|
|||||
|
|
The influence of obliquity on europan cycloid formation |
|
| Authors: | TA Hurford AR Sarid BG Bills |
| Institution: | a Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States b Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, United States c Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, United States d Jet Propulsion Laboratory, Pasadena, CA 90119, United States e Institute for Geophysics and Planetary Physics, Scripps Institution of Oceanography, La Jolla, CA 92093, United States |
| Abstract: | Tectonic patterns on Europa are influenced by tidal stress. An important well-recognized component is associated with the orbital eccentricity, which produces a diurnally varying stress as Jupiter's apparent position in Europa's sky oscillates in longitude. Cycloidal lineaments seem to have formed as cracks propagated in this diurnally varying stress field. Maps of theoretical cycloid patterns capture many of the characteristics of the observed distribution on Europa. However, a few details of the observed cycloid distribution have not been reproduced by previous models. Recently, it has been shown that Europa has a finite forced obliquity, so Jupiter's apparent position in Europa's sky will also oscillate in latitude. We explore this new type of diurnal effect on cycloid formation. We find that stress from obliquity may be the key to explaining several characteristics of observed cycloids such as the shape of equator-crossing cycloids and the shift in the crack patterns in the Argadnel Regio region. All of these improvements of the fit between observation and theory seem to require Jupiter crossing Europa's equatorial plane 45° to 180° after perijove passage, suggestive of complex orbital dynamics that locks the direction of Europa's pericenter with the direction of the ascending node at the time these cycloids were formed. |
| Keywords: | Europa Tectonics Rotational dynamics Tides solid body |
| 本文献已被 ScienceDirect 等数据库收录！ | |