NASA Innovative Advanced Concepts (NIAC)
Phase I Award
Magneto-Inductive Communications for Ocean Worlds
NASA Glenn Research Center
A mission to the under-ice ocean of Europa is one of the highest priority missions for NASA. Galileo magnetometer measurements and other observations suggest a deep layer of electrically conductive fluid beneath the surface. Concepts for a probe to melt through the 5 to 10 km thickness of briny ice to reach the buried ocean have been proposed.
Model predictions for magnesium sulfide concentrations vary but a conductivity range between 0.1 and 3 S/m seems reasonable. Conventional communications links that rely on propagation of an electromagnetic field cannot penetrate – even if the sea ice conductivity is only 0.1 S/m. The electric field attenuation would exceed 100 dB/km even at very low frequencies.
We propose “magneto-inductive” technology. Magneto-inductive signals differ from electromagnetic signals because the electric field is suppressed. The magnetic field is a non-propagating quasi-static field that can penetrate a highly conductive medium. And, the magnetic field can be modulated to encode information hence it can be used for communications.
But the magnetic field strength will degrade as distance cubed (independent of the medium so long as the medium is not magnetic) so a very sensitive receiver technology is needed to pick up the weak signal after penetrating several km of briny ice.
We intend to develop a magneto-inductive communication system based on an extremely high-sensitivity superconducting quantum interference device (SQUID) receiver and quasi-static magnetic field transmitter. Preliminary calculations indicate that we should achieve ≈kbps with a modest transmitter and relatively small antennas (coils) using a SQUID-based receiver.
This effort represents a potentially disruptive communications technology to enable a mission to the Europa ocean and other ocean worlds.