Dirty Bits in Low-Earth Orbit: The Carbon Footprint of Launching Computers

TL;DR

This paper examines the carbon footprint of space-based computing, revealing that launch and re-entry emissions significantly outweigh operational savings, emphasizing the need for sustainable design and regulation in orbital digital infrastructure.

Contribution

Introduces ESpaS, a novel tool for estimating orbital computing carbon intensities, and provides comparative analysis of launch technologies and in-orbit data processing emissions.

Findings

In-orbit systems have higher carbon costs than terrestrial counterparts.

Launch and re-entry emissions dominate the total carbon footprint.

Operational emissions are relatively lower but still significant.

Abstract

Low-Earth Orbit (LEO) satellites are increasingly proposed for communication and in-orbit computing, achieving low-latency global services. However, their sustainability remains largely unexamined. This paper investigates the carbon footprint of computing in space, focusing on lifecycle emissions from launch over orbital operation to re-entry. We present ESpaS, a lightweight tool for estimating carbon intensities across CPU usage, memory, and networking in orbital vs. terrestrial settings. Three worked examples compare (i) launch technologies (state-of-the-art rocket vs. potential next generation), (ii) operational emissions of data center workloads in orbit and on the ground and, (iii) in-orbit aggregation with raw data transmission. Results show that, even under optimistic assumptions, in-orbit systems incur significantly higher carbon costs - primarily due to embodied emissions from launch and re-entry. Our findings advocate for carbon-aware design principles and regulatory oversight in developing sustainable digital infrastructure in orbit.