Why We Can't Make Mars More Like Earth for Living

The current fervor, spearheaded by the likes of Elon Musk about colonizing Mars, often glosses over a more formidable challenge than merely setting foot on the Red Planet.

Making Mars a verdant, Earth-like haven for human habitation is a tantalizing dream that confronts stark realities, overshadowing the initial hurdle of travel with issues far more complex and profound.

At the heart of these challenges lie the insurmountable obstacles presented by Mars’ insufficient gravity and absent magnetic field, critical factors rooted in the very nature of the planet itself.

This article ventures beyond the initial excitement of space travel to explore why modifying these fundamental planetary characteristics to foster a sustainable, Earth-like environment on Mars borders on the impossible with our current grasp of physics and available energy resources.

Gravity: The Unalterable Force

Mars’ gravitational force, at only about 38% of Earth’s, is a product of its mass and size. Gravity is a fundamental force of nature, and its strength on a planetary scale is determined by the mass of the planet itself.

Intrinsic Planetary Trait: Altering a planet’s gravity would necessitate changing its mass, a feat that is beyond the realm of current or foreseeable technology. Adding or removing significant amounts of mass to or from Mars to impact its gravitational pull would require an astronomical amount of energy and resources, effectively making it a task beyond human capability.

Escape Velocity: Every planet has an escape velocity, the minimum speed a gas molecule needs to overcome a planet's gravity and escape into space. A higher gravitational pull creates a higher escape velocity, making it harder for gas molecules to break free.

Consequences for Atmosphere and Water: The lower gravitational pull affects Mars' ability to retain a thick atmosphere and maintain liquid water on its surface. Gases easily escape into space, and water cannot exist in a stable liquid state under the current atmospheric pressure, which is directly influenced by gravity. More on this in the next section.

Adding Mass: Increasing Mars's gravity by adding mass to the planet is theoretically the only way to achieve higher gravity, but it is not currently possible with our understanding of physics and technology. The mass of a planet is a fundamental characteristic determined by the amount of matter it contains. To significantly change it, one would need to import a substantial amount from another source. Increasing Mars's gravity to more closely resemble Earth's would involve challenges that are astronomical in scale and complexity, including:

  • Sourcing the Additional Mass: Identifying a viable source of the massive amount of matter required to increase Mars's gravity significantly is a fundamental challenge. This would likely involve redirecting countless asteroids or comets, a process that would demand an unprecedented level of energy and precision in manipulation of celestial bodies.
  • Delivery of Mass: Even if a suitable source of mass were identified, the logistics of safely delivering such mass to Mars without causing catastrophic impacts or destabilizing the planet's orbit presents another set of immense challenges.
  • Technological and Energy Requirements: The technology and energy required to effect such a change are far beyond what humanity or Earth currently possesses. Any attempt to increase a planet's mass on this scale would require breakthroughs in physics, engineering, and energy generation.

Magnetic Field: Mars' Vanished Shield

Earth's Protective Shield: The Sun emits energy across the entire electromagnetic spectrum, including visible light, ultraviolet light, infrared radiation, and other types of electromagnetic waves. This energy is generated by the nuclear fusion reactions happening in the Sun's core.

Earth's magnetic field plays a crucial role in protecting our atmosphere from solar winds—streams of charged particles ejected from the Sun. Without this protective shield, these particles would strip away the Earth's atmosphere over time, making life as we know it impossible.

Our planet's magnetic field is generated by the dynamo effect in its liquid outer core, a process driven by the rotation of Earth and the convection currents within the molten iron-rich material.

A strong magnetic field, like Earth's, is crucial for maintaining a stable atmosphere and supporting conditions conducive to life.

Mars' Lack Thereof: Mars does not possess a global magnetic field comparable to Earth’s.  Mars’ core, smaller and at best partially solidified or with a much weaker dynamo action, does not generate a significant magnetic field. This lack leaves the planet exposed to the solar wind, leading to the gradual stripping away of its atmosphere over aeons.

Boosting Mars's Magnetic Field: Boosting Mars's magnetic field is a concept that has been proposed as part of broader discussions on making the planet more habitable, specifically addressing the issue of atmospheric retention and protection from solar and cosmic radiation.

