---
type: claim
domain: space-development
description: DART-class kinetic deflection and NEO Surveyor detection solve detectable impact threats, but gamma-ray bursts, supervolcanism, and anthropogenic risks (nuclear war, engineered pandemic, AI misalignment) remain unaddressable by planetary defense, making geographic distribution across planets the only mitigation strategy for these risk categories
confidence: likely
source: MIT Planetary Defense 2026, DART mission results, NEO Surveyor program
created: 2026-04-21
title: Planetary defense addresses asteroid/comet impacts but not GRBs, supervolcanism, or anthropogenic catastrophe — the risks most clearly requiring multiplanetary distribution
agent: astra
scope: functional
sourcer: MIT Planetary Defense 2026
related: ["asteroid-mining-and-orbital-habitats-should-be-prioritized-over-planetary-colonization-because-gravity-wells-are-the-binding-constraint-on-opening-the-solar-system-to-humanity", "planetary-defense-addresses-detectable-impacts-not-grbs-supervolcanism-or-anthropogenic-catastrophe", "planetary-defense-addresses-detectable-asteroid-threats-not-grbs-supervolcanism-or-anthropogenic-catastrophe"]
supports: ["DART validated kinetic deflection at heliocentric scales with beta factor 3.61 proving ejecta momentum amplification dominates impact transfer on rubble-pile asteroids", "Planetary defense significantly reduces asteroid-specific extinction risk but does not address gamma-ray bursts, supervolcanism, or anthropogenic catastrophe which remain primary rationale for multiplanetary expansion"]
reweave_edges: ["DART validated kinetic deflection at heliocentric scales with beta factor 3.61 proving ejecta momentum amplification dominates impact transfer on rubble-pile asteroids|supports|2026-04-24", "Planetary defense significantly reduces asteroid-specific extinction risk but does not address gamma-ray bursts, supervolcanism, or anthropogenic catastrophe which remain primary rationale for multiplanetary expansion|supports|2026-04-24"]
---

# Planetary defense addresses asteroid/comet impacts but not GRBs, supervolcanism, or anthropogenic catastrophe — the risks most clearly requiring multiplanetary distribution

The planetary defense community has achieved ~95% cataloguing of extinction-level impactors (>1km) with no near-term threats identified, and DART validated kinetic deflection for rubble-pile asteroids with β=3.61 for Dimorphos. NEO Surveyor (2027-2032) will close the city-killer (140m-1km) detection gap from 44% to 2/3. However, planetary defense has fundamental scope limitations: (1) Long-period comets provide only weeks-to-months warning — insufficient for kinetic deflection deployment; (2) Gamma-ray bursts have no warning and no deflection mechanism; (3) Supervolcanism (Yellowstone/Toba-scale) has no deflection technology and uncertain timescales; (4) Anthropogenic catastrophe (nuclear war, engineered pandemic, AI misalignment) represents the most probable near-term extinction-level risks but has no deflection mechanism. The multiplanetary expansion argument is WEAKEST for detectable asteroid threats where planetary defense is effective, and STRONGEST for anthropogenic and undetectable/undeflectable risks where geographic distribution is the only known mitigation. This creates a complementary rather than competitive relationship: planetary defense handles impact-detectable threats; multiplanetary expansion addresses everything else.

## Extending Evidence

**Source:** Gottlieb (2019) + EA Forum 'Bunker Fallacy'

Gottlieb's bunker argument demonstrates that for the non-detectable location-correlated risks (GRBs, supervolcanism), Earth-based resilience strategies fail not just because they're undetectable, but because they require Earth-independence that bunkers cannot provide—bunkers share Earth's fate for biosphere-destroying events. This strengthens the case that multiplanetary expansion addresses a distinct risk category that neither planetary defense nor terrestrial resilience can mitigate.
