WASHINGTON — While NASA says its support for a mission to Jupiter’s moon Europa is now aligned with Congress, project officials are preparing for a possible “squeeze” on mission funding in the next fiscal year.

In presentations at an Aug. 11 meeting of NASA’s Outer Planets Assessment Group (OPAG) in Flagstaff, Arizona, officials involved with what’s widely known as the Europa Clipper mission said they are looking for ways to cut costs in 2017 while keeping the mission on track for a 2022 launch.

“There is this squeeze in FY17 that we have,” said Bob Pappalardo, the mission’s project scientist at the Jet Propulsion Laboratory, said. “We’re asking the instrument teams and various other aspects of the project, given that squeeze, what will it take in the out years to maintain that ’22 launch. We’re actively pursuing that question as we speak.”

Pappalardo didn’t elaborate on the budget details, but the administration’s request for the mission in its 2017 budget proposal, $49.6 million, is far less than the $175 million it received from Congress in 2016. There is uncertainty in Congress as well: a House appropriations bill for fiscal year 2017 offers $260 million for the Europa mission, yet a Senate bill, while “supportive” of the mission, does not explicitly allocate any funds for it. Neither bill has been passed by either chamber.

Similar mismatches have occurred in prior years, with the higher House level usually prevailing. That has created a perception among some mission advocates that NASA is not that interested in the mission, a view an agency official sought to dispel at the OPAG meeting.

“Everyone is aware of how supportive and generous Congress has been of this mission, and I’m happy to say that that support and encouragement is now shared by the administration, and by NASA as well,” said Curt Niebur, the mission’s program scientist at NASA Headquarters. “Everybody is on board the Europa Clipper and getting this mission to the launch pad as soon as our technical challenges and our budget will allow.”

Project officials said that, with the current funding, they are on schedule to be ready to launch in 2022, a date set by Congress in its 2016 appropriation bill and affirmed in the House version of a 2017 spending bill. Niebur said the project recently completed a process of accommodating all the previously selected instruments for the mission on the spacecraft bus, a complex process that takes into account the instruments’ technical requirements while maximizing the amount of data they can collect.

However, the mission is not pursuing any additional enhancements, such as the addition of free-flying probes to study the moon and plumes of water ice ejected from its surface, as well as a laser altimeter. “The additional science value provided by these additions was not commensurate with the associated impact to resources, to accommodation, to cost,” Niebur said. “There just wasn’t enough science there to balance that out.”

Development of the Europa mission is also encountering power issues. Illustrations of Europa Clipper show the solar-powered spacecraft with two arrays of four solar panels each. Niebur said the latest spacecraft design now includes a fifth panel on each array. “I really can’t stress enough what an impact and a burden it is to go from four to five,” he said. “That makes this spacecraft much more difficult to fly, so we really are quite focused on getting it back down to four.”

NASA has not yet selected a launch vehicle for the mission, but the baseline remains the Space Launch System, which allows the spacecraft to travel from Earth directly to Jupiter. Pappalardo said the mission is continuing to study the use of Delta 4 Heavy and Falcon Heavy as alternatives, but those would require the use of gravity assists that increase the mission’s flight time. The use of the Atlas 5 has been “closed off,” he said.

As development of Europa Clipper continues, NASA is working on a “pre-Phase A” study of a Europa lander mission while a science definition team (SDT) outlines its science goals. Niebur said that NASA is spending about $35 to $40 million of the $175 million allocated for a Europa mission in 2016 for either the lander study or related technology development work.

A notional plan for the lander mission calls for its launch in 2024 on an SLS, separate from the Europa Clipper spacecraft. The spacecraft would land on surface of Europa using a version of the “skycrane” system demonstrated by the Curiosity Mars rover in 2012. The spacecraft, powered solely by batteries, will operate after landing for about three weeks.

NASA, however, has not committed to a formal plan for the lander as it awaits the outcomes of the ongoing studies. “We’re interested in a mission, but we don’t know if a worthwhile mission is possible given the constraints we’re under,” Niebur said. “It’s up to the pre-Phase A study and the SDT to come up with a mission concept that doable and worthwhile, and present it to NASA.”

Niebur didn’t indicate when NASA would make a decision on proceeding with a lander mission, but said the SDT should complete its report late this year. “Let’s see if a worthwhile mission is doable,” he said. “I’m confident they’ll prove that’s the case.”

That assessment includes ambitious science goals for the lander. While Europa Clipper is designed to determine if the moon and its subsurface ocean of liquid water could support life, the lander is intended to directly detect evidence of any life there.

“Mission success, in NASA’s mind for this mission, which is 23 or so days long, is that on day 25 we have a press conference at NASA Headquarters and announce that we’ve found life,” Niebur said. “If that is an unrealistic expectation, I need to know it now and not on day 22 of the mission.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...