LISA Pathfinder To Proceed Despite 100% Cost Growth

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LE BOURGET, France — Europe’s space science policymaking body on June 22 agreed to cover new cost increases to the LISA Pathfinder science satellite rather than cancel the mission, which is nearly 100 percent over its initial projected budget, European Space Agency (ESA) Science Director Alvaro Gimenez said June 23.

Continued problems with two technologies aboard LISA Pathinder have pushed the mission’s launch into 2014 instead of 2013. The technological challenges, combined with the delayed launch, have added 70 million euros ($100 million) to Lisa Pathfinder’s total cost, which is now estimated to be 400 million euros.

LISA Pathfinder, which was designed as a relatively modest demonstration mission to prove out technologies needed for the much larger Laser Interferometry Space Antenna, or LISA, satellite, was budgeted at 185 million euros in 2006. The technology is being developed to detect gravitational waves generated by black holes and other cosmological phenomena.

Since it was approved, the larger LISA mission has been put on hold, raising questions about whether LISA Pathfinder could be justified on its own.

ESA and its science policy-making body, the Science Program Committee, have agreed to pursue the Pathfinder in the belief that even without a follow-on LISA satellite, the precursor probe’s drag-free-flight control system was a technology that ESA should master for future science missions.

That was before the latest estimates of what it will take to solve the problems on LISA Pathfinder. One issue relates to the Caging Mechanism Assembly’s hydraulic launch lock, which keeps LISA Pathfinder’s test mass in place as its launching rocket climbs through the atmosphere and transmits vibrations.

The second, more serious, headache in LISA Pathfinder is development of the Field Emission Electric Propulsion micropropulsion system. This is a key technology that ESA officials have said requires a large leap beyond anything ever developed.

Meeting June 21-22 in Saltjobaden, Sweden, the Science Program Committee was presented with three choices following the persistent glitches in the Pathfinder technologies: Accept the 70 million euros in cost increases, de-scope the mission with safer technologies or cancel it altogether.

In an interview here during the Paris air show, Gimenez said he remains hopeful that not all the 70 million euros in projected cost increases will come to pass.

“I wanted to be conservative, and above all I do not want to return to the [Science Program Committee] again with more news like this,” Gimenez said. “This is not a good situation, but I can say that it is very, very good that we did not go directly to designing a LISA mission and instead decided to test the technologies on Pathfinder. Imagine if we had been captured by these issues with LISA.”

Gimenez said he felt obligated to offer the Science Program Committee the option of canceling the Pathfinder because, for the moment, it looks unlikely that ESA and NASA will team on development of a LISA mission anytime soon.

He said the committee, in agreeing to continue LISA Pathfinder despite the accumulated cost increases, is voting for the future.

“The drag-free control system we are talking about here is an order of magnitude more precise than the system for GOCE and GOCE is already at the leading edge,” Gimenez said. GOCEis ESA’s Gravity Field and steady-state Ocean Circulation Explorer, an arrowhead-shaped satellite launched in March 2009 and operating in an orbit — about 255 kilometers — that no science satellite had ever used before.

 Key to GOCE’s success is a drag-free control system that uses ion-electric propulsion to compensate for the drag produced by the residual air molecules present at such a low operating altitude.

“The fact is that either we master this technology or we are not in the business of fundamental physics,” Gimenez said. He said that if the Field Emission Electric Propulsion system cannot be mastered within the revised budget, he will propose that a less-challenging, and less-precise, alternative technology be used in its place.

 

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