Mars summary
Mars is the fourth planet from the Sun in our Solar system. The planet is also known as "The Red Planet", because of its apparent red color. Mars has two moons - Phobos and Deimos, which are small and oddly-shaped, possibly being, captured asteroids. Mars is an Earth type planet. Its diameter is a little bit bigger than the half of the Earth's one. Mars has only a quarter the surface area of the Earth and only one-tenth the mass, though its surface area is approximately equal to that of the Earth's dry land because Mars lacks oceans. The solar day on Mars is very close to Earth's day: 24 hours, 39 minutes, and 35.244 seconds.

Today this planet is an attractive object for scientists from all over the world because of its future probable use. It will most likely be our next "HOME" when our native planet - the Earth, will be unappropriate for life existence. but don't go astray that surviving there is so easy to realize. There are a lot of things that shouldn't be ignored.

The planet had a strong influence on the life of ancient people. The ancient Greeks and Egyptians were the first to observe Mars in the sky. The Egyptians knew Mars as the "Her Deschel" or "The Red One". Among the Babylonians Mars was known as "Nergal" or "The Star of Death". However, the Romans were the ones to give Mars its modern name, after their god of war - Mars (respectively Ares in Greek mythology).

Asncient Greeks gave the red spot that was shining in their night sky the name of the god of war - Ares. So in the mytholigy of Greece this god had three sons in spite of not having a wife. His two twins used to accompany him in battles he took part in.Their names are Phobos (Horror) and Deimos (Fear). They were also given to Mars's two moons. And because of its red colour it was accepted as a symbol of blood. So it received the name of a fearless warrior.

In Roman mythology Mars was not initially associated with war, but the fertility and vegetation. His name soon became a synonym of Ares. Unlike Ares, Mars was the greatest god of his people. The legend says that he had two sons - Romulus and Remus.They were said to have founded Rome. As the consort of Rhea Sylvia and father of Romulus and Remus, Mars was considered the father of the Roman people. That's why he was much more worshipped than Ares was in the mythology of ancient Greece and any other god in Roman mythology.

Mars fact sheet
Physical parameters
Mars/Earth Comparison

  Mars Earth Ratio (Mars/Earth)
Mass (1024 kg) 0.64185 5.9736 0.107
Volume (1010 km3) 16.318 108.321 0.151
Equatorial radius (km) 3397 6378.1 0.533
Core radius (km) 1700 3485 0.488
Mean density (kg/m3) 3933 5515 0.713
Surface gravity (m/s2) 3.72 9.81 0.379
Escape velocity (km/s) 5.03 11.19 0.450
Visual geometric albedo 0.160 0.367 0.409
Visual magnitude -1.52 -1.4  
Surface temperature oC -140 / +20 -50 / +50  
Atmospheric pressure (bars) 0.007 1.01325 0.007

Orbital parameters
Mars/Earth Comparison

  Mars Earth Ratio (Mars/Earth)
Semimajor axis (106 km) 227.92 149.60 1.524 au
Sidereal orbit period (days) 686.980 365.256 1.881
Perihelion (106 km) 206.747 147.09 1.405
Aphelion (106 km) 249.23 152.10 1.639
Synodic period (days) 779.94    
Mean orbital velocity (km/s) 24.13 29.78 0.810
Max. orbital velocity (km/s) 26.50 30.29 0.875
Min. orbital velocity (km/s) 21.97 29.29 0.750
Orbit inclination (deg) 1.850 0.000  
Orbit eccentricity 0.0935 0.0167 5.599
Sidereal rotation period (hrs) 24.6229 23.9345 1.029
Length of day (hrs) 24.6597 24.0000 1.027

Mars' atmosphere is quite different than Earth's one. First of all of all it is only 1 percent of Earth's atmosphere! The air pressure on the surface is only 0.0075 bars, about 0.75% of the average on Earth. And the content of Carbon Dioxide (CO2) is much higher than it is on Earth- CO2 - 95.32%. Nitrogen (N2), on the other hand, is very little. It is only (N2) - 2.7%. Argon's (Ar) presence in the atmosphere of "The Red planet" is 1.6%. The gas that is required for human beings' breathing - Oxygen (O2) is just 0.13%. Another chemical compound which is absolutely necessary for our existence is water (H2O) is 0.03%. This quantity is small, but these amounts are enough for cloud's formation. And finally Neon (Ne). It exist there in 0.00025 %. An interesting fact is that methane occurs in the atmosphere of Mars. This gas is not evenly distributed all over the planet. We may say that it appears in "patches". Scientists suggest that it is being rapidly broken down before to have enough time to gistribute around. This presence is explained with some conjectures like possible Volcanic activity, comet impacts and even microorganisms (methanogens).

