Mars is the fourth planet from the Sun and is often referred to as the “Red Planet” due to its reddish appearance caused by iron oxide (rust) on its surface. Mars is a planet of great scientific interest due to its similarities to early Earth, its potential for past life, and its status as a future target for human exploration. While harsh and inhospitable today, Mars may hold the key to understanding more about the formation of planets and the potential for life beyond Earth.

1. 1. Size and Composition

• • • Diameter: Mars has a diameter of about 6,779 km (4,212 miles), making it about half the size of Earth.
    • Composition: Mars is a terrestrial planet with a rocky surface. Its crust is composed of basalt, while its interior likely consists of a silicate mantle and a core made of iron, nickel, and sulphur.

 

1. 2. Orbit and Rotation

• • • Orbit around the Sun: Mars takes about 687 Earth days to complete one orbit around the Sun, nearly twice as long as Earth’s year.
    • Day length: A day on Mars (known as a “sol”) is 24.6 hours, only slightly longer than a day on Earth.
    • Seasons: Mars has a tilted axis (about 25.2 degrees), similar to Earth, which gives it seasons. However, they are about twice as long due to the longer Martian year.

 

1. 3. Surface and Geography

• • • Mars has a diverse landscape, including the largest volcano in the Solar System, Olympus Mons, which stands about 22 km (13.6 miles) high, and the deepest canyon, Valles Marineris, which stretches over 4,000 km (2,500 miles) long.
    • Its surface is covered in dust and rocks, with evidence of ancient river valleys, lake beds, and dried-up deltas, suggesting that liquid water once flowed on Mars billions of years ago.
    • Mars also has polar ice caps made of water and carbon dioxide (dry ice) that grow and shrink with the changing seasons.

 

1. 4. Atmosphere

• • • Mars has a thin atmosphere, composed mainly of carbon dioxide (95%), with small amounts of nitrogen and argon. The atmosphere is too thin to support liquid water on the surface for long periods and provides little protection from harmful solar radiation.
    • The thin atmosphere also results in extreme temperature fluctuations, from 20°C (68°F) in the day to -125°C (-195°F) at night in some regions.

 

1. 5. Water

• • • While liquid water can’t exist on Mars’ surface today due to the low atmospheric pressure, there is water ice present, particularly at the poles and beneath the surface.
    • There is strong evidence that Mars had large amounts of liquid water in its ancient past, with riverbeds, lakes, and possibly even oceans, which raises the possibility that it could have supported microbial life.

 

1. 6. Moons

Mars has two small, irregularly shaped moons: Phobos and Deimos. These are thought to be captured asteroids from the asteroid belt and are much smaller than Earth’s Moon. Phobos is slowly spiralling toward Mars and may eventually crash into the planet or break apart to form a ring.

 

1. 7. Magnetic Field

Unlike Earth, Mars does not have a global magnetic field. However, parts of the crust are magnetized, which suggests that Mars may have had a magnetic field in the past. Without a magnetic field, Mars is more vulnerable to solar wind, which has contributed to the thinning of its atmosphere over time.

 

1. 8. Exploration

• • • Mars has been a primary target for robotic exploration. The Viking missions in the 1970s were the first to land on the planet, and since then, numerous missions have orbited and landed on Mars, including NASA’s Curiosity and Perseverance rovers, which are actively studying its surface and geology.
    • Perseverance, which landed in 2021, is searching for signs of ancient life and collecting rock samples to be returned to Earth in future missions.
    • Ingenuity, a small helicopter that travelled with Perseverance, has successfully flown on Mars, marking the first powered flight on another planet.
    • The European Space Agency and China’s CNSA have also sent missions to Mars, increasing our understanding of the planet.

 

1. 9. Mars and the Possibility of Life

• • • While no life has been discovered on Mars, the planet’s past, with its more hospitable climate and liquid water, has raised the possibility that microbial life may have existed billions of years ago. The discovery of organic molecules by the Curiosity rover also adds to the intrigue.
    • Ongoing missions aim to explore ancient lake beds and deltas where signs of life could be preserved.

 

1. 10. Future Human Exploration

• • • Mars is considered the most likely planet for future human exploration and possibly colonization. NASA’s Artemis program aims to return humans to the Moon as a stepping stone for sending astronauts to Mars in the 2030s or 2040s.
    • Private companies like SpaceX also have ambitious plans to send humans to Mars, with the goal of establishing a self-sustaining colony.