  • Technological Feasibility: Currently, there's no proven technology capable of generating a planet-wide magnetic field artificially, especially on the scale required for a planet like Mars.
  • Energy Requirements: The energy required to generate and maintain a significant magnetic field would be immense, likely beyond current and near-future energy production capabilities.
  • Understanding Mars's Core: The generation of a magnetic field on Earth is attributed to its molten outer core's convection currents. Mars's core is thought to be partially liquid but has cooled sufficiently that it no longer supports the dynamo effect needed for a strong magnetic field. Any attempt to boost Mars's magnetic field might involve stimulating this dynamo effect, a task that presents significant scientific and engineering challenges.

Atmospheric Pressure and Composition

The thinness of Mars' atmosphere and its composition are intrinsically linked to the planet's weak gravity and lack of a magnetic field. Without significant advancements in planetary engineering, the prospect of thickening the Martian atmosphere to Earth-like levels remains a daunting challenge.

Over billions of years, Mars is thought to have lost a significant portion of its atmosphere due to this weak gravity, especially during the early solar system when solar winds were more energetic.

Even if we could generate an Earth-like atmosphere on Mars through releasing CO2, importing volatiles, or manufacturing perfluorocarbons to create a greenhouse effect, maintaining it without a magnetic field to shield from solar wind and sufficient gravity to prevent atmospheric escape would be an ongoing battle against the forces of nature.

Atmospheric Pressure and Its Life-Sustaining Role: The atmospheric pressure on Earth plays a crucial role in maintaining water in its liquid state—a fundamental prerequisite for life as we know it. Mars’ atmosphere, thin and dominated by carbon dioxide, exerts a surface pressure less than 1% of Earth's. This low pressure poses significant challenges:

  • Water's Boiling Point: On Mars, the low atmospheric pressure reduces the boiling point of water so drastically that it can transition from ice to gas without ever becoming liquid. This sublimation point is below the freezing temperature of water, complicating the existence of stable liquid water essential for Earth-like life.
  • Human Survival: The Martian atmospheric pressure is outside the human survivable range. Without pressurized habitats and suits, humans would be unable to retain water in their bodies, leading to rapid dehydration and death.

Martian Conditions and Water's Phase Transitions: It's counterintuitive to think that water's boiling point could be lower than its freezing point on Mars. But, it is on Mars. This apparent paradox arises because the terms "boiling" and "freezing" points are relative to conditions where liquid water is stable.

  • Low Atmospheric Pressure: Mars' atmospheric pressure is much lower than Earth's, averaging about 6 millibars, compared to Earth's sea level pressure of 1013 millibars. This low pressure means that liquid water is not stable on the Martian surface under average conditions.
  • Boiling Point: At such low pressures, the boiling point of water drops significantly, even below 0°C (32°F) in some conditions, as mentioned with an approximate boiling point around -4.9°C (23.2°F). This is because the pressure is below the triple point of water (0.01°C and 6.1 millibars), where water can exist simultaneously as a solid, liquid, and gas.
  • Freezing Point: The freezing point of water remains relatively stable around 0°C as it is primarily determined by the properties of the water molecule itself and isn't significantly affected by pressure changes. However, due to the low atmospheric pressure on Mars, water would rarely be in liquid form to freeze anyway; it would more likely sublimate directly from ice to vapor under typical Martian conditions.

Final Thoughts: The Boundaries of Our Current Reality

In short, it seems very improbable that we could transform Mars into a more Earth-like planet. (Elon Musk may argue otherwise).

The endeavor to create an Earth-like atmosphere on Mars confronts, among many, two unyielding barriers: the planet's weak gravity and its lack of a protective magnetic field. These challenges are not merely technical but are woven into the very fabric of Mars itself. As we stand at the frontier of interplanetary exploration and dream of worlds beyond our own, we are reminded of the profound complexities and mysteries that govern the cosmos.

While the future may unveil new understandings and technologies that could edge us closer to the realm of terraforming, our current scientific knowledge and energy capabilities position the transformation of Mars into an Earth-like habitat as an endeavor that stretches far beyond our reach. This realization does not dampen the human spirit of exploration but rather highlights the importance of advancing our understanding of the universe, pushing the boundaries of what's possible, and cherishing the uniquely habitable world we currently call home.