Managers of Europe's space-science program will decide this month whether financial prudence or program ambition should be driving the mission-selection schedule.

 

Scheduled to meet Feb. 22, Europe's Science Program Committee (SPC) specifically will decide whether to begin the process of selecting two new missions costing a combined 950 million euros ($1.2 billion) on the assumption that 200 million euros in savings can be found among missions currently operating or planned.

 

The driving force for those who favor starting new missions is the concern among space scientists who say the European Space Agency (ESA) cannot afford to go several years without soliciting new ideas from the science community, even if the agency's existing program is already stretched to its financial limits.

 

The issue has sparked occasionally sharp debate between ESA's science directorate, led by David Southwood, and the Science Program Committee, currently headed by Genevieve Debouzy, deputy director for strategy and programs at the French space agency, CNES.

 

ESA's science budget is about 400 million euros per year and is funded by mandatory contributions from ESA member governments based on gross domestic product.

 

The SPC had planned to begin the process of selecting one new medium-class mission and one larger mission in 2006, with launches to occur in 2015 or 2016. Medium missions have a cost ceiling of 300 million euros. Large missions' cost ceiling is 650 million euros.

 

ESA's science directorate successfully delayed the call for new missions, citing financial uncertainties in the current program. Program officials also noted that in the past two decades, most ESA space-science budget problems were caused by events outside ESA's control, including launcher delays, missed instrument-delivery deadlines by ESA member nations, and schedule switches by ESA partners including NASA.

 

To these concerns have been added the likely cost increases in two programs already approved: the ESA contribution to NASA's James Webb Space Telescope, and unanticipated new charges for the 2009 Lisa Pathfinder technology-demonstration mission in 2009. The Pathfinder mission is intended to pave the way for the ESA-NASA Lisa mission to detect gravity waves around 2015.

 

Despite lingering doubts, the SPC at its Feb. 22 meeting is expected to agree to issue an announcement of opportunity for new missions.

 

What has changed in recent months is that ESA's Herschel and Planck satellites have progressed with no new budget overruns. In addition, ESA science managers say they have found 200 million euros in savings that provide sufficient breathing room to permit new missions to be considered.

 

Skeptics remain. Some think the 200 million euros in savings will not be realized, others think 200 million will not be enough to accommodate the new programs.

 

ESA Science Projects Director Jacques Louet said Feb. 1 that the savings estimate is realistic, and that the schedule for starting new programs is stretched out enough so that, in the event of a financial problem, the new missions could be stopped in their tracks in time to prevent a budget catastrophe.

 

"There are protections built into the schedule so we can stop the call for programs in time," Louet told reporters during a visit to the Planck science satellite, being readied for a mid-2008 launch.

 

The SPC will be asked to approve the new program selection based on the following cost-saving scenario.

 

Sixty percent of the 200 million euros in savings come from reducing the cost to ESA of the Solar Orbiter mission, tentatively scheduled for launch in 2015, to 300 million euros from the current 420 million euros.

 

The savings come mainly from making Solar Orbiter a part of NASA's Living With a Star Sentinels solar-science mission. No NASA-ESA agreement has been concluded, but ESA officials propose that NASA build three Sentinels spacecraft instead of four, with Solar Orbiter standing in as the fourth, carrying U.S. instruments as well as most of the instruments ESA had intended.

 

Under this plan, Solar Orbiter would be launched with the three Sentinels aboard a single Atlas 5 rocket financed by NASA.

 

Louet said that if the SPC accepts the proposal, ESA plans to negotiate a memorandum of agreement with NASA by November. ESA then would have about 18 months before making sizable financial commitments -- time enough to cancel Solar Orbiter if the NASA collaboration falls through.

 

An additional 60 million euros in savings will come from reduced operations and mission-extension costs of several satellites currently in orbit. Chief among these are the X-Ray Multi-Mirror satellite and Integral astronomy satellites. But operating expenses for the Mars Express and Venus Express missions also would be reduced.

 

The final 20-million-euro increment would be found by reducing ESA's internal costs, including expenses for the use of ESA centers, ESA staff and outside contractors.

 

The method used to assign ESA's overhead and field-center-operations charges to different agency directorates and programs is complicated and cannot easily be ratcheted up or down by individual directorates.

 

Louet said the science directorate will need the endorsement of ESA Director-General Jean-Jacques Dordain before it can forecast such savings with confidence.