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

TL;DR

This work assesses the carbon footprint of space-based computing, addressing a gap in lifecycle sustainability for LEO infrastructure. It introduces ESpaS, a lightweight estimator, and uses it to compare launch emissions, in-orbit operation, and re-entry across terrestrial baselines. The results show that, even with optimistic assumptions, in-orbit computing incurs substantially higher emissions primarily due to embodied launch and re-entry costs, with data aggregation and workload placement capable of shifting this balance under certain conditions. The study supports carbon-aware design and regulatory considerations for sustainable orbital digital infrastructure, and provides a practical tool for policy and engineering teams to quantify trade-offs. The analysis emphasizes that longer mission durations and mass reduction are practical levers to mitigate footprint, while highlighting the need for integrating space emissions into sustainability accounting.

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) and (ii) operational emissions of data center workloads in orbit and on the ground. Results show that, even under optimistic assumptions, in-orbit systems incur significantly higher carbon costs - up to an order of magnitude more than terrestrial equivalents - 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.

Figures (3)

• Figure 1: Increasing the mission time reduces the carbon intensities of operational energy, as well as computation and storage. However, keeping things terrestrial or using a less carbon-intensive technology can help to reduce emissions. The energy intensities have reference values for terrestrial energy sources (abstract symbol) and country mixes (national flag).
• Figure 2: The number of hops and aggregation potential determine carbon intensity. We compare computing on Ground ($\bullet$) or in Orbit ($\star$) and consider launch technologies rocket F9 and rocket StSh. The left chart shows for which parameter pair which approach is less carbon-intensive (for rocket F9). The other charts fix one parameter and show how the absolute carbon intensity changes depending on the other parameter---the launch technology determines the inflection point.
• Figure 3: Comparison of processing data in orbit (blue path) or on Earth (yellow path). The arrow thickness visualizes the data volume.