Skip to content

2024 Guest Speaker Schedule

Exploring Ocean Worlds Beyond Earth

February 8Steve Vance
NASA Jet Propulsion Laboratory
Spacecraft investigations of ocean world habitability
The Galileo and Cassini missions revolutionized our understanding of the outer solar system, revealing numerous confirmed and potential ice-covered ocean moons. The study of ocean worlds still relies on remote observations and extrapolation from conditions on Earth that feed informed speculation about the possibility for life. I will review the next generation of exploring ocean world habitability, represented by the Europa Clipper (Vance et al. 2023). My own research investigates how Europa might support life, and how geophysical measurements might constrain that. I will review possible redox conditions in Europa’s ocean (Vance et al. 2016), and our group’s approach for using laboratory physical and chemical data to explore how different possible Europa interiors might look to Europa Clipper and other future missions (Vance et al. 2018, 2021).
Suggested reading
February 15Tori Hoehler
NASA Ames Research Center
Biological Potential and Biosignature Potential of the Ocean Worlds
Life as we know it requires liquid water, specific elements, energy, and suitable physicochemical conditions. The last few decades of solar system exploration have revealed that several bodies in our solar system may possess extensive liquid water oceans. Spacecraft observations and theoretical considerations suggest that the elements required by life may be abundant within these oceans. However, lacking direct access to light or to the products of photosynthesis, any life in these oceans may be limited to fluxes of energy that are many orders of magnitude lower than they are on Earth. I will consider the resulting implications for the nature and abundance of evidence for life, using Earth’s oceans as an empirical point of reference.
February 22NO SPEAKER
February 29Donna Blackman
UC Santa Cruz
Taking (sub)seafloor Earth knowledge out to other Ocean Worlds in our Solar System
Half a century of marine geophysical research on Earth forms a strong basis for
interpreting the processes that shape our ocean floor and its subseafloor structure. The 'Rocky Interior' component of our Exploring Ocean Worlds collaborative project investigates aspects of knowledge from Earth's (sub)seafloor that can provide insight on other Ocean Worlds (OW) such as Enceladus, Europa, and Titan. This geophysical work is done with broader intent to provide results that can feed into subsequent investigations of geochemical exchange that could have potential to support life. Seafloor heterogeneity had been ignored in planetary studies prior to the ExOW project but on Earth it is a key factor controlling the nature and distribution of subseafloor hydrothermal flow. While many seafloor features are produced by tectonic forces on Earth, mechanisms to create ocean floor topography on OW could also (have) exist(ed). Enhanced thermal gradients associated with kilometer-scale seafloor features host known hydrothermal
venting on Earth. Here we explore whether such systems could be physically viable on OW where gravity is just a fraction of Earth's and the structure of the rocky interior could differ notably. We find that the occurence of km-scale relief with sustainable hydrothermal flow cannot be ruled out. While current planetary observations cannot discern whether such seafloor variability and hydrothermal flow occurs, our findings indicate that their presence should still be considered in ongoing modeling of OW processes.
March 7Laurie Barge
NASA Jet Propulsion Lab
Searching for Signs of Life and its Origin on Other Planets
Is there life elsewhere in the solar system, and if so how can we find it? Although Earth provides a variety of examples of what biology can look like, examples of the critical steps between abiotic and biotic systems are lacking because the prevalence of life on our planet has erased its record of prebiotic conditions. The distinction between biotic and abiotic is still often unclear in astrobiology, partly because abiotic chemistry can become more complex when devoid of biological influence. Prebiotic chemistry may still be a current or formerly active process on other worlds with detected chemical gradients and organics, for example on ocean worlds such as Enceladus which may host active hydrothermal systems. In this talk I will discuss our group’s work on simulating prebiotic systems that aim to bridge the gap between geochemistry and biochemistry, and how we can use this to aid the search for life and its origin on other planets.
March 14Justin Lawrence
Honeybee Robotics
Developing Advanced Robotics for Ocean World Exploration
March 21Wanying Kang
On icy satellites, size controls the ice geometry
Enceladus and Europa, two icy satellites in our solar system, share similar surface temperatures and mean ice thickness. Despite that, their ice shell geometries are likely to be very different. Gravity and shape measurements taken on Enceladus favor a strongly poleward thinning ice shell, whereas Europa’s ice shell seems to be much flatter, supported by its limb profile.
This work proposes a mechanism to explain such a difference, which may be generalized to make predictions for other icy satellites. The key behind is the ocean dynamics. Driven by the temperature and salinity gradients underneath a thickness-varying ice shell, overturning circulations and baroclinic eddies will form, redistributing heat and tracers over the globe. The ocean heat transport (OHT) will, in turn, flatten the ice shell through the ice-pump mechanism. The efficiency of the OHT, however, varies with the satellite’s size and rotation period. In this work, we derive scaling laws that govern the OHT amplitude, verify the scalings using numerical simulations, and use them to predict the equilibrium ice thickness variations for icy moons with various sizes and rotation periods. Because of Europa’s strong gravity and slow rotation, its ice thickness variation is predicted to be less than 2km, in contrast to a 12+km ice thickness variation predicted for Enceladus. Given the OHT scaling laws, we demonstrate the possible ice evolution pathways for Enceladus and Europa using an ice evolution model with parameterized OHT.
April 4Sam Howell
NASA Jet Propulsion Laboratory
Behaviours of Ice Shells on Ocean Worlds: Geophysical Insights
April 11Jill Mikucki
University of Tennessee
Potential for Life in Ice Shells on Ocean Worlds: Microbes in Extreme Environments
April 18Chris Glein
Southwest Research Institute
Using In Situ Sensors to Reveal the Chemistry of Ocean Worlds' Oceans
April 25Annette Rowe
University of Cincinnati
Rock Powered Life: Microbiology in Hydrothermal Systems
May 2Kevin Hand
NASA Jet Propulsion Laboratory
Future Missions to Ocean Worlds: Landing on Ice and Accessing Oceans