For over two decades, the United States has maintained a constant presence on Mars, and was recently joined by China with its Tianwen spacecraft.
The space agencies have been using spacecraft to explore the planet’s potential as a past or present habitat for life. However, every two years, these spacecraft experience a communication blackout for approximately two weeks due to an astronomical event known as solar conjunction.
Solar conjunction is a period when Earth and Mars, in their continuous orbit around the Sun, are obscured from each other by the Sun itself. This celestial alignment renders the two planets temporarily invisible to each other, much like dancers on either side of a massive bonfire.
Nasa has said that in 2023, the solar conjunction moratorium on commanding Mars spacecraft is scheduled from November 11 to November 25, during which Mars will be within 2 degrees of the Sun.
During this time, communication with any spacecraft in solar conjunction will be severely limited due to the Sun’s interference on radio transmissions from the spacecraft.
Mission controllers at Nasa’s Jet Propulsion Laboratory have developed various strategies to navigate this period. Some instruments are turned off, while data from others is collected and stored. In some cases, they continue sending data to Earth, fully aware that some data may be lost.
No new instructions are sent to Mars during solar conjunction. The unpredictability of what information might be lost due to interference from charged particles from the Sun poses a potential risk to the spacecraft. Instead, engineers send two weeks’ worth of instructions in advance and wait.
While this may seem risky, advancements in autopilot technology have significantly improved the ability of engineers to let spacecraft operate independently. Much like parents preparing their children for a short vacation with friends, mission teams ensure that all necessary commands are sent up before solar conjunction.
Apart from Nasa, China and UAE also have spacecraft hovering above the Red Planet.