MARS

EXPLORING THE RED PLANET

Mars, often referred to as the “Red Planet” because of the reddish colour of its surface is due to finely grained iron(III) oxide dust in the soil. It is the fourth planet from the Sun in our solar system and seventh in size and mass. It holds a special place in human imagination and scientific exploration due to its distinctive reddish appearance and its potential to host signs of past or present life. As the second closest planet to Earth, following Venus, Mars is typically easily observable in the night sky as its orbit lies beyond Earth’s. It is also the sole planet whose solid surface and atmospheric phenomena can be studied through telescopes from our vantage point.

Much like Earth, the red planet boasts clouds, winds, a roughly 24-hour day, distinct seasonal weather patterns, polar ice caps, volcanoes, canyons, and other recognizable features. Intriguing evidence suggests that billions of years in the past, Mars bore an even greater resemblance to Earth, with a more substantial, warmer atmosphere and a significantly larger water presence—potentially hosting rivers, lakes, flood channels, and maybe even oceans. Currently, Mars presents itself as a desolate, frozen terrain.

Nevertheless, detailed images reveal dark streaks on the slopes of certain craters during Martian spring and summer, hinting at the possibility of seasonal water flow on the planet’s surface, albeit in small quantities. Additionally, radar reflections from a potential lake beneath the south polar cap raise the possibility that water may persist in liquid form in sheltered regions beneath the surface.

With a radius of 3,389.5 kilometers (2,106 miles), the planet boasts the second smallest size among the planets in the Solar System. An observable dichotomy exists on its surface: generally, the terrain in the planet’s northern hemisphere is flatter and lower in elevation compared to the southern hemisphere. The red planet possesses a thin atmosphere primarily composed of carbon dioxide and two naturally occurring, irregularly shaped moons: Phobos and Deimos.

Extraordinary dust storms have the capacity to expand to such an extent that they envelop the entire planet. Temperatures can plummet to levels where carbon dioxide in the atmosphere directly condenses into snow or frost, and marsquakes, akin to earthquakes on Earth, are a regular occurrence. Given these intriguing features, it’s no wonder that this small red celestial body remains a source of fascination for scientists and is one of the most extensively explored objects in the solar system.

ABOUT THE PLANET – MARS

At an average distance of 228 million kilometers (140 million miles) from the Sun, Mars orbits about 1.5 times farther away from the Sun than Earth. Due to its relatively elongated orbit, the gap between Mars and the Sun fluctuates between 206.6 million and 249.2 million kilometers.

The red planet is most conveniently observed during opposition, when it and the Sun are positioned on opposite sides of the sky. During this time, Mars appears high in the sky, presenting its fully illuminated side. Successive oppositions occur approximately every 26 months. They can transpire at different points in Mars’ orbit, with the best viewings taking place when the planet is nearest to the Sun, and consequently closest to Earth, rendering Mars at its most brilliant and largest. These close oppositions occur roughly every 15 years.

The planet is roughly half the diameter of Earth, boasting a surface area that is only slightly smaller than the combined area of Earth’s terrestrial landmasses. It is less dense than Earth, having about 15% of Earth’s volume and 11% of Earth’s mass, resulting in about 38% of Earth’s surface gravity.

INTERNAL STRUCTURE

The red planet, like Earth, has an internal structure with distinct layers, although the composition and characteristics of these layers differ from those of our planet. The internal structure of Mars can be divided into several layers, from the centre outward:

CORE

Mars has a small solid core made primarily of iron and nickel. Unlike Earth, Mars’ core does not generate a significant magnetic field. This lack of a strong global magnetic field has contributed to the thinning of the planet atmosphere over time, as the solar wind can strip away particles from the upper atmosphere without a protective magnetic shield.

MANTLE

The mantle is the layer above the core and consists of silicate rocks. It is partially molten and capable of convective movement over geological time scales. This mantle convection is thought to have played a role in the formation of Mars’ various surface features, including its extensive volcanism and the Tharsis volcanic plateau.

CRUST

The crust is the outermost layer of Mars and is composed mainly of basaltic rocks. The Martian crust is relatively thin compared to Earth’s and is characterized by its many impact craters, as well as volcanic features like shield volcanoes, calderas, and lava flows. Mars’ crust has regions of different geological ages, with some areas showing signs of more recent volcanic and tectonic activity.

