Explore Mars guide

Updated Wednesday, 30th April 2008
From its craters and atmosphere to flyp-by missions and Beagle 2 – explore Mars with our guide. Or, if you would like a more visual experience, why not investigate the red planet with our Mars interactive.

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Observing Mars

Mars is named after the Roman God of War. Galileo Galilei was the first to observe Mars through a telescope in 1610. In 1878, Giovanni Schiaparelli announced that he had observed straight lines on the surface of Mars. He named these markings "canali", the Italian for "channels" or "grooves". This was translated into the English "canals", implying artificial waterways. This prompted the popular theory that there was indeed life on Mars. Today we are equally remote from Mars, but we send spaceships, landers and probes to view the planet up close and send images and data back to us.

Did you know?

Percival Lowell (1855–1916) devoted his life to the study of Mars. He proposed a theory that the “channels” were a result of attempts by struggling martian inhabitants to irrigate the planet from the melting polar ice-caps. The dawn of the space age and the exploration of Mars by spacecraft brought an abrupt end to such theories.

Further thinking:

To what extent does the technology used to observe Mars give rise to “myths”?



Like that of the Moon, the surface of Mars is pock-marked with impact craters. Formed by either asteroids or comets smashing into the planet’s surface, craters come in different shapes and sizes, depending upon the angle of impact, the size of the impacting object and whether the impact disrupts the entire tectonic structure of the planet. When an impact is this massive, it creates a multi-ring basin; Hellas Planitia is thought to be one of these. When the angle of impact is less than 10 degrees , the crater becomes elongated. If the angle is too low, the object ricochets off the surface of the planet.

Did you know?


Many martian impact craters look as though they were formed by objects that impacted on a surface with the consistency of wet cement. It is thought that this is the result of either the upflowing of trapped groundwater, or the thawing of the surface permafrost on impact.

Further thinking:

If identical objects travelling at the same interstellar speed were to hit Mars and the Earth, would they have the same impact velocity? What factors would influence their speed?

Why don't you have a look at the The Virtual Planisphere interactive?


Mars has two satellites, or moons, Phobos and Deimos, which are thought to be asteroids captured by Mars’ gravitational pull. They are quite tiny, Phobos is 26 km x 18 km and Deimos is about 16 km x 10 km in size. Phobos is only 6,000 km away from the surface of the planet. It is expected that it will crash into the surface of Mars sometime within the next 50 million years.

The solar system’s asteroid belt lies between Mars and Jupiter and orbits the sun. These rocky and metallic bodies collide with each other, going into orbits that can cause them to collide with planets.

Did you know?

Mars’ two moons were discovered in 1877. Its inner moon Phobos, is so close that the orbit velocity exceeds the rotation of the planet, so it rises in the west and sets in the east twice a day.

Further thinking:

How do you think collisions contribute to planetary formation?

Fly-by missions

From 1960 to 2003, over 30 space missions have tried to explore Mars. The first successful mission was in 1964, with the Mariner 4 fly-by, which transmitted 22 images of the planet to Earth. Several more Mariner missions led to Mariner 9, launched in 1971, which became the first spacecraft to orbit the planet, where it functioned for almost a year. Mariner 9 photographed a very different surface than was expected. Gigantic volcanoes, a massive canyon and a series of ancient riverbeds were revealed. Today the Mars Odyssey is orbiting and monitoring Mars.

Did you know?

Although Mars is much smaller than Earth, its surface area is about the same as the land surface area of Earth.

Further thinking:

What factors contributed to the fact that the images from Mariner 4 (launched 28th November 1965) took four days to transmit to Earth?

Missions to Mars

Mars up close

Forget for the moment the logistics of actually getting to Mars, here’s your chance to click and explore the planet risk-free. Find out more about the geology and atmosphere of Mars, as well as tips on what you would need to survive the red planet. Is there life out there? Discover the latest thinking…


Mars has a very thin atmosphere. It is made up of: 95.3 per cent carbon dioxide; 2.7 per cent nitrogen; 1.6 per cent argonand 0.13 per cent oxygen. There are traces of water vapour, neon, krypton and xenon. The atmospheric pressure is only 6 millibars, compared to 1,013 millibars on Earth. Because of this low pressure, the carbon dioxide and water that makes up the martian polar caps turn straight to gas from the frozen state. This is called sublimation. In summer in the northern hemisphere, carbon dioxide and water sublime and migrate to the southern pole where they condense to ice.

Did you know?

