Jupiter’s moon Europa hides an ocean of water beneath its icy crust that might harbor extraterrestrial life.

Unfortunately, big dollar signs have kept alive the fictional decree in Arthur C. Clarke’s Space Odyssey series to leave Europa alone: No robot has ever landed on, drilled into or orbited the chilly world. Only a handful of spacecraft have flown by.

A panel of scientists determined in 2011 that NASA’s plans to explore the moon with a single spacecraft, called the Jupiter Europa Orbiter, or JEO, would cost about $4.7 billion. That amount of cash, they wrote, “is so high that both a decrease in mission scope and an increase in NASA’s planetary budget are necessary to make it affordable.”

But even before the panel slammed the mission’s financial feasibility, astrobiologist Pabulo Henrique Rampelotto of Brazil’s Federal University of Pampa was plotting to save exploration of Europa.

In a study published July 13 in Astrobiology, Rampelotto argues that nixing one large orbiter and instead sending three small spacecraft — two orbiters and a probe carrying surface impactors — could spread out both the cost and the risk while hitting all of JEO’s science goals, and then some.

“[T]he main advantages are the complete access to the habitability of Europa, simpler mission design and low cost for each mission,” Rampelotto wrote in an e-mail to Wired. “Europa is considered the prime candidate in the search for life in our solar system. Its ocean may be in direct contact with the rocky mantle beneath, where the conditions could be similar to those on Earth’s biologically rich sea floor.”

Both NASA and the European Space Agency hope to explore Europa and Ganymede, another of Jupiter’s moons, sometime in the next two decades because both bodies may hide a liquid ocean. In the joint space exploration plan, called the Europa Jupiter System Mission, NASA would launch JEO within this decade. Around the same time that spacecraft launches, Europe would rocket its own Jupiter Ganymede Orbiter into deep space.

Budget hawks, however, aren’t buying into NASA’s $4.7 billion dream. Accounting for other higher-priority missions, JEO would stretch further NASA’s shrinking annual planetary science budget of $1.5 billion.

“I believe you will not find someone who continues to support the $4.7 billion … mission concept,” Rampelotto said. “And that is interesting because before the release, no one was considering the possibility of an alternative mission concept.”

'Europa is considered the prime candidate in the search for life in our solar system.' — Pabulo Henrique Rampelotto

Rampelotto beat the panelists to the punch by proposing his three-spacecraft mission. If built and launched within the next few years, mission one — an orbiter to measure the thickness of Europan ice and see how deep its oceans go — could reach Europa between 2020 and 2025. A second orbiter would launch a few years later, map the surface in visible and infrared light, and determine if any organic chemicals are present.

“Mission two is technically easier than mission one and could be launched very soon too,” Rampelotto wrote. “After we have those results from missions one and two, mission three would be mature enough to be launched.”

That mission would pound the surface with impactors, penetrate between 3 and 33 feet of ice, and then beam data about the ice’s composition to Earth. It’s unlikely any impactor would reach the subsurface ocean, however, because the thinnest ice may be 1.8 miles thick. Even below that depth, only lakes of water far above the ocean may be locked in the icy crust.

“But, if delivered in potential landing sites where liquid water from the ocean could have recently reached the surface or near surface, we could analyze indirectly the ocean composition, including signals of life,” Rampelotto wrote.

Rampelotto’s plan to barnstorm Europa offers no concrete costs for each mission, which he said would require “advanced studies” to determine. So the idea isn’t without its critics. “NASA team leaders … have advised me that penetrators are difficult and risky to deliver and the best option continues to be a lander,” Rampelotto wrote.

Bob Pappalardo, a planetary scientist who studies Europa and is helping NASA develop future missions to the moon, said Rampelotto’s scheme is a logical one during tight budgetary times. But he noted saving money by splitting up a big mission into smaller ones brings about another issue: fear of commitment.

“The reality is that NASA is not going to want to fund or begin a program of missions, based on the reaction to the Mars sample return suggestion,” said Pappalardo, who wasn’t involved in Rampelotto’s study. “That went over like a lead balloon [at the White House], in terms of being a long-term budgetary relationship.”

Pappalardo hopes that, if there are signs of a recovering U.S. economy in the next few years, they will spur the current presidential administration to open its tight wallet.

“Right now the goal is to do anything at Europa,” he said. “I really hope we’ll come back to our senses soon. I don’t see the vision for planetary science that was present in the past.”

“We need to be planning on the future,” he said. “As it stands, in a few years, we won’t be launching anything. We’re in danger of losing our leadership in planetary science.”