Transcript Mars - Dan Caton

Mars
Now: ~ opposition (rises when?)
magnitude -2.2
Popular Interest
Past and
present…
1938: Radio
broadcast of
War of the
Worlds
panics US
 2000: “Red
Planet”
 2005 (and
1953) “War
of the
Worlds”

First Observations
First observed by
Dutch physicist
Christian Huygens,
1659
 He noted…

Rotation
Motion of the feature Syrtis Major and
concluded P=24h
Giovanni Cassini

Determined to be
24:37 who also saw
the polar caps…
Polar Ice Caps

Ice cap
seen in
this
ground
based
photo

Similar to
view in
scope
Seasons and eccentricity
Seasons are affected (made more extreme) because
perihelion occurs at Southern Hemisphere summer
 This is unlike Earth seasons, since Earth’s orbital
eccentricity is small

Eccentricity and Oppositions

Causes some
oppositions
to be
“favorable”

September
2003’s was
especially
favorable

Note angular
size of Mars
Giovanni Schiaparelli
First proposed that
the caps made of ice
 Became famous when
he drew his sketch of
Mars in 1877 …

“Canali” (channels/canals)
Percival Lowell
Wealth “Boston
Brahman” (social
and cultural elite)
 Became interested
in the Mars canals
and established
an observatory in
Flagstaff, AZ

Lowell at the scope

Drew on 6-inch globes
to accommodate
perspective
Edward Barnard

In 1894 Edward
Barnard and
others could
not convince
himself the
canals existed
Mariner probes would resolve

dust storm here
frustrated first
photos in 1971
Mariner 9
When cleared…

Many features but
none lined up with
canals drawn by
Schiaparelli or
Lowell
Possible explanation based
on Lowell’s Venus “spokes”

Doctors noted that
Lowell had stopped
his scope down to a
few inches,
effectively creating a
pinhole camera at
eye, which displays
veins in retina

Similar to
ophthalmoscope, an
instrument used to
examine the interior
of the eye
Craters discovered

Not evenly distributed…
Mostly in southern hemisphere

Dust has eroded
rays and ejecta
Volcanoes found

Volcanoes such as Arsia Mons shown
above and...
.. In perspective 3D
The volcano Olympus Mons


rises 24 km (15 miles) above plains! (3x Mt Everest).
Great size of volcanoes on both Venus and Mars suggests no current
plate tectonics ... same surface sits above hot spot.
Tharsis Rise
Olympus Mons and
other volcanos
comprise the
Tharsis Rise
 Shown compared
to eastern US here
 Is an average of 5 6 km above most of
surface

Valley
Marineris
4000 km
long
 Would span
USA as
shown
 It is a huge
crust
fracture
 not formed
by water,
but…

These channels were formed by massive water flow
But where is the water now?...
Some water locked up in polar ice caps


South pole shown here
During summer CO2 portion sublimates, leaving H2O.
(Temperature rises above sublimation point)
color view of cap

shows ice melted off of sun-facing slopes, revealing
strange terraced slopes
North pole

this is almost all residual water ice shown here
Broken terrain
from outflow


in the Capri plateau, suggests water violently outgassed
when heated by volcanic activity below
Like similar event in eastern Washington state 14,000 years
ago that created the Channeled Scablands
Some water seen in fog
Early morning fog in canyons
1975-6: Two Viking Landers
Approaching Mars
dawn view
reveals clouds
along volcano
Olympus Mons,
Valley Marineris
 CO2 snow in
Argyre Basin

Viking I
Lander View
Landed in Chryse Planitia
(Golden Plains)
 Shows edge of crater on
horizon, probably
responsible for jagged
rocks in scene.
 Foreground shows
regolith covered with
other rocks that under
closer examination ...

…appear pocked (vesicular)
Suggests outgassing during igneous formation
Weather Report from mars
Other Results






95% CO2, 2% N2, 1.6% Argon
6-8 mBar pressure (Earth: 1000 mB)
no ozone layer
no magnetic field (therefore no iron core, also
supported by low avg density 3.9)
large temp swings ... -80OC to -20O C in warmer
areas!
seasonal pressure variationss as CO2 freezes
out/sublimates
Scoop Delivered Soil to Experiments
Geological Results
surface rich in iron (magnet) --> rust red!
 silicon --> 2/3 of Mars..
 little interior info since one seismometer
failed...


Biological…
gas-exchange
Sensed respiration of samples (used gaschromatograph/mass spectrometer)
labeled release
Used radioactive carbon nutrients -- checked for
metabolism...
pyrolytic-release
Checked for photosynthesis with
radioactive CO2 and artificial sunlight
Biological Results
no life found
 active chemical reactions believed due to
release of peroxides & superoxides
 surface is literally antiseptic!

Magnetosphere
almost no magnetic field
 Thus, core, if iron, not liquid, since Prot ~ PEarth
 Thus solar wind and cosmic rays hit surface

July 1997: Pathfinder
Mars Global
Surveyor
Imaging Mars from an orbit around it
 Recent image of delta-like fans

Other probes…

Mars Exploration
Rover Spirit and
Opportunity
landed in
January, 2004
Mars Odyssey continues
to map Mars in
infrared
Rover Assignment
Write up, in < 1 typed page…
 Current mission status (a paragraph)
 5 interesting things about the mission
 Use the link on our WebCT Class Links page
 Due next time (make a copy for yourself so
we can discuss it)

Asaph Hall
Discovered
two moons
in 1877
favorable
opposition
using the
26-inch
refractor at
the USNO, in
Washington,
DC
150 years before the were
“predicted” in Gulliver’s Travels
“They have likewise discovered two lesser Stars, or
Satellites, which revolve about Mars; whereof
the innermost is distant from the Center of the
primary Planet exactly three of his Diameters,
and the outermost five; the former revolves in
the space of ten Hours, and the latter in Twentyone and an Half; so that the Squares of their
periodical Times, are very near in the same
Proportion with the Cubes of their Distance from
the Center of Mars; which evidently shews them
to be governed by the same Law of Gravitation,
that influences the other heavenly Bodies. “
Phobos
Phobos is nearer and larger, P = 7:39! – rise to set in 5h!
Not spherical – why not?
Deimos
Almost Marsynchronous -- appears to take 3 days horizon to horizon.