A New Way to Navigate to Your Next Moon Landing

CAMBRIDGE, MA—Draper recently achieved a milestone toward future spaceflight missions focused on landing on the moon by demonstrating that its terrain-relative navigation (TRN) system can identify ground features from ranges necessary for safe, routine lunar landings. The capability enables access to more challenging landing sites through pin-point landing and large hazard avoidance.

The company demonstrated its TRN system onboard the Xodiac lander vehicle, developed and provided by Masten Space Systems, Inc., Mojave, Calif. The flight demonstration was carried out as part of the Safe and Precise Landing Integrated Capabilities Evolution (SPLICE) project led by NASA’s Johnson Space Center, with funding from NASA’s Flight Opportunities Program (FO).

Using an independent navigation package equipped with two cameras, an inertial measurement unit (IMU), barometer and onboard computer, the TRN system successfully identified features throughout the flight and maintained an accurate navigation solution to the landing.

Terrain-relative navigation will figure prominently in future exploration of the Moon and Mars. It gives spacecraft extremely accurate landing capabilities without the aid of GPS, according to Matthew Fritz, a space systems engineer at Draper and the principal investigator for the TRN flight demonstration.

“We have onboard satellite maps loaded onto the flight computer, and a camera acts as our sensor,” explained Matthew Fritz, principal investigator at Draper. “The camera captures images as the lander flies along a trajectory and those images are overlaid onto the preloaded satellite maps that include unique terrain features. Then by mapping the features in the live images, we’re able to know where the vehicle is relative to the features on the map.”

Draper has developed and field tested its TRN technology over the past decade with a focus on higher-altitude trajectories. For lunar applications, the TRN system will support vehicle navigation throughout the last stages of the flight and until just before landing.

Earlier this year, Flight Opportunities facilitated a test of the high-altitude part of Draper’s navigation algorithm on a balloon flight with World View Enterprises in Tucson, Arizona. The data from balloon flights combined with the research on Masten’s vehicle will be used to better calibrate the navigation algorithms.

Going forward, the Draper test team will use the results from this flight test to make updates to both software and hardware before targeting additional terrestrial test flight platforms to further evaluate the TRN system. With these upcoming flight test opportunities as well as performing algorithm testing using third-party surface rendering technologies, Draper plans to have the TRN system ready for deployment by 2021.