Navigating the Cosmic Eye: Astronauts Tackle Visual Perplexities at the Lunar South Pole

Humanity is headed back to the moon—this time, for a permanent stay. Due to the extended nature of our presence, NASA has chosen a site that optimizes line-of-sight communication with Earth, sunlight access, and availability of water ice: the Lunar South Pole (LSP).

Although the sun appears in the lunar sky more consistently at the poles, it never ascends more than a few degrees above the horizon; in the designated landing areas, the maximum elevation is just 7°. This creates an unforgiving lighting setting never encountered during the Apollo missions, nor in any human spaceflight history.

The surrounding light conditions will drastically impact the crews’ capacity to identify hazards and execute basic functions. This is due to the human visual system—which, despite possessing a high-dynamic range—struggles in intense brightness and cannot swiftly adjust from light to darkness or the opposite.

Effective vision is essential for carrying out a range of activities, from basic actions (e.g., strolling, using simple tools) to operating complex machinery (e.g., lander elevator, rovers). Hence, this environment presents an engineering hurdle for the agency: one that requires thorough comprehension before it can be properly tackled.

In prior NASA missions and initiatives, the development of lighting and functional vision support systems for extravehicular activity (EVA) or rover tasks was managed at the most fundamental program level. This approach was effective for Apollo and low Earth orbit since the sun angle was controlled through mission planning and astronauts’ self-positioning; helmet design managed all visual challenges.

The Artemis program introduces new obstacles for functional vision, as astronauts will frequently encounter direct sunlight while on the lunar surface. This necessity, coupled with the requirement for artificial illumination in the deep shadows at the LSP, indicates that new functional vision support systems must be devised across various projects and initiatives.

The construction of helmets, windows, and lighting systems must operate in a synergistic manner, both within and among programs, to establish a cohesive system of lighting and vision support that allows crews to navigate through darkness while light-adapted, perceive bright conditions while still dark-adapted, and shield their eyes from injury.

Numerous findings from the evaluation focused on the absence of explicit criteria to avert functional vision degradation due to the sun’s brightness (which differs from preventing eye injuries), while allowing astronauts to see sufficiently to perform specific functions. Specifically, the tasks anticipated for astronauts at the LSP were not integrated into system design prerequisites to enable system development that secures functional vision in the predicted lighting conditions.

As a result, the spacesuit, for instance, includes flexibility standards for permitting astronauts to walk, but does not ensure they can adequately see when shifting from bright sunlight to deep shadows and back, minimizing the risk of tripping or falling. Crucially, gaps were detected in the distribution of requirements across programs to guarantee that each program grasps the concept of functional vision.

NESC recommendations were proposed to make fostering functional vision in severe lighting conditions a distinct and new mandate for system designers. The suggestions also encompassed the integration of lighting, window, and visor designs.

The assessment team advised that a diverse range of simulation methodologies, both physical and virtual, should be developed, with each specifying different and clearly defined capabilities related to functional vision. Some would tackle the dazzling effects of sunlight at the LSP (which cannot be easily replicated through virtual means) to evaluate the efficiency of helmet shields and artificial lighting in relation to the environment and adaptation durations.

Other simulations would incorporate terrain attributes to pinpoint hazards encountered during simple (e.g., walking, sample collection) and intricate (e.g., maintenance and equipment operation) tasks.

Since distinct facilities possess varying strengths, they also exhibit different weaknesses. These strengths and constraints must be characterized to facilitate the verification of technical solutions and crew training.