Title : Boom deployment mechanism of Langmuir Probe and Electric Field Experiment (LPEX) Payload onboard MOM-2

Abstract

Langmuir probe and electric field experiment (LPEX) is a selected experiment for India’s Mars Mission-2. It is a payload which measures the electron density and electrostatic field in Martian ionosphere. In this payload, a boom is required for proper operation of the payload. For stowing and deploying the long boom a deployment mechanism is required. The preliminary configuration design of deployment mechanism has been completed. Deployment mechanism is integrated by torsion spring, boom, latching system, HDRM and Micro switch. In this mechanism 1 meter CFRP boom with probe at other end will be deployed into Mars orbit. Deployment is accomplished by releasing the strain energy stored by torsion spring. In this seminar I will discuss about mechanical system of deployment mechanism and its function. I will discuss about boom design, static analysis and Modal analysis (Theoretical as well as FEA (COMSOL) analysis) in stowed state and deployed state and finally I will show the 3D printed prototype of boom deployment mechanism.

Title : Infilled craters in the mare regions of the Moon

Abstract

Impact craters are the predominant features on the Mare and Highland regions of the Moon. The Moon has recorded more than one million impact craters of different diameters. The Mare region is known for its lava deposits, which covers ~17% of the moon surface. Interestingly, many craters within this Mare region hosts lava deposits within their floor, which indicates the post-impact modifications. Impact craters that are filled with lava, in general, appear as a nearly flat floor in the visible imagery, referred here as Infilled craters. The fractures formed beneath the crater floor during the impact event act as a pathway for these lava to intrude into the crater. This intrusion differs with crater diameter, the spatial location of Mare region, and with geological age of adjoining lava/surface. Due to the lack of plate tectonics and atmosphere Moon provides us with the desired setting to study such infilled craters, which are the record holders of the past geological activities. A detailed study of Infilled craters on the Moon is indeed important for the understanding of lava activities underwent on the Moon. In this current work, detailed scrutiny of infilled craters will be carried out over different Mare regions. This study will lead to understand: 1) the spatial distribution of infilled craters in the mare regions of the Moon, 2) the period of lava infilling activities underwent, and 3) the source of the lava and its variations. In the talk, I will discuss the different types of infilled craters identified in the mare regions, few observations from those craters, and the implications of this study.

Title : Gully fan formation processes: New insights from morphometric measurements

Abstract

Martian gullies are linear-to-sinuous channels linking an alcove at the top to a fan at the bottom. The gullies are interesting because they resemble gullies found on Earth carved by fluvial processes and that’s the reason their genesis is linked to possible episodes of past (scanty) flow of water on Mars. However, from the previous studies and our latest (Sinha et al., 2020) high-resolution global investigation of Martian gullies, we have noted that their mode of formation is controversial. This is because (1) the climate of Mars during the late Amazonian epochs (<100 Ma) is not believed to be conducive to the production and flow of liquid water – disagreement to the fluvial process, (2) the present-day activity in gullies may be driven by sublimation of seasonal carbon dioxide frost – favoring the dry process, and (3) the evidence of overlapping lobate deposits in gullies suggests possibility of a debris-flow like process (Sinha et al., 2020). Furthermore, the gully fans are often modified by post-depositional processes such as by draping of ice-dust mixture and aeolian processes – leading to concealment of key signatures vital for the interpretation of gully fan forming processes. In this work, we carry out morphometric measurements of the gully fans characterized by distinct morphologies using all the publicly available digital elevation models of gully fans within 30-75 deg. of the northern and southern hemispheres. The purpose of this global investigation is to quantitatively characterize a large variety of gully fans to conscientiously identify the attributes of the gully fan shape diagnostic of the gully fan formation processes. We believe that this work will eventually be an important step towards advancing our understanding of the role of past flow of ice and water in shaping the Martian surface.

Title : Detection of lightning in Planetary Atmosphere

Abstract

Lightning in planetary atmospheres is now a well-established concept. Planetary lightning detection technology has developed considerably since the first observations at Jupiter in the late 1970s. Space instruments for lightning detection have focused on radio and optical detection techniques. Here we discuss the available detection techniques for the observations of planetary (including earth) lightning by spacecraft. Space missions carrying lightning-related instrumentation will also be discussed.

Title : Radar exploration of the Moon: Scientific potentials of Chandrayaan-2 DFSAR

Abstract

Radar exploration of the Moon has started since the early 60's from ground-based radar telescopes that resulted in a vast majority of new information about the nearside of our Moon. This was followed by a couple of spacecraft-based radar instruments for the Moon in the last decade, which have provided some significant results about its physical properties. Some of these include about the subsurface structure of the mare, volcanic deposits, crypto mare and polar volatiles. In this talk, I will briefly concentrate on some of these prior results followed by a discussion on where the Ch-2 DFSAR instrument could fill the gaps and provide new insights into our current understanding. The speaker: Dr. Sriram Saran Bhiravarasu received the M.Sc. degree in Physics from Nagarjuna University, Andhra Pradesh, in 2006 and M.Tech. degree in Geomatics from Jawaharlal Nehru Technological University (JNTU), Hyderabad in 2008. He received his Ph.D. degree in Physics from Gujarat University in 2016. From 2010 to 2017, he worked as a Junior Research Fellow and a Research Associate at Space Applications Centre (ISRO), Ahmedabad, where he was involved in the polarimetric radar studies of the Moon using orbit-based radar data sets. From 2017 to 2018, he worked as a Postdoctoral Research Scientist with the Planetary Radar Group at the Arecibo Observatory, Puerto Rico, where he was involved in the radar observations of Near Earth Asteroids (NEAs), Comets, and the Moon. From 2018 to 2020, he was a Postdoctoral Fellow with the Lunar and Planetary Institute (LPI), Houston, where he was involved in the polarimetric radar studies of the Terrestrial Planets and Asteroids, along with laboratory simulation studies to investigate planetary radar scattering processes. Currently, he is back with the Space Applications Centre (ISRO), Ahmedabad as a Staff Scientist in the Planetary Science Group, working on the Chandrayaan-2 mission.