PARIS — Europe’s Euclid dark energy science mission, which is likely to cost more than 1 billion euros ($1.3 billion), is holding to its 2020 launch date and has remained trim enough to fit into its intended rocket, the medium-lift Europeanized Soyuz vehicle operated from Europe’s spaceport, Euclid Project Manager Giuseppe Racca said June 11.

Initial contracts are now being let and the principal partners to the 20-nation European Space Agency (ESA) in Euclid — France, Britain, Italy and NASA — have signed on for their shares of the mission, Racca said.

“So far we have remained on the schedule we announced a year ago,” when Euclid was approved by Europe’s Science Program Committee, Racca said. “We are going to be a bit tight in the Soyuz, but we have margin there that we can use.”

ESA late last year signed a contract valued at 72.5 million euros with Astrium to build the Euclid payload module, which Astrium announced June 11. The payload module includes a silicon carbide telescope capable of operating at 130 degrees Kelvin, or minus 143 degrees Celsius, for infrared measurements, and a 1.2-meter-diameter mirror to observe galaxies with Hubble Space Telescope precision.

In the coming weeks, a contract valued at more than 300 million euros is expected to be signed with Thales Alenia Space of France and Italy, which will be Euclid’s industrial prime contractor, according to European officials.

In an interview, Racca declined to identify the prime contractor or fix a precise cost to ESA of the Euclid mission because neither the contract nor the commitment of individual agency member states have cleared ESA’s various approvals, even if the mission is firmly under way.

Non-ESA funding for Euclid is expected to total around 350 million euros, including some $40 million in NASA investment in the satellite’s infrared detectors, to be built by Teledyne Scientific Engineering LLC of Thousand Oaks, Calif.

Racca said Teledyne’s heritage, including the Hubble Space Telescope and work on NASA’s future James Webb Space Telescope, has enabled the company to differentiate its detectors from the competition to such an extent that Teledyne was considered all but indispensable for Euclid.

ESA programs typically try to steer clear of U.S. or other non-European technologies unless they come as part of bilateral agreements including no exchanges of funds.

In this case, NASA’s inability to determine on ESA’s schedule whether it would be contributing to Euclid forced the agency to contract with Teledyne on a commercial basis. Racca said it is ESA, not NASA, that is paying Teledyne’s nonrecurring-engineering charges associated with developing and testing the Euclid detectors.

NASA ultimately agreed to take part in Euclid — 40 U.S. scientists are being brought in as a result of NASA’s involvement, in addition to the 14 U.S. scientists who were already part of the program — through an investment of around $40 million to purchase the flight-model Teledyne detectors that result from the ESA-financed development.

Racca said some ESA delegations raised their eyebrows at the Teledyne relationship but have since been won over.

“European [infrared detector] manufacturers are very good at looking down,” Racca said. “For Euclid, we are going to be looking at very, very faint sources. A second argument for Teledyne was that they have very good electronics in their ASICS,” or integrated circuits.

Racca said ESA has formalized the roles to be played by its individual delegations, led by France, Britain and Italy but including Germany and others, in the provision of Euclid’s science instruments and the creation of its various data centers.

“We are awaiting final signatures from some of the delegations, but they are fully behind this,” Racca said.

ESA science projects are typically financed both by the agency and by individual European governments and science laboratories that furnish the payload instruments. ESA is overall project manager and finances the satellite’s construction, launch and in-orbit operations.

ESA’s budget for the mission was some 606 million euros a year ago and has since crept up a bit, but not dramatically, Racca said. He declined to provide a cost-at-completion estimate until the industrial prime contract and other cost items had been confirmed.

Peter B. de Selding was the Paris Bureau Chief for SpaceNews.