Lunar Pathfinder – Case Study


Lunar Pathfinder is a unique spacecraft designed by Surrey Satellite Technology Ltd (SSTL) that will provide commercial communications services to lunar orbiters and surface assets such as rovers and instruments, as well as a lunar navigation services demonstrator and scientific experiments.

The Lunar Pathfinder mission will support the growing demand for lunar missions and serve the scientific community’s detailed study and analysis of the far side of the Moon, laying the foundation to support future sustainable science and exploration.

Polar Surface Data Relay

For polar surface assets, potentially with limited line-of-sight to Earth, the use of Lunar Pathfinder’s data relay service provides the assurance of a communications link, no matter how obstructive the terrain may be. put between the active and the Earth. Rovers, forced to stay within sight of the lander to relay their communication, will regain a new independence, both in how far they can get away from the lander and in how long they can survive beyond. beyond the limited life of the lander.

For all lunar missions, including near orbiters and surface assets, that could operate with direct communication to Earth, there is an additional economic and technical benefit to using proximity data relay service. Due to the proximity of the Lunar Pathfinder spacecraft, user assets could achieve higher data rates with a less capable, lighter, and less expensive onboard communications module.

Lunar exploration of the far side

The far side of the Moon, particularly the Aitkin South Pole Basin, is a key area for future robotic and human exploration due to its chemical and mineral composition. For surface assets on the far side of the Moon that operate without line of sight to Earth, Lunar Pathfinder’s communications relay service will be a mission enabler, providing the vital bridge between Earth and the lunar surface. . Lunar Pathfinder’s stable elliptical orbit will allow long-duration visibility of the lunar southern hemisphere every day, with maximum opportunity for data transmission and reception between Earth and the lunar surface.

Lunar Pathfinder Customers

Thanks to the UK’s subscription to the European Space Agency (ESA) Exploration Programme, ESA announced in December 2021 that it would be the lead customer for Lunar Pathfinder services. The agreement establishes ESA’s first commercial lunar services contract to provide new opportunities for low-cost lunar science, technology demonstration and exploration missions. Additionally, ESA is working with NASA on an agreement whereby NASA would launch and deliver the Lunar Pathfinder spacecraft to its operational lunar orbit in exchange for data relay services for their own missions, making NASA one early adopters of Lunar Pathfinder services. .

Additional customers for Lunar Pathfinder services are invited to calculate the service they might receive through SSTL’s Lunar Mission Builder app.

Lunar Pathfinder Experimental Payloads

In addition to providing communications services to orbiters and lunar surface assets, Lunar Pathfinder will host a number of navigation and science experiments, including:

  • an ESA GNSS receiver capable of detecting weak signals from terrestrial GNSS infrastructure (GPS and Galileo), demonstrating its potential role in lunar navigation services
  • a NASA retro-reflector to demonstrate laser ranging capabilities
  • an ESA radiation monitor to study orbital radiation conditions
Graphic representation of the communication between the Earth and the Moon


Here are some highlights of the mission:

  • The Lunar Pathfinder spacecraft is built by SSTL and is scheduled for launch in 2024. It will be operated by SSTL from its Spacecraft Operations Center in Guildford.
  • Lunar Pathfinder will operate in an Elliptical Lunar Frozen Orbit (ELFO) for an operational lifetime of 8 years.
  • Lunar Pathfinder will operate two simultaneous communication channels with lunar assets, one in S-band and one in UHF: communications are relayed to ground stations in X-band.
  • The Phase A/B1 Moonlight study is being conducted by a consortium of experienced European space companies led by SSTL. The consortium includes SES Techcom, Airbus, GMV-NSL, Kongsberg Satellite Services and Goonhilly Earth Station.

How is the UK involved?

Lunar Pathfinder is supported by UK Space Agency funding through the European Space Agency.

The Lunar Pathfinder spacecraft is built by Surrey Satellite Technology Ltd at the company’s facilities in Guildford, along with a number of subsystems, including an internal S-band antenna.

British company QinetiQ is using its historic experience in communicating with Mars to design and build the Moon-link payload for the Lunar Pathfinder spacecraft. QinetiQ is working on the development of user terminals specially designed for compatibility with the Lunar Pathfinder service, for future users to plug and play.

On the ground segment side, Lunar Pathfinder will use the services of the Goonhilly Earth Station space antenna in Cornwall, renovated since the Apollo years and at the heart of the sustainable return to the Moon.

The Moonlight Phase A/B1 study is supported by the UK Space Agency through two competing consortia, including UK companies SSTL, Airbus, Goonhilly Earth Station, GMV-NSL, KBR, Inmarsat and MDA UK. The implementation phase will be subject to future ESA subscriptions and competitive bidding following ESA processes.


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