Wolves and quantum bits: creating the Saga mission patch

What is QKD?

QKD is a technology that uses the laws of quantum physics to securely share encryption keys between two actors. In QKD, the key is broken into bits and sent using single particles of light, called photons. Any attempt to intercept the photons changes their quantum state, thus the two parties can immediately detect eavesdropping attempts.

“The idea of quantum key distribution is that you want to share a secret between two parties so that they can use this secret as a key to encrypt their data. You are not directly doing encryption and you're not transmitting any form of information. You're just sharing a common secret, which is a random string,” explains Daniele Dequal, Saga QKD Lead Engineer at ESA.

Mission patch

As preparations for the mission continue, the Saga team was asked to develop a mission patch. But how do you visually represent a mission based in quantum mechanics?

The team turned towards symbolism. Animal imagery is relatively rare among ESA mission patches, but the team saw potential. “I like the fact that we can have an animal as a symbol associated to a mission, because this is much more versatile.” says Pablo Sarasa Delgado, Saga’s Project Manager.

This symbolic approach opened the door to a representation that captures both the mission’s technical nature and its broader meaning, while reflecting its strong European identity. From this emerged the idea of the wolf; a species native to Europe and a symbol of coordination, vigilance,  and protection.

Running with the pack: Saga safeguarding Europe

Wolves are primarily nocturnal creatures, able to perceive and navigate in low-light environments. In a similar way, the mission relies on extremely weak optical signals; namely quantum bits transmitted through laser links.

Quantum bits are the fundamental units of quantum information. Unlike classical computer bits, which can only exist as 0 or 1, quantum bits can exist in multiple states simultaneously. In QKD, these quantum bits are usually encoded onto photons, allowing encryption keys to be exchanged securely.

The wolf also carries deep European symbolism. “The wolf is an animal that I personally like, and he is widespread throughout Central Italy – where I come from. He's also a very intelligent, logical and organized animal,” highlighted Riccardo Duca, Saga’s end-to-end Performance Lead. Rome’s foundational myth is inseparable from the wolf, and Rome itself can be seen as one of Europe’s foundational cities. Coincidentally, Saga’s prime contractor, Thales Alenia Space, is headquartered there as well, reinforcing the wolf’s place within the mission’s identity.

But the symbolism extends beyond geography. Wolves work in packs rather than alone, a principle the team saw reflected in Saga’s future. While the mission will initially act as a first demonstrator targeting high security assurance QKD services, it has the potential to scale to a larger network.

“A lone wolf can achieve many things, but through cooperation it can achieve much more. And this is exactly what we will do with Saga first and then EuroQCI. So, the mission capabilities will be significantly enhanced,” emphasised Pablo Sarasa Delgado.

The wolf therefore also represents the collaborative effort behind the mission and its wider ecosystem, bringing together ESA, the European Commission, Member States, and European industry.

This is additionally represented through the star in the patch, emitting laser beams against a backdrop of smaller stars. Saga’s satellite is intended to become the first star in a future constellation.

The sense of cooperation appears visually in the patch. Lasers extend outward from a central star across the European continent below. “We have Europe underneath the star and we have two rays connecting different nations of Europe, which gives a nice message about the role of ESA supporting ESA Member States’ cooperation,” says Enrico Casini, Saga Security Engineering Lead.

Even the wolf’s howl found an unexpected parallel. Wolf calls can travel over incredibly long distances and similar to space-based QKD, which allows encryption keys to be exchanged further than the limits of ground systems. Ground-based QKD is generally restricted to around 150 km without repeater stations, whereas satellites can extend secure communications across continents.

Above all, the wolf carries a meaningful association within the patch: vigilance. “The wolf on the patch is guarding Europe”, expressed Lucie Bricout, Saga Lead Space Segment Engineer. Saga’s role is to secure sensitive institutional data in an increasingly vulnerable digital environment, and the image of the wolf – alert, intelligent, discreetly watchful – subtly mirrors that responsibility.