Going to work on Mars became routine immediately. Each morning, engineers and scientists alike got their morning coffee or tea and opened up the files of images and data downlinked overnight from the rovers. Then, typically they would review the data, mentally teleport themselves to the rover’s site, and prepare for the work ahead.

The MERtians devoted themselves to their jobs and their robots. For seven years, they were working in two places at once, and a rover’s life, the mission’s life depended on them. They were cognizant of that every minute of every day.

The ethos resonated deeply, so deeply that team members lived their lives around the rovers and Mars. They scheduled life events, even the birth of children, around the Martian seasons and sacrificed many of Earth’s holidays. Every day they went to work on Mars and were happy for it. Mars became their new normal, Gusev Crater and/or Meridiani Planum their second homes.

Through the years, the bonds deepened and the entire team eventually would turn into one big family, a family that genuinely seemed to like each other even in the moments when they didn’t. In the space community, MER was admired, envied even. Everyone knew this mission was special. Still, there was something more, something different than any other mission I’d ever covered.

It was the way team members interacted with Spirit and Opportunity. Anyone who has followed the mission and The MER Update knows well that these two robots became way more than buckets of bolts or tools for so many on this team of Mars pioneers, not to mention their many followers around world. These rovers were, after all, Earth’s emissaries doing our bidding.

Designed to be identical twins, Spirit and Opportunity actually exhibited different personalities from the beginning, Callas told me years ago. He spent many nights with them in their “incubation room” during development. Spirit’s “infant” quirks likely resulted because everything was tested first on the alpha twin, so she bore the brunt of breakdowns and things going wrong. Opportunity benefited from that, but their individual “traits” would become clear soon enough.