The contract has been signed that will see the first UK satellite go to the Moon in 2024.
Lunar Pathfinder is a relay platform for telecommunications. It will feed the telemetry and data from other spacecraft at the Moon back to Earth.
This will make those other missions simpler and cheaper to operate.
The contract was signed in London between the European Space Agency and Pathfinder's manufacturer, Surrey Satellite Technology Limited (SSTL).
It is a service agreement. Esa is not funding Pathfinder's build; it's merely purchasing a proportion of its relay capacity.
This will be used by the agency's future missions, and also ventures run by its American counterpart, Nasa.
The quid pro quo is that Pathfinder will hitch a ride on a US rocket.
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There is an armada of missions - public and private - going to the Moon this decade, including ones that will take astronauts back to the lunar surface for the first time since Apollo.
Pathfinder will be in a position to service all these ventures, selling its bandwidth to anyone who needs it.
With Esa as its "anchor customer", SSTL will have confidence it can get a decent return on its self-investment.
This is a key moment then for all parties, not least Esa which is now following a procurement model routinely practised by Nasa.
The space agency sets the requirements, offers perhaps seed money to industry to develop the product solution, and then agrees to purchase the service.
California's SpaceX is the classic example of this model in action, producing novel rockets and crew-carrying capsules for use by Nasa at a fraction of the cost of more traditional contracting.
Josef Aschbacher, the new director general of Esa, is determined to push Europe down this same route, and Lunar Pathfinder is his poster child.
He's come into the job with the ambition - he calls it his Agenda 2025 - to shake up the way space is done across the continent of Europe.
If Europe doesn't become more fleet-of-foot in the space domain, it will fall behind geopolitically, he believes.
"Europe has to realise that first of all, space is extremely important for the development of a country or a region," he told me.
"I would claim that if you're not a space power, you cannot be a superpower. We see this best demonstrated in China, which is really using space as a tool to become a major superpower.
"The US, of course, is doing it since a long time. So Europe has to wake up."
Under Dr Aschbacher's leadership, there will be more projects where Esa acts as the first buyer, or anchor customer.
The agency will do more consulting to enable venture capital to have the confidence to back innovative ideas in Europe. There'll also be prizes and grants to stimulate this innovation. And the whole contracting process inside Esa will be re-assessed to speed things up.
"Time is crucial for the new space world," Dr Aschbacher said.
"Our procedures are too slow - time to contact, reviews, the various interactions with these fast-moving companies. This is about internal procedure where I need to work on Esa to be much faster."
Lunar Pathfinder will operate in a wide elliptical orbit at the Moon for at least eight years.
It will talk to other lunar missions - be they other satellites in orbit or rovers down on the surface - using S-band and UHF frequencies. Communications will be relayed back to Earth ground stations in X-band.
Additionally, there'll be a demonstration of technology that could one day lead to a sat-nav service at the Moon.
"Pathfinder will be hosting a weak signal detection receiver from Esa. Effectively, the idea is to test how signals from GPS or Galileo at Earth can be detected from lunar orbit and then used for navigation of lunar assets," explained Nelly Offord, the exploration business manager at SSTL.
Elodie Viau, the director of telecoms at Esa, said she expected Britain to play a leading role in the agency's new direction under Dr Aschbacher.
"What is great about the UK is its commercial mindset; it is very business-minded," she noted.