Context

Jupiter’s moon Europa is defined as a priority target for a NASA Flagship mission in the 2013 Planetary Division Decadal Survey, “Vision and Voyages for Planetary Science in the Decade 2013-2022”. Observations with the Hubble Space Telescope show evidence for gaseous plumes suggestive of outgassing from the sub-crustal ocean, possibly similar to that observed in Saturn’s moon Enceladus. Such plumes may enable a probe to sample Europa’s ocean without landing. The activity, however, is at best sporadic: Europa has been targeted for observation on 55 occasions; gaseous plumes have been tentatively detected on only four occasions. Given the potential importance of these observations, the STScI Director is constituting the present committee to provide advice on how Hubble can best support planning for potential future missions.

Charter

The committee is chartered to address the following question:

Is there a suite of observations with Hubble that can provide definitive answers on the frequency of outgassing from the Europan ocean and the characteristics of the associated gaseous plumes?

In answering this question, the committee should consider the following issues:

  • What are the pros and cons of observations in different instrumental modes?
  • What are optimal observing strategies to determine the frequency of active outgassing?

STScI will provide technical support for these inquiries. The committee will report back to the STScI Director by April 2017.

Constituted

November 2016

Membership
Chair: John Clarke (Boston University)

Members: Amanda Hendrix (Planetary Science institute), John Spencer (SWRI)

Report

Final report

Outcomes


Call for proposals to monitor Europa in conjunction with the Fall 2017 mid-cycle proposal opportunity; 3 proposals were selected for execution.

  • GO 15419: Abundance, composition, and variability of Europa's plumes: Pathfinding future habitability investigations, 55 orbits
  • GO 15424: An intensive ultraviolet imaging campaign for Europa's plumes, 30 orbits
  • GO 15425: Eclipse observations of Europa's water plumes, 10 orbits



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