Snakebot Anatomy

Snakebots are unlike any robotic probe ever to be used for space missions. In order for a robot to mimic the movements of a biological snake, some special design features have to be used. NASA's snakebots are a model of the polybot developed by Mark Yim of Xerox Palo Alto Research Center. Polybots are robots that are able to change their shape in order to perform a variety of tasks. Snakebots will slither and dig underneath the soil for geological surveying, or coil up to carry tools for construction in space.

Photo courtesy NASA

The main body of a snakebot consists of about 30, identical, hinge-like modules that are linked together in a chain. These modules are connected by a central spine and work together to perform various functions. The snakebot frame will be constructed out of a polycarbonate material and covered by an artificial skin to protect it from the Martian elements. Here's a closer look at a snakebot's architecture and individual modules:

• Electronics - Each snakebot will have a central computer, possibly located in the snakebot's head, that works in conjunction with smaller computers in each module. Wires will connect each module to its neighboring modules, creating a network of modules that work together as a unit. The wiring will also carry communications and power to and from the computer brain.
• Microcontrollers - These tiny computers will interpret signals from the main computer to control movement. In later models, they may be connected to a set of sensors to provide reflexes.
• Sensors - In later models, strain sensors may be added to the robot's metal-rib frame. These sensors will indicate if the snake is in contact with anything, where it's touching it and how hard the contact is.
• Motors - Two servomotors, which are like off-the-shelf hobby motors, will be used to move the various parts in each module. Each motor will be activated by a signal from the main processor.
• Wheels - Each module will be equipped with one wheel. The wheel won't be wholly responsible for transporting the snakebot -- it will only used to ease movement.
• Gears - Working in conjunction with the electronics, the gears will allow for movement of the hinges. This will give the snake the ability to coil, side-wind and inch-worm its way across the ground or wrap around objects.
• Camera - Small cameras attached to the snakebots will give NASA a never-before-seen view of the red planet.
• Connecting Rods - When one section begins to move, these ball-jointed connecting rods will pull and activate the section next to it.

Photo courtesy NASA An up-close look at the snakebot modules

Snakebots will be able to limit the weight of the spacecraft ferrying them to space. The snake-like design allows them to perform many tasks without a lot of extra equipment. "One of the many advantages of the snake-based design is that the robot is field-repairable," NASA engineer Gary Haith says. "We can include a bunch of identical spare modules with the snake on a space mission, and then we can fix the snakebot much easier than a regular robot that needs specific parts."

Unlike past robotic probes, snakebot will be very cheap. In contrast to the $135-million Mars Odyssey that was launched on April 7, 2001, snakebots will probably cost only a few hundred dollars each. In fact, the cost of the snakebot is so low that one researcher says there is a possibility of developing a toy version.