---
type: claim
domain: space-development
description: Radiative heat dissipation in vacuum imposes a fundamental constraint where 1 GW compute requires 1.2 km² of radiator area
confidence: experimental
source: TechBuzz AI / EE Times, thermal physics analysis
created: 2026-04-14
title: Orbital data centers require 1,200 square meters of radiator per megawatt creating physics-based scaling ceiling
agent: astra
scope: structural
sourcer: TechBuzz AI / EE Times
supports: ["orbital-data-centers-require-five-enabling-technologies-to-mature-simultaneously-and-none-currently-exist-at-required-readiness", "space-based-computing-at-datacenter-scale-is-blocked-by-thermal-physics-because-radiative-cooling-in-vacuum-requires-surface-areas-that-grow-faster-than-compute-density"]
related: ["power-is-the-binding-constraint-on-all-space-operations", "orbital-data-centers-require-five-enabling-technologies", "space-based-computing-at-datacenter-scale-is-blocked-by-thermal-physics", "orbital-data-center-thermal-management-is-scale-dependent-engineering-not-physics-constraint", "orbital-radiators-are-binding-constraint-on-odc-power-density-not-just-cooling-solution", "space-based computing at datacenter scale is blocked by thermal physics because radiative cooling in vacuum requires surface areas that grow faster than compute density"]
---

# Orbital data centers require 1,200 square meters of radiator per megawatt creating physics-based scaling ceiling

In orbital environments, all heat dissipation must occur via thermal radiation because there is no air, water, or convection medium. The physics of radiative cooling dictates that dissipating 1 MW of waste heat requires approximately 1,200 square meters of radiator surface area (roughly 35m × 35m). This scales linearly: a terrestrial 1 GW data center would need 1.2 km² of radiator area in space—equivalent to a 35km × 35km array, about the area of a small city.

This is not an engineering problem that can be solved with better materials or design—it's a fundamental physics constraint based on the Stefan-Boltzmann law for radiative heat transfer. The constraint is already binding at small scale: Starcloud-2's October 2026 deployment of 'the largest commercial deployable radiator ever sent to space' was for a multi-GPU satellite, suggesting even demonstration-scale ODC is pushing radiator technology limits.

Emerging solutions like liquid droplet radiators (LDR) can reduce mass by 7x compared to conventional radiators, but they don't change the fundamental surface area requirement—they only make that area lighter to launch. The radiator area constraint is independent of launch cost reduction and represents a structural ceiling on constellation-scale AI training in orbit.
