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

The Moon

Diameter

0.27DE

Distance from Earth 0.0025AU

Temperature

-233C to +123C

Atmosphere

none

Gravity

0.2g

Moons

none

Visits

>20 satellites

6 landings

Luna 2,3,9,10,16

Apollo

Clementine

MarsDiameter

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

Moons

2: Phobos Deimos

Visits

>20 satellites

Mariner 4,6,7, Mars 2,3..., Viking 1&2, MGS, Pathfinder, Spirit, Beagle 2

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

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.

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

Mars has weather. Dust storms can cover it's entire surface. And dust devils have been seen by Pathfinder.

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...

2002 – Mars Odyssey finds water?

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

July 1976 – The Viking landers reach Mars

Performed experiments on Martian soil to test for signs of life. The results were positive

but disbelieved.

Airbag system for landing rovers on Mars

1997 – Pathfinder and the Sojourner rover

2003 – The next generation rovers

(below) Gusev Crater

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

Opportunity lands on hematite covered uplands

Mars Express takes 3D images of the solar system's deepest and longest canyon

Beagle 2

The Future

Mars Flyers

Mars Reconnaissance Orbiter

Phoenix Lander

Sample Return

Manned Mission?