In the coming years, NASA and other space agencies will send humans back to the moon for the first time since the Apollo era – this time to stay! To maximize line of sight to Earth, solar visibility and access to water ice, NASA, ESA and China have selected the lunar south pole (LSP) as the location for their future lunar bases. This requires the creation of permanent infrastructure on the Moon and requires astronauts to have the proper equipment and training to cope with the conditions around the lunar south pole.
This also includes lighting conditions, which pose a major challenge for scientific operations and extra-vehicular activities (EVA). Around the LSP, day and night last two weeks each, and the sun never rises more than a few degrees above the horizon. This creates harsh lighting conditions that are very different from those experienced by the Apollo astronauts or other previous missions. To address this issue, the NASA Engineering and Safety Council (NESC) has recommended the development of a variety of physical and virtual techniques to simulate the visual experiences of Artemis astronauts.
In the past, the design of lighting and functional vision support systems was typically relegated to the lowest level of program planning. This worked well for the Apollo missions and Low Earth Orbit (LEO) EVAs, as the helmet design alone addressed any vision issues. The Artemis program will be different because astronauts cannot avoid getting bright sunlight in their eyes for much of the time they spend on EVAs. Added to the challenge is that extensive shadows appear around the LSP due to its cratered and uneven nature, not to mention the extensive lunar nights.
Additionally, astronaut vehicles and habitats require artificial lighting during missions, meaning astronauts must switch from ambient lighting to bright sunlight and/or intense darkness and vice versa. Because the human eye has difficulty adapting to these transitions, it affects an astronaut's “functional vision,” which is necessary to drive vehicles, safely conduct EVAs, operate tools, and manage complex machinery. This is particularly true for rovers and the HLS spacecraft landing elevator, both of which are used for the HLS spacecraft Artemis III And IV Missions.
As Meagan Chappell, knowledge management analyst at NASA's Langley Research Center, indicates, this requires the development of new functional vision support systems. That means helmets, windows and lighting systems that can work together to allow crews to “see in the dark while their eyes are adapted to the light, in bright light while they are still adapted to the dark, and their “To protect eyes from injury.” According to the NESC assessment, these challenges have not been addressed and need to be understood before solutions can be implemented.
In particular, they noted that functional vision and specific tasks for Artemis astronauts were not included in the system design requirements. For example, the new spacesuits developed for the Artemis program – the Axiom Extravehicular Mobility Unit (AxEMU) – offer more flexibility, allowing astronauts to walk more easily on the lunar surface. However, there are currently no features or systems that would allow astronauts to see well enough when transitioning from bright sunlight to dark shadow and back again without losing their footing.
The NESC assessment identified several additional gaps, leading them to recommend that methods that enable functional vision become a specific and new requirement for system designers. They also recommended integrating the design process for lighting, windows and visors. Finally, they recommended the development of various physical and virtual simulation techniques to meet specific requirements. These are virtual reality programs that simulate what it's like to walk around the LSP during the day and night, followed by “dress rehearsal” missions in analog environments (or a combination of both!).
As Chappell summarized, the simulations will likely focus on different aspects of the mission elements to measure the effectiveness of their designs:
“Some would look at the glare of sunlight at the LSP (which is not easily achieved through virtual approaches) to evaluate [the] Performance of helmet shields and artificial lighting in the context of the environment and adaptation times. Other simulations would add terrain features to identify threats in simple (e.g., walking, collecting samples) and complex (e.g., maintaining and operating equipment) tasks. Because different institutions have different strengths, they also have different weaknesses. These strengths and limitations must be characterized to enable verification of technical solutions and crew training.”
This latest set of recommendations reminds us that NASA is committed to achieving a regular human presence on the Moon by the end of this decade. As that day approaches, the need for more thorough preparation and planning becomes clearer. If astronauts are going to go to the moon regularly (once a year starting in 2028, according to NASA), they will need the best training and equipment we can find.
Further reading: NASA