PARIS — The European Space Agency on Nov. 17 signed a firm, fixed-price contract with Airbus Defence and Space for the construction of the service module for NASA’s Orion crew transport capsule, with a launch set for late 2017 or early 2018.

Under the contract, valued at 390 million euros ($488 million), Airbus will design and build one service module and build parts for a second to acquit ESA of its space station maintenance dues to NASA between 2017 and 2020.

The Orion service module, which provides propulsion, power, thermal control and elements of the life-support system for Orion, is based on ESA’s Automated Transfer Vehicle (ATV) cargo freighter. ESA had been reimbursing NASA for Europe’s 8 percent share of space station common operating charges by launching five ATV vehicles, which paid Europe’s station bills until 2017. The Orion service module completes this obligation through 2020.

ESA and NASA have evaluated ESA’s annual dues at around 150 million euros.

The two agencies have said they hope to extend the Orion partnership beyond a first unmanned flight. But for now, ESA has been unable to secure its member states’ commitment to the station beyond 2020 — and even 2020 is subject to final approval.

The NASA-ESA Orion agreement stops at provision of hardware for a second service module, which could be assembled in the United States by a U.S. contractor in the event the agreement is not extended.

ESA governments are scheduled to meet Dec. 2 to formalize their commitment to station operations to 2020 and to complete the financial backing needed for the Orion service module. At their last meeting, in late 2012, they agreed to commit 55 percent of the service module’s cost, with the remaining portion conditioned on a longer-term agreement among ESA nations on space station operations.

The contract signed with Airbus includes protections for ESA and for Airbus in the event — considered highly unlikely — that ESA governments do not agree to space station support to 2020.

ESA has pegged its Orion service module budget at around 470 million euros in 2014 economic conditions, meaning after accounting for inflation since 2011. It has spent around 80 million euros in the past two years to get to the service module’s preliminary design review, which is expected to conclude in the coming weeks.

A detailed critical design review is expected by late 2015, with flight-model construction to begin and then delivery to NASA.

ESA managers are planning to ask their governments for 800 million euros in station support at the Dec. 2 meeting, with the remaining 200 million euros needed to operate the facility to 2020 to be requested at a meeting of ESA governments in 2016.

“The fact that we now have a firm, fixed-price contract with industry should send a positive signal to our governments meeting on Dec. 2,” said one official involved in Europe’s space station program.

The German government, which is Europe’s biggest space station supporter, is demanding that France and Italy, whose financial support has softened, return to their previous levels of contribution instead of assuming Germany will cover any shortfall. Germany wants to cap its contribution at 37.7 percent of the total, in keeping with an agreement reached in 1995.

Neither France nor Italy has confirmed its space station budget to 2020.

For the Orion service module, Germany heads a list of contributors that include, in order, Italy, France, Switzerland and Belgium.

Peter B. de Selding was the Paris bureau chief for SpaceNews.