Overall, Mars’ internal structure is less differentiated than Earth‘s, meaning that it has not undergone as much layer separation and stratification. Its core is smaller and less active, leading to the absence of a strong global magnetic field. Despite these differences, studying Mars’ internal structure provides insights into its geological history, the processes that shaped its surface, and the conditions that might have prevailed in its distant past.

SURFACE

The surface of Mars is a diverse and intriguing landscape that has captured the fascination of scientists and space enthusiasts alike. It is characterized by a combination of rugged terrains, impact craters, volcanic features, and evidence of past water-related processes. Here are some key features and aspects of Mars’ surface:

IMPACT CRATERS

Mars, like other rocky planets, is covered with a vast array of impact craters that bear witness to its history of interactions with cosmic debris. These craters provide valuable insights into the planet’s geological past, the frequency of impacts in the solar system, and the processes that have shaped Mars’ surface over billions of years. Mars’ impact craters serve as a chronicle of the planet’s tumultuous history and offer scientists a window into the broader dynamics of our solar system. The ongoing study of these craters continues to refine our understanding of Martian geology, planetary evolution, and the interactions between celestial bodies within our cosmic neighbourhood.

VOLCANIC FEATURES

Mars exhibits a variety of volcanic features that provide important clues about its geological history and past volcanic activity. These features highlight the planet’s volcanic activity and the dynamic processes that have shaped its surface over time like shield volcanoes, calderas, cinder cones, lava flows, Tharsis volcanic plateau, Elysium volcanic province and volcanic plains. The presence of volcanic features on Mars suggests a history of volcanic activity that has shaped the planet’s surface and contributed to its unique landscape. While Mars’ volcanic activity has waned over time, the study of its volcanic features provides valuable insights into the planet’s geological evolution, tectonic processes, and the conditions that prevailed in its early history.

VALLEYS AND CHANNELS

Mars is home to intricate valley networks and channels that provide evidence of past water-related processes on the planet’s surface. Valley networks, erosion and paleo-climate suggest that liquid water once flowed across Mars, shaping its landscape and leaving behind a rich history of hydrological activity. Mars’ valleys and channels offer a tantalizing glimpse into its ancient past when liquid water flowed across its surface. These things serve as a testament to the dynamic and ever-changing nature of planetary environments, sparking ongoing scientific investigations into the history and potential habitability of the Red Planet.

POLAR ICE CAPS

Mars’ polar ice caps are prominent features that consist of frozen water and carbon dioxide ice. These polar ice caps play a significant role in the planet’s climate, seasonal changes, and potential insights into its geological history. Mars has both a northern polar ice cap and a southern polar ice cap. The northern cap, known as the North Polar Ice Cap, is composed mainly of water ice, while the southern cap, the South Polar Ice Cap, is a combination of water and carbon dioxide (dry ice) ice.

The polar ice caps are critical components of Mars’ climate system and water cycle. They contribute to the redistribution of water vapour in the atmosphere and play a role in the Martian hydrological cycle, even though liquid water is not stable on the surface due to the low atmospheric pressure.

DUNES

Mars is home to extensive dune fields that cover significant portions of its surface. These dunes are primarily composed of sand-sized particles and are sculpted by the planet’s thin atmosphere and prevailing winds. Wind-driven processes shape these dunes, creating intricate patterns and revealing information about the planet’s atmospheric dynamics.

ROVERS

Mars rovers are sophisticated robotic vehicles designed to explore the surface of Mars. These rovers, developed by space agencies like NASA, ESA, and others, have played a crucial role in advancing our understanding of the Red Planet. Equipped with a range of scientific instruments, cameras, and mobility systems, these rovers have allowed us to study Martian geology, climate, and potential habitability. Rovers like Spirit, Opportunity, Curiosity, and Perseverance have provided detailed images, conducted soil and rock analyses, and even searched for signs of past or present life. Through their tireless exploration, Mars rovers continue to unravel the mysteries of Mars and pave the way for future human missions to the planet.

REDDISH COLOR

Mars’ reddish colour is a distinctive and captivating feature that sets it apart in the night sky. This reddish hue is attributed to the presence of iron oxide, commonly known as rust, on the planet’s surface. The iron-rich rocks and dust on Mars give its landscapes a unique and desert-like appearance. The thin Martian atmosphere allows more sunlight to reach the surface, intensifying the reddish colour. This iconic characteristic has fascinated astronomers and stargazers for centuries and serves as a visual reminder of the planet’s geological history and unique surface composition.