Carbon Dioxide (C02) 95.32%
Argon (Ar) 1.6%
Oxygen (O2) 0.13%
Carbon Monoxide (CO) 0.07%
Water (H2O) 0.03%
Neon (Ne) 0.00025%
Krypton (Kr) 0.00003%
Xenon (Xe) 0.000008%
Ozone (O3) 0.000003%

Temperature and Pressure on Mars are too lower than these are used to live with. Average temperatures there are around - 63 C. Temperature's maximum is about 20 C and minimum is about -140 C. Pressure on Mars hasn't got a constant rate. It depends on the season, but average pressure is 7 millibars.

Climate of the "Red planet" is rather different than the one on Earth. This is because of the significantly elliptical orbit that causes big temperature variations. Dramatic weather changes and strongly variable atmosphere are observed there. There are also global dust storms. Weather on Mars is often more cloudy than dusty (HST, NRAO).

Seasons on Mars occur the same way they do on Earth. Mars' axis is tilted about 25 degrees (23.5 for Earth). When the northern hemisphere is facing the the Sun it is summer in the north. This occurs when Mars is at its farthest from the sun in its orbit (called "aphelion"). Summer in the southern hemisphere occurs when Mars is at the closest to the sun in its orbit. This is called the perihelion.

The mean distance of Mars to the Sun is about 228 million kilometers. As noted above, the martian orbit is quite eccentric which leads to a difference of nearly 42 million kilometers between the furthest distance from the Sun and the closest one (the perihelion). By comparison, there is only a 4 million mile difference between perihelion and aphelion for Earth. As for any body in a gravitationally bound orbit, Mars travels more swiftly in its orbit when it is close to the Sun than when it is distant. As a result the duration of the four martian seasons varies one from another, unlike the case on Earth where each season lasts for just one quarter of the year. Since the Martian year is about 687 Earth days long -- nearly twice as long as ours, the Martian seasons are similarly extended. The following table compares the length of the seasons on Mars and Earth:

Northern/Southern Hemisphere

Seasons Mars (in Earth days) Earth
Summer - Winter 199 94 (93,65)
Autumn - Spring 158 90 (89,85)
Winter - Summer 147 89 (88,89)
Spring - Autumn 183 93 (92,75)

In the Martian northern hemisphere, winter is short and relatively "mild" while summer is long and cool. Conversely for the southern hemisphere summer is short and relatively hot while winter is long and cold. Besides, perihelion climate (summer in S. H.) characterizes with dust storms (Viking, Mariner 9, NRAO). These storms can grow to encompass the whole planet. Some of these swirling storms rise 8 kilometers above the Martian surface and may carry several tens of tons of fine red dust. Aphelion climate, on the other hand, is known with the fact that wide belts of water ice clouds appear on the surface of the planet. They have not initially identified by the 1970's spacecrafts.

The axis of Mars does not point toward Polaris, our North Star, but is displaced about 40 towards Alpha Cygni. Because of this celestial displacement, the Martian seasons are 85 out of phase with respect to terrestrial seasons, or about one season earlier than ours. Consequently, when we observe Mars next spring and summer, it will be winter and spring, respectively, in the Martian southern hemisphere.

