The Flex mission will map global vegetation fluorescence to measure plant-stored carbon. This image, captured by an airborne sensor called Hyplant to support Flex, shows fluorescence from different types of vegetation. The highest fluorescence values (bright yellow-green) were found in sugar beet. Credit: U. Rascher, Forschungszentrum Jülich

PARIS — A European Earth observation advisory committee has selected a mission to map global vegetation fluorescence to measure plant-stored carbon ahead of a carbon- and methane-monitoring satellite as Europe’s next Earth Explorer mission.

Meeting in Krakow, Poland, after two days of debate between the two missions’ backers, the Earth Science Advisory Committee concluded that the Fluorescence Explorer (Flex) mission should move toward full funding, with a planned launch in 2021 or 2022.

The committee’s recommendation is all but certain to be adopted by the European Space Agency’s Earth Observation Program Board when it convenes in mid-November.

The decision means that the CarbonSat mission, which like Flex was designed to examine the carbon cycle and has been vying for ESA backing for years, will have to await the next round of mission competitions in a couple of years or seek backing outside the usual ESA context.

The committee’s endorsement of Flex came with a request that ESA not abandon CarbonSat, whose precision measurements were viewed as offering an unparalleled assessment of atmospheric carbon and methane.

Both proposals have a long history of seeking funding that has been delayed in part for technical-readiness reasons. The precision of the proposed CarbonSat instrument is still viewed as challenging and may yet win backing as a technology development on its own, even before the full mission is approved.

The Flex mission had been set aside following a previous ESA Earth observation competition, in part because of the complexity of its own instruments. That complexity has been reduced by the arrival of Europe’s Sentinel 3 Earth observation satellite, whose multispectral imagery will do some of the work of Flex.

The two satellites will now fly in tandem in polar low Earth orbit. Sentinel 3 is one of a fleet of environment-monitoring satellites financed by the European Commission as part of a long-term program called Copernicus.

To reduce the risk of budget growth or schedule slips, ESA financed two industrial consortia to work on each of the two proposed missions and to continue the work until what is called Phase B1.

This means spending more money before the winner is selected, but it eliminates sufficient technical and financial risk to be worthwhile, ESA Earth Observation Director Volker Liebig said. It is a procedure ESA adopted after previous Earth observation missions faced technical hurdles that were not foreseen when the contracts were signed.

To further reduce the likelihood of future bad surprises, ESA is almost certain to order the Flex instrument package by mid-2016 but to hold off on signing a full mission contract, including the satellite platform, until a year later. It is in the development and production of the sensors that most cost overruns and schedule delays have occurred.

Jose Moreno, an Earth physics professor at the University of Valencia, Spain, and chairman of the Flex Mission Advisory Committee, said Sept. 24 that starting instrument development in 2016 and platform construction in 2017 could advance the mission’s launch date by one year, to 2021. He said the Flex idea has been looking for ESA support since 1998.

In a Sept. 25 interview, Liebig said his division has more than half of the total financing needed for the Flex payload — enough to begin development early in 2016.

The remainder, including funds required for manufacturing the platform, assembly and testing of the full unit, launch and operations, will await a late-2016 meeting of ESA government ministers to decide a multiyear financial commitment.

Current estimates are that Flex’s industrial development will cost around 150 million euros ($165 million). When the launch — aboard a European Vega small-satellite vehicle — the ground infrastructure and operations are added in, total Flex mission costs are likely to come in just under 300 million euros.

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