PARIS — France and Germany said Feb. 4 they would jointly build an Earth observation satellite to measure atmospheric concentrations of methane, a contributor to the greenhouse effect linked to global warming, to be launched by 2014.

Meeting in Paris as part of a joint government summit led by French President Nicolas Sarkozy and German Chancellor Angela Merkel, the two governments also agreed to ask their respective space agencies to map a strategy for a next-generation Ariane rocket, with recommendations due by the end of this year.

The two governments called for the development of a common ground network for the different optical and radar Earth observation satellites that France, Germany, Italy and Spain plan to launch in the coming years. The common network, known as MUSIS, or Multinational Space-Based Imaging System, also includes Greece and Belgium. Its progress has been slowed by squabbling over financing the ground infrastructure.

France has told its MUSIS partners it needs decisions by the end of 2010 because of deadlines for replacing France’s Helios 2 optical reconnaissance satellite system.

In a statement issued following the meeting, the two governments said they were “determined to improve Ariane 5,” a likely reference to a new upper stage for the vehicle that European governments are expected to decide in late 2011 or 2012. Contracts for the early development of this upper stage are already under way.

“Nonetheless, we are also conscious of the need to address the question of a new generation of launchers, and we are asking CNES and DLR [the French and German space agencies, respectively] to explore the perspectives. We ask them to complete a report on the question by the end of 2010.”

The French government has already targeted an Ariane 6 rocket as one of three space-related projects that will be financed as part of France’s economic-stimulus package. A full engagement of work on a next-generation Ariane vehicle will await a planned meeting of the 18 European Space Agency governments in late 2011 or 2012.

France had also been studying, as part of the economic stimulus package, a satellite to monitor carbon dioxide levels in the atmosphere. It was unclear whether this idea would be replaced by the bilateral methane-monitoring spacecraft.

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