The materials problem has been handed off to a separate team, which is a huge weight off of my shoulders—no more pouring over spreadsheet after spreadsheet of yield strength and Young’s modulus for everything from Aluminum to carbon fiber! You may have noticed that our rover design is rather different from the more conventional rover chassis used by NASA. When you talk about “planetary rovers”, usually people think of the phenomenally successful models NASA sent to Mars, such as Sojourner, Spirit, and Opportunity. Perhaps the most obvious difference is that ours has only four wheels as opposed to the standard six—a decision that was the result of a bitter, three-week-long debate that nearly destroyed this team before it started. You see, your typical robotic exploration rover (The NASA/Jet Propulsion Laboratory MER Program) looks like a golden shoebox on six metal wheels with cheese grater treads, situated on a Tinkertoy suspension. This is called a “rocker-bogie” system, in which each independently powered wheel is at the end of a cantilever, so that, as one wheel elevates to climb over, say, a rock, support is transferred to the remaining wheels while the body “rocks” in place to remain stable and upright. It’s a brute force approach to navigating the terrain of other planets: Meet obstacles head-on, and plow right over them. Ours is designed differently because we came to the same realization that automobile engineers did some years ago. When the science of crash testing cars was a relatively new thing, it was done just the way you’d imagine: driving cars at high speeds into a wall to see how it crumples or deforms, and what harm would be caused to the occupants. At some point, however, some technician somewhere had an epiphany that saved countless lives (and, given the statistics for automotive fatalities, may have already saved yours). He realized that they were testing for an ideal situation that rarely occurs in the real world (we now know today that head-on collisions make up only 2% of all traffic accidents in the United States). He then had the technicians set up a new series of tests, this time colliding the car with objects at an angle or at an offset that would only contact part of the bumper, just what actually happens in real accidents. The results they obtained were frightening, to say the least, and revolutionized the way we look at automotive safety and how the cars we drive are designed. The lesson learned from this is an important one: in engineering, you can’t plan for the ideal situation, because nature (and life, for that matter) simply doesn’t work like that. A robotic rover on the surface of the Moon or Mars will almost never meet a ledge head-on. Even if it did, when was the last time you saw nature produce a perfectly straight edge in a rock formation? What this means for our team’s rover is that we only need it to be able to climb with one wheel at a time instead of two, as NASA builds their robots. If you accept the above premises regarding geology, that’s exactly what will happen every time, because the rover will always approach said obstacle at some angle or offset. In addition to terrain mitigation, it turns out that a four-wheel rocker-bogie is just as capable of “skid steering” (turning in place) and maintaining stability. At the end of the day, with both models performing pretty much the same, we simply went with the one that required less power—the four-wheeled design. Now, if you’ll excuse me, there’s word of a Delta IV-Heavy launch soon. Carpe Astra…