Earth

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Earth
Diameter 12756km Rotation Period 24
hours Orbital Period 365.25 days Distance
from Sun 150 x 106 km Orbit Eccentricity/Tilt
0.02 / 23.3 degrees Temperature 14C Atmosphere
N2,O2,Ar,CO2 Gravity 1g Moons 1
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The Moon
Diameter 0.27DE Distance from Earth 0.0025AU Temp
erature -233C to 123C Atmosphere none Gravity
0.2g Moons none Visits gt20 satellites 6
landings Luna 2,3,9,10,16 Apollo Clementine
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Mars
Diameter 0.53DE Rotation Period 24.5
hours Orbital Period 1.9 years Distance
from Sun 1.523AU Temperature -120C to 22C Orbit
Eccentricity 0.09 Tilt
23.6 degrees Atmosphere thin CO2 Gravity 0.38g M
oons 2 Phobos Deimos Visits gt20
satellites Mariner 4,6,7, Mars 2,3..., Viking
12, MGS, Pathfinder, Spirit, Beagle 2
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Mars' Moons
Phobos Deimos
Deimos' orbital period is longer than a Martian
day (a Sol), so it appears to move backwards in
the sky opposite to the direction of Phobos
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Mars and Martians
Astronomer Percival Lowell at the turn of the
20th C. observed canals on Mars, which he
suggested were created in a last ditch attempt by
Martians to prevent Mars from drying out and save
their civilisation. The canals were merely a
figment of his imagination. But Mars is dry, and
we are still looking for Martians and the water
needed to sustain them.... Mars is a small
world, so cooled down more quickly and is now
geologically dead.
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Mars has the largest volcano in the solar system
- Olympus Mons 15 miles high! The map below
shows other volcanos, Syrtis Major, planitia, ice
covered polar regions, and Valles Marineris
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Mars has weather. Dust storms can cover it's
entire surface. And dust devils have been seen by
Pathfinder.
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Mars' Geological History
Mars' tilt varies greatly from 15 to 35 degrees
over just a period of 5 million years leading to
regular ice ages. If there's substantial water
glaciers will form that towards the end of the
ice age melt and carve out geological features on
Mars' surface. Pressure is too low to form
liquid water on surface but water under the
surface may exist...
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2002 Mars Odyssey finds water?
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Mars is most frequently visited planet ever since
its first visit by Mariner 4 in 1965
Landers need to be near equator, in flat lands
with gentle winds The cooler mid-latitudes have
the most interesting geological features
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July 1976 The Viking landers reach Mars
Performed experiments on Martian soil to test
for signs of life. The results were positive but
disbelieved.
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Airbag system for landing rovers on Mars
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1997 Pathfinder and the Sojourner rover
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2003 The next generation rovers (below) Gusev
Crater
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Spirit finds mud? If so there's water under the
surface of Mars, and maybe Viking did detect
signs of life... ...but for water to exist, it
must be very salty, more so than organisms can
survive
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Opportunity lands on hematite covered uplands
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Mars Express takes 3D images of the solar
system's deepest and longest canyon
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Beagle 2
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The Future Mars Flyers Mars Reconnaissance
Orbiter Phoenix Lander Sample Return Manned
Mission?