Mars Remote Sensing (2)
with a demo of geospatial database for Mars
Lecture 17
Oct 26, 2005
Some factors of current Mars
• Radius: 3,397 km (~half of Earth 6378 km)
• One Mars year is 669.6 Mars days and 687
Earth days
• Extreme acidity (PH -1 to +3),
• Extreme salinity (over 10 times Earth’s
seawater)
• Extreme low temperature (210-260ºK, or -819 °F)
Not a bad place to visit, can we
live?
http://zebu.uoregon.edu/~soper/Mars/atmosphere.html
Recommended Marian coordinate
system
• Internation Astronomical Unin, IAU, 2000)
• Planetocentric latitude with west longitude (before 2002):
– 3396.0km for equatorial radius and
– 3376.8 km for polar radius
• Planetocentric latitude with east longitude (preferable)
– 3396.19km for equatorial radius
– 169.8944472236118 (1/f), or 3376.2 for polar radius
• Geographic or Projection coordinate system
– Sphere
– Projection: simple (or equidistant) cylindrical
• Central meridian
– 0, or
– 180
Marian Landers
Hecates Tholus
Meridiani Planum, Opportunity Landing site, eagle crater
(-5.63, -1.95)
The Gusev Crater, Spirit landing
site (-14.57°, 175.47°).
http://ltpwww.gsfc.nasa.gov/tharsis/mola.summary.pdf
Smith et al. 2000
Sprit Launched 6/10/2003
Landed on 1/3/2004
Opportunity Launched 7/7/2003
Landed on 1/24/2004
Spirit landing site
Opportunity landing site
Hematite mapped by TES
A
B
Hematite areal abundances
Terra Meridiani (A),
Aram Chaos (B),
and numerous
scattered locations
throughout Valles
Marineris (C).
C
Christensen et al. 2001
Hematite confirmed by Opportunity
A. Gray hematite or gray hematite bearing layer (unit Ph) on light-toned bedrock
outcrops (unit E) at the Endurance crater from rover Opportunity (Source:
http://origin.mars5.jpl.nasa.gov/mission/wir/)
B. Mars Orbiter Camera (MOC on MGS) narrow angle (NA) image (2m resolution)
just north of the Opportunity landing site showing unit E embayed by dark unit Ph.
(Source: Hynel, 2004)
THEMIS-derived thermal inertial map of Terra Meridiani of Mars
- Low inertial values (dark, about 175 Jm-2K-1s-1/2) correspond to unconsolidated
fine grains (Unit Ph or hetamtite-bearing plains) and
- higher inertial values (light, about 360 Jm-2K-1s-1/2) represent mixed surfaces
with increasing induration and rock abundance (Unit E or light-toned bedrocks). The
etched material outcrops around much of the low thermal inertia unit Ph, and
extends well beyond it.
- The ‘x’ marks the location of the Opportunity Rover (Source: Hynek, 2004)
Opportunity?
• From Opportunity exploration, the unit Ph (about 1 meter
thick) actually consists of dark, sand-sized and finer grained
basaltic materials overlain by sparsely to densely arrayed
spherules and irregular particles (gray hematite) with grain
sizes that range up to a few millimeters across (Soderblom
et al. 2004).
• The hematite-rich spherules at the surface are interpreted
to be due to differential aeolian erosion of the evaporitic
sedimentary rocks, leaving behind a lag or pavement of
relatively large and thus immobile materials (Arvidson et al.
2004). However, questions remain:
– where did the one-meter thick of basalt sands come from?
Soderblom et al (2004) only gives a guess that the basaltic sand
may come from vesicular clasts, but no prove;
– where did the thin hematite-rich spherules come from?
Arvidson et al. (2004) suggests that they came from Aeolian
erosion, but where it is the original rock and what it is the original
rock type: sediment or volcanic rocks?, there is no clue.
Some OMEGA results
Source: Gendrin et al. 2005
Source: Gendrin et al. 2005
OMECA mosaic of orbits 171, 278, 291, 314, 397, 430, 485, 518, 529, and 551 in
Terra Meridiani, showing kieserite (MgSO4·H2O, red) and polyhydrated sulfates
(green) in unit E. (Source: Gendrin et al. 2005)
OMEGA
Red - kieserite,
Green polyhydrated
sulfates,
Pink - other
hydrated
minerals
orbit401
308,334,360,515,548,581
TES
Hematite areal
abundances
Red - kieserite,
Green polyhydrated
sulfates,
Blue - gypsum
Pink - other
hydrated
minerals
(Source: Gendrin et al. 2005)
Sulfate detected in North Polar
Absorption feature at 1.927 um, with rainbow
color scale from 6% (purple) to >25% (red) in
terms of band strength. Polar cap is water ice
band strength at 1.5um exceeding 20%
Langevin et al. 2005
Mapping Olivine
Mustard et al. 2005
Identifying low calcite pyroxene (LCP)
0.9
1.8
Identifying high calcite pyroxene
(HCP, type1)
1.0
2.2
Mustard et al. 2005
H2O ice and CO2 ice
in north polar
Bibring et al. 2005
H2O ice and CO2 ice
in south polar
• H2O ice is found in the south polar, and
may be widespread around and under
perennial CO2 cap
Titus et al., 2002
Simultaneous THEMIS IR and
VIS images near the south
polar cap at Ls = 334°,
illumination from the top. The
false-color image is THEMIS
IR image I00910002 (Band 9,
12.6 µm). the strip is 32 km
wide. The gray insert is
THEMIS VIS image
V00910003 (Band 3, 654 nm).
The thermal image is overlaid
with a sketch of the individual
thermal units:
C – Solid CO2 on the surface;
D – a dry gently sloping unit
that is dark and hot (the
classic “dark lanes” through
the perennial cap);
I – the flat-lying unit of
intermediate albedo and
temperature (water ice); and
S – a warmer and darker flatlying unit (soil).
Titus et al., 2002
Visual MOC and Viking
images showing the water
ice unit near the south pole
of Mars.
(A) MOC Image M12- 02286
(Ls = 306) shows unit I is
largely covered by CO2 ice.
The “S’ unit is exposed.
(B) MOC image M14-00172
(Ls = 329) shows both units I
and S exposed; unit I is
visibly brighter than unit S.
(C) A Viking visual image of
the same region as the
THEMIS IR image acquired
25 years ago (Ls = 348); unit
I has intermediate
brightness.
(D) A sketch of the individual
units on THEMIS thermal
image:
Titus et al., 2002