Current Research at ORCCA

Small Body Shape Reconstruction, Uncertainty Quantification and Navigation Using Lidar Data (courtesy of Benjamin Bercovici)

The reconstruction and mapping of small bodies by means of Lidar data requires proper handling of the underlying uncertainties in the reconstructed map, as well as a guaranteed robustness to the lack of a-priori information in the targeted small body’s shape and dynamical environment. This research aims at providing such a robust framework allowing successive observation, shape reconstruction and navigation of an unknown asteroid or comet.

Analytical and Numerical Investigation of Orbit Evolution About An Active Comet (courtesy of Mark Moretto)

Mark studies how the gasses streaming off active comets perturb the motion of spacecraft or natural objects orbiting the comet. He is interested in how these natural forces can be leveraged for spacecraft operations, improving science return, and for studying natural processes at comets.

Optimal Guidance and Control of Spacecraft Around Small Bodies Using Low-Thrust Propulsion (courtesy of Don Kuettel)

(Left) Shows a ballistic trajectory propagated around Bennu with full dynamics over a period of 15 Earth days. At close distances, the gravity field of Bennu plays an import role in the evolution of orbits. (Right) Shows the results of a low-thrust orbital maneuver with uncorrected error components. As the figure shows, without active guidance the resulting trajectories vary substantially. 

Optimal Guidance and Control of Spacecraft Around Small Bodies Using Low-Thrust Propulsion (courtesy of Don Kuettel)
Optimal Guidance and Control of Spacecraft Around Small Bodies Using Low-Thrust Propulsion (courtesy of Don Kuettel)

(Left) Shows an orbital maneuver accomplished using a bi-linear tangent guidance algorithm. This maneuver, which is aggressive in both changing the shape and plane of the original orbit, was accomplished for only a few grams of fuel. (Right) Shows a family of Lambert guidance solutions when time-of-flight is varied. 

SRP-based Orbit Control for Small Body Exploration (courtesy of Ken Oguri)

Solar Radiation Pressure (SRP) is a ubiquitous force that acts on any objects in space. We can exploit the force to control spacecraft orbits without consuming fuel. We analytically derived an optimal orbit control law for the "SRP-based orbit control" and demonstrated it with some small body exploration scenarios, including asteroid landing (left) and science orbit transfer (right) scenarios.

Boulder motion on and off the surface of a fast rotation asteroid (courtesy of Daniel Brack)

Recent asteroid missions have shown that asteroid surfaces are endure different processes that shape and reshape the asteroid both globally and locally. Daniel's research seeks to describe the relationship between an asteroid's rotation and the processes on its surface. Using the Surface phenomena Effect on Asteroid Rotational And Translational State (SEA-RATS) tool developed at ORCCA Daniel investigates the conditions for surface activity such as boulder motion and quantifies their effect on asteroid rotation.

Capturing Comet Coma Gas for ISRU (courtesy of Anivid Pedros-Faura)

A polyhedral model approach is used for the cometary gas model incorporating diurnal effects for 67P. The density distribution (sun-direction in black) and non-radial component of the velocity field for the coma are provided. Making use of this coma model and including the main dynamical perturbations (SRP, non-spherical gravity, drag, and third body perturbations), an estimate of the potential mass that can be obtained by orbiting an active comet is given. In this case, different inclinations are tested to determine a preferred region to maximize the capture.

Entry, Descent, and Landing: End of Entry Phase Targeting and Atmospheric Prediction Using Machine Learning (courtesy of Shayna Hume)

Entry, Descent, and Landing on Mars requires the synchronization of a large number of subsystems, making lighter, nimbler systems valuable for automated entry processes. By testing novel methods for prediction of the atmosphere and targeting of mid-altitude coordinates, on-board systems can become more robust to handle a variety of mission profiles for the future.

Robust Spacecraft Guidance around Small Bodies under Uncertainty: Stochastic Optimal Control Approach (courtesy Ken Oguri)

Around asteroids, mission designers need to plan robust guidance and control of spacecraft orbits to meet operational requirements (e.g., science requirements) under complex, uncertain dynamical environments. We develop a robust guidance planner that minimizes the control effort while ensuring the requirement satisfaction with a user-defined confidence level.

Discrete-Event, Drag-Modulation Aerocapture Guidance (Courtesy of Evan Roelke)

Drag-modulation offers a straightforward solution to aerocapture (top left) guidance, leveraging vehicle geometric properties for trajectory control. (bottom left & top right) Jettisoning a rigid drag-skirt during the trajectory enables the guidance system to target a desired exit state. Investigations into multiple jettison events (bottom right) show promising improvements in aerocapture robustness and accuracy.

Autonomous Guidance Around Small Bodies Using Low-Thrust Propulsion

This research focuses on the development of an autonomous spacecraft guidance system to enable to use of low-thrust propulsion around small bodies. The ALT-G architecture is able to autonomously plan and execute finite, continuous low-thrust maneuvers between two orbits using a parametric bilinear tangent (BLT) guidance law and a predictor-corrector guidance scheme. The figures the slide show examples of the planning and guidance capabilities of low-thrust BLT using ALT-G.

SLAM for TRN and Quadrotor Algorithm Testbed (Courtesy of Matthew Givens)

On the left, this research investigates using methods from simultaneous localization and mapping for terrain relative navigation at small bodies and moons. On the right, we have a description of our quadrotor based testbed for navigation algorithms around small bodies, which we run in ASPEN Flight Lab in the Aerospace Engineering building at CU. 

Silhouette-Based Onboard Shape Modeling and Pole Estimation of Asteroids (Courtesy of Dahlia Baker)

Low-resolution mapping methods aid in the onboard processing of shape models for the purpose of proximity navigation when encountering and exploring small bodies. Our approach focuses on the optical data sources, taking limb and terminator information into account while building a visual hull. The aim of this work is to use computer vision approaches to enable shape modeling for SIMPLEx-level missions. 


Spacecraft formation flying is inherently very risky as multiple spacecraft need to operate in proximity with each other. There is an immense need for fast and efficient algorithms to compute safe, and collision-free relative trajectories for multi-spacecraft systems. At ORCCA, we leverage ideas from sampling-based motion planning in field of robotics and develop motion planning algorithms to achieve fuel-efficient, collision-free, and near-optimal trajectories for spacecraft reconfiguration in cluttered environments.

My research goals are broadly to lead technology development necessary to increase the pace of exploration and exploitation of our solar system. In other words, I want to enable faster, more efficient systems in space that will produce more scientific knowledge, increase economic production, and increase the human population living and working in space. A key area of technology that must be advanced to this end is autonomy.

My lab, the Orbital Research Cluster for Celestial Applications (ORCCA), is actively working to advance the state-of-the-art in autonomy for spacecraft (and space robotics) applications. Our work focuses on exploiting the unique dynamics of various environments to build robust autonomous guidance, navigation and control (GNC) algorithms. In trying to fully understand the environment on and around various planetary bodies in order to model and exploit what is known (and to properly deal with what is unknown), we regularly cross the border between engineering and planetary science. 

Our research can be categorized in a number of areas:

  • spacecraft autonomous guidance, navigation and control
  • small body missions
  • asteroid science - in particular geophysics and dynamical evolution
  • in-situ resource utilization
  • precise orbit determination
  • orbital debris dynamical evolution
  • satellite servicing, in-space assembly
  • entry, descent, and landing guidance and control

Several of our current major projects are (click links for details):

OSIRIS-REx Radio Science: Orbit B (courtesy of Jay McMahon, Andrew French & OREx radio science team)