PARIS — European scientists on Feb. 3 auditioned three teams competing to carry out Europe’s next billion-dollar mission but acknowledged that for all three the selection will depend on decisions to be made not in Europe, but in Washington and Tokyo.

Representatives of NASA and the Japan Aerospace Exploration Agency (JAXA) were present to lend moral support to the three projects, but said they were unable to commit to any of them yet. Whether they will be able to do so by June 21, the date Europe’s science mission selection body is scheduled to meet, was unclear.

“What will be decided depends on the selection made by [European] science advisory bodies and on the outcome of discussions with NASA and JAXA,” said Fabio Favata, head of the science planning office at the 18-nation European Space Agency (ESA). “We may not be able to get a firm engagement by NASA or JAXA by then, but we will have further indications of their priorities. The fact is that all three of these missions transcend the capability of any one agency and will require major international collaboration.”

The three missions in competition for ESA’s next L-Class or large science mission are the Europa Jupiter System Mission (EJSM)/Laplace two-satellite mission to Jupiter’s moons; the International X-ray Observatory (IXO); and the three-satellite Laser Interferometer Space Antenna (LISA) gravity-wave detector.

ESA’s budget ceiling for its share of the next L-class mission is 700 million euros ($966 million). That would be ESA’s share only, and would not include the contributions of individual European governments to the experiment payload, a common division of authority in ESA space science projects. The ability of these national laboratories to fund their work and complete it on time constitutes, in some cases, a risk factor nearly as big as the occasionally complex decision-making procedures at NASA and JAXA.


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An ESA-ordered independent analysis concluded that all three missions would fit, more or less, under the budget ceiling. EJSM/Laplace would cost ESA about 710 million euros, IXO would be 660 million euros and LISA, 750 million euros. ESA’s Frédéric Safa, after reminding the largely scientific audience of 350 that “we cannot afford any of these missions alone,” and that all three “are subject to partnership agreements not yet formalized,” said none of the three appears out of range given what is known of their technology requirements today.

As is typical of meetings of scientists, the presentation devoted to cost analysis was by far the shortest of the day. Favata said ESA’s method of assessing future costs has proved its value given the experience two years ago of assessing the costs of candidates for ESA’s next medium-class mission. The cost-at-completion estimates made then, Favata said, have stood up well after two years.

Europe’s Space Science Advisory Committee will look at all three and make preliminary recommendations this spring. On June 21, the decision-making body, called the Science Program Committee, will meet to determine whether one or two should be granted approval to continue to the next stage.

The mission ultimately selected would be ready to launch around 2022.

European scientists have long felt pressure to trim their imaginations to fit inside ESA’s annual science budget, which in 2011 is about 465 million euros. To do otherwise, ESA science managers have said, would be to hold European space science hostage to decisions made by Europe’s space-science partners, mainly NASA and JAXA, and occasionally Russia. According to this reasoning, European scientists should be able to think up valuable missions that can be executed in Europe for 700 million euros.

That is not the case this time. LISA depends so heavily on NASA, and IXO on both NASA and JAXA, that their defenders made only half-hearted attempts to say they could be done without the United States or Japan.

Even EJSM/Laplace, which is two satellites — one built and launched by Europe, one by the United States — whose core areas of interest are different jovian moons, would be much diminished without the presence of both agencies.

“The mission is an ESA-NASA collaboration, a choreographed dance [of two satellites] in the Jupiter system,” said Michele Dougherty of University College London, one of those who made the case for EJSM/Laplace here Feb. 3. “It would be OK on its own, but you get better results in tandem.”

Jim Green, director of planetary science at NASA, after insisting that NASA wanted more collaboration with Europe on space science in the future, said EJSM/Laplace has been favorably reviewed by U.S. scientists, but that a fresh decadal assessment by the U.S. National Academy of Sciences is due within weeks and that he could not presume what it would say.

Green said NASA is confident it has sufficient radiation-hardened parts to hold up its end of the mission. Unlike ESA’s satellite, which uses an advanced, and technically challenging, pair of solar arrays, NASA’s satellite would carry nuclear radioisotope generators, which use heat from decaying plutonium material to power spacecraft that are far from the sun.

ESA has begun investigating technologies for nuclear-powered satellites and future robotic landers, but the issue remains politically touchy among some ESA nations.

Tadayuki Takahashi, JAXA’s director of external relations, said Japanese scientists look favorably on IXO as a follow-on to Japan’s Astro-H satellite, to be launched in 2014. He said Japan will reserve judgment on IXO until it has survived the next round in Europe’s mission selection process.

Wilton Sanders of NASA’s astrophysics division said NASA supports LISA and IXO but would need to respect guidelines set by the National Academy of Sciences’ forthcoming planetary decadal survey, due for release March 7. He said the last survey gave IXO a lower-than-necessary rating because of questions about Europe’s mirror-technology development that have since been resolved.

Sanders noted that NASA’s ability to carry out its own priority missions, like those it would like to do with Europe, depends on funding decisions and other factors that NASA cannot settle on its own. These include progress of the James Webb Space Telescope, whose cost is so large — at least $6.5 billion, according to the latest outside review — that any additional overruns would have a domino effect on other missions.

Peter B. de Selding was the Paris bureau chief for SpaceNews.