NASA's Perseverance rover, which is set to deploy to Mars this July, is traveling to the red planet with a hidden message on board — in addition to the names of millions of people.

After nearly 11 million people participated in NASA's "Send Your Name to Mars" campaign, the names were stenciled by an electron beam onto three microchips and attached to a commemorative aluminum plate on the rover. Also etched into the chips are the essays of the 155 finalists in NASA's "Name the Rover" contest.

But eagle-eyed space fans spotted a hidden message on the plaque after NASA made the announcement last week. Etched onto it is a graphic of Earth and Mars joined together by the sun, which will be visible in pictures captured by the rover.

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NASA said the graphic commemorates the rover's connection between the two planets and pays tribute to plaques on board the Pioneer spacecraft and golden records carried by Voyagers 1 and 2. But fans noticed that the sun's rays aren't random — they're actually Morse code.

Some of you spotted the special message I’m carrying to Mars along with the 10.9+ million names you all sent in. “Explore As One” is written in Morse code in the Sun’s rays, which connect our home planet with the one I'll explore. Together, we persevere. https://t.co/Bsv1mqpxlA pic.twitter.com/GhcS1HgsIN — NASA's Perseverance Mars Rover (@NASAPersevere) March 30, 2020

"Some of you spotted the special message I'm carrying to Mars along with the 10.9+ million names you all sent in," the Twitter account for the rover confirmed. "'Explore As One' is written in Morse code in the Sun's rays, which connect our home planet with the one I'll explore. Together, we persevere."

It's not the first time the Jet Propulsion Laboratory (JPL) team has hidden a message in a Mars rover. The team also designed the Curiosity rover's wheels to spell out "JPL" in Morse code as it drives across Martian dirt.

NASA's Mars Perseverance rover seen on March 16, 2020, at NASA's Kennedy Space Center in Florida. NASA/JPL-Caltech

The spread of coronavirus has slowed work on some upcoming space missions, but Perseverance is still on track for its scheduled launch date this summer. The rover is expected to land at Jezero Crater on Mars on February 18, 2021.

After touchdown, it will scour the crater for signs of past life, explore its geology and collect samples to bring back to Earth for future research. The mission will pave the way for human exploration of the red planet.