An expert lecture on the topic ‘Optimal Low-Thrust Relative Orbital Transfer – Complete Analytical Solution of the Two-Point Boundary Value Problem’ was taken by Yajur Kumar, Assistant Professor, Department of Aeronautical Engineering on the 22^nd of March, 2017. The main objective of this special lecture was to make the audience, which included both students and faculty members, familiar about the research being done by the presenting faculty member. The lecture started at 10:00 AM in the Conference Room in C block. Apart from the students of fourth and sixth semester of Aeronautical Engineering, the aeronautical faculty members also attended the lecture.

Unlike the conventional rockets, low-thrust propulsion uses alternative power-sources for propulsion, like electric-ion thrusters and solar-sail. Low-thrust propulsion can be useful in increasing the overall life of a satellite. This lecture covers a portion of low-thrust transfers, the relative transfer of a spacecraft in the orbit. Since, the power source has limitations on the availability of thrust, the trajectory of the relative transfer needs to be optimized, which can either be done by popular Euler-Lagrange equations and using the familiar Pontryagin’s Minimization (Maximization) Problem or by a new approach, using Legendre-Gauss-Lobatto Pseudospectral Method. Regardless of the method we are opting for the non-linear optimization, the accuracy also depends on the model of the planet we are considering for the dynamic modelling of the system. Since, the familiar model for relative transfer in the orbit is one proposed by Clohessey and Wiltshire in 1960s, it has limits in its application since, it does not take in account the variations in the gravity field caused by the oblateness of the planet.