Hazard Detection and Avoidance

NGC is recognized internationally for its autonomous Hazard Detection and Avoidance (HDA) software system for planetary landers. It enables terrain mapping, hazard detection and safe-site designation in real time during landing.


NGC’s Hazard Detection and Avoidance software system enables terrain mapping, hazard detection and safe sites designation in real time during landing manoeuvres.

Autonomy is critical because communication delays with the ground and the need to react quickly preclude human intervention in the process. This system makes use of Light Detection and Ranging (Lidar) and camera sensor measurements to detect and identify surface hazards in real time during the descent.

Based on Lidar range measurements, camera images and knowledge of lander motion, this system computes various hazard-related properties of the terrain, such as surface slope, roughness, illumination and the propellant cost of reaching the site. This information is combined into a single hazard map that provides an overall safety assessment of each candidate landing area. The safest landing site, based on the evaluation of all these criteria, is proposed by the HDA system. This assessment is done in real time, a few hundreds of metres above the landing surface, while the lander is making its final approach.

One of the key features of NGC’s HDA system is its motion compensation function. The system can handle inputs from a scanning Lidar, which takes a few seconds to scan a complete frame. Since the lander is moving during the scanning process, the raw output of the sensor is distorted. However, based on the estimated lander motion during the scan, NGC’s software compensates for the motion and removes the distortions from the sensor measurement. This prevents imposing tight immobility constraints during the scanning process and improves the overall propellant efficiency of the mission.

Landing Site Selection through Safety Assessment

NGC’s software quantifies candidate landing sites’ safety in real-time during the descent. Safety of landing sites in terms of slope, roughness and shadows is evaluated with respect to a scale varying between completely safe (shown in blue) to unsafe for landing (shown in red).

Hazard Detection and Avoidance Demonstration


When you work with us, you’ll find we are very flexible when it comes to finding ways to integrate our technology into your project. We also provide in-depth training and the support of one of the most experienced Guidance, Navigation and Control (GNC) systems teams in the world.