Planetary Sciences Division Seminar
Title : Exploration of the Venus and Lunar Ionosphere Using Radio Science Experiments
Date : 02-09-2025
Time : 10:00:00
Speaker : Dr. Keshav R Tripathi
Area : Planetary Sciences Division
Venue : ONLINE
Abstract
Venus and the Moon, our two neighbouring celestial bodies, exhibit extreme contrasts in atmospheric conditions. Venus has a neutral density nearly 90 times that of Earth, while the Moon has an almost negligible atmosphere. Despite these differences, both bodies possess significant ionized layers capable of affecting radio signal propagation. This seminar will focus on the characteristics of these ionospheric layers as revealed through radio occultation experiments, with comparisons to Earth’s ionosphere. We will also discuss the implications of these findings for future exploration.
Title : Linear and Nonlinear Excitations in Rotating Dusty Plasmas across Coupling Regimes
Date : 08-09-2025
Time : 16:00:00
Speaker : Dr. Prince Kumar
Area : Planetary Sciences Division
Venue : Seminar Room # 113/114 (Thaltej Campus)
Abstract
Dusty plasmas consisting of dust particles, electrons and ions, can be found in various states of matter (solid, liquid, and gaseous) [1-3]. They, therefore, cover a broad range of parameter space relevant to both astrophysics as well as laboratory environments. Studies of the collective excitations in dusty plasmas provide valuable insights into their static and dynamic properties, as well as how these excitations can be controlled for practical applications [4-7]. For example, investigations of these excitations in the strongly coupled limit can be relevant to ion trap systems where the phonon mode spectrum is manipulated to enhance quantum gate performance efficiency [8]. From an astrophysical perspective, recent dusty plasma experiments have observed nonlinear excitations, such as pinned, precures solitons, generated by a moving charged obstacle [9]. These observations motivate the idea of indirect detection of space debris in the ionosphere through such structures[10]. In this talk, I first discuss magnetoplasmon excitations in rotating dusty plasma equilibria that can be generated in the absence of non-conservative fields [1-2]. These magnetoplasmon signatures have been observed in the absence of a real magnetic field across a wide range of dusty plasmas parameter [1]. Then, I address the nonlinear excitations such as Korteweg-De Vries (KdV) Soliton, pinned, precursor solitons in non-rotating dusty plasmas. The characterization of KdV Soliton structures is presented in details under the existing models to test their reliability, and new models are proposed to overcome their limitations [6-7]. Finally, I discuss the pinned and precursor solitons, which are induced in the medium by a moving charged source, appearing at and ahead the source, respectively, under specific Mach number values. The potential applications of these structures for detecting space debris in the lower Earth orbit (LEO) region of the ionosphere are also outlined.
Title : Exploring Fluvial activity around the circum-chryse basin on Mars
Date : 12-09-2025
Time : 16:00:00
Speaker : Rishav Sahoo
Area : Planetary Sciences Division
Venue : Seminar Room # 113/114 (Thaltej Campus)
Abstract
The Chryse Planitia is an asymmetrical basin centred at approximately 45oW and 24oN, about 2000 km northeast of Valles Marineris. It has a diameter of ~1600 km and is 2-3 km below the mean Mars elevation. This basin receives deposits from several major outflow channel systems. Two principal groups of channels terminate in this basin. The first originates from chaotic terrains near the eastern end of Valles Marineris and flows northward for over 1000 km into the southern part of the basin. This group includes Ares Vallis, Tiu Vallis, Simud Vallis, and Shalbatana Vallis. The second group, dominated by Kasei Vallis, enters the basin from the west. As such, Chryse Planitia receives sediment and water input from two widely separated source regions spanning over 2500 km. In this seminar I will discuss the interaction of the major fluvial channels with the rim of Chryse Planitia basin. I will be discussing a new method for estimating the discharge, volume and timescales of fluvial activities around the circum-chryse region. This new method involves simulation for Unsteady flow analysis through which I would be exploring one of the largest dam-break scenarios in the solar system.