With the Artemis program (named after the Greek goddess of the Moon, and twin sister of Apollo), we are now returning with a substantially different and more complicated mission. Between 1969 and 1972, Apollo landed 6 missions and 12 men on the Moon. These explorers were never stationed more than 3 days, and collectively spent a mere 82 hours walking on the lunar surface. With this limited experience, how can we sustain a long term existence (i.e. weeks or months) on another planet? In order to explore further into our Solar System and land humans on Mars, we need to know how to live and operate for long durations. The Moon provides an exceptional place for us to test and practice our capability to survive and thrive in exceptionally harsh conditions, and provides us with resources that can be used to sustain ourselves.
The target landing sites for the Artemis program are at the Lunar South Pole. There, the Sun’s light barely raises above the horizon, creating areas of permanent shadow that exist directly adjacent to areas of perpetual sunlight. Trapped in the shadows are traces of water ice in quantities large enough to allow extraction of water for drinking, oxygen for breathing, and hydrogen for rocket fuel. (H2O is a wonderful thing, isn’t it?…). Perpetually sunlit “Eternal Peaks of Light,” experience as little as 5 days of intermittent darkness per year, and provide a near limitless and readily available source of power for a sustained presence. Despite the benefits afforded by these shadowed and sunlit conditions, they present major challenges for operating on the lunar surface. The sun will sit directly on the horizon, never rising more than 3° above the surface. Down-Sun (i.e. the sun behind observer, 0° phase), there is no shadow detail and the scene is washed out. Up-Sun, the conditions will be blinding, and potentially hazardous for instruments (or Astronauts) that look in its direction. In between, the Sun will cast long shadows behind even small boulders, obscuring obstacles or exaggerating the appearance of slopes.
But it is in these conditions that exists the role for lidar. As an active source instrument, lidar can see into these shadows, mapping the topography and surveying the landscapes in ways that traditional photogrammetry based vision systems would struggle. lidar sensors, particularly those like frequency modulated continuous wave (FMCW) sensors that are robust to solar glare interference, provide the means for accurate navigation regardless of up- or down-Sun illumination and traverse conditions. Importantly, lidar enables a 3D representation of the environment that can be made in real-time (e.g. for an Astronaut’s heads-up display, and is ready-made for virtual reality immersion that will engage the public in ways never before possible. Lidar presents its own challenges, for example in terms of data volumes, operating temperatures, power consumption, and space-environment technology readiness levels, but the development of a space system has clear benefits that could get translated into defense and commercial applications. I’m confident that lidar will become an integral part of the future of planetary exploration in the Artemis program and beyond.