NASA keeps hiding ‘Easter eggs’ on Mars-bound spacecraft

When NASA’s Mars Curiosity rover landed on Mars back in 2012, it was far bigger than any other rover that had come before it. The difference was especially obvious in the spacecraft’s wheels, which looked like monster truck tires compared to those on the relatively diminutive Sojourner rover. That’s why space fans back on Earth were quick to analyze the strange tire marks Curiosity left behind after its first test drive on the Red Planet. 

It turns out, mission planners had imprinted the rover’s six wheels with a message in Morse code that reads “— [J], .–. [P], and .-.. [L].” JPL is short for NASA’s Jet Propulsion Laboratory, where the spacecraft was built.

However, this wasn’t just a fun way for engineers to write their names in the former beach sands of Mars. Instead, the imprints occur at regular, well-defined intervals, which helps managers back on Earth keep track of the exact distance each wheel travels. That way, they can monitor if any wheels are slipping in steep or loose soil.

Spirit and Opportunity’s World Trade Center relics

Engineers at Honeywell Robotics in Manhattan were working on a key feature of NASA’s Opportunity and Spirit rovers when terrorists attacked the World Trade Center less than a mile away on September 11, 2001. And with the spacecraft’s launch deadline swiftly approaching, the employees couldn’t spend much time helping in the recovery effort. They had to keep building the rovers’ Rock Abrasion Tool, a grinding instrument that would let the spacecraft peel back weathered layers of samples to study what was beneath. 

So, working together with JPL engineers, the team found another way to pay tribute. Honeywell Robotics networked with the New York City mayor’s office and secured an aluminum piece of wreckage that they repurposed into identical cable covers for both rovers. And each piece was adorned with an American flag.

The rovers completed their initial 3-month missions on Mars in early 2004, but no one from NASA, Honeywell, or the rover teams mentioned the World Trade Center connection until much later in the year. 

“It was meant to be a quiet tribute,” Stephen Gorevan, a Honeybee founder and Mars rover team member eventually told The New York Times. “Enough time has passed. We want the families to know.”

Both Spirit and Opportunity have now shut down, though Opportunity pressed on until a 2018 global dust storm engulfed it. Yet, without significant weather eroding the spacecraft, their metal frames will likely survive for millions of years, creating a permanent memorial on Mars to the lives lost during the World Trade Center attack. 

A similar memorial was also tucked away on Perseverance: The rover carries a memorial to healthcare workers and those lost during the COVID-19 pandemic.

Thanks to the hints of JPL engineers, we know Perseverance’s known Easter eggs aren’t the last. The latest rover is still hiding more secrets — and these are expected to be revealed in the coming weeks.