Credit: SES
LA PLATA, Maryland —Europe’s Eagle-1 quantum key distribution (QKD) satellite is facing fresh delays to its payload and will not be launched before late 2027 or early 2028, but program backers defended the project and said post-quantum cryptography (PQC) is no substitute for it for sensitive communications.
Eagle-1 is part of a larger EU Quantum Communications Infrastructure (EUQCI) program at the European Commission. The Commission is contributing part of the funding for Eagle-1 through its Horizon Europe and in-orbit demonstration program, which will pay for three years of operations.
The 23-nation European Space Agency (ESA) is financing most of the remaining costs, which began with a 2022 contract with SES to be prime contractor as part of a 20-company consortium including Sitael of Italy as satellite bus provider and Tesat Spacecom of Germany to provide the satellite’s optical terminal.
Eagle-1 is public-private partnership, with the original contract valued at 130 million euros ($150 million at current exchange rates), with the SES-led consortium paying a minority share of that.
Launch was scheduled for 2024 but the program confronted delays in the availability of Europe’s Vega-C rocket and technology challenges on the satellite’s payload.
Alan Kurešević. Credit: EU Space Days video
In a May 27 update at the EU Space Days conference, held in Nicosia as part of the Cyprus EU presidency, Alan Kurešević, managing director of SES Techcom, said the payload is still posing technology challenges, but that the satellite is in advanced stages of production. “We’re looking at launch at the end of 2027 or the beginning of 2028,” Kurešević said.
“Eagle-1 is a bridge toward industrialization and commercial utilization, an end-to-end demonstration of QKD and the value chain and the distribution of keys to the end user.”
The idea behind QKD is that transporting photons of light terrestrially, at extremely low power levels, is not feasible beyond 150 kilometers. “Satellite seems to be the most efficient,” Kurešević said.
Kyriacos Kalli. Credit: EU Space Days video
Kyriacos Kalli, a professor at Cyprus University of Technology, made the QKD case this way:
“Classical optical communications uses layers producing milliwatts of power to launch light on the ground from one end to another and. This is conditionally secure. Someone could harvest and decrypt that data at a later stage.
“But if you reduce the power significantly, to femtowatt — that 10 to the minus 15 watts of power — you’re in the realm of launching single photons. Anyone messing with it disrupts the key. You throw it away and use a new key.
“Take this network and rotate it vertically, with a trusted node in space and an optical ground station. You get unconditional security from the satellite to the ground station.”
Frédéric Domps, a policy offer at the Commission’s DG-Defis defense and space directorate, acknowledged conflicting views on whether QKD is worth the effort. “Those who interface with NSAs [national security agencies] say they don’t want to hear about QKD, that the security proof is not there.”
Cmdr. Michail Pothitos. Credit: EU Space Days
Cmdr. Michail Pothitos of the Hellenic Center for Defense Innovation agreed that PQC “provides certain solutions for the quantum resilience challenge, and QKD is not yet there in terms of the technology. That is why there is a big push for PQC rather than QKD.
“But if your data is very valuable, the answer is pretty obvious: Start with PQC and you will gradually adopt QKD as the technology matures.”
Kalli said the problems with QKD are multiple, including the link budget; the ability of detecting photons of light, which is not a problem in space but is a problem in the atmosphere; the need for adaptive optics to mitigate the effects of atmospheric turbulence.
“But once it’s working it’s worth the effort,” Kalli said.
With some 300 nearly cloud-free days per year, Cyprus and Greece are both positioning themselves as places for the optical ground stations.
“We have the EUQCI program and I have seen it in Greece,”Pothitos said. “We have three optical ground stations in Greece and companies can detect whether the conditions are good.
“We are getting there, step by step, some around 60 million [euros] funded in general for quantum. We want additional requirements from the armed forces and they will provide installations to assure we have the high security we need. We also need to check supply-chain security and we are not there yet.”
Kurešević said the Eagle-1 program is all-European, by design, to demonstrate sovereign QKD from space.
ESA governments in November subscribed to an additional 78 million euros in Eagle-1 funding, led by Luxembourg and the Netherlands. Another 46.7 million euros was budgeted for the Eagle-neXt project, which is for early work on a small constellation of QKD satellites to succeed Eagle-1, once it has made its case in orbit.