Details

Autor(en) / Beteiligte

• White, Oliver L.
• Schenk, Paul M.
• Bellagamba, Anthony W.
• Grimm, Ashley M.
• Dombard, Andrew J.
• Bray, Veronica J.

Titel

Impact crater relaxation on Dione and Tethys and relation to past heat flow

Ist Teil von

• Icarus (New York, N.Y. 1962), 2017-05, Vol.288, p.37-52

Ort / Verlag

Elsevier Inc

Erscheinungsjahr

2017

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• •Stereo topography is used to measure crater morphologies on Dione and Tethys.•Relaxation affects craters across a large diameter range on Dione and Tethys.•Heat flows >60mWm−2 are needed to relax several craters on both satellites.•Similar resonance-induced tidal heating may have affected Enceladus and Dione.•Odysseus impact on Tethys limits assessment of relaxation across its surface. Relating relaxation of impact crater topography to past heat flow through the crusts of icy satellites is a technique that has been applied to satellites around Jupiter and Saturn. We use global digital elevation models of the surfaces of Dione and Tethys generated from Cassini data to obtain crater depth/diameter (d/D) data. Relaxation is found to affect craters down to smaller diameters on these satellites compared to Rhea. We perform relaxation simulations in order to assess the heat flow necessary to relax craters on Dione and Tethys to their present morphologies. Heat flows exceeding 60mWm−2 are required to relax several craters on both satellites, and relaxation appears to be subject to geographical controls. On Dione, we define a ‘relaxation dichotomy’ that separates the more relaxed craters in sparsely cratered plains from the less relaxed craters in heavily cratered terrain. The configuration of this dichotomy resembles that of the structural-geological dichotomy on Enceladus, implying that a similar resonance-induced tidal heating mechanism concentrated in the southern hemisphere may have affected both satellites. Defining geographical distribution of relaxation on Tethys is hindered by the presence of the young Odysseus impact and its associated ejecta.