Mars’s surface is a testament to its geological history, which includes a period when liquid water flowed and shaped its landscapes. The various features and processes found on Mars provide insights into its past climate, volcanic activity, and the potential for habitability. As our understanding of Mars’ surface evolves through ongoing exploration, this intriguing world continues to reveal its secrets and mysteries.

CHARACTERISTICS

MASS	6.4171×10²³ kg
VOLUME	1.63118×10¹¹ km
SURFACE AREA	144.37×10⁶ km²
MEAN RADIUS	3389.5 ± 0.2 km
SURFACE PRESSURE	0.636 kPa
DENSITY	3.9335 g/cm³
ESCAPE VELOCITY	5.027 km/s
SURFACE GRAVITY	3.72076 m/s²
ABSOLUTE MAGNITUDE	-1.5
NATURAL SATELLITES	2
RINGS	NO
MEAN TEMPERATURE	-64°C
SEMI-MAJOR AXIS	227,939,366 km
ORBIT PERIOD	686.980 days
PERIHELION	206,650,000 km
APHELION	249,261,000 km
MEAN ORBITAL VELOCITY	24.08 km/s
MAXIMUM ORBITAL VELOCITY	26.50 km/s
MINIMUM ORBITAL VELOCITY	21.97 km/s
ORBIT INCLINATION	1.85°
ORBIT ECCENTRICITY	0.0934
SIDEREAL ROTATION PERIOD	1.025957 days
LENGTH OF DAY	1 day 37 minutes
MINIMUM DISTANCE FROM EARTH	54,600,000 km
MAXIMUM DISTANCE FROM EARTH	401,000,000 km
MAXIMUM VISUAL MAGNITUDE	-2.3

ORBIT AND ROTATION

Mars orbits the Sun at an average distance of approximately 230 million kilometers (143 million miles) and completes an orbital cycle in 687 Earth days. A Martian day, or “sol,” is just slightly longer than an Earth day, lasting 24 hours, 39 minutes, and 35.244 seconds. A Martian year corresponds to 1.8809 Earth years, equivalent to 1 year, 320 days, and 18.2 hours. The axial tilt of Mars is 25.19° in relation to its orbital plane, akin to Earth’s tilt. This alignment gives rise to seasons on Mars, though they are nearly twice as lengthy due to its elongated orbital period.

Nevertheless, the seasons on Mars are more intense compared to those on Earth because of the Red Planet’s elliptical orbit, which is more elongated than that of any other major planet. When Mars is nearest to the Sun, the southern hemisphere tilts toward the star, resulting in a brief, warm summer in that hemisphere and a short, cold winter in the northern hemisphere. Conversely, when Mars is farthest from the Sun, the northern hemisphere is inclined toward the star, resulting in a prolonged, mild summer in the north and an extended, chilly winter in the south.

The tilt of Mars’ axis undergoes significant variations over time due to the absence of a large moon to stabilize it. This has led to different climatic conditions on the Martian surface throughout its history. A 2017 study suggests that the changing tilt also influenced the release of methane into the planet’s atmosphere, causing temporary warming periods that allowed water to flow.

Mars approaches Earth in a synodic period of 779.94 days. Earth orbits the Sun the closest to Mars’s orbit around the Sun, and Mars’s orbit is the second closest to Earth after the orbit of Venus. Therefore, their closest approaches, the inferior conjunctions, are the second closest to Earth after those with Venus, and the closest to Mars to any other planet. The gravitational potential difference, and thus the delta-v needed to transfer between Mars and Earth is the second lowest for Earth and the lowest for Mars to any other planet, while transfers can be optimized with Venus flybys.

ATMOSPHERE

The carbon-dioxide-rich atmosphere is also much colder than Earth, in large part due to its greater distance from the Sun. The atmosphere is very thin, exerting less than 1 per cent of Earth’s atmospheric pressure at the surface. The surface pressures on Mars exhibit a variation of up to a factor of 15, primarily due to the extensive differences in altitudes across the planet’s topography.

Only small amounts of water are present in the atmosphere today. If it all precipitated out, it would form a layer of ice crystals only 10 micrometers (0.0004 inches) thick, which could be gathered into a solid block of ice not much larger than a medium-sized terrestrial iceberg. Although there is a limited quantity of water, the atmosphere is almost saturated, resulting in the frequent occurrence of water-ice clouds.

