way to Ceres
(2011)
Ceres, as imaged by Dawn 1/14/15
The Top Four Icy Moons
Europa
Triton
Enceladus Titan
Most icy satellites are smaller than our moon.
What surface features should we see on them?
Europa
Triton
Jupiter
Neptune
Enceladus
Titan
Saturn
Huygens images of Titan’s surface
Methane lakes on Titan
A water-ammonia volcano on Titan through 3
wavelengths
L-Infrared,
C-Radar,
R-Ultraviolet
Fountains of Enceladus
Enceladus
enceladus sounds.mov
Neptune’s moon Triton-a Plutonian twin?
Triton from Voyager
Triton and Pluto
at Best HST
Resolution
Importance of water in human
space exploration
• Water to drink.
Water to grow plants.
• Water can be broken apart to make air
(oxygen) and rocket fuel (oxygen + hydrogen)
• Water can be used to provide electrical power
• (fuel cells used by Gemini, Apollo, and ISS).
• Water for protection.
• Water is heavy, too expensive to carry.