How do you get home from deep space if your communication systems fail?
John Christian, assistant professor of mechanical and aerospace engineering at West Virginia University, explores his research into helping astronauts with this problem.
Dr. John Christian is an aerospace engineer with expertise in spacecraft navigation and space systems. He is presently an assistant professor in the Department of Mechanical and Aerospace Engineering in the Benjamin M. Statler College of Engineering and Mineral Resources at West Virginia University where he directs a research program focused on spacecraft relative navigation, attitude estimation, and spacecraft design. Prior to joining WVU’s faculty, Christian worked as an engineer in the Guidance, Navigation, and Control Autonomous Flight Systems Branch at the NASA Johnson Space Center in Houston, TX. He has experience with navigation system design, flight tests of relative navigation sensor hardware (STORRM experiment on STS-134), parachute drop tests, Inertial Measurement Unit data processing, system requirements definition, and space systems analysis. He holds a BS and MS in aerospace engineering from the Georgia Institute of Technology and a Ph.D. in aerospace engineering from the University of Texas at Austin.
Space Optical Navigation
In December of 1972 the crew of Apollo 17 splashed down in the South Pacific Ocean after their two-week trip to the Moon and back. This marked the end of the Apollo Program and humankind’s brief flirtation with sending people beyond a little bubble surrounding the Earth.
In fact, since Apollo 17 — whether on the Space Shuttle, the International Space Station, the Soyuz, or any other spacecraft — humans have ventured no further than just a few hundred miles above Earth’s surface.
But all this will soon change with NASA’s Orion spacecraft, which promises to once again to carry humans beyond low Earth orbit. The task of leaving Earth’s warm embrace, however, is dangerous, and deep space is harsh and unforgiving.
As a result, the crew and their spacecraft must be capable of a new level of independence when they are so far away that a return could take many days.
Our research group is developing technologies for NASA to help make such autonomy possible. Most spacecraft today know their location from Earth-based tracking. We use antennas located around the world to track the spacecraft and then use these same antennas to send a message telling the spacecraft where it is.
But what is the crew to do if they’re far away from Earth, and their communication system fails? They would have no way of knowing where they are or how to get home. We are addressing this problem using a technique called optical navigation.
It is possible to use camera images of stars and planets to autonomously estimate both your position and orientation in space. By combining a sequence of such images with the dynamics of motion in space, the crew can determine their trajectory and plot a course home on their own.
By creating reliable algorithms to do all this onboard a spacecraft, we are doing our small part in helping humankind once again break free from low Earth orbit.
