Sublimation of CO2 Ice on Mars

1
Sublimation of CO2 Ice on Mars
K.F. White1,2, D.W.G. Sears2,3, V. Chevrier2 ,
K.L. Bryson2 1 Ball State University, Muncie, IN
46947, 2 Arkansas Center for Space and Planetary
Science, Fayetteville, AR 72071, 3 Arkansas
University Department of Chemistry and
Biochemistry, Fayetteville, AR 72071
RESULTS
PRELIMINARY RESULTS
INTRODUCTION
Thus far, there have been four experiments.
Two having gravel sized pieces of CO2 ice (Figure
3) and two having cylinder shaped solid pieces of
CO2 ice (Figure 4). Figure
3 Gravel Sized CO2 Ice Figure
4 Solid Cylinder CO2 Ice By using the slope
of the graphs for the g/min rate and converting
it into g/hr, the following formula was used
along with the measured surface area over
time (g/hr) x (625 mm3/g) x (1/Surface
Area) (g/hr) Grams lost per hour according to
slope of graphed data. (625 mm3/g) 1 / Density
of CO2 Experiments the CO2 (solid, gravel
size), sample was contained in a small beaker for
purposes of measuring the surface area before and
after accurately.

• The sublimation rate of CO2 on Mars is
  currently unknown and can offer a valuable
  addition to any research done on Mars, including
  the explanation of dark spots1 and sublimation of
  CO2 ice on the polar ice caps2.
• Figure 1
• Jets on Martian Polar Cap1

Gravel Sized Sublimation Rate Sample 1
134.75 mm/hr Sample 2 123.12
mm/hr Average 128.93 mm/hr Solid Cylindrical
Sublimation Rate Sample 3 101.91
mm/hr Sample 4 101.11 mm/hr Average
101.51 mm/hr
FUTURE PLANS
Other future plans include testing CO2 and
H2O mixtures as well as adding 1-3 mm of Martian
equivalent dust over the ice to measure its
affects upon the sublimation rate. Also this
research is to attempt to explain the origin of
the dark spots on Mars, determining of jets are
possible.
OBJECTIVES

• The purpose of this project is to obtain the
  sublimation rate of CO2 ice on Mars under various
  conditions.
• Is there a sublimation rate difference between
  grain sizes of CO2 ice?
• Is there a sublimation rate difference if Martian
  equivalent soil dust covers different grain sized
  CO2 ice?
• Can these rates explain the observed rates of
  polar recession on Mars during the summer season?

ACKNOWLEDGEMENTS
Experimental chamber provided and funded by
the Arkansas Space and Planetary Science
Department of University of Arkansas. 1
Kieffer, H.H., P.R. Christensen, and T.N. Titus,
CO2 jets formed by sublimation beneath
translucent slab ice in Mars' seasonal
south polar cap, Nature, 442, 793-796, 2006
2 Byrne, S. and Ingersoll, A.P., A Sublimation
Model for Martian South Polar Ice Features,
Science, 299, 1051-1053, 2003 Figure 2
http//uark.edu/ua/kecklab/facilities
PROCEDURE
Using the Andromeda Chamber (Figure 2) at the W.
M. Keck Laboratory for Space Simulation at the
University of Arkansas, Mars like conditions were
created and maintained over an average
experimental duration of 1hr 30min with various
conditional samples of CO2.
CONDITIONS

• CO2 atmosphere at 7 mbar
• Atmospheric temperature -10C
• CO ice forms solid cylinder, broken up gravel
  sized, and finely crushed powder.

Figure 2 Schematic of Andromeda Chamber