The Jason-3 spacecraft must be ordered soon if a remarkable 18-year record of ocean height is to be maintained.
Eumetsat, which looks after Europe’s weather satellites, needs at least 58m euros ($87m; £53m) from its member states to initiate the programme.
Jason-3 would launch in 2013, allowing time to cross-check its data in orbit with the current Jason-2 mission.
Only by flying the pair in tandem for a period of months can scientists minimise calibration errors between the two satellites’ datasets.
The Eumetsat Council has extended the deadline for interested member states to subscribe to Jason-3 through the end of the year into January.
The altimetry project stretches back to 1992, and provides the global reference data for satellite-measured ocean topography. It is the Jason series and its predecessor, the Topex/Poseiden spacecraft, that have traced the recent 3mm per year rise in sea levels.
The UK funding contribution to Jason-3 is… being actively addressed in government. Bruce Truscott, UK Met Office
The surface height information has been invaluable to oceanographers, weather forecasters and climatologists.
This week’s Council Meeting of Eumetsat recognised that a number of member states needed more time to organise their financing.
The total cost of the Jason-3 programme is estimated to be 252m euros ($380m; £228m), with the biggest individual contributions pledged by the lead nations – the US and France.
With the EU and the European Space Agency also willing to contribute to the flagship project, Eumetsat members are being asked to find 63.6m euros, with a requirement that binding commitments cover at least 90% of that figure to trigger development work.
So far, 13 out of 19 potential participating states have subscribed to the programme.
Among the six outstanding nations are Eumetsat’s two biggest members – Germany and the UK.
Their participation could be critical to the outcome of the subscription process.
Bruce Truscott at the UK Met Office, which leads the UK’s involvement in Eumetsat, told BBC News: “We recognise the potential value offered by the Jason-3 satellite programme and the need to carefully consider the relative merits of our national investments.
“The UK funding contribution to Jason-3 is therefore being actively addressed in government, with a view to reaching a conclusion before the declaration due date at the end of December.”
By Jonathan Amos. Science reporter, BBC News
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