Samuel M. Howell, PhD
Ocean Worlds Scientist
Samuel M. Howell, PhD
Ocean Worlds Scientist
nasa.gov homepage featuring work on Europa ocean material exposure through faulting processes
Accessing Subsurface Oceans
I am working with JPL, Honeybee Robotics (SLUSH vehicle pictured), and other partners to develop future ocean world exploration technologies. In addition to science development, I simulate the goelogic stress, strain, thermal, and compositional state of ocean world ice shells to constrain the system capabilities of ice shell penetrating drills, water jets, and melt probe hybrids.
Can Earth-like plate tectonics occur in ocean world ice shells? (2019, Icarus)
This study explores whether a cycle of buoyantly-driven plate tectonics is possible on worlds with oceans hidden away by thick ice shells, like Jupiter's Europa and Ganymede, Saturn's Enceladus, or Neptune's Triton
Camilla: A Centaur reconnaissance and impact mission concept (2018, Planetary and Space Science)
This mission concept was the result of the 2018 NASA Planetary Science Summer Seminar, for which I served as Principle Investigator, and outlines a flyby mission with impactor to visit 10199 Chariklo, a double ringed Centaur.
Band formation and ocean-surface interaction on Europa and Ganymede (2018, Geophysical Research Letters)
This study explores tectonic bands on Europa, including why they look the way they do, and which ones might expose material from Europa's deep ocean at the surface.
Seafloor expression of oceanic detachment faulting reflects gradients in mid-ocean ridge magma supply (2019, Earth and Planetary Science letters)
This study explores controls on the formation and evolution of oceanic core complexes. We are merging 2-D physical simulation with the basic physics of faulting in 1-D to learn why these important mid-ocean ridge structures look the way they look.
The vertical fingerprint of earthquake cycle loading in Southern California (2016, Nature Geoscience)
We use statistic modeling of vertical GPS data near the southern San Andreas Fault System and physics-based models to identify the current pattern of uplift and subsidence due to earthquake cycle loading. This research received national attention, including a 2016 Popular Mechanics Breakthrough Award.
Sam is an Ocean Worlds Scientist in the Planetary Interiors and Geophysics Group at JPL, as well as a Project Science Affiliate on the Europa Clipper mission. He works on constraining geologic processes that shape ocean world ice shells, and the future exploration technologies capable of accessing the interior oceans.
He obtained his B.S. in Engineering Physics from the Rose-Hulman Institute of Technology with a concentration in Mechanical Engineering and minor in Thermal Fluid Mechanics. Sam obtained his M.S. and PhD in Geology and Geophysics University of Hawaiʻi at Mānoa, where he explored planetary-scale process through studies of local surface features. His research on Earth, the first-discovered ocean world, focused on the simple understanding that observable features are fingerprints of the planetary processes at depth: failure, flow, melting, mixing, and material transport. Samuel’s graduate research garnered national attention, including a 2016 Popular Mechanics Breakthrough Award for innovation detecting and predicting motions on the San Andreas Fault.
Samuel’s current and proposed research concerns the mechanisms and timescales of ocean world material mixing and evolution, as well as the exchange of materials between interior oceans and outer ice shells. His recent research linking tectonic processes on Europa and Ganymede to the surface exposure of fossilized ocean material received NASA-wide coverage and the 2016 JPL Outstanding Postdoctoral Research Award in Planetary Science and Astrobiology.
In his spare time, he has climbed Mount Kilimanjaro, completed triathlons and marathons, and serendipitously met his wife, Marissa, an expert on the surfaces of icy moons.
