We Don’t Know: A Case for Mars
Thoughts on science, knowledge, and colonization of Mars.
Introduction
Humanity has no backup.
If a cataclysmic event befell Earth, we could go extinct.
The Milky Way is a sprawling, spectacular collection of 400 billion stars, and Earth could be its sole locus of consciousness. As Carl Sagan once noted, we may be the only way the Universe has to know itself. Without us, the cosmos is a vast expanse of unthinking matter.
Our astronomical rarity, jewels in an eternal night, can be thought to mean that we have a responsibility for maintaining our existence. If we die off, the galaxy—perhaps Universe—could plunge into silent indifference forever, bereft of eyes to behold its wonders, devoid of minds to study (its) existence. Losing that cosmic awareness would be a tragedy unto itself, to say nothing of love, passion, joy, laughter, or friendship.
With all the social problems we face on Earth, people wonder whether we ought to expend resources colonizing Mars.
Anthropic cataclysms
As the Doomsday Clock approaches midnight, let’s reflect on how we could bring about our own extinction.
Nuclear war
Since the Trinity test in 1945, humanity has possessed the ability to annihilate itself in an afternoon. Nuclear weapons represent a perversion of scientific discovery: atomic power harnessed to obliterate rather than liberate. A large-scale exchange would vapourise global population centres and trigger a nuclear winter. The biosphere would be choked off, starving whomever survived the initial blasts.
Runaway greenhouse
Our extraction and combustion of fossil fuels has fundamentally altered the atmospheric chemistry of our Blue Sapphire. If pushed past critical tipping points, the Earth’s climate could enter a runaway greenhouse effect: a self-sustaining cascade of positive feedback loops, such as thawing permafrost releasing massive methane deposits. Unchecked, this irreversible warming trajectory could render the biosphere hostile to human survival, eventually transforming our vibrant world into a sterile, Venus-like nightmare.
Rogue celestial bodies
Earth’s location in the Milky Way’s boonies places us in what’s known as the Galactic Habitable Zone. Closer to the galactic core dangers abound. Still, many of the following scenarios, despite being unlikely, would cut our time on Earth short: lotteries that are only won once.
Lunar ringfire
Imagine a dark, rogue planet from outside the solar system that passes extraordinarily close behind the Moon. The rogue’s gravity would act as a lunar brake, stripping away the Moon’s orbital momentum and sending it into a steep, plunging spiral toward Earth. Gravity weakens with distance, so Earth would pull significantly harder on the near side of the falling Moon than on its far side; the Roche limit is the altitude where this unequal pull becomes stronger than the Moon’s own internal gravity gluing itself together.
Appearing as an enormous, fast-moving sphere grazing the Moon, the rogue planet would vacate, leaving the Moon to loom unnervingly large in our sky in the ensuing days. Upon crossing the Roche limit, the disparity in gravitational forces would violently shatter the Moon, forming a spectacular, glowing ring of debris across the sky, followed by a catastrophic, world-ending bombardment of lunar fragments.
Thermal collapse
If a rogue gas giant flew behind Earth, it could strip the planet from its heliocentric bond. This gravitational kick could accelerate Earth beyond the Sun’s escape velocity, severing our orbital tether, and launching our home into the cold, interstellar void. As the Sun recedes into a distant pinpoint, our biosphere’s primary engine would shut down.
Without solar energy, Earth’s surface would undergo a thermal collapse. Temperatures would plummet, causing carbon dioxide to snow out of the sky. The air would liquefy and then freeze into a solid crust of nitrogen and oxygen. Surface life would die off, leaving only the heat of Earth’s radioactive core to sustain isolated ecosystems buried beneath layers of insulating ice.
Gravitational ghost
Space is mostly empty, but could contain primordial black holes that formed in the high-density environment of the early universe. These objects can possess planetary masses while remaining nearly invisible; a black hole with the mass of Earth would be no larger than a marble. The first hint of its approach would be inexplicable orbital shifts in distant Kuiper belt objects. While a direct collision is statistically improbable, the intense gravity of a close flyby would exert devastating tidal forces or provide a gravitational kick, slinging Earth into the interstellar void.
Distant timeline
Even if Earth escapes the consequences of our own making and never encounters rogue objects, humanity must contend with adversarial events over time. Geological and cosmic upheavals operate on vast timescales.
Miyake event
Miyake events are massive blasts of radiation from space. When they occur, they leave radioactive signatures inside tree rings and ancient ice. The most likely cause is a solar super-flare. The last major event was over a thousand years ago. Although humanity would survive a Miyake event, if one struck today, the surge would fry power grids, disable our satellites, and silence telecommunications. In effect, it would dismantle our modern world.
Cosmic rays
When stars ten times the size of the Sun die, they end existence with a powerful, spectacular explosion. These events, called supernova, are so bright that they can briefly outshine an entire galaxy. The only known star close enough to possibly affect Earth is Wolf 1130, which may go supernova in six billion years. Life on Earth won’t be around to experience that event.
Pangaea Ultima
In roughly 250 million years, Earth’s continents are expected to merge at the equator into a single landmass, Pangaea Ultima. This migration, combined with the Sun being up to 2.5% larger and more luminous than today, will likely render the planet largely uninhabitable and usher in mass extinctions.
Massive volcanic activity triggered by merging continental plates will flood the atmosphere with CO2. Combined with a stronger Sun, global temperatures will regularly exceed 40°C. The supercontinent’s immense size means moisture from the oceans cannot reach the interior. This will create a barren, sun-scorched wasteland across most of the landmass.
Parts of the surface (such as coastal strips and extreme northern and southern regions) may remain cool enough to support complex life. Eventually, though, the Sun will expand to the point that no life will survive.
Supervolcano
Large supereruptions have caused extiction-level events and early human population bottlenecks. While an active supervolcano—one showing signs of active magma chambers—won’t exterminate us, the aftermath would stymie our forward march.
Billions of tons of ash and sulfur dioxide injected into the stratosphere would reflect sunlight, plunging Earth into a volcanic winter. Global temperatures could plummet for years, resulting in widespread crop failures and broken food supply chains. Blanketing ash would contaminate water sources and spark economic collapse.
We don’t believe this will happen anytime soon, but we’re monitoring them.
Epistemology
For some, acknowledging a lack of knowledge can be difficult. Stating “I don’t know” feels weak, yet such an admission draws from security in oneself. Moreover, it can open questions, curiosity, and discovery. Quenching curiosity about nature and reality stands on the shoulders of rationalism and empiricism. The scientific method synthesises both to stop us from tricking ourselves into thinking we know something (about Nature) when we don’t.
Science offers probabilistic models, not absolute certainties. When I write “we know,” it is shorthand for: empirical evidence corroborates this idea, making it a likely model of nature.
We know the Universe mind-bogglingly big. We don’t know what all may be hiding in the cosmos. We don’t know how our civilization will fair in the future. However, we can make predictions based on what we do know.
Summary
It’s true that cataclysmic events can happen to Mars, or both Earth and Mars around the same time. Nevertheless, the odds of our species being wiped out decreases dramatically by colonizing Mars. I believe in humanity. I believe that the troubles facing us today will, in time, become hiccoughs of history. I also believe that surviving whatever the cosmos may throw our way necessitates becoming an interplantary species; we must expand beyond a single point of failure.
About the Author
My career has spanned tele- and radio communications, enterprise-level e-commerce solutions, finance, transportation, modernization projects in both health and education, and much more.