Cislunar Space: The Region Between Earth and the Moon

For decades, almost all space activity happened in Earth orbit. That is changing. Government programmes, commercial landers and military planners are all now focused on the region between Earth and the Moon: cislunar space.

This guide explains what cislunar space is, how big it is, its key orbits, why governments and companies are investing in it, and the transport and logistics a cislunar economy will need.

What is cislunar space?

Cislunar space is the region of space between Earth and the Moon, including the space around the Moon itself. The word comes from the Latin “cis”, meaning “on this side of”, so cislunar literally means “on this side of the Moon”.

The US government's 2022 National Cislunar Science and Technology Strategy gave a formal definition: the three-dimensional region of space beyond Earth's geosynchronous orbit (GEO) that is still within the gravitational influence of the Earth and Moon. Under that definition, cislunar space includes:

• Orbits beyond GEO, out towards the Moon.
• The Earth-Moon Lagrange points, where Earth's and the Moon's gravity balance.
• Orbits around the Moon, and the lunar surface.

How big is cislunar space?

Cislunar space is enormous compared with the orbits most satellites use. Geosynchronous orbit sits about 36,000 km above Earth's surface, around 42,000 km from Earth's centre. The Moon orbits about 384,000 km away, and cislunar space extends past it to the far side of the Moon.

Cislunar orbits and Lagrange points

Cislunar space contains orbits that do not exist close to Earth. Several are valuable because they need little propellant to maintain, or give constant views of Earth or the Moon.

How far is it in propellant terms?

Getting from low Earth orbit to lunar orbit takes a change in velocity (delta-v) of around 4 km/s, similar to moving from low Earth orbit to GEO. Communications from the Moon to Earth take about 1.3 seconds each way, which is why operations in cislunar space need more autonomy than in Earth orbit.

Why cislunar space matters now

Cislunar activity is growing faster than at any time since Apollo. The main drivers are:

• NASA's Artemis programme, which aims to return astronauts to the Moon and has already sent an uncrewed Orion capsule around it on Artemis I.
• Commercial lunar landers under NASA's Commercial Lunar Payload Services (CLPS) programme. Intuitive Machines made the first commercial lunar landing in 2024, and Firefly's Blue Ghost landed successfully in 2025.
• China's Chang'e programme, including the first sample return from the lunar far side in 2024, supported by relay satellites near Earth-Moon L2.
• Lunar resources, especially water ice at the poles, which could be turned into drinking water, oxygen and rocket propellant.
• Navigation and communications infrastructure, such as NASA's CAPSTONE mission and autonomous positioning research.

Why the Pentagon is focusing on cislunar space

Military interest in cislunar space is about awareness rather than weapons. Existing space surveillance networks are designed to watch Earth orbits, mostly within GEO. As more missions travel to the Moon, governments want to know what is operating in cislunar space, where it is going and whether it poses a collision risk.

The US Space Force has been planning for operations beyond GEO, and the Air Force Research Laboratory's Oracle programme is developing spacecraft to provide cislunar space domain awareness. Strategy papers from the National Defense University and others debate how much military focus the region deserves compared with threats closer to Earth.

The cislunar economy

The cislunar economy is the set of commercial activities that operate in the Earth-Moon system. NASA's lunar strategy deliberately buys services from companies, as it does in low Earth orbit, to grow that market. Emerging segments include:

• Lunar delivery: landers carrying science payloads, rovers and equipment to the surface.
• Communications and navigation: relay satellites and positioning services around the Moon.
• Resources: prospecting for water ice and other materials, and processing them into propellant.
• Infrastructure: power, habitats and computing, including early experiments in lunar data storage.
• Transport: moving cargo, crew and propellant between Earth orbit, lunar orbit and the surface.

Our guide to space mining companies covers the startups prospecting for lunar and asteroid resources.

Some of the infrastructure being developed closer to Earth, such as commercial space stations and data centres in space, could eventually extend into cislunar space as transport costs fall.

Getting around: cislunar logistics

A cislunar economy only works if cargo can move efficiently through it. Today, most lunar missions are launched directly from Earth on a single trajectory, with each mission carrying everything it needs. As traffic grows, that becomes expensive and inflexible.

The alternative is a logistics network: reusable vehicles that carry cargo between staging points in Earth orbit, lunar orbit and the Lagrange points, and in future propellant depots and in-orbit refuelling supplied from Earth or the Moon. Our guide to in-space transportation explains the orbital transfer vehicles and space tugs that make this possible.

Building that reusable, station-to-station transport layer is the focus of Orbit2Orbit's in-space logistics network: autonomous spacecraft designed to dock, deliver and redeploy between orbital platforms.

Frequently asked questions