The European Environment Agency (EEA) expects to produce by the end of July an estimate of what it will cost to design, install and maintain a network of ground-based sensors and other facilities to work as part of Europe’s Global Monitoring for Environment and Security (GMES) Earth observation system, according to Chris Steenmans, head of EEA’s Shared Environmental Information System division.

Acknowledging the breadth of the task, Steenmans said the challenge will be to separate “the essential from the desirable and the nice to have. There will be costs, but further clarification is needed” before EEA presents an estimate, he said.

EEA, whose budget for now is a relatively modest 40 million euros ($50 million) per year, has put 10 people full-time on the GMES in-situ effort.

While GMES is best known currently for the Sentinel and other satellites that will contribute to it, the system also will feature a large number of terrestrial sensors — in rivers, oceans and in the air — to complement the satellite data.

EEA will be one of the agencies responsible for ensuring that the GMES data are assembled, archived and distributed in a way that users can easily access and understand.

The amount of satellite data alone is daunting. Mirko Albani of the Earth observation strategy division at the European Space Agency (ESA) said the agency’s imagery archives totaled 150 terabytes in the mid-1990s. It amounts to four petabytes now and is expected to expand to some 27 petabytes by 2020 — and that is when only so-called Level 0 sets of raw data are counted.

“You can multiply the number by four if we count Level 1 and Level 2 data,” Albani said, referring imagery that has been put into product form.

ESA’s Envisat satellite, with 10 instruments including a synthetic-aperture radar, is generating 200 gigabytes of data per day. ESA’s Sentinel satellites will produce four terabytes daily.

Albani said one challenge for ESA will be to secure funding to house and maintain this data in an easily retrievable way on a long-term basis, through generations of data storage computing standards. ESA’s biggest member states — France, Germany and Italy — and the Canadian Space Agency have agreed to a set of principles on long-term data preservation, but harmonizing national policies on standards will take several years, Albani said.

“We need more cooperation among the member states and ESA,” Albani said. “It has been poor in the past, and it is difficult to locate funding” for long-term data archiving. “It is a very long-term commitment, and to provide long-term funding is not very easy.”

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