While I’m on the subject of rover suspension and ground clearance, I want to take a detour to recognize the less famous rovers that didn’t make the trip to Mars. My rover fandom has mostly been focused on siblings Curiosity and Perseverance, but those rovers would not exist if it weren’t for the twin rovers Spirit and Opportunity. Formally the Mars Exploration Rover program, they followed Sojourner the rover technology demonstrator. Each rover generation was larger and more sophisticated than the last, but one thing all those rovers had in common was the rocker-bogie suspension design that I replicated with my own Sawppy rover using references like a rover family portrait published by NASA.
But the real rovers are on Mars. Who are the rovers in this picture? The little one is named Marie Curie, and is a “Flight Spare” for Sojourner (Truth). Meaning it is fully equipped and qualified to be sent to Mars as an alternate if necessary, but there was no need so Marie Curie stayed on Earth. I assume it played a role during the mission as a testbed as the other two rovers did.
Representing Spirit and Opportunity is the MER Surface System Test Bed. This rover duplicates many of the mechanicals of Spirit and Opportunity, but is not fully equipped to go to Mars. For one thing, it runs on a power tether and have no functioning solar panels, just passive stand-ins. This machine stayed at JPL’s Mars Yard to help scientists and engineers on Earth test ideas and solutions before commands are sent to Mars.
MER SSTB is a mouthful, and I remember seeing JPL people on Twitter calling the test rover “Dusty” but I found no official confirmation of this name. After the Mars Exploration Rover program ended, Dusty(?) was given to the Smithsonian where it will continue to represent the MER program when put on display.
The Mars Science Laboratory (MSL) mission included the Earthbound Vehicle System Test Bed counterpart to Curiosity shown in the family photo, again with some differences such as powered by a tether instead of faithfully duplicating an onboard radio-thermal nuclear reactor. According to this article, the MSL VSTB counterpart to Curiosity is “Maggie”, and the Mars 2020 test bed counterpart to Perseverance is “Optimism”.
And since these are engineering tools, both names are officially engineering acronyms. Or more likely, “backronyms” where the acronym was chosen first, then words were chosen to fit it. That’s why we have convoluted names like “Mars Automated Giant Gizmo for Integrated Engineering” and “Operational Perseverance Twin for Integration of Mechanisms and Instruments Sent to Mars.”
These rovers won’t get nearly as much fame as their Mars-bound counterparts, but they all play vital roles contributing to mission success.
[Image credit: NASA/JPL-Caltech]