This Week On Galileo - June 15-21, 1998
This week is entirely devoted to processing and transmitting to Earth pictures and other science information stored on the spacecraft's onboard tape recorder. The data was gathered late last month during Galileo's most recent encounter of Jupiter's moon Europa. At each encounter, for a few days surrounding the spacecraft's passage through the heart of Jupiter's system, the instruments gather at a rate many times higher than the available radio transmission rates. To avoid loss of the data, the main computer sends the data to the tape recorder for storage. The time between encounters (typically a couple of months) is used to retrieve the stored data from the tape recorder, and process, package and transmit the data to Earth.
This week's data return schedule contains information gathered during two observations made by the near infrared spectrometer, one observation by the spacecraft camera, and one joint observation by the fields and particles instruments.
The near infrared spectrometer observations looked at two different regions of Jupiter's moon Europa and will provide information on the different types of materials found in these regions. The first of these observations targets an area near the equator between longitudes 100 and 120 degrees west, while the second sees a similar area at latitude 30 degrees north. These areas are away from Europa's trailing side, which is continually impacted by particles carried with Jupiter's magnetosphere. The magnetosphere rotates with Jupiter once every 10 hours. In doing so, it approaches the satellites from behind, sweeps past them, and peppers the trailing side with the particles being carried within. So, since they are away from the trailing side, the surface materials observed are less contaminated with magnetospheric particles and the data may reveal new information on the composition of the surface. These data represent the first high-resolution spectral observations of Europa's leading side.
The single observation returned by the spacecraft camera contains an image of a previously unexplored region of Europa. The region is characterized by a mottled or blotchy appearance, which is believed to indicate the presence of contaminants in the ice. Finally, throughout the week, the fields and particles instruments return portions of a high time resolution recording of the environment surrounding Europa. The data set includes measurements of the amount of dust and the strength of any magnetic and electric fields.