ESA’s funding shortfall is bad news for CarbonSat, a mission aiming to track atmospheric carbon dioxide. Credit: Astrium

For Europe’s space chiefs, the outcome of last week’s European Space Agency (ESA) budget negotiations was better than expected, given the continent’s economic troubles. But for Volker Liebig, ESA’s head of Earth observation, there is a sting in the agreement. The multi-year budget that member states approved — which falls some €2 billion (US$2.6 billion) short of ESA’s proposed spending of about €12 billion — could force him to postpone or cancel a mission aimed at pinning down the mysterious carbon sinks that are slowing the rise of greenhouse gases in Earth’s atmosphere.

Ahead of the budget negotiations in Naples, Italy, on 20–21 November, Liebig had hoped to secure around €1.25 billion for new research satellites. With France, Italy and Spain contributing much less than expected, he received €1.9 billion for Earth-observation projects. But €808 million has already been allocated for a new generation of weather-forecasting satellites, leaving him with little more than €1 billion for research missions. “We have to discuss with scientists in the next few weeks what to do,” Liebig says. “But we will not be able to develop all the science satellites we wanted to.”

Most vulnerable, he says, is a planned €250-million climate-change mission scheduled for launch in about 2018. One of the two contenders for the mission, CarbonSat, would map atmospheric concentrations of carbon dioxide and methane at high-enough resolution to investigate a long-standing puzzle: why only about half of the CO2 emitted by human activities remains in the atmosphere. Scientists assume that the rest is absorbed largely by the oceans and plants, but ground-based monitoring stations are too few and far apart to pinpoint the sinks.

Satellites could fill in the gaps in the picture, but in April ESA lost contact with Envisat, the one satellite providing such data (see Nature 484, 423–424; 2012). Neither Japan’s existing Greenhouse Gases Observing Satellite nor NASA’s Orbiting Carbon Observatory-2 (OCO-2), scheduled for launch in 2014, will map greenhouse-gas concentrations in as much detail as CarbonSat, which would survey the whole globe with a resolution of 4 square kilometres. “The information that it would collect is essential for developing, implementing, and monitoring greenhouse-gas-emission policies,” says atmospheric physicist David Crisp of NASA’s Jet Propulsion Laboratory in Pasadena, California, who is the science team leader of OCO-2. “A timely launch of this satellite should be among the highest priorities of ESA”.

CarbonSat’s competitor for ESA funding, FLEX, would also help to pin down carbon sinks, by measuring the faint fluorescence generated by plants during photosynthesis — a measure of how efficiently they absorb carbon. “The last thing we want to do is to destroy the forests or whatever is absorbing almost half of the CO2 that we are emitting,” says Crisp. “Wouldn’t it be good to know where these processes are occurring?”

However, there was better news for other ESA programmes. Europe’s Ariane 5 rocket launcher, which is more expensive than competitors, was the focus of fraught discussions: Germany argued for a more powerful and versatile upgrade, whereas France maintained that it would be better to switch straight to a new and more economical launcher. Following late-night discussions, ministers decided to fund both designs over the next couple of years and to review progress in 2014.

They also reached a deal on how to pay for Europe’s contribution to operating the International Space Station between 2017 and 2020. The costs will be covered in kind by a German-backed plan to provide the propulsion and avionics for NASA’s Orion manned spacecraft. ESA also agreed to Russian involvement in its twin ExoMars missions, an ambitious programme of orbiters and landers scheduled for launch in 2016 and 2018. NASA pulled out of the project earlier this year.

But ESA’s science programme faces a squeeze: it will receive €508 million a year for the five-year period from 2013 to 2017. Although slightly higher than its 2012 funding of €480 million, thanks to the contributions from new member states Poland and Romania, after inflation is taken into account this effectively amounts to a cut. Willy Benz of the University of Bern, chair of ESA’s Space Science Advisory Committee, says that this could force the agency to delay a future large mission; cancel mission extensions for existing probes; or cancel smaller missions.

Benz thinks that the science programme got less than expected because in hard economic times spending is channelled towards activities that can more directly boost industry, such as designing and building new launchers.

“I would say that the budget outcome was the best we could have hoped for given the economic circumstances,” says Benz. “But if you cut budgets in the science programme, you cut science. There is only so much you can save by reducing travel or not making phone calls.”