At this distance, it takes 38 minutes for radio signals to reach Earth from Galileo, or vice-versa. This survey provides information on the spatial and temporal variations of the innermost, and most active, portion of the magnetosphere. Today's remote sensing schedule includes observations of Europa, Jupiter and Io, with participation from the ultraviolet spectrometer, the photopolarimeter radiometer, the near-infrared mapping spectrometer, the spacecraft camera and the radio science team. The ultraviolet spectrometer kicks off the observing campaign by looking for atmospheric emissions from Europa, including possible detection of outgassing events. The photopolarimeter radiometer will collect a low resolution, global scale polarimetry map of Europa.
Polarimetric measurements provide information on the texture and composition of Europa.
Later in the day, the ultraviolet spectrometer collaborates with the near-infrared spectrometer to perform a global observation of Europa. This observation is the first of two of this type for this encounter and will provide more data on the composition of Europa's surface. For 20 hours surrounding the point of closest approach, the radio science team monitors Galileo's radio signal and measures changes in frequency caused by Europa's gravitational pull on the spacecraft. Using the Doppler effect, the team will be able to refine gravity field maps produced with measurements from previous orbits. The near-infrared mapping spectrometer is today's sole observer of Jupiter.