Research within the STAR Group is centered around three main focii within the field of astrodynamics.

Frameworks and Methods for Exploration of the Solar System

Leveraging the Moon and Stable Libration Point Orbits Around L4/L5 to Observe the Solar Corona and Lunar Occultations

There is a significant interest in studying the Solar Corona to gather information about the Sun. This investigation provides an efficient approach to observe the Solar Corona by using the Moon as an occulter to suppress the blinding luminosity of the Sun's surface. Another objective is an analysis and comparison of diffraction patterns created by Lunar Occultations (LO) from L4 and from Earth. By exploiting the Libration point L4 within the Cislunar region, a spacecraft would be within proper position to observe the Solar Corona every sidereal month. 

Family of short period orbits about L4.

Perturbed Lambert Problem Using the Theory of Functional Connections

This project aims at creating an algorithm that uses TFC to solve Lambert's problem in a highly efficient and fast process. The investigation deals with the mathematical and software development of the algorithm, while testing under various scenarios. These include LEO, GEO, elliptical orbits, and future iterations will test Earth-Moon transfers and other transfers in extra-terrestrial gravitational systems.

Shown are the perturbed (black) and unperturbed (red) Lambert's arcs computed using TFC. The convergence time for each are 0.26s and 0.078s, respectively.

Cislunar Surveillance

A Low-Complexity Algorithm to Determine Motion in the Circular Restricted Three-Body Problem

The research develops an algorithm that lowers the computational time required to propagate a trajectory by solving for an analytical polynomial between boundary conditions. The algorithm is tested on many popular orbital trajectories in the Earth-Moon circular restricted three-body problem and compared to iterative methods. 

Computational time of algorithm on well-known Cislunar orbits.

A Review on Hot-Spot Areas Within the Cislunar Region and Upon the Moon's Surface

The research identifies key regions of interest within the Cislunar region, both on the Lunar surface and Cislunar space. Then, an orbital framework of low lunar orbits, that can enable passive information gain techniques, is developed to service the identified regions of interest on the Lunar surface.

Ground-track of orbital framework.

Orbit and Attitude Coupling in the Full Higher Ephemeris Model within the Context of the Geometric Mechanics Framework

The ability to predict the attitude of a spacecraft in complex dynamical environments such as the Cislunar region is necessary for the success of future missions. This research is an expansion of existing work done to develop the Circular Restricted Three-Body Problem, a reduction of the full N-body problem. The CRF3BP seeks to consider a rigid-body spacecraft in a 3-body system, allowing for attitude to be predicted in areas of space such as the Cislunar region and allowing for orbit/attitude coupling to be considered. The orbit that is analyzed was first considered in the CRF3BP as an initial guess, then transitioned into a full ephemeris model considering the Sun as well as the Moon's alliptical orbit to determine if the newly formulated CRF3BP was capable of accurately predicting attitude.

Comparison between CRF3BP and full ephemeris attitude metric for the ISS with nonzero rotational initial conditions (left) and null rotational initial conditions (right).

RSO Identification in Arbitrary Unresolved Space Imagery

Identifying Resident Space Objects (RSOs) in arbitrary space imagery with little prior information is a challenging, yet crucial next step in space domain awareness applications. This work proposes improvements to an existing RSO identification process for unresolved space images. The algorithm has three main phases: image processing, star elimination, and RSO association. Star elimination and RSO association use nearest neighbor association and tresholds on inertial frame-to-frame motion of observations to associate objects. Given a set of unresolved space images contiguous in time, the product of the algorithm presented is a set of measurements for orbit estimation.

Two RSO trails identified using the RSO identification algorithm.

Space Applications

Simulator Development for Coverage Planning of a 6G/loT Constellation 

This investigation relates to creating a simulator that can propagate motion of satellites belonging to constellations, specifically with a telecommunications role. This simulator has the capability of accurately computing visibility of coordinates and areas, taking into account field-of-view, as well as computing charge generated during Sun-visibility events.

Shown are the field-of-view cones of the satellite (green), ground stations (blue), and user equipments (red). The satellite's motion is propagated alongside the cones' motion while the windows of coverage for the locations are computed simultaneously.


Orbit and Attitude Coupling in the Full Higher-Fidelity Ephemeris Model within the context of the Geometric Mechanics Framework 

Creation of a Trajectory Framework that is Sustainable for a Continuous Exploration of Mars and its Moons

A review on hot-spot areas within the Cislunar region and an orbital framework for key regions 

Resident Space Object Identification in Arbitrary Unresolved Space Images

Leveraging the Moon and Stable Libration Point Orbits around L4/L5 to Observe the Solar Corona