---
type: source
title: "Space Data Centers Hit Physics Wall on Cooling Problem — Heat Dissipation in Vacuum"
author: "TechBuzz AI / EE Times (@techbuzz)"
url: https://www.techbuzz.ai/articles/space-data-centers-hit-physics-wall-on-cooling-problem
date: 2026-02-27
domain: space-development
secondary_domains: [manufacturing]
format: article
status: processed
processed_by: astra
processed_date: 2026-04-14
priority: high
tags: [orbital-data-centers, thermal-management, cooling, radiators, heat-dissipation, physics-constraint]
extraction_model: "anthropic/claude-sonnet-4.5"
---

## Content

Technical analysis of heat dissipation constraints for orbital data centers, published ~February 2026.

**Core physics problem:**
- In orbit: no air, no water, no convection. All heat dissipation must occur via thermal radiation.
- "It's counterintuitive, but it's hard to actually cool things in space because there's no medium to transmit hot to cold."
- Standard data center cooling (air cooling, liquid cooling to air) is impossible in vacuum.

**Scale of radiators required:**
- To dissipate 1 MW of waste heat in orbit: ~1,200 sq meters of radiator (35 × 35 meters)
- A terrestrial 1 GW data center would need 1.2 km² of radiator area in space
- Radiators must point away from the sun — constraining satellite orientation and solar panel orientation simultaneously

**Current cooling solutions:**
- ISS uses pumped ammonia loops to conduct heat to large external radiators
- Satellites use heat pipes and loop heat pipes for smaller-scale thermal control
- For data center loads: internal liquid cooling loop carrying heat from GPUs/CPUs to exterior radiators

**Emerging solutions:**
- Liquid droplet radiators (LDR): sprays microscopic droplets that radiate heat as they travel, then recollects them. NASA research since 1980s. 7x lighter than conventional radiators. Not yet deployed at scale.
- Starcloud-2 (October 2026): "largest commercial deployable radiator ever sent to space" — for a multi-GPU satellite. Suggests even small-scale ODC is pushing radiator technology limits.

**Thermal cycling stress:**
- LEO: 90-minute orbital period, alternating between full solar exposure and eclipse
- GPUs need consistent operating temperature; thermal cycling causes material fatigue
- At 500-1800km SSO (Blue Origin Project Sunrise): similar cycling profile, more intense radiation

## Agent Notes
**Why this matters:** The thermal management constraint is physics, not engineering. You can't solve radiative heat dissipation with better software or cheaper launch. The 1,200 sq meter per MW figure is fundamental. For a 1 GW orbital data center, you need a 35km × 35km radiator array — about the area of a small city. This is not a near-term engineering problem; it's a structural design constraint for every future ODC.

**What surprised me:** Starcloud-2's radiator claim ("largest commercial deployable radiator ever") suggests that even a multi-GPU demonstrator is already pushing the state of the art in space radiator technology. The thermal management gap is not hypothetical — it's already binding at small scale.

**What I expected but didn't find:** Any analysis of what fraction of satellite mass is consumed by radiators vs. compute vs. solar panels. This mass ratio is critical for the economics: if 70% of mass is radiator and solar, then 30% is compute — which means the compute density is much lower than terrestrial data centers.

**KB connections:** power is the binding constraint on all space operations — extends directly: power generation (solar panels) and power dissipation (radiators) are the two dominant mass fractions for any ODC satellite. The compute itself may be the smallest mass component.

**Extraction hints:**
- CLAIM CANDIDATE: Orbital data centers face a physics-based thermal constraint requiring ~1,200 sq meters of radiator per megawatt of waste heat, making the 1,200 sq km of radiator area needed for 1 GW of compute a structural ceiling on constellation-scale AI training.
- Note: this is the binding constraint, not launch cost — even at $10/kg, you can't launch enough radiator area for gigawatt-scale ODC with current radiator technology.

## Curator Notes
PRIMARY CONNECTION: [[power is the binding constraint on all space operations because every capability from ISRU to manufacturing to life support is power-limited]] — this is the most direct evidence that the power-constraint pattern generalizes to the new ODC use case.
WHY ARCHIVED: The radiator area calculation is the most important technical constraint on ODC scaling and is not captured in current KB claims.
EXTRACTION HINT: The 1,200 sq meters per MW figure is the key extractable claim — it's physics-based, falsifiable, and not widely understood in the ODC discourse.
