HR: 11:20h
AN: P31C-05    [PDF]
TI: Fine-scale Fractures on the Surface of 433 Eros: Implications for Structural Control and Tectonic Resurfacing of Craters
AU: * Prockter, L
EM: Louise.Prockter@jhuapl.edu
AF: Johns Hopkins University Applied Physics Laboratory, MP3-E128, 11100 Johns Hopkins Road, Laurel, MD 20723 United States
AU: Barnouin-Jha, O
EM: Olivier.Barnouin-Jha@jhuapl.edu
AF: Johns Hopkins University Applied Physics Laboratory, MP3-E128, 11100 Johns Hopkins Road, Laurel, MD 20723 United States
AB: Detailed lineament mapping of the surface of Eros is underway, using high-resolution images obtained by the NEAR-Shoemaker spacecraft during its recent highly successful mission. It is likely that most of the grooves on the asteroid's surface are the result of disturbances of regolith overlying deeper fractures in a coherent substrate, an interpretation that is also plausible for other asteroids and small bodies such as Ida, Gaspra, and Phobos. The presence of numerous single and cross-cutting grooves which may be continuous for several kilometers, implies that the underlying material of which Eros is comprised is largely coherent, and that it is likely not a rubble pile. In addition to grooves, some regions of Eros' surface have a high density of fine-scale lineaments, spaced tens of meters apart. Preexisting structural features have clearly influenced the shapes of some craters, leading to squared-off outlines. Close examination of the surface shows that fine-scale fractures may also be responsible for erasing craters. This type of "tectonic resurfacing" has been inferred on Ganymede, where there are examples of craters strained tens of percent by the formation of fractures and grooves. On Eros, examples can be found of craters that are highly degraded due to numerous parallel fractures running through their interiors. Topographic profiles across these craters show that some are unusually shallow, in part because of regolith infilling, but also possibly as a result of tectonic disruption. We examine the hypothesis that closely-spaced fractures within craters post-date crater formation, since they may not survive the impact process. Such fractures may be the result of reactivation of preexisting structure by later, possibly distant, impact events and may cause subsequent degradation.
DE: 5104 Fracture and flow
DE: 5470 Surface materials and properties
DE: 6000 PLANETOLOGY: COMETS AND SMALL BODIES
DE: 6022 Impact phenomena
DE: 6205 Asteroids and meteoroids
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting