NASA, Europe explore mission to outer planets

Potential partners
"There are between one and five different spacecraft elements that comprise these missions," Niebur noted, along with potential contributions from the Japan Aerospace Exploration Agency, as well Russia's Federal Space Agency.

"At this point we have firm agreement with ESA. We don't have firm agreements with other potential partners," Niebur added.

For NASA, the outer planet flagship mission is cost-capped at $2.1 billion, Niebur said. "That's all the money we have ... that's all the money NASA has to put towards this."

NASA and ESA will both down-select to one outer planet mission this fall, Niebur explained. The mission to the outer planet would be launched via an Atlas 5, a Delta 4 Heavy or an Ares V no later than 2017. The launch would be designed to send the spacecraft on a lengthy cruise toward its destination but one that would be no longer than seven years.

Leonard Dudzinski, NASA's program officer for radioisotope power capability, said the outer planet flagship would make use of Multi-Mission Radioisotope Thermoelectric Generators.

At present, there is enough plutonium-238 dioxide allocated for 800 watts of power for an outer planet flagship mission — although due to the shortfall of the nuclear fuel, "we've encouraged studies this year to look at reduced power requirements to save some of that plutonium," Dudzinski advised the OPAG attendees.

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Eyes wide open
NASA and ESA also are planning to issue a joint Announcement of Opportunity for scientific experiments to fly on the mission. The first of three NASA-hosted Outer Planet Flagship Mission Instrument Workshops is to be held June 3-5 in Pasadena, Calif., Niebur said.

"Whether or not it's Europa or Titan as the major target isn't at all clear," Bagenal said. Two large science definition teams are working hard to make these missions happen, she said.

Bagenal emphasized that by careful, early study of these missions it is hoped that any cost overrun can be short-circuited.

Disney Enterprises, Inc. / Walde In this conceptual rendering, NASA's "melt probe" is about to begin its journey deep through the ice of Europa, the second moon of Jupiter, on a quest to penetrate through to the hidden ocean.

"There's no point in having an outer planet flagship mission that ends up costing so much that we can't afford to go to another target in the outer solar system for another 15 years or 20 years," Bagenal pointed out. "So we really have the pressure on us to make sure that we can do something that is technically and fiscally responsible."

Whatever outer planet target is chosen — likely to occur this November — getting to that locale is tough, Bagenal told SPACE.com, be it taking a payload to the surface of Titan or going into orbit around Europa.

"The technologies are being worked ... they are being lined up," Bagenal said.

"It's just an issue of can you be clever and squeeze things down and do things very efficiently to save money. And it's money, money, money," Bagenal said. "All these studies are being done to make sure we're going in carefully ... with our eyes wide open."

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