At those ridiculous temperatures, you would expect materials to be a worry, but AVIATR will be made of fiberglass, the same stuff used to construct the containers that store liquid helium. Problem solved. Lemke and Foch say their biggest concern is the longevity of the electronics, actuators, motors, computers, and other small components. “No one’s ever built an airplane that can fly a year or two,” says Foch, because no one has had to. Reliability will be a must, and critical parts will need backups.
Turbulence is a minor concern; Titan’s air is obviously not as well understood as Earth’s. The only direct experience with the lower atmosphere that Lemke and Foch have to go on is Huygens’ parachute drop in 2005. The feeble sunlight on Titan doesn’t deliver much energy, so winds should be light, but just in case, the engineers are designing the airplane to be as inherently stable and self-correcting as possible. More than any airplane in history, AVIATR will be on its own.
Since NASA spacecraft operate so far from home, they’re designed so that if they lose orientation, they go into “safe mode”: Find Earth or some other recognizable target, lock onto it, and await instructions. AVIATR’s equivalent of a safe mode will be a Dutch roll—a steady side-to-side rocking that would prevent the airplane from going into a graveyard spiral down to Titan. The designers have come up with a modifier vane—a “unique feature of this airplane,” says Foch—that could pop up from the nose to add lateral stability if AVIATR’s autopilot fails.
Foch and Lemke plan to verify the effectiveness of the flight controls in wind tunnel and atmospheric tests before launch—if there is a launch. AVIATR will have to compete for the 2016 Discovery slot, which is sure to draw at least a dozen other clever, well-thought-out proposals.
Ralph Lorenz of the Applied Physics Lab loves the idea of flying around his favorite moon. He has even designed his own two-pound UAV, which he calls the Titan Bumblebee, for hovering over the surface. But for this Discovery round, he is part of a team proposing a different concept. Called TIME, for Titan Mare Explorer, it would land a floating spacecraft on one of the moon’s methane lakes. Lorenz thinks an airplane may well be included on some future multibillion-dollar expedition to Titan, but figures NASA might be nervous gambling an entire Discovery mission on its first extraterrestrial airplane—which some people still consider a pretty far-out concept.
Not Rick Foch and Larry Lemke, who have been quietly working that problem for years. AVIATR is probably their most advanced vehicle yet, and their best shot at moving beyond the prototype stage. And somewhere on Titan’s dim, frozen surface may be their Kitty Hawk.
Tony Reichhardt is a senior editor at Air & Space.