WASHINGTON — In an effort to keep a planned — but unfunded — mission to Jupiter’s ice-covered moon Europa on track for full-scale development, NASA is preparing to spend $15 million over the next year or so for preliminary instrument work.

The study money, being sought by “a variety of institutions” that responded to NASA’s Instrument Concepts for Europa Exploration (ICEE) solicitation in June, is expected to be awarded in mid-August, said Curt Niebur, lead program scientist for NASA’s New Frontiers program.

Speaking here July 15 at a meeting of the NASA-chartered Outer Planets Assessment Group, Niebur said the funds will be provided in one-year grants. The money came from a $75 million appropriation Congress provided especially for Europa exploration in the continuing resolution that, until Oct. 1, will fund NASA and the rest of the federal government at 2012 levels, minus cuts imposed by the ongoing budget sequester.

In some cases, proposers had ideas for entire instruments for the probe, dubbed Europa Clipper, Niebur said. Other proposals are “just for subsystems,” he said. “Some [instruments] need one specific component matured so that the end-to-end instrument is viable.”

Given the mission’s estimated $2 billion development price tag, the Europa Clipper team is not interested in taking big risks.

Above all, proposers were encouraged to focus on technology that has already proved its mettle in a space environment on some other project’s dime, Niebur said. The team set the same standard for noninstrument spacecraft components, including avionics and radiation shielding.

“The avionics that we would like to use … need to be avionics that currently exist, that are currently qualified, and somebody else has paid to qualify them,” Brian Cooke, Europa Clipper’s project system engineer, said during the meeting. “Our target radiation dose is no bigger than 300 kilorads. We’d like to push that down to 100 kilorads, if we can. But we know there exists a class of commercial parts, commercial space-grade parts, that someone has already paid to qualify, typically for use in geosynchronous satellites.”

Because the 2013 appropriations bill with the Europa Clipper funding was signed halfway through the fiscal year, NASA will not be able to spend it all before the year ends Oct. 1, Niebur said. “As a result, a lot of that 70-ish million is going to be carried forward in 2014 and keep the team going,” he said.

Personnel involved with Europa Clipper at this point include a science definition team chaired by Louise Proctor at the Johns Hopkins University’s Applied Physics Laboratory in Laurel, Md., and a Jet Propulsion Laboratory (JPL) team led by Project Manager Barry Goldstein.

NASA has not committed to flying Europa Clipper, but the mission enjoys support in Congress. The House Appropriations Committee is especially keen on the project and has, as part of a $47.4 billion commerce, justice, science appropriations bill that holds spending to sequestered levels, approved another $80 million for Europa in 2014. The committee’s bill passed July 17 and is awaiting vote by the full House. The Senate Appropriations Committee moved a NASA spending bill to the floor July 18, but it included no specific mention of Europa.

The money in the proposed 2014 legislation is “for pre-formulation and/or formulation activities including an Announcement of Opportunity for instrument development in support of a mission that meets the scientific goals outlined for the Jupiter Europa mission in the Planetary Science decadal survey,” the report accompanying the bill said.

That language dovetails with NASA’s plan for the $15 million worth of instrument maturation contracts due to be awarded in August.

“The goal of the ICEE program is to … be ready to propose an instrument [announcement of opportunity] should the stars align and it be released in the near future,” Niebur said July 15.

“Near future” in this case likely means three to five years, Niebur said.

According to the current mission plan from JPL, Clipper would notionally launch in 2021 aboard the most powerful variant of United Launch Alliance’s Atlas 5, the 551.

The craft would arrive at the Jovian system in spring 2028, according to JPL’s preliminary mission design, dropping into orbit around Jupiter, rather than Europa. Clipper would piece together data gathered through a series of Europa flybys, rather than by orbiting the planet directly.

It is not clear when the estimated $2 billion the mission requires might become available, but launch opportunities to Jupiter would come annually due to the flightpath mission planners have honed in on.

Mission planners have also considered whether the Space Launch System heavy-lift rocket NASA is building would be suitable for the mission. Assuming that vehicle is available — and it is not clear that it would be, given its projected low flight rate, and Congress’ desire to utilize it for crewed missions — the length of Clipper’s cruise could be cut in half.  If launched aboard the heavy lifter in 2022, the probe would arrive at  Jupiter by 2025, according to estimates by the JPL team.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.