NASA publishes stunning images of the moon’s dark south pole

NASA’s highly sensitive ShadowCam optical camera aboard the South Korean lunar orbiter Danori, which was launched in August 2022, has sent stunning images of the moon’s dim south pole to Earth, the destination for future manned missions.

Developed by Malin Space Science Systems and Arizona State University (ASU), ShadowCam is more sensitive to light than similar lunar cameras. Obtain high-resolution images of permanently shaded areas, which never receive direct sunlight, to support science and exploration planning for Artemis and robotic missions.

Since Danuri entered lunar orbit last December, ShadowCam has been routinely taking images of the Arctic and Antarctic regions. Here are some of the standout images so far, and what they reveal.

One of the first ShadowCam images from lunar orbit, pictured above in more detail than ever before, is of the permanently shadowed wall and floor of Shackleton Crater, which lies near the south pole. The level of detail in this image is made possible by ShadowCam’s ability to work in very low-light conditions: it is 200 times more sensitive than the narrow-angle camera in the Lunar Reconnaissance Orbiter.

The arrow indicates the footprint of a boulder that rolled down the crater wall. Observing these tracks helps scientists determine the shape and velocity of rock and regolith properties, which advances our understanding of the moon’s geotechnical properties.

ShadowCam is designed to provide views of the shaded areas near the poles. However, this image was taken under Earth’s light in the Moon’s equatorial region as part of the instrument’s sensitivity test. It reveals the inside of the Bruce Hole and the glowing streamers that formed from the soil that slid down the crater walls.

ShadowCam captured this image just after the new moon. During the new moon, at the same time that we see a thin crescent of the earth, the person on the moon will see a near-full earth. Just as the Moon can provide illumination on the Earth, so the full Earth can provide illumination on the Moon; This is known as Earth’s brilliance.

Although the Earth’s brightness is about ten times dimmer than the available illumination in the middle region permanently shaded by sunlight reflected from lunar geological features, ShadowCam was still able to image the surface using Earth’s brightness, indicating the instrument’s ability to see the dimmer regions of Antarctica. .

Two types of secondary lighting allow the ShadowCam to capture images in areas that do not receive direct sunlight. The first is luminosity, which illuminates the moon’s surface away from the poles with sunlight reflected from Earth. The second is the illumination that results from sunlight reflecting off nearby geological features, such as mountains and crater walls at the poles that are high enough above the surface to reflect direct sunlight.

Another image, taken in the latter type of lighting, shows the rim of Marvin crater, about 16 miles (26 kilometers) from the south pole. There is a more than 90° difference in the direction of illumination in small rim craters compared to small inner craters because the secondary illumination emerges from a broad arc rather than a point light source.

The image below shows a larger area surrounding Marvin Crater. The white area on the left side is where the surface was exposed to direct sunlight, the secondary light source within the shaded areas. ShadowCam is designed to work in low light, so sunlit areas are oversaturated (white areas are indicated).

Although ShadowCam was primarily designed to use secondary illumination of lunar geological features for imaging, this image, showing the central peak of Aristarchus crater (left), was taken using light from Earth.

ShadowCam will not be able to take pictures of Artemis astronauts walking on the surface of the Moon if they are exposed to direct sunlight because the strong light will saturate the images. However, this image shows that it may be possible to use the brightness of the Earth, if the astronauts were spacewalks during the lunar night.

In another, the shadow cast by the central peak of Aristarchus is caused by the brightness of the Earth, which was caused by the Earth’s elevation of 35 degrees above the horizon at the time. The different shades at the central peak are believed to represent different types of rock.