This Week On Galileo
November 9-15, 1998
With only two weeks until Galileo's next encounter with Europa, Jupiter's icy moon, the spacecraft spends most of the week returning science data stored on its onboard tape recorder. The data were acquired during Galileo's previous flyby of the icy moon, back in September. Data processing and transmission is suspended twice this week so the spacecraft can perform regular maintenance on its propulsion system, and perform a standard gyroscope performance test.
This week's playback time is used to fill gaps in previously returned data, select new data, or to re-process data with different parameters. Data from fifteen observations, all describing Europa, are returned by the spacecraft camera, near-infrared mapping spectrometer and ultraviolet spectrometer.
The spacecraft camera returns the majority of observations this week, 12 of the 15 planned. The first observation is a mosaic of images taken near Europa's terminator. The observation cuts across various terrain types that are considered to be the best evidence for the existence of a liquid layer under Europa's surface. Three sets of images, some in color, are returned this week showing Europa's Agenor Linea. Agenor Linea's brightness is believed to be an indication that the feature is fairly young. A single observation is returned of Thrace Macula. The images are expected to clarify the nature of a large dark area that may be similar to other regions which have been found to contain iceberg-like fragments of older crust. The remaining seven observations returned by the camera this week contain images of Libya Linea, Thynia Linea, Europa's south polar region, pull-apart wedges, dissected terrain, a strike-slip fault, and regions of unexplored terrain.
The remaining three observations are returned by the near-infrared mapping spectrometer together with the ultraviolet spectrometer. All three observations aim to provide more information on the spectral characteristics of Europa's surface, which will help scientists understand more about its composition. Two of the observations have a special emphasis on detecting non-ice components.