ShadowCam: NASA's hypersensitive optical camera images lunar south pole region

NASA's ShadowCam, aboard KPLO, is gathering detailed images of the lunar South Pole, using earthshine and reflection of sunlight.
Kavita Verma
An image from lunar South Pole.
An image from lunar South Pole.


In preparation for Artemis III, NASA is gathering information to aid humanity's first-ever journey to the lunar South Pole region. One method being used is the utilization of a highly sensitive optical camera called ShadowCam, which was developed by Malin Space Science Systems and Arizona State University. 

ShadowCam is capable of acquiring high-resolution images of areas that never receive direct sunlight, such as permanently shadowed regions. It is significantly more light-sensitive than other lunar cameras. ShadowCam is currently aboard the Korea Aerospace Research Institute's KPLO (Korea Pathfinder Lunar Orbiter), also known as Danuri, which launched in August 2022. Since December, ShadowCam has been regularly capturing images of the North and South Pole regions of the Moon. 

Among ShadowCam's first images from lunar orbit is a highly detailed image of the permanently shadowed wall and floor of Shackleton crater, which is located near the South Pole. ShadowCam's ability to operate in extremely low-light conditions enables such detailed images, and it is 200 times more sensitive than the Lunar Reconnaissance Orbiter Narrow Angle Camera. The image also shows boulder trails, which allows scientists to better understand the shape and velocity of the boulders as well as the properties of the Moon's regolith.

The earthshine test

As a part of an instrument sensitivity test, ShadowCam took a picture of the Moon's equatorial region using earthshine to illuminate the surface. The captured image shows the interior of Bruce crater and bright streamers created by soil sliding down the crater's walls. Earthshine is the illumination on the Moon caused by sunlight reflected off the Earth, which lights up the Moon's surface beyond its poles.

Using earthshine during a new Moon

ShadowCam was designed primarily to capture images using secondary illumination from the Moon's geologic features. However, this (main image) picture suggests that it could potentially use earthshine to image Artemis astronauts walking on the Moon's surface during the lunar night. The shadow of the Aristarchus central peak in the image was formed by the earthshine created when the Earth was 35 degrees above the horizon. The central peak exhibits various shades that are believed to signify different rock types.

The power of reflection

ShadowCam employs two secondary lighting methods to take images in areas that are not directly illuminated by sunlight. The first method is earthshine, and the second is the reflection of sunlight off nearby geologic features such as mountains and crater walls at the poles that rise high enough above the surface to reflect direct sunlight. Images captured with the latter type of illumination show the rim of the Marvin crater, which is located about 16 miles from the South Pole.

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