Mars Temporarily Vanishes Behind the Sun; NASA's Robots Operate Autonomously Until Conclusion of Solar Conjunction

On Saturday, November 18, Mars vanished from Earth's view as it seemingly merged with the Sun. This apparent disappearance is merely the Red Planet moving to the opposite side of the Sun in an astronomical occurrence known as solar conjunction.

Mars Nears Sun, Entering Solar Conjunction and Fading from View

During its close approach to the Sun, Mars will be less than one degree separated from the star, both located in the constellation of Libra. As a consequence, the Red Planet will become unobservable for several weeks due to the Sun's glare.

This event, known as solar conjunction, occurs every two Earth years when Earth and Mars are at their greatest separation. Under usual circumstances, these planets maintain a distance of about 140 million miles; however, during solar conjunction, their separation widens to approximately 235 million miles, surpassing two and a half times the average Earth-Sun distance.

At the point of closest approach, Mars will be a mere 0°06' from the Sun, rendering it completely unobservable for several weeks due to being immersed in the Sun's brightness. Simultaneously, Mars will be at its farthest distance from Earth, reaching 2.53 astronomical units (AU), positioning the two planets on opposite sides of the solar system.

If observable, Mars would appear at its smallest and faintest, measuring 3.7 arcsec in diameter. In the subsequent weeks and months, Mars will gradually reappear to the west of the Sun, becoming visible for longer periods in the pre-dawn sky. After approximately a year, it will reach opposition, making it visible for nearly the entire night.

NASA's Mars Fleet on Hold

The solar conjunction of Mars holds importance beyond casual observation, affecting NASA's robotic missions such as the Curiosity and Perseverance rovers, the Ingenuity helicopter, and orbiting spacecraft around the Red Planet.

Lasting from November 11 to 25, this event prompts a temporary loss of communication between Earth's mission controllers and the robotic Mars missions, resulting in the suspension of rover activities, grounding Ingenuity, and halting the transmission of spacecraft data to Earth.

This precautionary measure prevents potential interference from partial commands during the Mars solar conjunction, which occurs every two years when Earth and Mars are positioned on opposite sides of the Sun.

NASA's decision to abstain from sending commands to its Mars fleet during the two-week period, as announced in a statement, is a response to the potential corruption of radio signals by the Sun's hot, ionized gas emanating from the corona. Such interference could lead to unpredictable behaviors in the Mars spacecraft.

During the communication pause, Mars missions will continue collecting data on surface conditions, weather, and sand movement on the Martian terrain. Roy Gladden, the Mars Relay Network manager, highlighted the meticulous preparation of to-do lists for all Mars spacecraft, ensuring continuous health monitoring during the hiatus.

In the upcoming months, Mars will gradually become visible for longer periods before dawn as it emerges from the Sun's wider side. About a year from now, Mars is set to reach opposition, becoming observable for a significant portion of the night from Earth.

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