The proposed instrument, which uses experimental techniques adapted from high energy physics, is a passive receiver of a naturally occurring signal generated by interactions of deep penetrating cosmic ray neutrinos. It could measure ice thickness directly,and at a significant savings to spacecraft resources. In addition to getting the global average ice thickness this instrument can beconfigured to make low resolution global maps of the ice shell. Such maps would be invaluable for understanding planetary features and finding the best places for future landers to explore. The approach and our findings so far are described in our paper in Icarus (Miller, et al., 2012, Icarus 220, 877–888). The basic idea is to use radio receiver technology to detect cosmic ray neutrinos passing through the ice sheet and generating Cerenkov radio pulses (the Askaryan effect). The rate and directional distribution of the detected neutrino interactions will depend upon the thickness of the observed ice sheet. This technology has previously been demonstrated on Antarctic balloon flights by the ANITA neutrino project. In this work we will extend the scope of our original investigation and explore in greater detail the possibility of making low resolution global maps of the ice shells - instead of simply getting a global average ice thickness. In addition, we will improve the fidelity of our initial simulation used to analyze the concept in several important areas in order to more precisely determine the final measurement capabilities of the instrument.
More »We have conducted an initial exploration of a concept for a novel and innovative low cost, low power, low mass passive instrument to measure ice depth on outer planet moons, such as Europa, Ganymede, Callisto, and Enceladus. Indirect measurements by the Galileo and Cassini spacecraft indicate that liquid water oceans are likely present beneath the icy shells of such moons (see e.g., the JPL press release The Solar System and Beyond is Awash in Water). This has important astrobiological implications, and the exploration of such moons is a high priority. The formation, structure, and evolution of these planetary objects are subjects of great interest for understanding how the conditions of life can form, and more generally for understanding the formation of these types of moons. The characteristics of the ice layer are important for deriving properties of the oceans underneath, and for planning future probes and determining possible locations for future landers. For example, on Europa the thickness of the ice layer is key to understanding the possible exchange of ocean nutrients with the surface, understanding the mechanism for heating the ocean, and determining whether the ice might be thin enough to allow a future probe to reach the ocean for sampling. Currently, there is no easy way to measure the thickness of ice that could be tens of km deep, as doing so is very challenging given spacecraft size, weight and power resources. The currently favored approach uses a suite of instruments, including a high power, massive ice penetrating radar, to provide constraints on ice thickness. The described proposed instrument, which uses experimental techniques adapted from high energy physics, is a passive receiver of a naturally occurring signal generated by interactions of deep penetrating cosmic ray neutrinos. It could measure ice thickness directly, and at a significant savings to spacecraft resources. In addition to measuring the global average ice thickness this instrument can be configured to make low resolution global maps of the ice shell. Such maps would be invaluable for understanding planetary features and finding the best sites for future landers to explore.
More »Organizations Performing Work | Role | Type | Location |
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Johns Hopkins University: Applied Physics Laboratory (JHU/APL) | Lead Organization | FFRDC/UARC | Laurel, Maryland |
Ohio State University-Main Campus | Supporting Organization | Academia | Columbus, Ohio |
The Lebedev Physical Institute of the Russian Academy of Sciences (LPI RAS) | Supporting Organization | Academia | Moscow, Outside the United States, Russian Federation |
University of California-Irvine | Supporting Organization | Academia | Irvine, California |
University of Kansas | Supporting Organization | Academia | Lawrence, Kansas |