The third prototype rover from the Astrobotic Technology team recently gained a mock camera and antenna head, making it nearly complete and ready for high-end photography. Yesterday it was posed in front of a green screen so that it can later be combined via Photoshop in combination with actual Apollo surface imagery and a rendering of the new design for the Astrobotic spacecraft / lander.

The overriding technical challenge of operating a rover near the Moon’s equator is the intense, prolonged heat produced by solar radiation and the hot regolith over which the rover travels. All powered equipment inside the robot generates its own heat as well, which must be routed to the radiator for release into space. In the photo below, the team has a key composite part sealed in vacuum to achieve better bonding of the layers. This part, the motor strap, connects the heat-generating 28v brushless motor to other high-conductivity composite straps leading up to the radiator.

The schematic below shows where the motor strap fits into the design of one of the two drive motors, mounted in the “shoulder” of the robot. The motors power chain drives on either side of the robot that connect to the wheels. The rover steers by driving the two sides at different speeds, or reversing one side to turn in place.

The third prototype lunar robot developed by the Astrobotic team has been crowned by a mock camera/antenna head, completing its overall look. The unit was robotically machined to perfect the team’s skills in creating the foam molds over which carbon fiber will be laid up to build the actual camera and antenna housings. The horizontal section will house two wide-field cameras with a telephoto zoom between them. The white top of this unit is a radiator to regulate internal temperatures. The dome will house an S-band “evolved” antenna.

The Astrobotic rover will carry a battery pack (273 WHr) to ensure power during the high-activity landing and also for the brief periods during roving when the solar panels won’t be fully oriented toward the Sun. The team is fabricating a battery pack that straps the lithium ion cells to a main I-beam, which connects to the radiator to disperse heat.

This image shows the top piece of an aluminum mold for the battery pack over which a carbon-fiber structure will be built up.

This image shows the bottom piece of an aluminum mold for the battery pack over which a carbon-fiber structure will be built up, forming a container something like a U clamp to hold the individual small cells together.

This image shows some of the carbon fiber strips that will be laid up over the battery molds to create the battery pack structure.

The Astrobotic team has initiated testing of an experimental inertial measurement unit (IMU) loaned from Intel Labs. (IMUs measure a spacecraft’s velocity, orientation and gravitational forces.)

The tiny device provides six degree of freedom orientation data, utilizing a bluetooth wireless connection to a host computer. It contains three accelerometers, three gyroscopes, three magnetometers, and a microprocessor. The 9.8 gram IMU runs for six hours on a single charge.

Video of IMU test screen

For the Astrobotic rover to survive hibernation during the lunar night’s cryogenic cold, the team must find commercial components that perform to extremes far beyond their published spec sheets. This week an Asus netbook entered the cryo-freezer to see if its Intel Atom processor would bounce back from the ordeal. (See photos below)

The team brought the board’s temperature down by 1 degree C per minute until it reached -180 degrees C. After 30 minutes there, it was warmed at the same rate to reach room temperature. The Asus then successfully booted up Windows and displayed a Word document. Now that basic functionality is shown, the team will vary the rate and duration of the cold and then subject the Atom to more rigorous tests of proper operation after it is thawed.