Search Publications
Probabilistic constraints from existing and future radar imaging on volcanic activity on Venus
Lorenz, Ralph D.
We explore the quantitative limits that may be placed on Venus' present-day volcanic activity by radar imaging of surface landforms. The apparent nondetection of new lava flows in the areas observed twice by Magellan suggests that there is a ~60% chance that the eruption rate is ~1 km3/yr or less, using the eruption history and area/vol…
On the status of orbital high-resolution repeat imaging of Mars for the observation of dynamic surface processes
Muller, J. -P.; Sidiropoulos, P.
This work deals with the meta-data analysis of high-resolution orbital imagery that was acquired over the last four decades of Mars. The objective of this analysis is to provide a starting point for planetary scientists who are interested in examining the martian surface in order to detect changes that are related to not fully understood natural p…
The capabilities of ROSINA/DFMS to measure argon isotopes at comet 67P/Churyumov-Gerasimenko
Altwegg, K.; Berthelier, J. J.; Fuselier, S. A. +8 more
Little is known about the noble gas abundances in comets. These highly volatile atoms are possible tracers of the history of cometary matter including the thermal evolution. They can help quantify the contribution of cometary impacts to terrestrial oceans and help elucidate on the formation history of comets and their role in the formation and evo…
Cometary ion instabilities in the solar wind
Hellinger, P.; Matteini, L.; Schwartz, S. J.
We review some of the processes that characterize the interaction of the solar wind with newborn cometary ions. Instabilities generated by the typical ring-beam velocity-space configuration of the pick-up ions in the solar wind frame are studied by means of one- and two-dimensional hybrid numerical simulations. In agreement with previous studies, …
Results from the worldwide coma morphology campaign for comet ISON (C/2012 S1)
Samarasinha, Nalin H.; Mueller, Beatrice E. A.; Schleicher, David G. +46 more
We present the results of a global coma morphology campaign for comet C/2012 S1 (ISON), which was organized to involve both professional and amateur observers. In response to the campaign, many hundreds of images, from nearly two dozen groups were collected. Images were taken primarily in the continuum, which help to characterize the behavior of d…
Pile driving models for the evaluation of soil penetration resistance measurements from planetary subsurface probes
Kömle, Norbert I.; Kargl, Günter; Poganski, Joshua +1 more
Several planetary lander missions conducted in the past and planned for the near future have instruments on board, which are dedicated to the determination of various material properties, among them mechanical properties of the surface like material strength and penetration resistance. In this paper two instruments are considered in more detail: (…
The Venus-solar wind interaction: Is it purely ionospheric?
Luhmann, J. G.; Wei, H. Y.; Zhang, T. L. +2 more
The Venus solar wind interaction is often regarded as the prototypical example of an induced magnetosphere. Pioneer Venus Orbiter (PVO) observations during a period of moderate to strong solar EUV fluxes led to a fairly detailed picture in which the currents in the conducting ionosphere produce a nearly impenetrable obstacle to the incident magnet…
Touchdown on Venus: Analytic wind models and a heuristic approach to estimating landing dispersions
Lorenz, Ralph D.
The 'landing ellipse' or region of uncertainty within which an unguided probe to Venus may be expected to land is calculated. The region can be usefully seen as the convolution of three different factors: an initial circular delivery uncertainty which is smeared at a grazing entry angle onto the planetary sphere, an along-track uncertainty due to …
Mars atmospheric losses induced by the solar wind: Comparison of observations with models
Vaisberg, Oleg
With new results from Mars-Express on plasma environment of Mars and two new Mars satellites the study Martian atmospheric losses receives new attention. Paper summarizes experimental results concentrating on configuration of Martian magnetosphere and the measurements of planetary ion escape induced by the solar wind. Several plasma populations co…
Study of olivine-rich dark halo crater - Beaumont L in Mare Nectaris using high resolution remote sensing data
Chauhan, Prakash; Rajawat, A. S.; Kumar, A. S. Kiran +1 more
Study of dark-haloed craters (DHCs) can provide important information about the geology, mineralogy and evolution of certain hidden mare deposits known as cryptomare. Some DHCs have been identified in the Mare Nectaris region of the near side of the Moon. Beaumont L represents one such DHC situated on the western flank of the Nectaris basin. Moon …