What happened on Earth?

The Great Stripping (The Magnetosphere Collapse)

The Nature of the Threat

The collapse of the Earth’s magnetosphere was not a sudden explosion but a progressive, terminal decay of the planet’s planetary-scale shielding. As the core cooled, the geomagnetic field intensity dropped below a critical threshold, leaving the atmosphere exposed to unmitigated solar wind and high-energy cosmic radiation.

• Symptoms: Rapid ozone depletion, massive increase in surface-level ionizing radiation, and the eventual "boil-off" of the upper atmosphere as solar winds stripped away lighter gasses.

• The Atmospheric Impact: Within years, the surface of the Earth became a radioactive, mutagenic wasteland. The atmosphere was no longer a protective blanket; it was an active hazard.

Why the Trenches?

• The Shielding Factor: The Committee chose deep-ocean trenches (3,000+ meters) for construction because water is an exceptional radiation shield. At depths $> 3,000$ meters, the massive water column provided the only viable protection from cosmic rays and solar radiation while the sensitive fusion-drive components were being assembled.

• The "Clean Room" Environment: The trenches were "cold" and protected, allowing the Committee to build the Arks away from the accelerating chaos on the surface.

The Committee’s "No-Choice" Gambit

• The 6-Month Cadence: The magnetosphere was collapsing according to a predictable, albeit terminal, model. The Committee knew the atmosphere would reach a point of "no return" in $< 24$ months. Every six months, they launched an Ark because they knew the window of launch viability was closing—once the upper atmosphere reached a certain density of ionized particles, the plasma-drive ignition would have triggered atmospheric ignition, destroying the ship during ascent.

• The Secrecy: The Committee suppressed the data not to protect their own reputations, but to prevent the "Panic Collapse." They knew that if the population realized the Earth was effectively "dying" and that only a select few would survive, total societal breakdown would occur long before the Arks were finished.

The Legacy of the Collapse

• The CSD/CRS Mandate: The Council’s obsession with CSD (Cordis Sensitivity Disorder) and strict biological monitoring is a direct, institutionalized trauma response to the radiation poisoning that defined the final days of Earth.

• The Fear of the "Open Sky": Even centuries later, the "Arbour" leadership treats any exposure to "unfiltered" environment (or unregulated radiation) as an existential threat. They are still building their society with the logic of a bunker, terrified that the radiation that killed their home planet is waiting for them if they ever stop "shielding" themselves.