Doubts hang over EU's Sentinel radar mission
The European Space Agency will ask its member states next week if their new radar satellite should simply be put in store rather than launched into orbit.
Sentinel-1ais supposed to lead a new wave of Earth observation spacecraft that are being built to provide an unprecedented view of the planet.
But this project's future financing has become mired in arguments over the 2014-2020 European Union budget.
Esa directors do not want to launch the Sentinel without full funds in place.
"We will ask our member states for guidance at our council meeting," said Dr Volker Liebig, the agency's head of Earth observation.
"It makes no sense launching Sentinel-1 if we do not have the operational budget," he told BBC News.
In or out?
Esa has a deadline of June when it must reserve a rocket to take the satellite into space in the summer of 2013. But without clarity on where the money will come from to manage the spacecraft once in orbit, it is likely the Sentinel's launch opportunity will be passed up and the valuable asset will instead be held in safe storage when its construction is complete.
The satellite is the first in a series of orbiting sensors for a multi-billion-euro project intended to inform European policies to deal with global change, and to help enforce EU law. A radar satellite, for example, can be used to track illegal oil discharges from ships, to monitor land subsidence and to support flood relief efforts.
The venture, known as Global Monitoring for Environment and Security (GMES), is a European Commission initiative on which Esa is acting as the technical adviser and procurement agent.
The EC is currently in dispute with its member states over the future financing of the endeavour.
The Commission, which is the executive arm of the 27-nation bloc, wants GMES funded as an intergovernmental venture, in which the big participating states would cover most of the costs.
The majority of the EU's member nations, on the other hand, want GMES included inside the Union's next multi-annual budget (2014 to 2020) to provide the project with continuity and certainty. The European Parliament feels the same way.
The sums involved are considerable. Already, the EU and Esa have committed 2.3bn euros to the construction of a fleet of spacecraft, and it is envisaged a further 5.8bn will be needed to carry the project operationally through to the end of the decade and plan for its ongoing maintenance.
GMES is a flagship space project for the Commission alongside its much-delayed and over-budget Galileo satellite-navigation system. So to see GMES stall right at the outset because of a financial dispute would therefore represent a major embarrassment.
Efforts will be made in the coming weeks to try to resolve the impasse. Even if the project's final funding pot is not established, just knowing GMES was inside the budget might give Esa the confidence to go ahead and book a rocket in the expectation that financing would be available to operate Sentinel-1a once it was in the sky.
"First, we have to know whether GMES is in the budget or not," said Dr Liebig.
"What I could expect is that our council give us authorisation to proceed if we are in the negotiation box. It makes sense for member states to take a stepwise approach.
"We are still ready to store, but if the commission puts GMES in the negotiation box, we can take the next step and announce a three-month launch window."
Rocket operators want a year's notice from customers that their payloads will arrive at the launch pad at the designated time.
Sentinel-1a will be followed by Sentinels-2a and 3a. These platforms, which will image changes on the land and over the oceans, will need their launchers reserved at the end of this year if they are to fly on time.
The fear is that a protracted dispute could see these spacecraft also head into storage once they are built.
Jonathan.Amos-INTERNET@bbc.co.uk and follow me onTwitter