Transcript Mars – The Last of the Inner Planets

Mars – The Last of the
Inner Planets
Comparison of Mars and Earth in their correct relative sizes.
Mars (diameter 6790 kilometers) is only slightly more than
half the size of Earth (diameter 12750 kilometers).
The mass of Mars is roughly one-tenth the mass of the Earth.
Interestingly enough, although Mars is so much smaller than
Earth, the lack of water on Mars makes its land surface area
roughly equal to the land surface of the Earth.
Mars has the
highest
mountain in
the Solar
System.
Olympus Mons
rises 24
kilometers, or
78,000 feet,
from the
surface of the
planet.
The diameter of of the crater on top of Olympus Mons is more than 600
kilometers (the size of Arizona). The relative ages of the surface in
various parts of Mars can be estimated from the number of impact craters
present in a given area. Only two craters are visible here, indicating that
Olympus Mons is young, probably the youngest volcanic feature on
Mars. By some
estimates, the most
recent large volcanic
eruption at Olympus
Mons occurred only
25 million years
ago. The oldest
activity here could
be much older than
this and would have
been buried by
younger lava flows.
This image is based on Viking Orbiter images and shows the Tharsis
region of Mars with a map of the western United States for scale. The
three large, aligned volcanos are Arsia Mons (lower left), Pavonis
Mons (center), and Ascraeus Mons (upper right). Olympus Mons is the
volcano at upper left, and a portion of Valles Marineris is on the right.
Each of the four large volcanos in this figure is at least 400 kilometers
across at its base.
This shaded relief painting is based on Viking Orbiter
images and shows the Valles Marineris trough system
with a map of the United States for scale.
Valles Marineris is 4000 kilometers long, nearly enough to stretch from
New York to California. Valles Marineris reaches a maximum depth of
10 kilometers. The red box outlines the region shown in the next slide.
The so-called “face” on Mars.
The Face Unmasked
This 3D perspective view of the Face using April
8, 2001 laser altimeter data from MOLA was
produced by Jim Garvin (NASA) and Jim Frawley
(Herring Bay Geophysics). It proves that the
“face” is a natural phenomenon, rather than a
deliberate creation.
The left image is a portion of Viking Orbiter 1 frame 070A13, the middle
image is a portion of Mars Orbiter Camera (MOC) frame 22003 shown
normally, and the right image is the same MOC frame but with the
contrast reversed to simulate the approximate lighting conditions of the
Viking image.
In 1877, Giovanni Schiaparelli (1835 - 1910) announces that
he has seen "canali" on Mars. If translated correctly, this
announcement would have been interpreted as "channels", but
with the excitement building over the Suez Canal, it was
translated as "canals", and thus began a detour in the history of
Mars exploration.
This image shows data from missions separated by
decades that were put together to create the first threedimensional perspective of the polar regions of Mars
The south polar cap consists
mainly of frozen carbon dioxide.
This carbon dioxide cap never
melts completely.
Unlike the south polar cap,
the north polar cap probably
consists of water-ice.
Just as Earth’s atmosphere can be
seen as a blue veil around the planet,
Mars’ atmosphere can be seen as a
thin, red veil.
The presence of
an atmosphere
means that
weather occurs
on Mars. One
example of this
is the Great Dust
Storm of 2001.
“Perfect Storm”
Building on
Mars
9/26/01
There is also frost on Mars on occasion, as evidenced by
this color enhanced picture of frost at the Viking 2 Lander
site
Scientists believe Mar’s interior is like the Earth – with a
core, a mantle, and a crust.
While Earth has only one moon, Mars
has two - Phobos and Deimos.
The oblong crater to the north of the volcano Ceraunius Tholus is a
possible source crater for Martian meteorites. The crater's elongated
shape suggests that it formed by a shallow-angle (grazing) impact, which
might have helped eject rocks off the Martian surface. These rocks would
have orbited the Sun for millions of years before finally landing on
Earth.
This painting of a large meteorite
impact shows how rocks might be
ejected from Mars into space. In a
sufficiently energetic impact, rocks
from the Martian surface can be
ejected with enough velocity to
escape the planet's gravity. Painting
by Don Davis. Copyright SETI
Institute, 1994
A rain of 40 stones fell from the sky in 1911 near Nakhla in
Egypt. One meteorite hit and killed a dog. The stones
ranged in size from 20g to 1813g, and it is estimated a
total weight of 10kg (22 pounds) had fallen. Meteorites
from Mars are classed as "SNC meteorites", refering to
the places where meteorites of their kind were found
(Shergotty-Nakhla-Chassigny).
Researchers have found magnetic
material in a 4.5-billion-year-old
Martian meteorite that some
scientists believe could only have
been produced by bacteria.
This meteorite was found on the ice in Antarctica. For scale, the cube at the lower right
is 1 centimeter on a side. The meteorite is partly covered by a black glassy layer, the
fusion crust. The fusion crust forms when the meteorite enters the Earth's atmosphere at
high speed, with friction heating and melting the outer portion of the meteorite. Inside,
the meteorite is gray. It formed in a volcanic eruption about 180 million years ago; other
Martian meteorites formed in eruptions about 1.3 billion years ago. This meteorite is
almost certainly from Mars because it contains a small amount of gas that is chemically
identical to the Martian atmosphere. NASA Johnson Space Center S80-37480
Rocks are often made of small mineral grains that can't be seen clearly without a
microscope. To see these small grains, scientists grind and polish rock samples very thin
(0.03 millimeters) so light can pass through them. This picture is a microscopic view,
about 2.3 millimeters across, of a martian meteorite. The brown areas are grains of the
mineral pyroxene and the clear white areas are the mineral plagioclase. These are the
two most abundant minerals in basalt, both on Earth and Mars. The black areas are
magnetite, an iron-oxide mineral. Photograph by Allan Treiman, Lunar and Planetary
Institute
This microscopic view, 2.3 millimeters across, is in false color, produced by holding
polarizing filters above and below the microscopic slide. These filters cause different
minerals to have distinctive colors, allowing easy identification of the minerals. Most
of this meteorite (in yellow, green, pink, and black) is the mineral olivine, which is
common in some basaltic rocks. The striped grain near the center is the mineral
pyroxene. Photograph by Allan Treiman, Lunar and Planetary Institute
This microscopic view of another martian meteorite shows the real colors of the mineral
grains in the meteorite. The clear and cracked areas are the minerals olivine and
pyroxene. The reddish and black veinlets and patches are clay and rust where the
pyroxene and olivine reacted with liquid water. These veinlets of clay and rust are
truncated by the the meteorite's fusion crust, which formed when the meteorite came
through the Earth's atmosphere. The veinlets therefore must have formed before the
meteorite came to Earth; it is most likely that the veinlets formed from water on Mars.
Photograph by Allan Treiman, Lunar and Planetary Institute
This year, Mars became a major focal point for people around
the world as it made its closest approach to Earth in 60,000
years. These “close” approaches are known as perihelic
oppositions.
To put it more simply, the the fact that not only are
Mars and Earth are in a “direct line of sight,” the
planes of their orbits are slightly tilted, creating
optimum viewing conditions
By early 2004, there will be seven spacecraft at Mars,
sent by nations around the world.