Satellites from different makers can’t easily connect or be repaired in orbit. EU-funded researchers have built and tested a universal, USB-like standard that could change that.
By Jonathan O’Callaghan
Don’t you hate it when you go on holiday and need to bring a variety of plugs with you? The same, it turns out, is true in space, with spacecraft and satellites often using different connectors to transfer power, data and other services.
An international team of researchers has been exploring whether one common interface can make those connections easier. Their idea, developed through the EU-funded SPACE USB project, is a little like the widely used USB ports in computing: one standard connection that can support different functions across various satellite designs.
“It speaks to everybody,” said Raphael Boissonnade of Thales Alenia Space in France, who coordinated the project. “We propose the same plugs, but with different services and different technology.”
The need for such flexibility is growing. More than 16 000 satellites are now orbiting Earth, and the number continues to rise. Yet once a satellite runs out of fuel or its equipment becomes obsolete, it is generally replaced rather than repaired or upgraded in orbit.
That creates costs and risks. A satellite that can no longer manoeuvre can become space debris, potentially threatening other spacecraft. A single collision can scatter thousands of fragments that threaten other missions for decades. Being able to service and repair satellites instead would extend their useful lives, avoid collision risks and reduce the need to launch costly replacements.
Today, satellites do not have one standardised way to attach devices for power, data, heat and other services. There is no single interface that allows equipment from different systems to connect easily.
“In Europe we have three different interfaces,” said Mehmed Yüksel of the German Research Centre for Artificial Intelligence (DFKI). Each was developed independently, by rival companies, with no shared incentive to make their systems talk to one another.
The SPACE USB researchers set out to see whether a common alternative was possible. The connector needed to cope with a small amount of force as it was attached, remain relatively light and compact, and lock into place in a few minutes.
By the time the project concluded in late 2025, the team had produced a working prototype called the Common Passive Interface. It is larger than a future flight version would need to be, but demonstrates the principle.
The researchers tested it against the three established European interfaces – HOTDOCK, SIROM and iSSI – and demonstrated full mechanical and electrical compatibility with all three.
Using a robotic test bench at Thales Alenia Space, they demonstrated how the connector can be attached to a dummy satellite for different purposes.
“We were able to interconnect every device, showing that standardisation is possible,” said Boissonnade.
The connection is secured using a rotating cylinder or a series of latches. Its purpose is not to dock two spacecraft with each other. Instead, the system is designed to let additional equipment connect to a satellite already in orbit, potentially prolonging its life.
Today, a failed satellite is typically brought down to burn up in the atmosphere or moved into a higher “graveyard orbit,” a process that can take years. A common interface could make repair a more viable alternative, keeping satellites in service rather than retiring them.
A servicing spacecraft might fly up to a satellite with a faulty component and replace it. New equipment could also be added, giving an existing satellite new capabilities.
“It could open up new possibilities, such as adding new sensors, computing units and graphics processing units for AI in orbit,” said Yüksel.
Star trackers, for example, help spacecraft determine their orientation and can potentially be replaced if they fail. Other sensors could also be upgraded without replacing the entire satellite.
“If you still have plenty of fuel in your spacecraft, it’s a pity to stop your mission,” said Boissonnade.
A servicing spacecraft equipped with a compatible connector would be able to visit several satellites, replacing or upgrading equipment as required. Standardisation therefore makes it easier to develop an ecosystem of servicing vehicles and replacement components, rather than designing each mission from scratch.
That idea is increasingly reflected in European space policy. In June 2026, the European Commission and the European Space Agency signed a joint declaration supporting an In-Space Operations and Services (ISOS) pilot mission. The declaration has also been signed by 10 European countries and supports work on satellite inspection, repair, repositioning, refuelling, manufacturing and debris removal.
The Commission is developing a pilot mission, targeted for launch by 2030, as a step towards a European in-space service infrastructure.
The EU’s proposed Space Act points in a similar direction. Its draft rules would require certain EU-owned spacecraft to have a minimum capacity to receive in-space services, including dedicated spacecraft service interfaces. The proposal is still subject to the EU legislative process.
For technologies such as SPACE USB, the timing is therefore significant: as Europe begins to envisage spacecraft that can be serviced by design, common interfaces would help make those services practical and sustainable.
A common connection would also be useful for something more ambitious: building structures in space.
Rather than launching a large satellite or platform fully assembled from Earth, modules can be sent up separately and connected in orbit. Standard interfaces would allow different pieces of equipment to be added as needed.
“If you want to make a big structure in orbit, and you want to attach things with an electrical connection, why not install it with a standard connection?” said Boissonnade.
This can eventually support applications such as in-space manufacturing, where microgravity offers conditions that are difficult or impossible to reproduce on Earth.
Semiconductors and pharmaceuticals are among the products being explored for manufacture in orbit. Larger, modular platforms may provide the infrastructure needed for such activities.
The SPACE USB researchers have demonstrated that equipment built around three different European interfaces can be connected through a common system. The project has also produced specifications intended to provide a basis for future European and international interface designs.
Turning that prototype into an operational standard will depend on whether spacecraft manufacturers, equipment suppliers and servicing companies adopt it.
“If there is a huge demand for servicing, we do believe that standardisation will be required,” said Boissonnade.
A common connector may seem like a small piece of hardware. But as Europe moves towards a more serviceable and reusable space infrastructure, it stands to become one of the building blocks for a future in which satellites are not simply used and discarded, but repaired, upgraded and connected in orbit.
For now, a variety of different connectors are used across the space industry. But if the SPACE USB team has its way, one universal standard will someday make them all interoperable.
This article was originally published in Horizon, the EU Research and Innovation Magazine.