CO2 deposit at polar regions. Comparison between HEND (Mars Odyssey) and MOLA (MGS)

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CO2 deposit at polar regions. Comparison between
HEND (Mars Odyssey) and MOLA (MGS)
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• Litvak M.L1), Mitrofanov I.G.1), Zuber M.T.2)
  Smith D.E.3), Kozyrev A.S. 1),
• Sanin A.B.1), Tretyakov V.I.1) , Boynton, W.
  4),Hamara D.4), Shinohara C.4)
• Saunders R.S.5), Drake D.6)
• 1) Space Research Institute, Moscow, Russia
• 2) Massachusetts Institute
  of Technology, Cambridge,USA
• 3) NASA/Goddard Space Flight Center, USA
• 4) University of Arizona, Tucson, USA
• 5) JPL, Pasadena, USA
• 6) LANL, USA

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OBSERVATIONS
North
South
Ls3300 - 3600
Ls300 - 600
Ls900 - 1200
North Summer
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North hemisphere ? sublimation of CO2 frost
Latitude belts 85N-90N ? 80N-85N ? 75N-80N
? 70N-75N ? 65N-70N ? 60N-65N ?
Normalized neutron flux
Ls, degree
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South hemisphere ? accumulation of CO2 frost
Latitude belts 85S-90S ? 80S-85S ? 75S-80S
? 70S-75S ? 65S-70S ? 60S-65S ?
Normalized neutron flux
Ls, degree
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MULTI LAYER MODEL
1 Atmosphere thickness 5-25 g/cm2
1 Atmosphere thickness 5-25 g/cm2
2 Seasonal CO2 frost variable thickness
2 Seasonal CO2 frost variable thickness
3 Upper dry layer 1-3 wt H2O variable thickness
3 Upper dry layer 1-3 wt H2O variable thickness
4 Bottom infinite ice layer gt30 wt H2O
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COMPARISON BETWEEN HEND AND MOLA

• North The comparison between HEND and MOLA has
  been done for the same Ls in different latitude
  belts.
• There is good agreement between HEND vs. MOLA
  observations and model curves calculated for
  regolith model with 75 wt H2O in bottom layer.
• 80N-85N 10 g/cm2 depth of ice layer.
• 75N-80N 40 g/cm2 depth of ice layer.

HEND data
MOLA data
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Model Upper layer thickness estimations
North hemisphere
South hemisphere
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CO2 frost at different seasons Ls345o
North hemisphere
South hemisphere
No CO2 frost
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CO2 frost at different seasons Ls15o
North hemisphere
South hemisphere
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CO2 frost at different seasons Ls40o
North hemisphere
South hemisphere
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CO2 frost at different seasons Ls70o
North hemisphere
South hemisphere
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CO2 frost at different seasons Ls95o
North hemisphere
South hemisphere
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CO2 frost at different seasons Ls125o
North hemisphere
South hemisphere
No CO2 frost
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CONCLUSIONS

• Mars seasonal changes are distinctly seen in
  HEND data.
• There is good correlation between HEND (Mars
  Odyssey) data and MOLA (MGS) measurements of CO2
  frost at different north latitudes.
• Comparison HEND and MOLA data shows that visible
  effects may be easily explained based on
  two-layers model of regolith.
• The model estimation of CO2 frost thickness
  shows that North and South differs each other.
  CO2 frost on South is thinner at near pole
  latitudes and demonstrate more irregular behavior
  then on North.