In June 2022, Jean-Marc Salotti, a Professor at the National School of Cognitive Engineering, Bordeaux INP, and a member of the International Academy of Astronautics as well as the Mars Society, published an article on the risk of humanity’s extinction due to the potential impact of a giant celestial object. The author, specialized in this field, continued his research by focusing on the survival capabilities of the human species in such a scenario.
This question is highly complex, particularly due to the challenge of determining the maximum survival duration under such circumstances. It also helps broaden our understanding of the stakes related to humanity’s survival in the event of a major cosmic catastrophe, emphasizing the need to explore and comprehend the multiple aspects involved in such critical situations.
In his new article, recently published in the journal Acta Astronautica, Jean-Marc Salotti specifically examines humanity’s survival capabilities after the impact of a long-period giant comet. These comets, originating from the Oort Cloud, have unstable orbits, and it is relatively common for one of them to approach the inner Solar System and potentially be on a collision course with Earth. However, they are detected very late, usually only when they approach Neptune’s orbit, about five years before a potential impact.
“They are detected very late, usually only when they approach Neptune’s orbit, about five years before a potential impact“
Jean-Marc Salotti’s study focuses on the impact consequences and the resulting environmental conditions, leading to complete sterilization and the annihilation of all terrestrial animal and plant species, even microscopic ones. It proposes a classification of shelters based on their capacity to ensure long-term survival.
The article highlights the complexity of the situation, emphasizing that survival depends on both the energy released during the impact and the duration.Surviving the winter without sunlight, commonly referred to as “nuclear winter,” poses challenges in constructing complete shelters capable of ensuring humanity’s survival for decades to over a century in the event of a major impact by a giant comet. The study aims to address the possibility of survival and the conditions under which it could occur.
To enhance the article, Jean-Marc Salotti provides insights and answers questions regarding the scientific and political relevance of such articles in terms of warning, launching programs, identifying and protecting potential shelter locations.
From a scientific perspective, the article sheds light on the risk of humanity’s annihilation if a long-period giant comet were suddenly detected and predicted to collide with Earth. It helps understand the survival context in underground shelters, the challenges to be faced, and potential causes of humanity’s demise. Politically, no explicit recommendations are made. While theoretically possible to build and test massive underground shelters over several decades, the cost seems prohibitive. To safeguard humanity, an alternative requiring strong political commitment is to proactively establish permanent, autonomous bases on other planets without waiting for the detection of a giant comet, as it would be too late.
Regarding the adequacy of current terrestrial or space surveillance programs to detect potential threats with over five years’ notice, Salotti mentions that even the most powerful terrestrial telescopes can only detect celestial objects of 100 kilometers in diameter if they are relatively close, about the distance of the planet Neptune. A recent study suggests thousands of asteroids of this size exist in the Kuiper Belt.The Kuiper Belt extends beyond Neptune, and there are asteroids further out that haven’t been detected due to their faint light. Detecting these asteroids comprehensively would require sending thousands of probes equipped with telescopes, which would be tedious and costly. Similarly, detecting long-period giant comets would be even more challenging as they come from much farther away. Current projects like the Pan-Starrs program aim to develop highly precise monitoring systems for detecting objects from distant space regions. However, these programs may not be sufficient to detect all asteroids or comets with low reflectivity.
Shelters for long-duration protection would need various systems to manage air, energy, food production, health, and manufacturing. While individual systems may be at a high Technology Readiness Level (TRL) for functioning for a few years, the challenge lies in sustaining them for decades through maintenance and repair. As of now, the feasibility level for such shelters is around TRL 3, as predicting malfunctions and planning for maintenance can be complex.
In terms of technological readiness to construct long-lasting shelters within five years, it is speculated that humanity may be able to test and validate these technologies during the establishment of permanent bases on the Moon or Mars. However, achieving this milestone could still be about fifty years away, as the validation of technologies on celestial bodies may not directly apply to surviving a cataclysmic event on Earth. It may even prove more challenging to survive on Earth than on Mars without access to solar energy.
Should We Consider Financing Exploratory Programs for Building Such Shelters?
Jean-Marc Salotti: I’m not sure about that. However, it’s an additional reason to promote space exploration.
Should Natural Sites That Could Serve as Shelters be Protected?
Jean-Marc Salotti: Yes, it’s a good idea. It would be necessary to study and catalog large cavities with significant underground water reservoirs. There are many constraints to consider, such as the presence of solid walls that are unlikely to fracture in the event of an earthquake. The presence of water is advantageous as it is likely the most essential element for survival. The water could be used for various purposes, including regulating the temperature of a mini-nuclear power plant.
As Time Passes, Humanity Will Continue to Expand Its Colonization in the Solar System. Therefore, Could it be Argued that in Case of an Imminent Threat to Earth in a Century, the Best Solution Would be to Accelerate Human Presence Beyond the Planet, Where the Chances of Survival of Our Species Would Potentially be Higher than in Earth Shelters or Closed Reserves?
Jean-Marc Salotti: Yes, this is one of the conclusions that can be drawn from this study. It’s not just the human species at risk, but all terrestrial living organisms would face extinction. Another conclusion is that humanity may be more resilient than expected, as it seems possible to survive for about thirty years in accumulation shelters. In other words, contrary to what other studies suggest, it is not certain that the impact of a 100-kilometer comet would be energetic enough to annihilate humanity. A slightly larger comet or one with higher velocity might be required.