1. page 1 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 CO 2 deposit at polar regions. Comparison between HEND (Mars Odyssey) and MOLA (MGS)

2. page 2 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 Litvak M.L 1), 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

3. page 3 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 Ls=330 0 - 360 0 Ls=30 0 - 60 0 Ls=90 0 - 120 0 North Summer South North OBSERVATIONS

4. page 4 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 North hemisphere → sublimation of CO 2 frost Latitude belts: 85N-90N → 80N-85N → 75N-80N → 70N-75N → 65N-70N → 60N-65N → Normalized neutron flux Ls, degree

5. page 5 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 South hemisphere → accumulation of CO 2 frost Latitude belts: 85S-90S → 80S-85S → 75S-80S → 70S-75S → 65S-70S → 60S-65S → Normalized neutron flux Ls, degree

6. page 6 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 MULTI LAYER MODEL 1 Atmosphere thickness: 5-25 g/cm2 2 Seasonal CO2 frost : variable thickness 3 Upper dry layer: 1-3% wt H2O; variable thickness 4 Bottom infinite ice layer: >30% wt H 2 O 1 Atmosphere thickness: 5-25 g/cm 2 2 Seasonal CO 2 frost : variable thickness 3 Upper dry layer: 1-3% wt H 2 O; variable thickness

7. page 7 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 COMPARISON BETWEEN HEND AND MOLA HEND data MOLA data  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 H 2 O in bottom layer.  80N-85N: 10 g/cm 2 depth of ice layer.  75N-80N: 40 g/cm 2 depth of ice layer.

8. page 8 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 North hemisphere South hemisphere Model: Upper layer thickness estimations

9. page 9 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 North hemisphere South hemisphere CO 2 frost at different seasons: Ls=345 o No CO 2 frost

10. page 10 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 North hemisphere South hemisphere CO 2 frost at different seasons: Ls=15 o

11. page 11 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 North hemisphere South hemisphere CO 2 frost at different seasons: Ls=40 o

12. page 12 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 North hemisphere South hemisphere CO 2 frost at different seasons: Ls=70 o

13. page 13 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 North hemisphere South hemisphere CO 2 frost at different seasons: Ls=95 o

14. page 14 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 North hemisphere South hemisphere CO 2 frost at different seasons: Ls=125 o No CO 2 frost

15. page 15 W o r k s h o p H E N D - 2003 2001 Mars Odyssey Institute for Space Research, June 9 - 11, 2003 CONCLUSIONS  Mars seasonal changes are distinctly seen in HEND data.  There is good correlation between HEND (Mars Odyssey) data and MOLA (MGS) measurements of CO 2 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 CO 2 frost thickness shows that North and South differs each other. CO 2 frost on South is thinner at near pole latitudes and demonstrate more irregular behavior then on North.