Like Earth, Mars has seasons, but unlike Earth, one pole is significantly warmer than the other. At present, the south pole on Mars has much warmer summers than the north pole does; this changes every 51,000 years. This is because Mars’ spin axis "precesses" (wobbles around like a top) over a slow cycle of 51,000 years.

Further thinking:

Why do you think that Mars’ greenhouse effect only adds about 6oC to the mean temperature of the planet (which is -50oC)?


The martian landscape has dry river channels, canyons and valleys, evidence that water once flowed on the surface. However, the cratering record suggests that these features were formed very early in the planet’s history, between 4 billion and 3 billion years ago. Tantalisingly, there is more recent evidence of water, in delicately structured gully systems. Formed, it is believed, by swimming-pool volumes of water that are entombed underground, trapped by a plug of ice. Suddenly it becomes warm, the ice plug melts, sending the water gushing down the gullies before it quickly evaporates.

Did you know?

The evidence of these intricate gullies, which can be less than 10 metres wide, have made planetary geologists think that Mars may have undergone massive, short-term climate changes. Some scientists believe that water may still exist today, buried deep underground.

Further thinking:

What effect do you think the martian seasons may have on these small channels?


No, we’re not talking about little green men here, the extensive mapping and subsequent spacecraft landing on the surface has put paid to those theories. The debate, however, is ongoing as to whether there is life on Mars. But what evidence is there? The Viking 1 and 2 landers failed to produce any sign of organic compounds on the surface of Mars. However, the most compelling evidence comes from a meteorite of martian origin (ALH 84001), which appears to provide fossil evidence of microbes. But this meteorite is about 4,500 million years old, so the search for present day life continues…

Did you know?

The phrase "little green men" probably comes from Edgar Rice Burroughs first novel on Mars in which he refers to the "green men of mars".

Further thinking:

“It’s life, Jim, but not as we know it.” How do we define life and what sort of life is now being looked for?


A spacesuit is needed to protect the astronaut from extremes of temperature. The martian surface temperature ranges from -100oC to +17oC. Spacesuits also protect the astronaut from bombardment by tiny space dust particles (micrometeoroids). Even though these are very small indeed they travel at phenomenal speeds, and could cause catastrophic damage. It is also needed to provide oxygen for breathing and to maintain pressure around the body to keep the astronaut’s body fluids liquid. On Mars the air pressure is so low that without the protection of a spacesuit blood would simply boil.

Did you know?

Before leaving the space shuttle on a spacewalk, an astronaut has to spend several hours breathing pure oxygen. This reduces the amount of nitrogen dissolved in body fluids, thereby minimising its release as gas bubbles when atmospheric pressure is reduced (a potentially fatal condition called ‘the bends’).

Further thinking:

What parallels are there between deep sea diving and space travel?

The Spacesuit

Cooling system

Spacesuits are insulated with layers of fabric like Neoprene and Gore-Tex to trap the astronaut’s body heat. They’re also covered with other materials to reflect sunlight. This insulation works so well that the spacesuit has to have a cooling system. This consists of a cooling and ventilation undergarment, with water-cooled tubes running through it to keep the wearer comfortable. The astronaut’s backpack cools and circulates the water round the garment. The backpack also supplies oxygen for breathing, and removes carbon dioxide and odours from inside the suit, as well as pressurising it.

Did you know?

The Martian day is almost the same as the Earth's day, but the year is almost twice as long.

Further thinking:

What gas needs to be removed from the spacesuit lest it build up to deadly levels?

How a Spacesuit Works

Beagle 2

Beagle 2 was an ambitious project that was supposed to carry out a series of experiments on Mars, looking for: the presence of water; the existence of carbonate minerals; the occurrence of organic residues; the complexity and structure of organic material; the isotopic fractionation between organic and inorganic phases and to seek trace atmospheric species indicative of extant life. It is also going to be testing the atmosphere and examining various aspects of the geology of the planet.

Beagle 2 was the first martian lander since Viking to carry instruments designed to detect evidence of present or past life. Unfortunately it was lost upon separation from the Mars Express orbiter.

Did you know?

Beagle 2 would have landed in a region of Mars named Isidis Planitia. This region is probably a very ancient impact basin caused by the collision of a comet or a 50 km diameter asteroid onto the surface of Mars about 3-4 billion years ago. Subsequently its floor may have become flooded by volcanic lava before being further buried by sediment derived from the surrounding highlands.

Further thinking:

What other spacecraft was scheduled to land on Mars in January 2004?

