Chapter 1: The Quest to Populate Other Worlds

What might we fill the cosmos with? By the close of the 21st century, it is likely that humanity could begin transferring life from Earth to other celestial bodies. However, this ambitious undertaking poses some critical questions.

[Photo: Reimund Bertrams / Pixabay]

The Cassini spacecraft, which explored Saturn, concluded its mission on September 15, 2017. It was intentionally directed into the gas giant's atmosphere, where it succumbed to crushing pressure and intense heat. This fate was not unavoidable; mission controllers could have allowed it to orbit Saturn for years. However, they chose not to, concerned about the potential for a future collision with Enceladus, Saturn’s icy moon. Scientists believe that beneath its frozen surface lies a vast ocean of liquid water, a potential habitat for life. If Cassini had impacted Enceladus, Earth microbes it carried could have contaminated this pristine environment, potentially obliterating undiscovered life forms.

Cassini Huygens — [Photo: NASA, Public domain, via Wikimedia Commons]

Had Cassini made contact with Enceladus, it could have provided evidence for the panspermia theory, which posits that life can traverse the universe via comets, asteroids, or specially designed spacecraft. Currently, humanity lacks the capability for such deliberate actions, but within a few decades, we may be able to send microorganisms to other planets.

Enceladus — [Photo: NASA/JPL, Public domain, via Wikimedia Commons]

Michael Mautner, a biochemist from Virginia Commonwealth University and a proponent of “guided panspermia,” wrote in The Economist about life’s inherent drive to expand. As humanity advances technologically, the notion of sending Earth life to other planets may soon become a logical next step in biological evolution. Some experts argue that establishing life on exoplanets could eventually create new habitats for humans in a future where Earth is no longer sustainable.

Section 1.1: Overcoming Distance

For humanity to succeed in spreading life to other systems, significant challenges must be addressed. The foremost issue is distance. The closest known exoplanet, Proxima b, orbits Proxima Centauri, located over 4.2 light-years away. Light takes more than four years to traverse this immense gap. Meanwhile, the fastest human-made probes would require around 60,000 to 70,000 years to reach Proxima b. Innovators are exploring theoretical concepts for tiny spacecraft, weighing just a few grams, that could accelerate to one-fifth the speed of light. Even with such advancements, travel could still take decades, and sending larger ships for panspermia would demand generations of human effort.

Proxima Centauri — [Photo: ESA/Hubble, CC BY 4.0, via Wikimedia Commons]

The second challenge lies in safely landing the vessel carrying life on the target planet, which requires immense energy and fuel—factors that increase the spacecraft's mass. This is why NASA’s New Horizons probe, which flew past Pluto in July 2015, merely conducted a flyby rather than a landing.

The first video, "How Could We Create A Second Earth?", discusses the potential for human life to thrive on other planets and the scientific advancements necessary for such endeavors.

Section 1.2: Selecting Life Forms

Assuming these challenges are surmountable, how should we choose which organisms to send? The ideal candidates will likely need to be in a state of anabiosis, where their biological activity is minimal, as they will endure years of exposure to harmful cosmic radiation. Protecting them from radiation would necessitate additional shielding, further complicating the spacecraft's design.

Natural candidates for this mission include the non-parasitic nematode, Caenorhabditis elegans, renowned for its resilience. It can endure extreme temperatures, high salinity, crushing pressures, and even significant radiation. Remarkably, it can survive without water for over a century, making it a promising candidate for space travel.

Caenorhabditis elegans — [Photo: Dan Dickinson, Goldstein lab, UNC Chapel Hill, CC BY-SA 3.0, via Wikimedia Commons]

Another intriguing approach comes from Hajime Yano of JAXA, who suggests genetically modifying Earth bacteria to enhance their resilience for panspermia. For instance, scientists have discovered that the bacterium Deinococcus radiodurans can repair its DNA after radiation damage.

Chapter 2: Ethical Considerations

One pressing question arises: do we, as the dominant species on Earth, have the right to manipulate cosmic panspermia? Physicist Claudius Gros warns that this might equate to playing God. The risks echo those recognized by the Cassini mission team: introducing Earth bacteria could extinguish native life forms that have evolved independently in other environments. If we aim to introduce terrestrial organisms, we must carefully select worlds with conditions conducive to life.

[Photo: Patricio González / Pixabay]

Astronomers can analyze the light from stars to determine the atmospheric composition of exoplanets, helping to identify potential signs of life, such as bacteria. The James Webb Space Telescope will significantly enhance our ability to locate habitable worlds. However, researchers often cannot confirm with absolute certainty that no life exists on a given planet, particularly if it might harbor forms of life unlike those on Earth.

Some assert that humanity has the right to disseminate its microbes across the galaxy, claiming that if Earth organisms can outcompete alien life, it reflects the natural order of evolution. This perspective, termed "galactic imperialism" by The Economist, raises ethical concerns.

Bioethicist Jan Hartman advocates for a cautious approach to panspermia. He notes that while the urge to propagate life is deeply rooted in human nature, randomly dispersing Earth organisms could be wasteful and reckless. If a planet appears devoid of life, he suggests that revitalizing it might be acceptable. However, interfering with existing extraterrestrial ecosystems is a different matter entirely. Humanity has already inflicted enough damage on Earth; it would be prudent to refrain from similar actions elsewhere.

The second video, "Will We Colonize Space?", explores humanity's potential future in space and the ethical implications of colonization efforts.