Cygnus spacecraft as seen from seeker-1 satellite
A view from the Seeker-1 satellite’s intelligent vision system as it is being deployed from the Cygnus spacecraft.

Professor Maruthi Akella and students in the Texas Spacecraft Laboratory (TSL) in the Department of Aerospace Engineering and Engineering Mechanics spent the past two years collaborating with the NASA Johnson Space Center (JSC) on a technology demonstration project that could help make space travel safer for astronauts and the spacecraft that transport them.

JSC’s Seeker-1 program, or Seeker Robotic External CubeSat Inspection Vehicle DTO, was developed by NASA to demonstrate that small spacecraft have the capability to fly autonomously and maneuver safely around larger crewed space vehicles in order to perform low-cost, rapidly deployable external vehicle inspections, ultimately creating safer space travel and habitat modules for astronauts. Current methods for on-orbit space vehicle inspections include crew member spacewalks and the use of robotic arms which can not only be dangerous, but also require significant planning and crew time.

The Seeker spacecraft is 3U CubeSat and was designed and built at NASA-JSC. Seeker’s demonstration mission was to perform autonomous flight involving specific maneuvers around the Cygnus International Space Station resupply spacecraft while also capturing high resolution video and images of Cygnus using an intelligent monocular vision system.

Akella and his team were tasked by NASA with designing and developing the monocular vision system for Seeker. The intelligent vision system consists of a commercially available camera driven by state-of-the-art computer vision algorithms developed by UT students and faculty. The algorithms were designed to help the camera “identify” and “localize” the Cygnus spacecraft as it flew around it, while also computing its relative azimuth and elevation across a wide range of lighting conditions, orientations, and backgrounds with a convolutional neural network pre-trained to recognize Cygnus. Measurements derived from the vision system were used in real-time to generate a relative navigation solution Seeker while it flew around Cygnus.

In May 2018, the TSL delivered their newly developed Seeker-1 vision system to JSC. NASA then conducted an extensive test campaign inside the Orion optical testbed that included rigorous performance comparisons of the UT Austin vision solution with a competing visual navigation algorithm delivered by a NASA contracted organization that used traditional approaches involving the scale-invariant feature transform (SIFT). This run-off demonstrated the superior performance and robustness of the UT Austin vision system, leading to its final selection by NASA for flight.

The Seeker-1 spacecraft was launched onboard the Cygnus CRS-11 mission in April 2019 and was deployed on September 16 after Cygnus had completed its mission to the ISS. Following its successful deployment, Seeker collected over 200 high resolution images of the Cygnus spacecraft while performing autonomous vision-based navigation using the UT Austin intelligent vision system. Akella and the TSL team performed post-flight analysis using the Seeker-1 flight recorded images with engineering data and these results were presented to JSC on November 4.

image of cygnus spacecraft taken from seeker-1 cubest
The Seeker-1 CubeSat took over 200 high resolution images of Cygnus such as this one during its autonomous flight mission.

"This NASA partnership is super exciting. I find it particularly rewarding that our UT Austin team from TSL is playing a leadership role in the development of intelligent vision systems for space applications,” Akella said. “Free-flying small robotic spacecraft performing autonomous inspections at pre-specified intervals would be major enablers to human exploration beyond the Earth-Moon system.”

Following the successful flight of Seeker-1, Akella and the TSL team are currently in discussions with NASA for Seeker “follow-on” missions. Many human spacecraft such as Orion, Starliner, and Crewed Dragon have neither readily available spacewalk capability nor robotic arms to perform inspections. This makes inspections prior to critical events such as entry, descent, and landing infeasible. Seeker’s compact size and operational flexibility nicely lends itself to many high-value use cases for current and future human exploration. This would be especially attractive to spacecraft with long mission durations such as a trans-mars tug and those which will be un-crewed for long durations such as Gateway.