Exploring a Martian Day: From Sunrise to Sunset, Curiosity Chronicles the Red Planet

During a temporary pause in its exploration, NASA’s Curiosity Mars rover demonstrated an unexpected talent as a sundial, showcasing this phenomenon in two captivating black-and-white videos recorded on November 8, marking the 4,002nd Martian day, or sol, of its mission. Using its black-and-white Hazard-Avoidance Cameras (Hazcams), the rover skillfully documented the gradual movement of its own shadow across the Martian terrain.

The decision to capture these videos was part of the final set of commands transmitted to Curiosity just before the commencement of Mars’ solar conjunction—a phase when the sun aligns between Earth and Mars. This precautionary measure, taken to avoid interference with radio communications caused by solar plasma, meant a temporary halt in sending commands to the rover during this period. Although the rover remained in contact through regular health check-ins, the downtime provided an opportunity for a unique experiment.

Curiosity’s Hazcams, typically employed for identifying potential obstacles and hazards, were repurposed to record a series of 12-hour snapshots for the first time. The goal was to capture phenomena such as clouds or dust devils, offering insights into the Martian weather. While the images did not reveal any significant weather patterns, the resulting pair of 25-frame videos beautifully document the passage of time from 5:30 a.m. to 5:30 p.m. local Martian time, showcasing the rover’s silhouette transitioning through morning, afternoon, and evening on the Red Planet.

The initial video, compiled from images captured by the front Hazard-Avoidance Camera (Hazcam), provides a mesmerizing view southeast along Gediz Vallis—a valley situated on Mount Sharp within Gale Crater. Curiosity has been steadily ascending this 3-mile-tall (5-kilometer-tall) mountain since 2014.

The footage captures the unfolding Martian day as the sun rises, illuminating the landscape. During sunrise, the shadow of Curiosity’s 7-foot (2-meter) robotic arm gracefully shifts to the left, and the rover’s front wheels emerge from the darkness on either side of the frame. Additionally, a circular calibration target mounted on the robotic arm’s shoulder becomes visible on the left. This target serves as a testing tool for the accuracy of the Alpha Particle X-ray Spectrometer, an instrument designed to detect chemical elements on the Martian surface.

As the Martian day progresses, the front Hazcam’s autoexposure algorithm adjusts, settling on exposure times of approximately one-third of a second during the middle of the day. As night falls, the exposure time extends to over a minute, leading to the appearance of “hot pixels,” a typical sensor noise resembling white snow scattered across the final image. The video encapsulates the rover’s interaction with its environment, from the freshness of dawn to the tranquility of Martian nightfall.

In the second captivating video, Curiosity’s rear Hazard-Avoidance Camera (Hazcam) provides a panoramic view looking northwestward down the slopes of Mount Sharp, extending to the floor of Gale Crater on Mars. The footage captures the rover’s right rear wheel and the shadow cast by Curiosity’s power system. Notably, a small black artifact appearing in the 17th frame resulted from a cosmic ray striking the camera sensor.

Towards the end of the video, bright flashing and additional noise are observed, stemming from the heat emitted by the spacecraft’s power system affecting the Hazcam’s image sensor. These visually engaging images have undergone re-projection to correct the wide-angle lenses of the Hazcams. The speckled appearance, particularly noticeable in the rear-camera video, is attributed to 11 years of Martian dust settling on the camera lenses, adding a unique texture to the visual record of Curiosity’s Martian sojourn.

Resources

1. ^{ONLINE NEWS} NASA. (2023, December 29). Curiosity captures a martian day, from dawn to dusk. Phys.org. [Phys.org]

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