WASHINGTON — The team working on the leading concept for a mission to Europa believes it can be ready for launch as soon as 2022, several years ahead of the schedule NASA officials recently stated.

In a Feb. 19 presentation to NASA’s Outer Planets Assessment Group (OPAG) at the Ames Research Center, Barry Goldstein, Europa Clipper pre-project manager at the Jet Propulsion Laboratory, said they are taking advantage of additional funding provided by Congress to accelerate work on the mission.

“It’s our responsibility to drive as hard as we can to launch as early as we can,” he said. “Our best-case scenario is launching in an opportunity that opens up in May to June of 2022, and we’re holding to that.”

That schedule is more aggressive than what NASA officials said Feb. 2 when they released the agency’s 2016 budget proposal. That proposal included $30 million for a Europa mission, with the projected budget gradually increasing to $100 million per year by 2020.

“For the first time, this budget does assume a five-year funding profile for a mission to Europa,” NASA Chief Financial Officer David Radzanowski told reporters in a Feb. 2 conference call. “The current funding profile would assume a launch in the mid-2020s.”

Congress, though, has been more generous with funding for a Europa mission, appropriating about a quarter billion dollars in the last three years, including $100 million for 2015. That has allowed NASA to accelerate risk reduction work on the Europa Clipper mission design and seek proposals for instruments the spacecraft will carry.

“Congress has really been quite generous,” said Jim Green, director of NASA’s Planetary Science Division, in a separate presentation at the OPAG meeting. “We’re forward funding a lot of work.”

That included determining whether Europa Clipper should use solar panels or a nuclear-powered radioisotope thermoelectric generator (RTG). “We had a mandate to show that if we are going to use RTGs, it was something that was required for this mission,” Goldstein said.

Those studies found that solar panels could work in the vicinity of Jupiter, surviving the harsh radiation environment there as well as “cryogenic” temperatures when the spacecraft flies through the planet’s shadow. The performance of the panels also will degrade more slowly than an RTG, allowing for an extended mission. Goldstein said an independent panel endorsed the team’s decision to use solar power for Europa Clipper.

“Today we don’t have any significant engineering risks on the baseline engineering subsystems,” Goldstein said of the overall Europa Clipper design. He added, though, there will likely be challenges later, when instruments are selected and incorporated into the spacecraft.

While Europa Clipper is considered the leading concept for the Europa mission NASA plans to formally start this spring, Green cautioned that there may yet be changes to its design. He said NASA has yet to select instruments for it, and that the agency is looking at potential international partnerships, including with the European Space Agency.

Green called Europa Clipper “a proof of concept,” but acknowledged it appeared more viable that alternative concepts. “There’s no doubt that Clipper has popped to the top, but it’s also not yet at Phase A.”

Green also said it was premature to establish formal cost and schedule estimates for the mission, something he said would not come until the mission reached a development milestone known as Key Decision Point C. In the schedule presented by Goldstein at the meeting, that would not take place until May 2018.

Earlier studies, though, concluded Europa Clipper would cost approximately $2 billion, about half the estimated cost of previous designs for a Europa orbiter. That lower cost has made Europa Clipper much more palatable to NASA and the White House.

“If you think the administration is going to allow us to do a $4 billion Europa mission, you’re wrong,” Green told scientists at the OPAG meeting. “That isn’t going to happen.”