While the sun is in the lunar sky more consistently at the poles, it never rises more than a few degrees above the horizon; in the target landing regions, the highest possible elevation is 7°. This presents a harsh lighting environment never experienced during the Apollo missions, or in fact, in any human spaceflight experience.

The ambient lighting will severely affect the crews' ability to see hazards and to perform simple work. This is because the human vision system—which, despite having a high-dynamic range—cannot see well in bright light and cannot adapt quickly from bright to dark or vice versa.

Functional vision is required to perform a variety of tasks, from simple tasks (e.g., walking, operating simple tools) to managing complex machines (e.g., lander elevator, rovers). Thus, the environment presents an engineering challenge to the agency: one that must be widely understood before it can be effectively addressed.

In past NASA missions and programs, the design of lighting and functional vision support systems for extravehicular activity (EVA) or rover operations has been managed at the lowest program level. This worked well for Apollo and low Earth orbit because the sun angle was managed by mission planning and astronaut self-positioning; helmet design alone addressed all vision challenges.