If you think the weather on Earth is unpredictable, try living on Mars. One week, the sky is pink and cloudless, filled with windblown dust raised from the rusty Martian surface. By Martian standards, it's warm, about minus 40oC. Then, in a few days, the dust is swept from the atmosphere, temperatures plummet 40 degrees, and brilliant water ice clouds appear against a dark blue sky. Dramatic weather changes like these may not seem very different from a batch of severe thunderstorms passing through some hometown, but for Mars these changes can sweep over the entire planet every week. It appears that Mars' roller coaster-like weather is more chaotic and unpredictable than scientists first thought. Observations by the Hubble Space Telescope and the National Radio Astronomy Observatory (NRAO) radio telescope at Kitt Peak, Ariz., show that the atmosphere of Mars is more complex and variable than the picture revealed by the Viking and Mariner 9 orbiters A state of emergency would be declared on Earth if an ice or dust storm blanketed the entire planet. These shifts in climate are driven by three important factors: Mars' thin atmosphere, its elliptical orbit around the sun, and strong climatic interactions between dust and water ice clouds in the atmosphere. Mars' atmosphere is so thin that it weighs less than 1 percent of Earth's atmosphere. Because Mars' atmosphere is so paper-thin and there are no oceans to store up heat from the sun, the planet's temperatures respond more quickly and intensely to surface changes and atmospheric heating by the sun. There are also much larger annual changes in sunlight falling on Mars than on Earth. During perihelion, (summer in the southern hemisphere), the planet receives 40 percent more sunlight than during aphelion, when it is farthest from the sun (summer in the northern hemisphere).

Geology and surface of Mars

Mars is a rocky planet, like Earth, that formed aproximately at the same time. Its surface is cold and desert-like. From a distance Mars looks generally red, or rather pale orange pink with two white polar ice caps. The red area isn't entirely uniform; there are some very distinguishable lighter and darker areas, which sometimes seem quite green or even blue. Unlike the early observers thought, the dark areas aren't water oceans, as water can't exist on Mars in liquid form due to the low pressure.

Like the Moon, Mars was bombarded with asteroids in the past. That caused Mars' surface to be mainly composed of basalt. There are proofs for silica or silica glass presence. A thin layer of dust (like talcum powder) covers the surface of the planet.

Comparing the albedo of different parts of Mars, it can be divided in two kinds of areas. The pallid ones are Marian "continents" (Arabia Terra, Amazonis Platinia). The darker ones are "seas" (Mare Erythraeum, Mare Sirenum, Aurorae Sinus and the largest- Syrtis Major). These albedo features are caused by different kinds of surface materials; the red is iron-oxide-rich dust and sand, and the darker areas are generally more stony and rocky areas.

The highest point in the Solar system Olympus Mons (Mount Olympus) is at 26 km in a vast region- Tharsis (containing several large volcanoes). This place is also famous for the solar system's largest canyon system, Valleys Marineris or the Mariner Valley, which is 4000 km long and 7 km deep. Mars' surface contains many impact craters. The largest - Hellas impact basin. It is covered with light red sand.

The difference between Mars' highest and lowest points is 31 km (from Olympus Mons -26 km, to the bottom-Hellas impact basin- 4 km below the datum). In comparison, the difference between Earth's highest and lowest points is only 19.7 km. Combined with the planets' different radiuses, this means Mars is nearly three times "rougher" than the Earth.

Polar caps
Like the Earth, Mars also has polar caps. They differ from these on our planet. They consist of "dry" ice (frozen CO2). Each cap has surface deposits of it. So they form a polar "hood" in winter, which sublimates in summer. The southern polar cap contains at least some deposits of CO2,but they change through years.

People believed that life had existed on Mars. These theories were popularized by Percival Lowell and Giovanni Schiaparelli in 19th century. Schiaparelli called these observed features channels ("canali" in Italian). The myth of the Martian canals began from people's misinterpretation as 'canals'. They were apparently artificial linear features that were asserted to be canals. This gave rise to many stories concerning Martians. These features are now known to be mostly non-existent or dry ancient watercourses. The colour changes during seasons have been ascribed to dust storms.

Ice patches
On 29 July 2005, it was reported for an "ice lake", discovered in a crater in the north polar region of Mars. Images clearly showed a broad sheet of ice in the bottom of an unnamed crater located on Vastitas Borealis (70.5 North, 103 East), a broad plain that covers much of Mars' far northern latitudes. The crater was 35 km wide and about 2 km deep.

