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When something is put on autopilot, human input is no longer necessary, unless intervention is necessary to avoid an accident. Lasers, in particular LiDAR, appear to be a popular choice for aiding autonomous actions in space.
LiDAR is employed in many autonomous vehicles being developed. Google and Uber, for example, are developing cars with a continuously spinning box on their roof that fires a laser and creates a complex 3D map from the returning information to help the car navigate and avoid obstacles. LiDAR – which stands for LIght Detection And Ranging - is perhaps considered the most significant piece of hardware in self-driving cars.
In space, NASA has also favored LiDAR, which it has employed in Kodiak, part of the satellite servicing project named Restore-L. The mission has seen scientists develop an autonomous vehicle that can ‘drive’ to a satellite before grasping it, refueling and repositioning it in space. Kodiak uses a low-power, eye-safe laser, a micro-electromechanical scanner, and a photodetector to paint a picture of the scene from a distance, providing real-time, high-resolution images to mission controllers on the ground. They are able to see the satellite as the robotic servicer approaches, as well as automatically determining the location and relative orientation of the satellite. Kodiak could also be used in asteroid retrieval and observation where the lidar laser would be flashed to illuminate the target, much like the flash of a traditional camera.
LiDAR is also utilized in the docking of Orbital Science Corporation’s Cygnus cargo transport spacecraft to the International Space Station (ISS). TriDAR is a navigation system featuring a long-range LiDAR system combined with a laser camera system (LCS). It was commercialized by Neptec Design Group, a Canada-based company contracted by the Canadian Space Agency, who funded the system along with NASA. It relies on a laser-based 3D sensor and thermal imager to offer guidance information that can direct an unmanned vehicle during rendezvous and docking in space. It can automatically acquire and track a target without using any markers - only knowledge about its shape - and was tested on three NASA space shuttle missions before the program ended in 2011.
Orion is a Multi-Purpose Crew Vehicle currently under development by NASA and the European Space Agency. It is intended to carry astronauts to destinations at or beyond low Earth orbit (LEO): the moon, asteroids, and Mars, as well as recovering crew or supplies from the ISS. Orion features a Lunar Surface Access Module which will take astronauts to the Moon’s surface, while it orbits unmanned; should the worst happen, it could fly unpiloted to rescue the astronauts using a system of sensors and smart navigation software. At first, it would listen to radio signals from the lander to determine its direction while the autopilot software fires the engines to move it closer to the lander’s position. Once 3km or so from the lander, a laser-based sensor would take over.
It is thought the system under development could feature a wide-angle laser that would be fired out into space while a video camera watches for reflections from a pattern of mirrors mounted on the lunar lander that the sensor software could recognize. The software could then judge the distance and orientation of the lander. It is also hoped that the system could be used to help Orion dock with the ISS or help assist human pilots.
These are just a few examples of how NASA is employing lasers in autopiloting; they are likely many more, but these serve to show the role that such technology can have in space, as well as back on Earth.
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