The History And Inventory Of Water On Mars
B. M. Jakosky, Laboratory For Atmospheric And Space Physics, Univ. Of Colorado, Usa
(Bruce.Jakosky@Lasp.Colorado.Edu) And L. J. Hallis, Univ. Of Glasgow, Uk (Lydia.Hallis@Glasgow.Ac.Uk)

Introduction:
Key Questions About Mars Relate To The History
And Abundance Of Water At The Surface And The Forms
That It Can Take (Vapor, Liquid, Solid). Water Interacts
With The Surface, Affecting The Geological And Geochemical History. And Water Is Intimately Connected
To The Potential For Life To Exist Or Have Existed.
We Use Measurements Related To The Enrichment
Of D/H In H2o Due To Escape To Space, Surface Morphology, And Surface And Subsurface Mineralogy, To
Derive An Observational Estimate For The Total Inventory Of Water, Its Current Distribution On The Planet, And
Its History.
Measurements Of D/H:
The Ratio Of D/H In H2o Is Fundamental To Determining The History Of Water, Due To Its Large Enrichment Relative To Its Initial Value. D/H In Atmospheric
Water Vapor Today Is Enhanced By An Average Of ~6x
Relative To Its Starting Point. This Value Varies Seasonally And Spatially Between ~2-10x, Apparently Due
To Wintertime Condensation And Springtime Sublimation Of Water. This Large A Global Enrichment Can Be
Produced Only By Escape Of A Large Fraction Of The H