The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. The atmosphere is quite dusty, containing particulates about 1.5 μm in diameter which give the Martian sky a tawny color when seen from the surface. It may take on a pink hue due to iron oxide particles suspended in it. The concentration of methane in the Martian atmosphere fluctuates from about 0.24 ppb during the northern winter to about 0.65 ppb during the summer.

Estimates of its lifetime range from 0.6 to 4 years, so its presence indicates that an active source of the gas must be present. Methane could be produced by non-biological processes such as serpentinization involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars, or by Martian life. Auroras have been detected on Mars because the planet lacks a global magnetic field, The types and distribution of auroras there differ from those on Earth; rather than being mostly restricted to polar regions as is the case on Earth, a Martian aurora can encompass the planet.

The broad temperature fluctuations on Mars arise from several factors: the sparse atmosphere, which cannot retain much solar heat, the low atmospheric pressure (about 1% of Earth’s atmosphere), and the limited thermal capacity of Martian soil. Positioned at a distance from the Sun that is 1.52 times farther than Earth, Mars receives only 43% of the sunlight.

If Mars followed an orbit akin to Earth’s, its seasons would bear a resemblance to Earth’s due to their similar axial tilts. However, the marked eccentricity of Mars’ orbit brings about a significant impact. The planet approaches perihelion (closest point to the Sun) during Southern Hemisphere summer and Northern Hemisphere winter, and nears aphelion (farthest point from the Sun) during Southern Hemisphere winter and Northern Hemisphere summer. Consequently, seasons in the Southern Hemisphere are more pronounced, while those in the Northern Hemisphere are milder than they would otherwise be under different circumstances.

MAGNETIC FIELD

Mars presents a magnetic enigma distinct from that of its terrestrial counterpart. Unlike Earth, Mars lacks a robust and global magnetic field generated by a dynamic molten core. The planet’s magnetic field is much weaker and sporadic, confined to small pockets of crustal magnetism scattered across its surface. This stands in stark contrast to Earth’s steady magnetic shield, which protects the planet from the solar wind’s charged particles.

The puzzling nature of Mars’ magnetic field has intrigued scientists for decades. It is believed that the planet once possessed a more active magnetic dynamo, akin to Earth‘s, generated by the churning of molten iron in its core. However, as the planet’s interior cooled over billions of years, this dynamo waned, eventually leading to the weakening and fragmentation of its magnetic field.

The consequences of Mars’ feeble magnetic protection are evident in its thin and vulnerable atmosphere. Unlike Earth’s atmosphere, which is retained and protected by the magnetic field, Mars’ atmosphere has been gradually stripped away by the solar wind, causing the planet’s climate and surface conditions to evolve dramatically. This phenomenon offers a remarkable window into the interconnectedness of a planet’s magnetic field, atmosphere, and overall habitability.

The remnants of crustal magnetic fields on Mars hold a wealth of information about the planet’s geological history, tectonic activity, and the processes that shaped its magnetic behaviour. Studying these remnants helps researchers reconstruct the planet’s past magnetic state and understand how it influenced Mars’ evolution.

In essence, Mars’ magnetic field—or lack thereof—is a testament to the dynamic nature of planetary geophysics. It underscores the critical role that a planet’s magnetic shield plays in shaping its atmosphere, climate, and overall potential for habitability. As our exploration of the planet continues, unravelling the mysteries of its magnetic past holds promise for unravelling the story of its geological transformation and its place in the complex tapestry of the solar system.

GRAVITY

The fourth planet from the Sun in our solar system, possesses a gravitational force notably weaker than that of Earth. This distinction arises from Mars’ smaller size and lower mass, which collectively result in a surface gravity of approximately 3.71 meters per second squared—only about 38% of Earth’s surface gravity. In practical terms, this means that objects on Mars weigh significantly less than they do on our home planet. For instance, a 100-kilogram object on Earth would weigh merely 38 kilograms on Mars. This lower gravitational force also contributes to Mars’ thin atmosphere, influencing its weather patterns, temperatures, and potential for liquid water.

The reduced gravity on the planet necessitates unique engineering solutions for spacecraft landings and human mobility on the planet’s surface, and it presents health challenges for potential future Mars missions, including issues related to muscle and bone density loss in astronauts exposed to the planet’s gravity for extended periods.

Previous Planet – “Earth“

Next Planet – “Jupiter“