Abstract
Abstract Considering that aeolian sand ripples are formed primarily by creeping particles caused by wind-driven saltation sand particles, we obtain a formulation for determining the height of saturated aeolian sand ripples by incorporating the reptation fluxes with previous experimental results on migration velocities of sand ripples. Based on existing observational results of terrestrial sand ripples on Earth's surface, it estimates that the wavelength of aeolian sand ripples on Mars is generally up to several meters. This implies a possibility that there is another sand ripple on Mars similar in scale to Transverse Aeolian Ridges (TARs) at some time when surface saltation was prevalent. Moreover, perhaps part of the widely observed TARs is the degradation of saltation sand ripples, whose formation is intimately related to saltation and reptation of sand particles. While the other two types of ripple-like morphologies (plain ripples and crater ripples) found by Opportunity Rover are essentially not. Further, we propose that the main factor controlling the scale feature of Martian sand ripples is the intense particle-bed collision process.
Highlights
The surprising discovery of aeolian features on Mars provides an opportunity and a challenge for geologists and planetary physicists to figure out the evolution process and present status of the Martian atmosphere and climate [1]
Except for the various aeolian features with similar patterns to terrestrial dunes, such as barchans, transverse dunes, longitudinal dunes, and star dunes [2,3], a large number of ripple-like aeolian bedforms have been revealed to exist on the Martian surface by the Mars Orbiter Camera (MOC) installed on the Mars Global Surveyor (MGS) and the Mars Exploration Rovers, and recently by the Opportunity Rover at Cape St
An expression used to calculate the height of saturated ripples formed by wind-driven reptating sand particles is derived, which is available for the prediction of the height of ripples produced by the particle-bed splash process based on a series of physical parameters
Summary
For the crater and plains ripples, there is a supposition that both of them show characteristics similar to those of terrestrial ripples [6]. Many TARs have different shapes compared with the ripples on Earth, that is, they have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines [4] Based on these observations, new viewpoints about TARs are proposed recently, for example, the paper of Geissler suggests that TARs are primary depositional bedforms that accumulated in place with the dust carried by the winds in suspension millions of years ago, perhaps in a manner comparable to antidunes on Earth, and were subsequently indurated and eroded to their current states by eons of sandblasting [20]. It can be concluded that there is a possibility that some of the TARs on Mars were aeolian ripples or transformed by terrestrial sand ripples, which is in accordance with the view of Zimbelman [22]
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