Transcript Mars - University of Chicago

Mars
Vital Statistics
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R = 3394 km
M = 6.42 x 1023 kg
Rorbit = 1.082 x 108 km
T = 180-270º K
Eccentricity = 0.093
Axial tilt = 23.98 º
“day” = 1.026 days
“year” = 1.88 years
orbital inclination = 1.85º
• R = 0.53 R
• M = 0.11 M
• Rorbit = 1.52 A.U.
A bit of background
• The “red” planet
• Known since prehistoric times
• Lowell thought he saw canals, which led to
LOTS of Sci-Fi
• Roman god Mars was a god of agriculture
before becoming associated with the Greek
Ares (who was the god of War)
Claims to fame
• Sports the largest volcano in the Solar
System
• We’ve sent more landers to Mars than
anywhere else in the Solar System
• (Note: Mars’ orbit is eccentric enough to
affect its seasons.)
Probes: Landers
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Mars 2
Viking I and II
Mars Pathfinder (see replica upstairs)
Mars Expedition Rovers, Spirit and
Opportunity
• Many others
Probes: Orbiters
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Mariner 4
Mars Global Surveyor
Odyssey
Mars Express
Others
Mariner 4
• Sister probe to Mariner 3, whose protective shield
failed to eject
• First probe to reach Mars - Flew by in 1965
• Took 22 images of Martian surface
• Found a cratered world with an atmosphere much
thinner than previously thought: object lesson
• May have concluded the general change in
SF from alians on Mars to dwellers on
planets in other Star Systems
Mariner 4 images
The first closeup image ever taken of Mars
Mariner 4 images
Mariner 4 images
Viking I
Viking I and II
• Each had both an orbiter and a lander
• Arrived summer of ‘76
• V. I showed that Mars’ sky is pinkish, not
dark blue as was previously thought
• V. I searched for micro-organisms - found?
• V. I sent back great color panoramas
• V. II seismometer worked, and recorded one
marsquake
Viking pictures
First image that Viking I sent back (yes, that’s its foot
Viking pictures - Martian sunset
Viking pictures
This image was aquired at the Viking Lander 1 site.The large
rock just left of the center is about 2 m wide, and was named
“Big Joe” by Viking scientitsts. The top is covered with red
soil. The portions not covered with soil are similar to basaltic
rocks here on Earth.
Viking 1 landing site
This image was
taken by the Mars
Reconnaissance
Orbiter on Dec. 5,
2006.
Mars Reconnaissance Orbiter
(MRO)
• Goals: Determine whether life ever arose on
Mars, characterize climate of Mars,
characterize geology of Mars, prepare for
human exploration
• Launched in 1995, now orbiting
• Set the record for most data sent back in a
single day
Mars Reconnaissance Orbiter
(MRO)
Mars Reconnaissance Orbiter
(MRO)
Mars Reconnaissance Orbiter
(MRO)
Erosion has exposed light-toned, layered rocks on the
northern rim of Hellas Basin, the largest impact crater
on Mars. Details in the layering seen in this image
from the High-Resolution Imaging Science
Experiment (HiRISE) reveal variations in brightness
that may indicate differing mineralogies.
Layers in Terby Crater
Mars Global Surveyor (MGS)
• Launched Nov 1996
• Went silent in Nov 2006 due to a battery
failure (caused by a complex sequence of
events)
• Orbited 12 times per day
MGS
• Monitored long-term cycles and variability
of the martian atmosphere and volatile
systems
• Characterized the solid planet, including
surface areas of geological importance and
improvements in knowledge of internal
structure
• Support for future Mars missions, including
landing site assessment, relaying data, etc.
MGS
MGS
Topographic
depression eroded
into layered rocks.
Erosion has
revealed layers of
different ages - the
oldest are at the
bottom of the depression. Within this depression are two sets
of alluvial - that is, water-lain - sedimentary rock units that
retain their original shape, indicating how the sediments were
deposited long before the material became rock. In these
cases, the processes created fans of debris with finger-like
protrusions at the ends and sides of the fans. Aslo preserved
are the channels through which water and sediment flowed.
MGS
Structure (?)
• Dense core about 1700km in radius, molten
rocky mantle somewhat denser that Earth’s
then a thin crust (crust is 80 km thick in
southern hemisphere, but only 35 km thick
in north)
• Lacks plate techtonics, so hot spots (and
low surface gravity) make BIG volcanoes
• No current tectonic activity, but there
probably was in the past
Atmosphere
• 95.3 % CO2 (tiny
amount compared to
what it once had)
• 2.7% N2
• 1.6% Ar
• traces of O2 (0.15%)
and water (0.03%)
History
• Was more like Earth
• most of CO2 was absorbed into rocks, but since it
has no plate techtonics, it can’t recycle CO2 back
into its atmosphere (no greenhouse effect to keep
it warm)
• Had running water once, maybe it’s all below
the surface now?
• Probably had a large ocean
• Northern hemisphere “younger” than southern
Ancient ocean?
Inset is Grand Canyon, to scale
Valles Marineris - 4000km long, 7km deep, and 120 km wide
a) Crater on the moon - powder ejecta
b) Crater on Mars - liquid “splosh”
A network of valleys - water erosion feature
Our view has become better with time.
a) Ground-based view
b) HST
c) Viking image
A comparison with the Red River running from
Shreveport, LA, to the Mississippi. The Martian
channel is about 400 km long and 5 km wide.
Gullies apparently formed by running water in the
recent past (MGS)
Dust storm
a) As the Sun’s light reaches and heats the canyon floor, it
drives water vapor from the surface. When this vapor comes
in contact with the coler air above the surface, it condenses
again, and a temporary water-ice “fog” results. b) This is the
200-km-wide Lowell Crater, as seen by MGS.
Deimos (panic)
Radius = 11 km
Phobos (fear)
Radius = 9 km
Pathfinder 360º panorama