Transient water vapor at Europa's south pole

Area of Science:

• Planetary Science
• Astrobiology
• Space Exploration

Background:

• Europa, Jupiter's moon, is a prime target in the search for extraterrestrial life due to its subsurface ocean.
• Previous observations have hinted at water vapor plumes, but definitive evidence has been elusive.

Purpose of the Study:

• To investigate Europa's potential for water vapor plume activity using ultraviolet emissions.
• To determine the characteristics and variability of any detected plumes.

Main Methods:

• Utilized the Hubble Space Telescope (HST) to image Europa's ultraviolet emissions in November and December 2012.
• Analyzed hydrogen Lyman-α and oxygen OI 130.4-nanometer emissions for signs of plume activity.

Main Results:

• Detected statistically significant surpluses of hydrogen and oxygen emissions above Europa's southern hemisphere in December 2012.
• These emissions persisted for 7 hours, consistent with two 200-km-high water vapor plumes.
• No plume activity was detected in November 2012 or in earlier 1999 HST images.

Conclusions:

• Europa exhibits variable water vapor plume activity, potentially linked to its orbital position and tidal stresses.
• The findings support models predicting plume presence near apocenter and absence near pericenter.
• This research enhances our understanding of Europa's dynamic environment and potential habitability.