The fact that Charles Elachi is retiring after 15 years of directing NASA's Jet Propulsion Laboratory in June may have him willing to speak freely. During a hearing Thursday before a Congressional committee, Elachi apparently had no qualms about contradicting NASA's administrator, Charles Bolden.

Bolden has said NASA should fully explore Europa with a flyby mission before building and flying a lander to Jupiter's ice-covered moon, which contains a vast, subsurface ocean. "Our belief is that that is imprudent from a scientific perspective," NASA's administrator told Ars late last year.

During the Congressional hearing, however, Elachi said his engineers could design both a flyby spacecraft and lander that could fly to Europa in tandem. Moreover, Elachi said, to really begin addressing the question of life existing on Europa, such a mission must have the capability to reach the surface. "In order to make sure we have confirmation, we really need to make direct measurements on the surface, to take samples," he said. "Clearly a lander, in my mind, is a necessity to understand the oceans on Europa."

The mission

Although design work remains preliminary, Elachi did discuss several new details about a mission to Europa that could launch as early as 2023. His engineers have designed two separate spacecraft, which could launch together on a single large rocket or on separate launch vehicles. That decision doesn't have to be made for two or three years.

The first spacecraft, a flyby mission, would make dozens of passes by Europa, swooping into the harsh radiation environment near Jupiter to closely survey the moon and then move back out to a much more benign environment. There, it would transmit images and scientific data back to Earth.

This flyby spacecraft might be able tell scientists whether complex organic molecules exist on the moon's surface, but to learn whether they're indicative of life below the moon's ice shell would require a lander, said Elachi, as well as another researcher at the hearing, Cornell University's Jonathan Lunine. After studying data collected by the flyby mission, engineers would then command a second spacecraft parked a safe distance from Europa to advance toward the most biologically interesting and safest location.

One of Bolden's concerns has been that it would not be safe to land on Europa. However, Elachi said his laboratory is designing a lander that will take pictures as it is coming down and have the capability to move to a safer place on its descent. This technology will be demonstrated on a lander flying to Mars in 2020, he said. Moreover, even if the pod carrying the lander to the surface tips over upon reaching the ice, it will be able to right itself. "These are some of the steps that will ensure we will be able to land safely on the surface," Elachi said.

The lander would likely carry cameras and a seismometer to test the thickness of the ice, Elachi said. In addition, the rover will likely carry both mass and Raman spectrometers to analyze ice samples drilled from the surface of the moon. "This is the only way to study the organic molecules on the surface," he said. "That's why the lander is critical."

Elachi's tenure at the California lab, which designs and develops most of NASA's robotic spacecraft, has been marked in particular by the successful exploration of Mars with the Spirit, Opportunity, and Curiosity rovers. In April, he will be honored with the prestigious National Space Trophy from the Rotary National Award for Space Achievement Foundation.

Politics

The House Appropriations Subcommittee with jurisdiction over NASA's budget convened the hearing. Its chairman, John Culberson, a Republican from Texas, has championed the Europa mission for several years. He wants to explore the question of life existing elsewhere in the solar system, and Europa is the highest priority target of the planetary science community. "The goal of this mission is to achieve the scientific objectives of the decadal survey," Culberson said during the hearing.

Bolden has suggested that NASA should go slower, however, and the White House has shown a disinclination to support Congressional desires to explore Europa. In its 2013 and 2014 budgets, the White House didn't request any funding for a Europa mission. But Culberson, through his position on the Appropriations subommittee and by working with the Senate, provided a total of more than $120 million for Elachi and his team to study preliminary designs.

Finally, in its fiscal year 2015 budget request, NASA acquiesced and created a Europa program. The president’s budget called for $15 million to begin preliminary studies. Culberson appropriated $100 million. For fiscal year 2016, NASA requested $30 million. It got nearly six times that. For the coming fiscal year, the White House has asked for $50 million. Culberson told scientists and engineers on Thursday to ignore that.

Meanwhile, behind the scenes, NASA has been moving forward with preliminary work on the lander. At the end of February, the agency's Planetary Science Division announced plans to conduct a "Pre-Phase A" study of a Europa lander mission concept, with a goal of defining the science objectives and feasibility of specific lander mission. This work would help define the scientific payloads that would best address the question of life in Europa's oceans.

During the hearing, Elachi said this process could take about three months and that time is of the essence, as his engineers can't design the lander spacecraft without a better understanding of the size and nature of these scientific instruments. "We will push NASA to make sure they get this done as rapidly as possible," Culberson told him.