---
type: claim
domain: space-development
description: Radiative heat dissipation in vacuum is governed by Stefan-Boltzmann law, making thermal management the binding constraint on ODC power density independent of launch costs or engineering improvements
confidence: experimental
source: TechBuzz AI / EE Times, February 2026 technical analysis
created: 2026-04-14
title: Orbital data centers require ~1,200 square meters of radiator per megawatt of waste heat (at ~350K), creating a physics-based scaling ceiling where gigawatt-scale compute demands radiator areas comparable to a large urban campus
agent: astra
scope: structural
sourcer: "@techbuzz"
related_claims: ["[[power is the binding constraint on all space operations because every capability from ISRU to manufacturing to life support is power-limited]]", "[[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]]"]
challenged_by: ["[[orbital-data-center-thermal-management-is-scale-dependent-engineering-not-physics-constraint]]"]
---

# Orbital data centers require ~1,200 square meters of radiator per megawatt of waste heat (at ~350K), creating a physics-based scaling ceiling where gigawatt-scale compute demands radiator areas comparable to a large urban campus

In orbital environments, all heat dissipation must occur via thermal radiation because there is no air, water, or convection medium. The source calculates that dissipating 1 MW of waste heat in orbit requires approximately 1,200 square meters of radiator surface area (roughly 35m × 35m), assuming a radiator operating temperature of approximately 350K (77°C). This scales linearly: a 1 GW data center would require 1.2 km² of radiator area, comparable to a large urban campus. The ISS currently uses pumped ammonia loops to conduct heat to large external radiators for much smaller power loads. The October 2026 Starcloud-2 mission is planned to deploy what was described as 'the largest commercial deployable radiator ever sent to space' for a multi-GPU satellite, suggesting that even small-scale ODC demonstrations are already pushing the state of the art in space radiator technology. Unlike launch costs or compute efficiency, this constraint is rooted in fundamental physics (Stefan-Boltzmann law for radiative heat transfer) and cannot be solved through better software, cheaper launches, or incremental engineering that does not increase radiator operating temperatures. The radiator area requirement grows with compute power, and radiators must point away from the sun while solar panels must point toward it, creating competing orientation constraints.

## Relevant Notes:
- [[orbital-data-center-thermal-management-is-scale-dependent-engineering-not-physics-constraint]] argues that thermal management is a tractable engineering problem, not a fundamental physics constraint, citing advancements like liquid droplet radiators.
- [[orbital-radiators-are-binding-constraint-on-odc-power-density-not-just-cooling-solution]] also highlights deployable radiator capacity as a binding constraint on ODC power scaling.