Growing congressional support and tantalizing scientific possibilities are behind a NASA plan to spend $25 million on instrument development for an unmanned mission to Europa, the moon of Jupiter where Earthlings were warned to "attempt no landing there" in Arthur C. Clarke’s "2010: Odyssey Two."

Despite the warning, the agency lists characterizing a landing site as one of its priorities for an initial Europa mission. Presently NASA is focusing on an orbiter or a "multiple flyby mission" in the near term, according to its announcement of opportunity for instrument development.

"NASA places high priority on this goal to enable a potential future lander mission to Europa," the agency stated in announcing the instrument opportunity. "Current data does not provide sufficient information to identify landing sites and design a landing system capable of safely reaching the surface."

Characterizing a landing site was the fourth in a list of priorities for a Europa mission highlighted by the U.S. National Research Council’s Planetary Science Decadal Survey of the scientific community, which listed a Europa mission high on its overall list of scientific targets. The frozen moon is believed to have a liquid-water ocean beneath its crust with more volume than the oceans on Earth. Scientists consider liquid water a prerequisite for life as it is known on Earth, and recent work with the Hubble Space Telescope suggests that some of that water is escaping into space to an altitude high enough for direct analysis by an orbiter or flyby probe.

"The possibility of life on Europa is a motivating force for scientists and engineers around the world," stated John Grunsfeld, associate administrator for NASA’s Science Mission Directorate at the agency’s headquarters in Washington. "This solicitation will select instruments which may provide a big leap in our search to answer the question: Are we alone in the universe?"

The agency plans to select about 20 proposals in April 2015, and to provide about $25 million to those selected for Phase A concept studies, to include advancing instrument formulation and development. NASA plans to select about eight instruments for an orbital or multiple-flyby mission in orbit around Jupiter that can target landing sites and address all of the NRC survey priorities: characterize the extent of the ocean and its relation to the moon’s interior; characterize the ice "shell" and how it relates to the liquid ocean below; determine the moon’s habitability by studying surface chemistry, and study how the moon interacts with the space environment around Jupiter.

Also on the list is instrumentation for in situ analysis of the plumes, if their existence is confirmed with additional observations. Instruments must be able to withstand the harsh radiation environment around Jupiter, and meet strict standards against forward contamination of the moon’s environment with Earth-born microbes.

"Proposals must be responsive to one or more of the six objectives," stated Curt Niebur, NASA’s outer planets program scientist. "Plans could be adjusted to programmatic decisions made by NASA in the future."