(818) 393 - 82
Howell, S., R.T. Pappalardo (2019), Can Earth-like plate tectonics occur in the outer ice shells of icy satellites? Icarus, doi:10.1016/j.icarus.2019.01.011
Howell, S., J-A. Olive, G. Ito. M. D. Behn, J. Escartin, B. Kaus (2019), Seafloor expression of oceanic detachment faults reflects gradients in mid-ocean ridge magma supply, Earth and Planetary Science Letters, doi:10.1016/j.epsl.2019.04.001
Howell, S., L. Chou, 2017 NPSSS team (2018), Centaur reconnaissance mission concept: Chariklo flyby and impact, Planetary and Space Science, doi:10.1016/j.pss.2018.07.008
2017 JPL Outstanding Postdoctoral Research Award Recipient
Howell, S., R.T. Pappalardo (2018), Band formation and ocean-surface interaction on Europa and Ganymede, Geophysical Research Letters, doi:10.1029/2018GL077594
Howell, S., G. Ito, M. D. Behn, F. Martinez, J.-A. Olive, and J. Escartín (2016), Magmatic and tectonic extension at the Chile Ridge: Evidence for mantle controls on ridge segmentation, Geochem. Geophys. Geosyst., doi:10.1002/2016GC006380
2016 Popular Mechanics Breakthrough Award Recipient
Howell, S., B. Smith-Konter, N. Frazier, X. Tong, D. Sandwell (2016), The vertical fingerprint of earthquake cycle loading in Southern California, Nature Geoscience, doi:10.1038/ngeo2741
Olive, J.-A., M. D. Behn, G. Ito, W. R. Buck, J. Escartín, S. Howell (2016), Response to Comment on “Sensitivity of seafloor bathymetry to climate-driven fluctuations in mid-ocean ridge magma supply”, Science, doi:10.1126/science.aaf2021
Olive, J.-A., M. D. Behn, G. Ito, W. R. Buck, J. Escartín, S. Howell (2015), Sensitivity of seafloor bathymetry to climate-driven fluctuations in mid-ocean ridge magma supply, Science, doi:10.1126/science.aad0715
Howell, S., G. Ito, A.J. Breivik, A. Rai, R. Mjelde, B. Hanan, K. Sayit, P. Vogt (2014), The origin of the asymmetry in the Iceland hotspot along the Mid-Atlantic Ridge from continental breakup to present-day, Earth Planet. Sci. Lett., doi:10.1016/j.epsl.2014.02.020
B. Boston, S. Howell, J. Sleeper, A. Anderson, M. Cameron, T. Sigurdardottir, J. Tree, H. Togia, B. Smith-Konter, G. F. Moore, (2018), Seafloor Mapping at Your Fingertips: Setting Sail on Sonar Education with an Interactive Exhibit, The Earth Scientist, 34, 1, 11-15.
B. Boston, S. Howell, G. Moore, University of Hawaii Geophysical Society (2014), A miniature research vessel: A small-scale ocean-exploration demonstration of geophysical methods, The Leading Edge, SEG, doi:10.1190/tle33121408.1
TN273, The tectonics, igneous activity, and mineralization of the southern Mariana Forearc, Technician aboard the R/V Thomas G. Thompson, 22 Dec., 2011 – 22 Jan., 2012 (Arpa Harbor, Guam)
Scientific Objective: Map the Malaguana-Gadao ridge in the southeastern Mariana forearc riftzone and other sites using deep-towed sidescan sonar, multibeam, gravimetry and magnetometry, and sample these areas with wax core and chain dredge
Contribution: Technician for the Hawaiʻi Mapping Research Group; I piloted the IMI-30 30 kHz deep-towed sidescan sonar towbody, and aided in deployment/recovery of the towbody, and set-up/tear-down of laboratory space
ARGGH2010, Aegir Ridge Geology/Geophysics and Hotspot Interaction, Shipboard Scientist aboard the R/V Haakon Mosby, 27 May – 13 June, 2010 (Bergen, Norway)
Scientific Objective: Active source OBS seismic refraction and dredging survey at the extinct Aegir Ridge in the Norway Basin to better understand hotspot-ridge interaction
Contribution: I aided in dredge deployment/recovery, operated the winch controlling the dredge, and cataloged samples