November 5, 2009
Written by Professor Cesar Ocampo
Associate Professor Cesar Ocampo is currently involved in several specific projects associated with the optimization of spacecraft trajectories. This research examines all the different aspects associated with determining the optimal orbital paths for one or more spacecraft, that may operate in simple to complex gravitational field environments, and that may use a broad range of propulsion systems. The different aspects include the associated theory, the computational algorithms, and numerical methods needed to solve these types of problems.
The field of spacecraft trajectory optimization has been important since the first artificial satellites were placed in orbit about the Earth over 50 years ago. There have been many advances since which have facilitated the exploration of the Earth, the Moon, the Planets, and all other types of solar system bodies. For example, the use of the well known gravitational assist, the “Sling Shot Effect”, has allowed spacecraft such as the Voyager pair of vehicles to explore all of the outer planets of the Solar system with minimal propellant requirements.
Also the clever use of the complex and dynamic gravitational fields that exist around several celestial bodies has facilitated the design of spacecraft missions that float and hang between the Earth and Sun for uninterrupted solar observation. These advances have also uncovered the possibility of getting captured around the Moon without the need to use an engine to slow down the spacecraft. The moon has also been used to salvage (using the Slingshot Effect) spacecraft that have been stranded in incorrect orbits due to partial launch vehicle failures. And just recently, the moon was used to place a spacecraft into an orbit that will allow the spacecraft to crash into its south pole in search of sub-surface water at the bottom of a crater.
New algorithms and software systems are being developed here in the department to allow engineers and analysts to quickly understand and solve complex trajectory design and optimization problems. The renewed interest in sending cargo and humans to the Lunar surface using a new line of rockets and space vehicles has motivated and inspired the development and operational use of these systems. One such system that is operational and continues to evolve is Copernicus which is being developed in collaboration with the NASA Johnson Space Center. Graduate and undergraduate students work on the different aspects of the system either directly or indirectly. Some work involves producing automatic algorithms to compute emergency abort and return trajectories from the Moon to the Earth for human crews. Other work involves optimizing Earth to Moon trajectories with the added condition that guarantees a safe return to the Earth in the event of an emergency.
This work, along with the successful use and introduction of Copernicus to the Astrodynamics community, will change and improve the way spacecraft trajectories are designed. It enables a wider range of students and engineers with the capability to design and optimize simple to complex spacecraft missions; a capability that was limited to only a few experts in the field.
This story adapted from the Fall 2009 "Longhorn Liftoff".
