Gravity is a fundamental force of attraction between any two objects with mass. It keeps objects grounded on a planet’s surface and dictates celestial orbits. Like Earth, Mars possesses its own gravitational pull, a natural consequence of its significant planetary mass.
The Source of Martian Gravity
The strength of a celestial body’s gravitational pull is directly proportional to its mass. Mars, as a planet, has a substantial mass, which generates its gravitational field.
However, Mars is considerably smaller and less massive than Earth, with a diameter a little more than half of Earth’s. Consequently, Mars’s mass is about 10.7% of Earth’s total mass. Mars is also less dense than Earth. The combined effect of Mars’s smaller mass and lower density results in a significantly reduced gravitational attraction at its surface compared to our home planet.
How Martian Gravity Compares to Earth’s
The gravitational acceleration on Mars averages about 3.71 meters per second squared (m/s²). This figure represents approximately 38% of Earth’s gravity, which is about 9.8 m/s². This means that if an object weighs 100 pounds on Earth, it would weigh only about 38 pounds on Mars.
The lower gravitational force would make everyday activities feel very different for a human on the Martian surface. For instance, a person could jump significantly higher and lift heavy objects with much greater ease on Mars than on Earth. This altered sense of weight and movement is a direct result of the planet’s reduced mass and density. Understanding this gravitational difference is important for planning both robotic and human missions to the Red Planet.
Impact of Lower Gravity on Mars Exploration
The reduced gravity on Mars presents both opportunities and challenges for future human exploration and potential long-term habitation. For astronauts, extended exposure to Mars’s 0.38g environment is expected to have notable physiological effects. Research indicates that low gravity can lead to bone mineral density loss, muscle atrophy, and cardiovascular deconditioning. These changes occur because the body’s systems, accustomed to Earth’s stronger pull, no longer need to work as hard to counteract gravity.
To mitigate these health concerns, astronauts would require rigorous exercise regimens and potentially other countermeasures, such as artificial gravity during transit or in habitats, to maintain their physical health. The transition between gravity fields, from Earth’s full gravity to the microgravity of space travel, and then to Mars’s partial gravity, can affect spatial orientation, coordination, and balance.
For spacecraft and surface operations, Mars’s lower gravity also has significant implications. During landing, less gravitational force means a spacecraft accelerates slower towards the planet, requiring less thrust for descent. However, Mars’s atmosphere is extremely thin, about 0.6% of Earth’s atmospheric pressure, which means it provides very little aerodynamic drag to slow down a descending spacecraft. Engineers must therefore employ a combination of heat shields, large parachutes, and retro-rockets to ensure a safe and controlled landing for probes and future crewed vehicles.
Moreover, the lower gravity impacts rover mobility and construction activities. Martian soil, or regolith, behaves differently under reduced gravity, remaining looser and fluffier than Earth soils, which can lead to rovers sinking deeper and experiencing reduced traction. Conversely, the decreased weight of materials simplifies construction, allowing for the movement of larger components with less effort. The ability to jump higher or lift more also aids astronauts in surface tasks.