July 27, 2015
Vivek Vittaldev, PhD Candidate
Professor Ryan Russell, Faculty Advisor
Vivek Vittaldev, an aerospace engineering PhD student working with faculty advisor and professor Ryan Russell, is developing computer models that could ultimately help prevent satellite collisions with space debris and other satellites currently orbiting around Earth.
More than 20,000 objects including active satellites and debris are being tracked today as they orbit Earth, as even the smallest of particles travel fast enough to severely damage a spacecraft or satellite. New tracking hardware will soon raise the number of actively tracked objects to near 200,000. Space debris can include inactive satellites, abandoned launch vehicle stages and fragmented debris from past space missions and natural particles, such as meteoroids.
Funded by the United States Air Force Research Laboratory, the research project aims to simplify current methods of predicting the uncertainty in a satellite’s path. Vittaldev and Russell hope their findings will help protect current and future satellites from collisions with space debris or other spacecraft. GPS, communication and scientific satellites all provide indispensable services that could greatly disrupt everyday life if compromised by collisions in outer space.
“It’s very expensive to get satellites up in space and they don’t have much propellant, so if you can accurately predict collision probabilities and let the operator of the satellite know, they can make an informed decision whether or not to maneuver,” Vittaldev said.
In a worst-case scenario, a collision of one satellite with another object could cause an explosion, setting off a ripple effect. Two such collisions in recent years acted as a wake-up alarm for the international community. The work of Vittaldev and Russell attempts to reduce the possibility of those types of situations so that it might be possible to preserve the satellites we rely on for navigation, communication and research.
Currently, the most accurate method of determining the path of a satellite is known as the Monte Carlo method. To conduct a Monte Carlo simulation, operators generate several random samples of the satellite’s uncertainty distribution and simulate each sample for a given period of time, usually over one to ten days. This method however, is computationally expensive. Russell and Vittaldev are currently using it as a benchmark to test the accuracy of methods they are developing.
The research team is developing three new computational methods to streamline the process. The first is an alternative to the Monte Carlo, because the initial conditions for the simulations may have to be generated deterministically and not randomly; the second two can be used with the new alternative method or with the Monte Carlo.
By either substituting Monte Carlo simulations with a new approach or supplementing them with new methods, the duo hopes they can predict satellite paths with greater speed and accuracy.
“As more countries around the world are joining the club of space faring nations, and the industry as a whole is leaning towards smaller and cheaper satellites, the predicted population growth of space objects has the potential to be exponential,” Russell said.
"On the other hand, government resources to accurately track objects cannot keep up with the expected demand. In order to maintain a safe space environment, computational models must improve. Our work is part of this long-term effort to build better prediction models for the Air Force’s next-generation space catalogue. Furthermore, our results may be useful in other disciplines involving non-linear dynamics and propagation of uncertainty.”
Vittaldev notes the importance of Russell’s influence on his research.
“He has been an essential part of my research and guidance. He has expertise that’s already built up so I can always go to him with questions and he can always answer them or help guide me to the right answer,” Vittaldev said.
Vittaldev plans to finish his dissertation this fall and graduate in December. He hopes to continue working in the field of research after graduation.
