Autonomous Landing Hazard Avoidance Technology
[4][5] According to the NASA web page on the project, it will provide state-of-the-art automated descent and landing system for planetary lander craft.
The technology will work in any lighting conditions, from the harsh glare of an unshielded Sun to the cloudy, gaseous murk of a distant Solar System body.
[7] The ALHAT technologies include a Hazard Detection System, a lidar Doppler velocimeter, a laser altimeter, software, sensor algorithms and path-to-space computer processors.
[2] The instrumentation has been tested by operating from moving vehicles – a truck, NASA's Huey helicopter and the Project Morpheus lander.
At the end of testing the project is aiming for the ALHAT equipment to have reached Technology Readiness Level (TRL) 6.
NASA claim that COBALT's Navigation Doppler Lidar (NDL) is 60 percent smaller, operates at nearly triple the speed and provides longer range measurement.
[10] The flash lidar uses imagery technology to detect objects larger than the size of a basketball on a planetary surface under all lighting conditions.
The onboard system uses the data to build a terrain and elevation map of potential landing sites in real time.
ALHAT first scans from a high altitude giving the spacecraft sufficient to respond to obstacles or craters at the landing site.
Support is also provided by Charles Stark Draper Labs and the Johns Hopkins Applied Physics Laboratory, Baltimore.
In conjunction with this, NASA's Jet Propulsion Laboratory developed algorithms for analysing the terrain based upon these lidar measurements.
The new optics permit the Navigation Doppler Lidar to accurately measure the vehicle's velocity relative to the ground.
[1] The ALHAT's ability to detect items larger than a baseball from a distance of 2,500 feet (760 m) whilst moving was tested by placing the system on a truck.
[22] A lunar terrain field was constructed at Kennedy Space Centre (KSC) for ALHAT on Morpheus lander testing.
The KSC helicopter tests included flight profiles approximating planetary approaches, with the entire ALHAT system interfaced with all appropriate Morpheus subsystems and operated in real-time.
Tests included placing the lander on blocks to verify that the ALHAT Inertial Measurement Unit (IMU) worked when tilted.
In FF11, as in FF10, ALHAT operated in open-loop mode, imaging the Hazard Field and calculating navigation solutions in real time during the flight.
[29] A swing test was performed on April 28, 2014 to obtain accurate data on ALHAT's 3-beam Navigation Doppler Lidar to calibrate and confirm its range and velocity measurements.
The ALHAT Hazard Detection System (HDS) performed well, but identified a safe site just 0.5 m outside the conservatively established limits around the center of the landing pad.
