It all began decades ago

After the two Voyager flybys in 1979, NASA sent a dedicated probe named #Galileo to Jupiter in the 1990s.

This spacecraft made several passes by #Europa during its nearly eight years in orbit around Jupiter, and data from this mission indicated the likely presence of a water ocean beneath the moon's icy surface.

In the nearly three decades since then, planetary scientists have had little more to go on than these tantalizing clues.

They've desperately wanted to know more.

Almost immediately after the first Europa data from Galileo beamed back to Earth in 1996, the administrator of NASA at the time,
#Dan #Goldin,
asked scientists at the agency's Jet Propulsion Laboratory in California whether a small mission dedicated to the study of Europa was possible.

Fitting within Goldin's ethos of
"faster, better, and cheaper,"
he wanted a design for a spacecraft carrying just 27 kg of scientific instruments to Europa,
about the same mass as a suitcase than can be checked on to an airplane.

"That was the beginning of a Europa orbiter concept," said science writer David Brown, author of
"The Mission", which tells the definitive story of the Europa Clipper mission.

The original science objectives outlined during the development of this orbiter mission
—to investigate the composition of Europa’s ice shell and ocean, the world's geology, and to search for and characterize any plumes emanating from the ocean below
—remain more or less the same with #Clipper.

However, as often happens with deep space missions, the budget doubled.

NASA's chief of science at the turn of the century, astrophysicist Ed Weiler, killed the nascent Europa program.

But scientists were still interested.

In 2003, the National Research Council published its first "decadal survey,"
a process by which the scientific community outlines research priorities for NASA.

Over the years, these decadal surveys have become influential tools for guiding NASA policy.

In this first survey, scientists recommended that NASA establish a "large-class" mission to study #Europa