Buzz
Two images show Mars' position during opposition and conjunction. In opposition, Earth passes close to Mars, making it easily visible in the night sky. In contrast, during conjunction, like the one occurring between Oct. 2 and 14, Mars and Earth are positioned far apart, with the sun blocking direct communication, making interaction between the two planets challenging. NASASoon, Mars and Earth will perform their cosmic dance around the sun in an event known as the Mars solar conjunction. Essentially, it's a period when the two planets are on opposite sides of the sun. But why is it important?
Every two years, for about two weeks, the solar conjunction happens. This year, it's from Oct. 2 to Oct. 14. During this time, the sun blocks the connection between Earth and Mars, rendering the two planets effectively invisible to each other. As a result, communication with NASA spacecraft on Mars slows to a quiet murmur.
Why is there no communication?
The sun typically ejects hot, ionized gas from its corona, which then spreads through space. This usually isn't an issue, but during solar conjunction, this gas can disrupt radio signals when engineers try to communicate with their spacecraft on or near Mars. This interference can corrupt commands, causing unexpected behavior from Mars' mission equipment.
As a result, a communication blackout is implemented, with mission controllers at NASA's Jet Propulsion Lab (JPL) shutting down certain instruments. They collect and store data from the Odyssey and Mars Reconnaissance Orbiters, which gather information from the stationary Curiosity and Perseverance rovers, as well as the InSight lander during this period.
During the solar conjunction, only the Odyssey Orbiter attempts to transmit any data to Earth, knowing that some of the information will be lost. However, NASA halts sending new commands to Mars to prevent any unintended outcomes from misinterpreted signals.
What takes place during conjunction?
During the solar conjunction, NASA pauses sending new signals to its spacecraft. To mitigate the heightened risk of radio interference, controllers pre-load two weeks' worth of messages. This also gives the mission teams a rare chance to take time off, provided there are no pressing projects. Similar to setting an out-of-office reply, they'll return to work once the solar conjunction is over.
Once the solar conjunction ends, the spacecraft will transmit the data they've gathered to NASA's Deep Space Network, a network of large radio antennas on Earth managed by the JPL. Engineers will spend approximately a week downloading the data before resuming regular communications.
If any data is found to be corrupted, engineers can usually have it retransmitted, much like asking a colleague to resend a lost or unreadable file—just from a much greater distance.
Though the length of a day on Mars is quite similar to that of Earth—24 hours 37 minutes compared to 23 hours 56 minutes—a Martian year lasts 687 Earth days, much longer than Earth's 365.25 days.
