Goddard's GIANT optical navigation software helped guide the OSIRIS-REx mission to the asteroid Bennu. Today its developers continue to add functionality and simplify usability for future tasks.
As NASA scientists study fragments returned from asteroid Bennu, the team that helped navigate the mission on its journey is refining their technology for potential use in future robotic and manned missions.
The Optical Navigation Team at NASA's Goddard Space Flight Center in Greenbelt, Maryland, served as a backup navigation resource for the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer) mission to the near-Earth asteroid Bennu. They again examined the work of the basic navigation team and demonstrated the feasibility of navigation by visual cues.
Visual navigation uses feedback from cameras, sensors, or other sensors to navigate the way humans do. This advanced technology works by taking images of a target, such as Bennu, and identifying features on the surface. GIANT software — short for Goddard Image Analysis and Navigation Tool — analyzes those images to provide information, such as the exact distance to the target, and develop 3D maps of potential landing zones and hazards. It can also analyze an orbiting object to help calculate the target's mass and determine its center, important details to know for a mission trying to enter orbit.
“Onboard autonomous visual navigation is an enabling technology for current and future mission ideas and proposals,” said Andrew Leonis, lead developer of GIANT at Goddard. “It reduces the amount of data that must be linked back to Earth, which reduces the cost of communications for small missions, and allows more science data to be linked back to larger missions. It also reduces the number of people required for orbit determination and navigation on Earth.”
During OSIRIS-REx's orbit around Bennu, GIANT identified particles emitted from the asteroid's surface. The optical navigation team used the images to calculate the particles' motion and mass, which ultimately helped determine that they did not pose a significant threat to the spacecraft.
Since then, lead developer Andrew Leonis said they have improved and expanded GIANT's core set of utilities and scripts.
GIANT's new developments include an open source version of its software released to the public, celestial navigation for traveling into deep space by observing the stars, the Sun, and solar system objects. They are now working on a slimmed down package to assist in autonomous operations throughout the mission life cycle.
“We are also looking forward to using GIANT to process some of the Cassini data with partners at the University of Maryland in order to study Saturn’s interactions with its moons,” Leonis said.
Other innovators like Goddard engineer Alvin Yu are adapting the software to help rovers and human explorers on the moon or other planets.
Adapt and improve
Shortly after OSIRIS-REx left Bennu, Liounis' team released a revised, open-source version for public use. “We have considered a lot of changes to make it easier for the user and some changes to make it work more efficiently,” he said.
One intern modified their code to take advantage of the graphics processor for ground operations, enhancing the image processing at the heart of GIANT's navigation system.
A simplified version called cGIANT works with Goddard's autonomous navigation, guidance and control software package, or autoNGC, in ways that could be critical for both small and large missions, Leonis said.
Leonis and his colleague Chris Gnnam have developed a celestial navigation capability that uses the GIANT system to guide a spacecraft by processing images of stars, planets, asteroids and even the sun. Conventional deep space navigation uses mission-specific radio signals to determine position, speed, and distance from Earth. Ghannam said reducing the mission's dependence on NASA's Deep Space Network frees up a valuable resource shared by many ongoing missions.
Next on their agenda, the team hopes to develop planning capabilities so mission controllers can develop flight paths and orbits within GIANT — streamlining mission design.
“In OSIRIS-REx, it will take up to three months to plan our next trajectory or orbit,” Leonis said. “Now we can reduce that to a week or so of computer processing time.”
Their innovations have gained the team continued support from Goddard's internal research and development program, individual missions, and NASA's Communications and Astronautics Program.
“As mission concepts become more advanced, visual navigation will remain a necessary component of the navigation toolkit,” Leonis said.
Written by Carl B. Hailey
NASA's Goddard Space Flight Center in Greenbelt, Maryland.
