They have a number of ideas that could fit as add-ons to US missions that are likely to be launched in the 2020s.
The concepts range from remote-sensing instruments to penetrators that would try to burrow beneath Europa's ice-encrusted surface.
Whatever option is chosen, it will first have to win the support of the European Space Agency.
The Paris-based organisation is about to issue a call for proposals to fill a medium-cost launch opportunity - and the invitation will cover the full gamut of space exploration, not just planetary science.
Nonetheless, there is an offer on the table to Esa from its American counterpart, Nasa, to participate in the Europa ventures.
These missions will likely include a probe, to be launched in 2022, that will make repeated passes of the moon.
It is very probable also that Nasa will send another craft to make a soft landing. This could launch in 2022 with the first mission, or separately a couple of years later.