Matthew Polacek
Web Summary
November 17th Web Summary
Escape velocity, (to leave the planet), can also be planetary mass, plotted against
stellar heating, shows that as you get hotter you need to be bigger to hold on to you
business. (this function does not account for geology/volcanism) volcanism takes
water out and puts it into the atmosphere//when you lose hotspots you lose input
of water into the atmosphere
Jeans Escape: Thermosphere top atmosphere, with enough energy, you can leave the
planet, hydrogen escapes; earth has a stratosphere that slows down jean escape. It is
more difficult for water to escape on earth, cold trap of the atmosphere Ozone.
1/6 graph, shows that with smaller planets you can lose larger things due to small
escape velocity
Hydrodynamic Escape: happens when the atmosphere is thick, particular with H2
molecules and it is very excited by EUV enhanced UV radiation, able to excite so
much that the H leaving is pulling out other molecules with it.
Hydrodynamic escape occurs most on young planets, then tappers off and becomes
jeans escape, D/H vs. time on graph
Abundance, ratio to silica VS specific noble gasses (does not change), primordial is
sun values, noble gasses must be loss through hydrodynamic escape because the
gasses that have left are too heavy for jeans escape.
Ryans Mahaffy et al.
 Deuterium all formed during the big bang, leaves slower than lighter
hydrogen
 SAM measures composition of hydrogen oxygen and nitrogen. Drilled into
Mars for D/H analysis from Curiosity, revealed a smectite clay mineral, an
amorphous component and basaltic minerals, isochemical alteration yields
smectite.
 Reservoir Models
o Single reservoir model, the reservoir for mars is considered one body
exposed to atm. Loss. D/H ratio reveals the amount of water on the
planet with time
o Multiple reservoir model, ice caps result in inaccessible reservoirs
that do not get exposed to atm. Loss
 D/H ratio in SMOW units vs. temperature

o Higher temperatures, lower amounts of D/H in water
Conclusions
o Amount of water lose since Yellowknife bay clay minerals formed
would be 1-1.5 times the loss //water equivalent global layer at the
time of formation of mudstone would be at least 100-150 m
Water on Mars
o We have images of bedding most likely fluvial, stratification of
sediment at base of mountain that curiosity will explore. Pressure is
so low on mars that it doesn’t matter, gasses condenses as ice and
sublimates to vapor, with higher pressure water would be possible
o Mars goes through obliquity cycles, the pressure increases enough
during high obliquity for liquid water? Goes through huge changes in
solar variations.
o Salt can also introduce liquid water
Ojha paper presentation
 Recurring slope lineae: narrow low reflectance features possibly due to
transient flow. Fade a reappear annually
 Hydrated salts, loosely attached to water
 Salts have been found on Mars, can lower the freezing point of water, up to
80 K change, lowers the evaporation rate of water
 Can absorb atmospheric moisture
 Matching transient flow event between rsl at the compositional level
 Palikir crater
o The data is ‘good’ and indicates absorbtions are too narrow for liquid
water itself, the hydration state may stay longer than we are
recording, combination of salts match the spectra of Martian soil
 Horowitz Crater
o Yields similar results, both peaks have dips meaning more absorbtion
 Perchlorates and chlorates found in mars meteroites
 Assuming that liquid water exists periodically
o Possibly surface melting of ice, unlikely at middle latitudes
o Could be from atmosphere, unclear whether there is enough
o Season discharge from local aquifer
 There is a genetic connection between the salts an the RSL’s, might support
near surface microbial life