Science and engineering are often characterized by the dichotomy between theory and practice, organic and mechanic, qualitative and quantitative, virtual and real. My research juxtaposes  apparently different aspects of engineering and science in order to find interrelated, cooperative characteristics, yielding transdisciplinary tools for engineering design on one hand, and scientific analysis on the other hand. I am exploring how scientific principles might be navigated, probed or extended in order to yield new engineering insights; in particular, I strive to utilize the synergetic multidisciplinary relations of science and engineering to develop new tools for design and analysis of space systems.

An example for this holistic standpoint is my research in astrodynamics, a science dealing with the interaction of spacecraft with the space environment, in particular the orbital mechanics and dynamics of motion in a gravitational field. I implemented gauge theory - an attempt to develop a unified theory of the fundamental forces based on the idea of symmetry - to find a new realm of spacecraft orbits. I am  also working on implementing the symmetry embodied in the gauge theory to improve numerical integration of ordinary differential equations.

Following the interdisciplinary interpretation of astrodynamical sciences, my research entails the development of new astrodynamical modeling tools by implementing ideas taken from attitude dynamics on problems of orbital mechanics. In particular, I have been studying the benefits of controlling and stabilizing spacecraft attitude dynamics by using a Hamiltonian formalism known as the Serret-Andoyer variables.

As a researcher in the field of space systems, I seek more efficient methods of carrying out scientific missions using space vehicles. Many future missions, however, cannot be efficiently and reliably performed using a single spacecraft; instead, the functionality of the spacecraft must be distributed, giving rise to the emerging field of distributed space systems. Within this new realm of possibilities, spacecraft formation flying (SFF) is an evolving technology for distributing the functionality of a single spacecraft among several closely-flying satellites. This notion is expected to have the advantages of lower life-cycle cost, better performance, more adaptability to changing mission goals, and less susceptibility to the loss of individual satellites. My SFF research deals with high-fidelity astrodynamical modeling of spacecraft relative motion, and control and optimization of relative spacecraft position and attitude.

Most existing models for spacecraft relative motion are linear, hence inducing considerable errors over long time scales. I am developing nonlinear models of spacecraft relative motion, characterizing the geometry and topology of relative spacecraft dynamics. This knowledge is essential for any multi-spacecraft systems, including satellite constellations. Based on the these models, I have designed a number of precision formation flying controllers. The first family of controllers utilizes adaptive control to achieve relative position control in the sub-millimeter precision level, which requires low-thrust micro-Newton thrusters. The second family comprises optimal impulsive controllers. I have shown that by using impulsive control, spacecraft formations can be designed in a fuel-efficient manner, keeping the spacecraft in tight formation while minimizing the required formation-keeping maneuvers.

Understanding that spacecraft formations are a particular case of the broader discipline of multi-agent systems, I have been investigating task assignment and heuristic decentralized control of general multi-agents systems. My research group has developed task-assignment algorithms for flocks of unmanned aerial vehicles (UAVs).

I believe that identifying great research problems is a prerequisite for great research accomplishments. I devote time to identifying important research problems by performing exploratory research in four main disciplines: astrodynamics, attitude dynamics, spacecraft formation flying and multi-agent systems.

I have been fortunate to collaborate with many gifted people. Here are some of my past and present research collaborators and co-authors: Jeremy Kasdin, Edgar Choueiri, Bob Vanderbei, Ed Belbruno, Mike Littman, Dave Spergel, Egemen Kolemen, Kurt Polzin (Princeton University); Bernard Friedland (NJIT); Anthony Bloch (University of Michigan, Ann Arbor); Antonio Elipe (Universidad de Zaragoza); Michael Efroimsky, Bill Tangren (USNO); Konstantin Kholshevnikov (St. Petersburg University); Dan Butanriu, Yair Censor, Yosi Ben-Asher (Haifa University); Valery Lainey (Royal Observatory of Belgium); Antonios Tsourdos, Brian White (Cranfield University); Dave Folta (NASA/GSFC);Amir Give'on (Caltech).