New Doppler lidar technology poised to improve accuracy and stability during planetary landings

03 October 2024

New Doppler lidar technology poised to improve accuracy and stability during planetary landings

Technology offers a cost-effective alternative to radar, demonstrated on the Odysseus lunar lander

WASHINGTON - Researchers have developed a coherent Doppler lidar system that can precisely measure a vehicle's altitude and velocity while landing on planetary bodies such as the Moon or Mars. The new technology, called Navigation Doppler Lidar (NDL), was successfully demonstrated onboard the Odysseus lunar lander. As an alternative to radar, NDL could not only reduce the cost and risk of landing missions but also enable more accurate navigation and a smoother, more stable touchdown.

Farzin Amzajerdian from the NASA Langley Research Center will present this research at the Optica Laser Congress and Exhibition, held 20 - 24 October 2024 in Osaka, Japan.

"As we move toward sustained human presence on the Moon and manned missions to Mars, we are going to need low risk and cost-effective landing vehicles that can land in rough terrain or near pre-deployed assets, said Amzajerdian. "NDL can play a major role in enabling these missions."

Landing on a planetary body typically relies on radar if no GPS signal is available. The researchers developed NDL to provide several advantages over radar, including significantly higher precision from a system that is smaller and requires less power. The new sensor is also less susceptible to measurement inferences from uneven terrain or signals bouncing off the lander.

In operation, NDL transmits three laser beams at fixed, but different, angles toward the ground and measures range and velocity along each beam using a frequency-modulated continuous wave technique. Combining the three line-of-sight measurements makes it possible to determine the three components of the vehicle velocity vector and the vehicle's altitude relative to the ground.

To test the new technology, an NDL sensor was used onboard the Odysseus lunar lander, part of a series of missions planned for carrying science payloads as part of NASA's Commercial Lunar Payload Services initiative. The sensor operated flawlessly, measuring velocity and range along all three laser beams from an 8-kilometer altitude, which exceeded the projected 5 kilometers. This outcome was partly due to lower vehicle vibration and higher surface reflectivity than had been used to calculate conservative performance estimates. The NDL system also provided almost 100% valid velocity and range measurements with precisions of better than 0.8 centimeters per second and 0.8 meters, respectively.

"Odysseus mission was an excellent demonstration of the NDL for future robotic and manned missions to the Moon and Mars," said Amzajerdian. "We would like to continue advancing the NDL technology into more compact and capable sensors that not only help space exploration but also help autonomous aerial and ground vehicles here on earth."

About the Optica Laser Congress and Exhibition

The Optica Laser Congress and Exhibition provides a comprehensive view of the latest advances in solid-state laser development and new applications. Beyond innovations in laser technology, the congress will also cover new science made possible by ultra-high brightness and high-power radiation sources, sources and devices for free space and quantum communications, LIDAR for autonomous vehicles, beam steering, materials processing and laser manufacturing. An accompanying exhibition features the latest products resulting from these advances.

About Optica

Optica, Advancing Optics and Photonics Worldwide, is the society dedicated to promoting the generation, application, archiving and dissemination of knowledge in the field. Founded in 1916, it is the leading organization for scientists, engineers, business professionals, students and others interested in the science of light. Optica's renowned publications, meetings, online resources and in-person activities fuel discoveries, shape real-life applications and accelerate scientific, technical and educational achievement. Discover more at: Optica.org

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