BRUSSELS, Belgium — Europe’s broad Earth observation satellite program, Global Monitoring for Environment and Security (GMES), is still lacking a clear data-access policy and has yet to seal agreements with national Earth observation satellite systems whose satellites are a key piece of the GMES architecture, European government officials said.

GMES already has secured nearly 2.3 billion euros ($3.4 billion) to build the first set of five Sentinel observation satellites — three dedicated satellites and two payloads on other satellites. The program is being managed by the European Commission, although most of the funds so far have come from the 18-nation European Space Agency (ESA). The funds include building duplicate models of the three dedicated satellites, and European government officials are preparing to ask their governments for additional funds to order third copies quickly enough to take advantage of bulk-order reductions of up to 40 percent at the satellite manufacturers.

In addition to the Sentinel spacecraft being built expressly for it, GMES intends to use satellites built by France, Germany, Spain and Italy, among others, to furnish its broad suite of services to European Commission environmental, agricultural, maritime and other directorates. Ultimately these agencies, which are not used to paying for satellites, will be the principal customers of GMES.

But how future GMES hardware will be financed remains unclear. ESA governments have said their role should stop at the first series of Sentinels, plus a second set of so-called “B” models that ESA agreed to pay for to give the European Commission time to craft a user-financed program after 2013.

Josef Aschbacher, head of ESA’s GMES space office, said Oct. 15 during a space policy conference here organized by Business Bridge Europe that the European Commission needs to decide in short order how to assure that GMES satellites will be available over the long term. If the commission acts quickly, he said, it can order further copies of the Sentinel satellites at a discount of perhaps 40 percent by piggybacking on the current production of the first-generation Sentinels.

Also needed for GMES is a policy that will guide the program’s access to satellites built by individual European nations, he said.

Valere Montarlier, head of the European Commission’s GMES Bureau, agreed that one of GMES’s current weaknesses is the absence of any certainty that, as the satellites currently on order near retirement, spacecraft with similar sensors will replace them. Without such assurances, he said, many prospective GMES users will refuse to fully participate in the program.

Addressing the conference Oct. 15, Montarlier said identical “C-unit” models of the three dedicated Sentinel satellites should be purchased, but he suggested ESA should be involved in their purchase. Montarlier also noted that, despite ESA and European Commission backing for construction of the B-unit models of Sentinels 1, 2 and 3, the launch of the second series has yet to be financed. Several ESA governments balked at financing the launch, saying it was the commission’s job. Whether they can be persuaded to contribute to a third series of identical satellites remains to be seen.

Montarlier said “full and open access” to GMES data will be the general rule, but that security concerns may force some restrictions. He did not elaborate.

What appears clear is that the European Commission is moving away from the idea that GMES data should be paid for by its users to permit the sponsors to recover their investment.

Hugo De Groof, of the commission’s directorate-general on environment, said the experience of the Austrian Mapping Agency (BEV) offers lessons in how Earth observation data should be distributed. BEV, he said, cut prices for certain Earth observation data by up to 97 percent. There followed a large increase in the number of users.

“Use of the information has exploded, in some cases by 7,000 percent,” De Groof said Sept. 21 during the GMES Sentinel Data Policy conference, also held here. “New users have emerged from small and medium-sized enterprises and new re-use sectors such as health and agriculture. The decrease in prices has been offset by the enormous demand and BEV’s total turnover has remained stable.”

De Groof cited a 2004 study in the United States concluding that state and local governments trying to recoup their operating costs seldom succeed and, at the same time, “act as a drag on private-sector investments that would otherwise add to the tax base and grow the economy.”

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