The height difference between the crater floor and the surface of the water ice is about 200 metres. While scientists do not refer to the patch as a "lake", the water ice patch is remarkable for its size and for being present throughout the year. Water ice and layers of frost have been found in many different locations on the planet.

Inner structure
There is no sure evidence about Mars' inner structure. But we may make some conjectures about it. They can be concluded from the data of the surface and also the bulk characteristics. One of the theories that is most likely to be true is the one that claims that the inner structure of Mars consists of a dense core, molten mantle and, of course, Martian crust. This solid core is about 3400 km in diameter| (that makes 1700 km in radius). Martian mantle, on the one hand, is much similar to the one of Earth, but it is rocky and a bit denser than it is on Earth. But Mars is less denser than the other Earth-type planets and because of this fact we can conclude that its core includes iron and iron sulfide. In addition to them there also might be a relatively large fraction of sulphur. There is also a thin crust. Martian and Earth crust are alike, but they are not exactly the same. As you probably know, Earth's crust is about 10 km under the seas and the oceans, but it can reach 80 km under the mountains. The one on Mars also has different width, but it doesn't depend on seas and mountains but on the hemisphere it is situated in. Data from Mars Global Surveyor indicates that Mars' crust is about 80 km thick in the southern hemisphere but only about 35 km thick in the north. If you are interested in geology you'd like to know that there are no plate tectonics on its surface at present, but there are proves that this kind of motion existed in the past. So this lack of lateral movement enables hot-spots under the crust stay in a fixed position relative to the surface. These facts plus lower surface gravity may account for the Tharis bulge and its enormous volcanoes. There is no evidence of current volcanic activity.

Mars missions
Mars has long been a subject of human interest. Early telescopic observations revealed color changes on the surface which were originally attributed to seasonal vegetation and linear features, which were ascribed to intelligent design. Other telescopic observations found Mars' two tiny moons, dry channels and depressions, polar ice caps, Olympus Mons, the solar system's tallest mountain, and the solar system's largest canyon system - Valles Marineris, These discoveries have only piqued further interest in the study and exploration of the red planet.

Here is the list of past, present and future missions to Mars.

(In the beginning of Mars' exploration the missions simply flew by Mars, taking as many pictures as possible).

Soviet Union Mars 1960A, Mars 1960B
Mars 1962A, Mars 1962B

All of them failed
Mariner 4 - the first close-up image ever taken of Mars
NASA Mariner 3-4
Mariner 6-7
Mariner 3 - failed

(Spacecrafts in orbit around Mars for longer term, global studies)

NASA Mariner 8-9
Viking 1-2

Mars Observer
Mars Climate Orbiter
Mars Global Surveyor

2001 Mars Odyssey
Mars Reconnaissance Orbiter


Mariner 8 - failed
Incl. Orbiters and landers

Lost contact
Lost on arrival, 1999
The first successful mission in two decades

image from Mars Global
Surveyor- a region about
1500 meters across
Italian space
agency and NASA
Mars Express 2003 Orbiter and lander - Beagle 2 - lost
Mars Express orbiter
image, oblique view generated from
stereoscopic data
Soviet Union Phobos 1 and 2 1998 Phobos 1 - lost

Landers and Rovers

Soviet Union Mars 2 and 3

Mars 4 and 5

Mars 6 and 7


the first human artifacts to touch down on Mars

Mars 4 and 7 - missed the planet

Mars 5 - succeeded

Mars 3 lander


Mars Pathfinder

Mars Polar Lander/Deep Space 2

Mars Exploration Rovers - Spirit and Opportunity


2004 arr.

Lost on arrival

The most successful rovers

Ares Vallis, by Mars Pathfinder

photo of the Gusev crater landing site, taken by Spirit

Future missions

Phoenix Mars Lander - It will be launched by a Boeing Delta 2925 launch vehicle in 2007. In May, 2008, it will land in the planet's water-ice-rich northern polar region, and dig its robotic arm into arctic terrain searching for clues on the history of water, and search for environments suitable for microbes.

Mars Science Laboratory - launch in December 2009 and perform a precision landing on Mars in October 2010.

Phobos-Grunt is a planned Russian sample return mission to Phobos, one of the moons of Mars. It will be the first Russian interplanetary mission since the failed Mars 96 mission.