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Europe is looking to roll out its ambitious Earth observation programme even though the long-term budget to support it has still not been agreed.

The European Space Agency has taken a decision this week to reserve a rocket to launch the Sentinel-1 radar satellite in 2013.

It should be followed into orbit by further satellites in 2014.

But the European Union, which owns the programme and will fund its operation, has stalled on the financing.

It means - at the moment - that Sentinel-1 would get into space with only a few months of guaranteed budget to sustain its observations of the planet.

Nonetheless, the council of Esa, which has been meeting in Paris over the past two days, is confident the money issues can soon be resolved.

"The council has asked the executive to go ahead, to start all the activities that will make a launch possible next year, between October and the end of 2013," explained European Space Agency (Esa) spokesman Franco Bonacina.

"We cannot wait; if we wait, we risk losing our launch slot and that could end up costing us more money," he told ³ÉÈË¿ìÊÖ News.

Sentinel-1 would ride into orbit on a Soyuz rocket from the Sinnamary spaceport in French Guiana. The spaceport's operator, Arianespace, needs a year's notice that a satellite will be ready to fly so that it can plan a launch schedule.

Without a reservation being made now, Sentinel-1's flight would almost certainly be bumped to 2014.

The radar mission will be engaged in wide range of land and ocean surveillance tasks, such as oil-spill monitoring and earthquake hazard assessment.

Until recently, this data was provided by the Envisat spacecraft. But its sudden failure in orbit in April has put some urgency behind the desire to launch its successor.

Sentinel-1 is just the first in a series of orbiting sensors for the multi-billion-euro project intended to inform European policies to deal with global change, and to help enforce EU law.

This 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. Simply put, Esa is building GMES for the EU.

But the EC is currently in dispute with its own member states over the future financing of the endeavour.

The commission, which is the executive arm of the 27-nation bloc, had wanted GMES funded as an intergovernmental venture, in which the big participating states would cover most of the costs.

The EU's member nations, on the other hand, demanded GMES be included inside the union's next multi-annual budget (2014 to 2020) to provide the project with continuity and certainty.

The European Parliament felt the same way, and Denmark, which currently holds the Presidency of the Council of the European Union, has just told the Commission that GMES's position in the multi-annual framework should go into negotiation.

"This has helped ease concerns and convince everyone that these issues will soon be sorted out," Mr Bonacina said. "And of course the Envisat users are desperately waiting for something to replace the satellite they have lost."

However, the Esa council decision to go ahead and reserve a Soyuz is not a hard decision to actually launch Sentinel-1, and if the EU fails to fix a satisfactory budget then the programme will be plunged into crisis.

The sums involved in GMES financing are considerable. Already, the EU and Esa have committed 2.3bn euros (£1.9bn) 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.

The Sentinels represent the biggest commitment to Earth observation from any geopolitical bloc.

Sentinel-2 will be an optical imager, focusing on land changes. Sentinel-3 will carry instruments to measure sea-surface topography, and ocean and land surface temperature. Sentinels 4 and 5 are sensors dedicated to the study of atmospheric chemistry and will be hosted on Europe's meteorological satellites.

The other significant development to come out of the Esa council meeting concerned Europe's ExoMars programme.

This involves two missions to the Red Planet that are planned to launch later this decade.

Esa is currently trying put in place the technical and financial arrangements that will permit these missions to proceed. Changes were required when the US space agency (Nasa) withdrew from the projects last year.

Esa's council noted the efforts of its executive to find a full budget for ExoMars (it is short by several hundred million euros) but took no formal decision on the future of the programme.

It is expected a sum of about 80m euros will be released to industry later this month to enable the building of the spacecraft to continue. The situation will then be reviewed again at the end of the year.

The 2016 mission would put a satellite in orbit around Mars to study its atmosphere. It will also have a small landing demonstrator that will do some very short-lived science on the surface of the planet.

In 2018, a rover would then be sent to land on Mars and search for signs of past or present life.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on <link> <caption>Twitter</caption> <url href="https://twitter.com/#!/³ÉÈË¿ìÊÖAmos" platform="highweb"/> </link>