Beagle 2

Planetary and Space Sciences Research Institute


For decades now man has attempted to land spacecraft on Mars. The Soviet Union were the first to attempt Mars landers, but it was NASA who succeeded in 1975 with the Viking 1 and 2 missions. The Mars Pathfinder mission landed in 1997 and carried a small rover called the Sojourner, a six-wheeled vehicle that was controlled by an operator back on Earth. The European Space Agency’s (ESA) Mars Express spacecraft was launched in June 2003, carrying the Beagle 2 lander and NASA launched the Mars Exploration Rovers mission in July 2003.

Did you know?

The first attempted mission to Mars was way back in October 1960. The USSR mission Mars 1960A (Marsnik 1) failed on launch. The first attempted lander was the Mars 1962B (Sputnik 24) spacecraft, which broke up during the burn to transfer it to the Mars trajectory.

Further thinking:

Have a think about camera technology. What was the greatest improvement offered by the equipment in the Mars Global Surveyor in 1996?

Beagle 2

Mars in popular culture


Pop culture Mars


Mars is a small planet – it has a radius a little over half of that of the Earth. However, the martian landscape has some of the most dramatic features in the Solar System.

The geology of Mars, although dissimilar, is not as totally alien as one might think.

  • Volcanism on Mars
  • Canals
  • Sedimentation
  • Rock composition

Volcanism on Mars

Although there is no evidence of plate tectonics on Mars, that doesn’t mean that the planet has a single, uniformly old surface. Mars has some superb volcanoes, a result of the heat from the interior of the planet breaching the crust. Olympus Mons, Mars’ largest volcano, lies at the western edge of the Tharis Rise, a 10 km high, 4,000 km wide bulge in the planet’s surface. This northern plain is dominated by large volcanoes. The other major volcanic area on Mars is the Elysium Planitia, a small bulge rising only 2-3 km above the planet’s surface.

Did you know?

Olympus Mons on Mars is the largest volcano and the tallest mountain in the Solar System. It is 27 km high and 550 km across. This makes it taller than three Mount Everests.

Further thinking:

How does the thickness of Mars’ crust contribute to the massive size of its volcanoes?

A Crewed Mission to Mars: a case study by NASA


The Valles Marineris is a huge canyon system that represents a fracture in the planet’s surface that extends 4,000 km. This canyon dwarfs our own Grand Canyon, having regions that are 11km deep and 200 km wide. This may have been one of the features labelled by early astronomers as the canals of Mars. It is believed to have formed in several stages: first the surface collapsed into a few deep depressions that became filled with deposits. Many huge ancient river channels begin from the chaotic terrain and north-central canyons and run north.

Did you know?

The 2003 opposition of Mars, was the closest opposition in 73,000 years (or maybe 59,604 years, depending on how you calculate it). At its closest approach, on 27 Aug 2003, Mars was 34,646,418 miles (55,758,006 km) from the Earth.

Further thinking:

Apart from the action of water, what else could contribute to erosion on Mars?

The Internet Encyclopedia of Science: Mars


The effects of water and the wind – fluvial and aeolian processes are major surface modification processes. These fundamental parts of the geological cycle lead to the formation of sedimentary rocks. Tiny fragments of rock are transported by water, wind or ice and deposited elsewhere in roughly horizontal layers known as strata. When first deposited, sediments can be quite soft and malleable, but over time they are buried and compressed, forming harder rock. The Mars Global Surveyor took numerous images of beautifully layered terrains, which drape over crater walls and form beds at angles near the walls.

Did you know?

Changes to the surface of Mars have been observed over times as short as a single martian year.

Further thinking:

What other martian geological process leads to the layering of rock?

Rock composition

Mars isn’t called the red planet for nothing. Its rocks contain a high amount of iron oxide, or rust, as we call it here on Earth. We know there is also sedimentary rock on Mars, formed by the action of water, ice and wind, but what sort of rocks these are is unknown. They could be mudstones, high in clay minerals, or sandstones. Breccias can be formed from the debris thrown out from impact craters. They are found on the Moon, so they are another possible rock type. There is compelling evidence that the vast majority of the lava found in the martian landscape is basaltic in nature, like it is here on Earth.

Did you know?

Metamorphic rocks, such as slate and marble, originate from mudstones that have been heated to between 200 degree Celsius and 350 degrees Celsius at depths of 5-10 km below the planet’s surface. Heating at greater temperatures produces a rock called gneiss, which is coarser grained. However, there is no conclusive evidence of metamorphic rock on Mars.

Further thinking:

Why do you think scientists are unlikely to find metamorphic rock on the surface of Mars?

Mars in the Mind of Earth

Take your interest further

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