The Europa Clipper Magnetometer (ECM), designed and built in a collaborative effort between NASA’s Jet Propulsion Laboratory (JPL) and the University of California, Los Angeles, has completed its rigorous testing and calibration at JPL and is ready for integration onto the Europa Clipper spacecraft.
The ECM instrument is composed of three fluxgate magnetic field sensors on a 28-foot (8.5-meter) boom. The sensors are strategically placed to enable the team to identify and remove from their measurements the contributions of magnetic fields originating from the spacecraft. The sensors are connected through long harnesses to an electronics unit that is housed inside the spacecraft’s protective vault.
ECM will measure the ambient magnetic field in the vicinity of Europa, but the instrument team will require sophisticated algorithms to untangle the various sources of magnetic field. Europa is surrounded by plasma, consisting of ionized particles mainly sourced from neighboring moon Io. The plasma carries electrical currents that contribute magnetic noise to the measurements.
To understand the external sources of the magnetic field, the investigation will use the plasma environment measurements made by the Plasma Instrument for Magnetic Sounding (PIMS), an instrument developed by the Johns Hopkins University Applied Physics Laboratory. Those measurements will help the team identify the contributions of Jupiter's dominant magnetic field as modified by magnetospheric plasma, Europa’s ionosphere, the induced magnetic field originating from Europa's subsurface ocean, and the spacecraft’s magnetic field. Using data from both instruments, scientists will be able to better isolate the induced response of Europa’s subsurface ocean and, thus, to better constrain its properties.
The magnetic field measurements will give scientists estimates of both the thickness and conductivity of Europa's subsurface ocean and the thickness of the ice shell. In combination with compositional data from other Europa Clipper instruments, understanding the conductivity will tell us how salty Europa’s ocean is - which will help scientists determine if the ocean could be habitable.
After the launch of Europa Clipper in October 2024, ECM scientists will routinely calibrate the instrument’s sensors using data from the solar wind. An additional calibration opportunity will take place during the Earth flyby gravity assist maneuver, currently planned in December 2026. This flyby will allow ECM scientists to compare the measurements made by ECM to those made by other magnetometers on spacecraft in Earth’s orbit, thus providing a convenient way to calibrate the instrument. The ECM sensors will also be used for a meticulous magnetic characterization campaign of the spacecraft and its subsystems during its five-and-a-half year cruise to the Jovian system. Additional instrument calibration will happen once the spacecraft reaches the Jovian system.