In 2008, FUTEK was approached by NASA to design measurement solutions for its upcoming Mars rover Curiosity. The goal of the mission was to explore the Martian climate and geology through drilling, collecting, and analyzing soil samples from its surface to assess if the Red Planet’s conditions were, or had ever been, favorable to microbial life.
Our Technical Director Richard Walker was a key player in this program. We asked him to travel back in time to share what it was like to be part of this important scientific achievement.
The first sensor FUTEK created was the QLA295, a through-hole load cell. “Its primary focus was to monitor what was known as ‘weight on bit,’ meaning the amount of force they were putting on the drill bit,” Walker said. “The goal was to not inflict any damage on the bit because if they broke it, or something happened to it, it would be useless.”
Because it needed to operate 100 million miles from Earth, a damaged sensor — let alone a drill bit — couldn’t be sent back to the factory for repair. The key component to ensuring continuous operation was a second Wheatstone bridge. “Because they needed the sensor to measure the force at a remarkably high level of accuracy and resolution, it was necessary to include a dual bridge. That allowed for redundancy in the system, which reduced the risk of the drill becoming inoperable in extreme conditions,” Walker explained.
With an atmosphere 100 times thinner than Earth’s, the average temperature on the Red Planet is a frigid 80 degrees below zero F (–60°C), and even colder near the poles. “The main challenge was that the sensors had to be able to handle a non-operating temperature of –200°F and an operating temperature at –124°F,” Walker explained. “To achieve that, we drew from a lot of our experience with previous NASA/JPL programs, where the parts had to be submerged in liquid nitrogen, which was closer tonus 300°F. Because those had worked very well for their application, we had gained confidence from their team so we could move into supporting this project.”
“Working on such an amazing program was fun and nerve-wracking all at the same time. You know that you had to make sure that everything on the part was absolutely perfect because any slightest nick or damage could completely ruin everything. So, you are highly aware that you have to do the best you’ve ever done before. And that goes for everyone who worked on it, all the operators and the calibration technicians because NASA relied on this thing being perfect.”Richard Walker, Technical Director
Some of the most complex science instrumentation lives at the end of an articulated arm mounted to the front of the rover. Back on the ground, it was critical to know where and how that arm was positioned in three-dimensional space. FUTEK had a sensor for that: a three-component sensor that measured torque and force. “This one operates within the rover’s robotic arm, and as the arm maneuvers, the sensor provides feedback to the operating device about the levels of applied torsion and force. The goal is to be able to control the arm’s movements so it does not get damaged. If there’s over-exertion, the arm could break off, or it could get stuck.”
As critical as this was, there wasn’t an obvious place to put the strain gauge sensors. “This was a more complicated process because we were not really doing any design work,” Walker explained. “We were basically handed a flexure that we had to make into a sensor without machining and affecting anything, which is ten times more challenging. We had to run an analysis on it to see where we could put the strain elements. The part had a lot of unique surfaces that were not flat, like curved shapes in multiple directions. So that is where we had to get a little bit more creative, not just about putting the strain elements on there, but how we were going to bond and clamp them into those cavities. We had to come up with special tooling.”
To have sensors operating flawlessly on Mars for over a decade defines going above and beyond, but it doesn’t stop there. In an unexpected turn of events, FUTEK really learned the definition of “mission-critical.” “The mission was originally supposed to run for two years. Knowing that we did the best work we had ever done at that point, I was expecting our sensors to last a long time. But the fact that they have been operating on Mars for over a decade? That exceeds my expectations. And even though we knew that the sensors’ capabilities went above and beyond the requirements that they were initially designed for, it was still very cool to learn that they helped save the mission at one point. When the rover’s original drill mechanism failed, the JPL team found a way to configure our sensors to stabilize and control the drilling so the sample collection and analysis could resume.”
To see the team’s creativity and skill makes Walker proud. “To be part of this program was a huge moment for us. During the launch, we gathered everybody in the lunchroom and watched it together via NASA’s channels. It was extremely exciting for all of us to be tied to such a wonderful achievement. It is definitely one of the highlights for our company.”