Mars symbol

The image below shows the large, darkened Syrtis Major region of Mars. On the far side of the planet lies the vast Valles Marineris canyon system, and some of the biggest volcanoes in the Solar System (including the largest of them all, Olympus Mons) in Tharsis Montes.

Mars - the Syrtis Major region, imaged by Viking

[ NASA / JPL / Caltech ]


Mars is currently the target of a large amount of planetary research by NASA, the ESA and other space programmes. In fact, for the forseeable future, whenever a launch window from Earth to Mars is available, spacecraft will be sent to study it. This 'invasion' of the Red Planet is a sure sign that many nations believe that Mars is the next big step in mankind's exploration of the Solar System.

Axial Tilt
Axial Period
(d, h, m)
686.98 d 1.38 1.67 1.9 25.19 1, 0, 37.4
Diameter (km)
Oblateness Mass
(Earth = 1)
(water = 1)
No. of
6, 795 0.005 0.11 3.9 0.15 2


Martian Chronological History

The following table shows a chronological timescale of Mars, in which the dates are in billions of years (Ga).

Martian epoch Age (Ga) Events
Late Amazonian 0.7 to present  
Middle Amazonian 2.3 - 0.7 Liquid water is no longer present on surface
Early Amazonian 3.5 - 2.3  
Late Hesperian 3.7 - 3.5 Liquid water begins to disappear from surface
Early Hesperian 3.8 - 3.7 Early heavy impact cratering ends
Late Noachian 4.1 - 3.8 Cratering
Middle Noachian 4.4 - 4.1 Cratering; Water flooding of surface begins
Early Noachian 4.6 - 4.4 Accretion of Mars ends; Cratering


Missions to Mars

Mars exploration programmes have had their successes, but also an unusually high number of failures, which have jokingly led to the theory of the 'Martian Ghoul' which supposedly destroys approaching spacecraft! Russia has never had much luck with Mars, and has not sent a mission since the Mars '96 package failed to enter the correct cruise trajectory to Mars from Earth, and crashed into the Pacific the day after launch. Several NASA missions have failed in the last 15 years or so, such as the keenly anticipated Mars Observer in 1992 and the two Mars Surveyor '98 probes (Mars Climate Orbiter and Mars Polar Lander) in 1998 and 1999.

NASA has also had some fantastic successes, however, and as of August 2006 the agency has four active missions underway at the Red Planet, including three orbiters and the two surface probes Spirit (MER1) and Opportunity (MER2) comprising the Mars Exploration Rovers mission. The European Space Agency (ESA) mission Mars Express, the objectives of which are based on those of Mars '96, is also underway and is returning fantastic Martian topographic data whilst also attempting to discover more about the history of water on Mars, amongst other things.

Current missions: -

For a complete list of missions to Mars, see the links page.