Human survival on Earth faces severe long-term challenges, but the ultimate survival of our species or our descendants over billions of years will require massive megastructures and stellar engineering projects, according to a new paper authored by Gabriel Harry and accepted for publication in the Journal of the British Interplanetary Society.
Stellar Engineering and Dyson Swarms to Extend the Sun’s Life
The Sun is currently in its main sequence phase, fusing hydrogen into helium at its core, but this phase will end in approximately 5 billion years when the star expands and potentially engulfs Earth. According to the paper, Earth is likely to become uninhabitable much sooner, with a recent study projecting a timeline of 1.8 billion years. Because interstellar distances make relocating to a new star system via generational ships unfeasible, humanity may choose to stay in the home Solar System and deploy engineering projects to slow down the Sun’s evolution, according to Gabriel Harry’s research available on the preprint server arXiv.
One proposed strategy involves building a Dyson swarm to remove mass from the Sun’s surface, which would reduce core pressure and slow down fusion. While Dyson swarms are considered unstable over time, the paper notes that an advanced civilization utilizing robotic drones could systematically dismantle Mercury to collect construction materials. Assuming this megastructure can be achieved, the paper estimates it would keep the Sun in its main sequence for an extra 400 million years while extending Earth’s habitable zone lifespan by an extra 7.5 billion years.
Did you know? Dyson spheres were initially proposed as a joke before becoming a staple concept in theoretical megastructure engineering and science fiction.
Solar Shades and Planetary Orbital Adjustments
An alternative strategy involves blocking out solar radiation using giant sunshades placed at strategic Lagrange points, which NASA defines as gravitational parking spots in space requiring minimal fuel consumption. To counteract the radiative pressure and gravitational influences that make such shades unstable, the paper suggests attaching the sunshade via a tether to a counterweight, requiring significant advancements in materials science. This tactic would require an alternative energy source, such as mining gas giants like Jupiter and Saturn for fusion energy and beaming it back to Earth via microwaves, as outlined by Harry.
A more desperate option involves physically moving Earth out to the Solar System’s new habitable zone by passing a gigantic Kuiper belt object close to the planet every 6,000 years. This maneuver would slowly impart orbital energy to lift Earth out to 1.5 astronomical units (AU), though the paper warns that the object would impart roughly 10 times the Moon’s tidal force, potentially altering Earth’s rotation and causing severe flooding.
Long-Term Survival Challenges and Future Timeline
Even if humanity or its successors manage these megastructure projects, the paper highlights that additional natural hurdles remain, including the eventual end of plate tectonics, the continuous loss of water to space, and the constant threat of incoming space rocks. “If the safeguards were implemented and maintained, life on Earth would be able to continue as normal, enjoying comfortable security, geology and climate, and for 100 trillion years be able to look up at the night sky and see the stars – after which, natural star formation in the visible universe would end and the last stars would wink out,” Harry concludes in the paper. “However, on Earth the Sun would still rise the next morning – with 9.0 million billion years of artificial sunlight remaining, the Earth’s biosphere would still be very much in its infancy.”
Frequently Asked Questions
When will the Sun run out of hydrogen?
According to astronomical studies cited in the paper, the Sun will expand and exit its main sequence phase in approximately 5 billion years.
How can a Dyson swarm extend Earth’s habitability?
By removing mass from the Sun’s surface to reduce core pressure, a Dyson swarm can slow down stellar evolution, keeping Earth in the habitable zone for an extra 7.5 billion years according to Gabriel Harry’s research.
What are Lagrange points?
According to NASA, Lagrange points are positions in space where the gravitational forces of a two-body system like the Sun and Earth produce enhanced regions of attraction and repulsion, acting as parking spots for spacecraft.
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