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Vivek Muralidharan

Postdoctoral researcher

Department Space Robotics
Adresse postale Campus Kirchberg, Université du Luxembourg
6, rue Richard Coudenhove-Kalergi
L-1359 Luxembourg
Bureau sur le campus L 118

Vivek Muralidharan, a native of Vadodara, Gujarat, India, is currently a Post-Doctoral Researcher in the Space Robotics research group, SpaceR, headed by Prof. Miguel Angel Olivares Mendez at the Interdisciplinary Centre for Security, Reliability and Trust (SnT), Université du Luxembourg. He was born in Payyanur, Kerala, India in 1994. 

Vivek graduated with a Bachelor's in Mechanical Engineering from the National Institute of Technology Karnataka (NITK), India in 2015. While pursuing his undergraduate degree, he worked on Formula student race cars and was also elected as the captain of the NITK Racing team. 

He moved to Purdue University, USA, to pursue a Master of Science (M.S.) degree in Aeronautics and Astronautics, which he completed in 2017. His Master's thesis was titled Orbit Maintenance Strategies for Sun-Earth/Moon Libration Point Missions: Parameter Selection for Target Point and Cauchy-Green Tensor Approaches. In 2021, Vivek received a Ph.D. for his dissertation titled Stretching Directions in Cislunar Space: Stationkeeping and an Application to Transfer Trajectory Design. He worked under the supervision of Dr. Kathleen Howell at the Multi-Body Dynamics Research Group for both his M.S. and Ph.D. degrees. His major field of research is Astrodynamics and Space Applications.  His research focus includes orbital dynamics, the circular-restricted three-body problem, stationkeeping strategies, orbit determination, as well as guidance, navigation and control.  

During the course of his career, he has interned at the Indian Institute of Space Science and Technology in Thiruvananthapuram, India (2013, 2014 and 2016) and Mitsubishi Electric Research Laboratories (MERL) in Massachusetts, USA (2019). He also worked at the Purdue University Minority Engineering Program (MEP) while he was a graduate student.  

Last updated on: mercredi 27 juillet 2022

Title: Stretching Directions in Cislunar Space: Stationkeeping and an Application to Transfer Trajectory Design



The orbits of interest for potential missions are stable or nearly stable to maintain long term presence for conducting scientific studies and to reduce the possibility of rapid departure. Near Rectilinear Halo Orbits (NRHOs) offer such stable or nearly stable orbits that are defined as part of the L1 and L2 halo orbit families in the circular restricted three-body problem. Within the Earth-Moon regime, the L1 and L2 NRHOs are proposed as long-horizon trajectories for cislunar exploration missions, including NASA's upcoming Gateway mission. These stable or nearly stable orbits do not possess well-distinguished unstable and stable manifold structures. As a consequence, existing tools for stationkeeping and transfer trajectory design that exploit such underlying manifold structures are not reliable for orbits that are linearly stable. The current investigation focuses on leveraging stretching direction as an alternative for visualizing the flow of perturbations in the neighborhood of a reference trajectory. The information supplemented by the stretching directions are utilized to investigate the impact of maneuvers for two contrasting applications; the stationkeeping problem, where the goal is to maintain a spacecraft near a reference trajectory for a long period of time, and the transfer trajectory design application, where rapid departure and/or insertion is of concern. 

Particularly, for the stationkeeping problem, a spacecraft incurs continuous deviations due to unmodeled forces and orbit determination errors in the complex multi-body dynamical regime. The flow dynamics in the region, using stretching directions, are utilized to identify appropriate maneuver and target locations to support a long-lasting presence for the spacecraft near the desired path. The investigation reflects the impact of various factors on maneuver cost and boundedness. For orbits that are particularly sensitive to epoch time and possess distinct characteristics in the higher-fidelity ephemeris model compared to their CR3BP counterpart, an additional feedback control is applied for appropriate phasing. The effect of constraining maneuvers in a particular direction is also investigated for the 9:2 synodic resonant southern L2 NRHO, the current baseline for the Gateway mission. The stationkeeping strategy is applied to a range of L1 and L2 NRHOs, and validated in the higher-fidelity ephemeris model. 

For missions with potential human presence, a rapid transfer between orbits of interest is a priority. The magnitude of the state variations along the maximum stretching direction is expected to grow rapidly and, therefore, offers information to depart from the orbit. Similarly, the maximum stretching in reverse time, enables arrival with a minimal maneuver magnitude. The impact of maneuvers in such sensitive directions is investigated. Further, enabling transfer design options to connect between two stable orbits. The transfer design strategy developed in this investigation is not restricted to a particular orbit but applicable to a broad range of stable and nearly stable orbits in the cislunar space, including the Distant Retrograde Orbit (DROs) and the Low Lunar Orbits (LLO) that are considered for potential missions. Examples for transfers linking a southern and a northern NRHO, a southern NRHO to a planar DRO, and a southern NRHO to a planar LLO are demonstrated.


Adviser: Prof. Kathleen C. Howell (Purdue University, USA)

Last updated on: 30 mars 2022

Dated: March 2022

Last updated on: 30 mars 2022


Last updated on: 06 mai 2022