Curiosity Rover Uses LEDs for Nighttime Imaging of Martian Rock

NASA's Curiosity Mars rover has conducted an unusual nighttime imaging operation, using LED lights on its robotic arm to illuminate a drill hole named "Nevado Sajama."

This method allowed scientists to capture detailed images of the rock's interior layers, providing insights into its composition and texture that are not achievable through traditional daytime observations alone.

The exercise is part of a broader strategy to maximize the scientific output of the aging rover by adapting its existing instrumentation.

Curiosity's Nighttime Operations

The Curiosity rover, operational on Mars for nearly 14 years, employs LED lights integrated into its Mars Hand Lens Imager (MAHLI) camera, which is mounted on its robotic arm. These lights, capable of emitting both UV and white light, enable the rover to photograph the Martian surface in darkness or in deeply shadowed areas, such as the interiors of drill holes or instrument inlets. This capability facilitates detailed observation of rock compositions and structures.

Mars experiences nights lasting over 12 hours, with temperatures near the equator dropping to approximately -100 degrees Fahrenheit. The planet's axial tilt influences the length of nights, making them longer in winter and shorter in summer. The absence of artificial light on Mars allows for clear visibility of standard star constellations in the night sky.

Nevado Sajama Drilling and Imaging

The "Nevado Sajama" rock target was drilled on November 13, 2025, marking Curiosity's 4,740th Martian day. The drilling occurred in a region characterized by "boxwork" geological formations. An image of this drill hole, illuminated by the rover's LEDs, was subsequently captured on December 6, 2025, and released by NASA.

Unlike some previous drilling efforts in 2018, which resulted in rougher holes that obscured internal details, the Nevado Sajama hole featured notably smoother walls. This smoothness provided a rare opportunity for scientists to examine the rock's subsurface layering effectively under controlled lighting conditions. The Mast Camera (Mastcam) was used to capture the overall scene illuminated by the MAHLI LEDs.

Technological Capabilities and Advantages

The MAHLI camera is one of Curiosity's seventeen cameras and can capture true-color images at a resolution of 1,600 by 1,200 pixels. The precision LEDs on MAHLI are primarily designed for close-range illumination.

Using artificial lighting at night offers several advantages for scientific observation:

• It creates consistent lighting angles, eliminating variable shadows and solar glare that can interfere with daytime imaging.
• It reduces visual noise caused by dust reflecting sunlight.
• It enhances the ability to assess minute details such as grain size, texture, and subtle color variations within the rock layers.

Scientific Rationale and Mission Context

This nighttime imaging experiment represents a targeted decision by NASA. It aligns with the agency's broader strategy of adapting and innovating with Curiosity's existing tools to extract new high-value data as the rover continues its extended mission. This approach helps expand operational methods for both current and future Mars exploration missions.

The Jet Propulsion Laboratory (JPL), managed by Caltech, is responsible for developing these innovative uses for the rover's hardware.