Sciences and Exploration Directorate

Wade G Henning


Wade G Henning's Contact Card & Information.
Phone: 301.614.5649
Org Code: 698
Mail Code 698
Greenbelt, MD 20771

Brief Bio

The research of Dr. Wade Henning focuses on the thermal evolution of terrestrial planet interiors. This work encompasses many target objects, including the Earth and Earth's Moon, the terrestrial planets of our Solar System including Mercury, Venus, and Mars, as well as many moons of the outer Solar System such as Io, Europa, Ganymede, Callisto, Enceladus, Triton, and Charon. Henning's research acts as a bridge, from the molecular level behavior of planetary materials at high temperatures, to the behavior of global-scale geophysical systems, to the manner by which such activity alters the orbits and long-term orbital evolution of entire Solar Systems. This work extends beyond the more familiar worlds of our home system, to the realm of extrasolar planets. As extrasolar planet discovery advances, more and more planets at or below the size of Earth are being identified. Because such worlds are challenging to observe in detail, Henning's research attempts to model the interior dynamics of extrasolar terrestrial planets, in part by reasoning through analogy from similar worlds in our own Solar System: an act referred to as comparative planetology. Such work helps to address questions about worlds many hundreds of lightyears from Earth, well in advance of humankind's ability to resolve these worlds in a detailed manner within our telescopes.

Henning's research interests regarding planetary thermal evolution specifically highlight the role of a process known as tidal heating. In many circumstances, tidal heating can induce dynamic surface activity on worlds that might otherwise by geophysically quiescent. This phenomenon is well-known in the planetary research community to cause widespread silicate volcanism on Jupiter's moon Io, to assist in maintaining a subsurface liquid water ocean on Jupiter's moon Europa, and to power water vapor geysers on Saturn's moon Enceladus. Proceeding by analogy to extrasolar planets, more energetic tidal heating scenarios are readily possible, including cases where tides cause melting on an Earth-sized world so severe that it may easily produce a surface magma ocean. Alternatively, for exoplanets or exomoons that might otherwise be too cold for habitability, tidal heating can also blend with radiogenic heating to produce and maintain liquid water oceans, perhaps suitable for life as we know it. Tidal heating has the unique ability, as it does for Europa and Enceladus, to enhance habitability at arbitrary distances from a host star, helping to provide niches for liquid water far outside of the classical habitable zone of stellar systems. Henning's research has investigated several pathways by which such geological activity may even be observable on extrasolar worlds, including the possible future observation of exoplanet volcanism, tectonics, and cryovolcanism. The energy required to power such geological activity is in fact extracted from orbital energy, and acts as a major form of energy dissipation in deep space. In effect, tides serve as a form of orbital friction. In one example of this behavior, Henning's research group has discovered that the partial melting of an Earth-sized planet by severe tides, while temporality harming the surface with widespread magmatic activity, may in the long run "Save Earths from orbital chaos", by acting as an intense calming agent on early Solar Systems where planetary scattering can sometimes be commonplace.