LPL  MAGI Instrumentation Software Laboratory

RAC - Robotic Arm Camera
	An image of the Mars Polar Lander (MPL, Mars '98) spacecraft showing the SSI and RAC locations. The RAC to be flown on the upcoming Phoenix mission is almost identical to the one used for the MPL mission.

The Phoenix lander includes a robotic arm for retrieving soil samples from the Martian surface and delivering them to either the MECA or TEGA analysis experiments. The SSI will be used to monitor the progress of the arm from a vantage point above the spacecraft. In order to get a closer look at what the scoop at the end of the arm may have collected a small camera will be attached near the end of the arm with a view directly into the scoop. The RAC, or Robotic Arm Camera, includes banks of red, blue and green LED lamps to provide multi-spectral illumination, and has the ability to focus from a few centimeters into the scoop out to infinity.

The animation below shows an example of the range of focus possible with the RAC when examining a soil sample (it may take a few minutes to load, depending on your connection speed).

The RAC was developed and built by the Max Planck Institute for Aeronomy (MPAe) under the direction of H. Uwe Keller, and at the Lunar and Planetary Laboratory (LPL) at The University of Arizona (UA) under the direction of Peter Smith (UA) for the Mars Polar Lander mission, which was unfortunately lost during descent onto Mars in 1998. The unit which will be onboard the Phoenix lander is a flight spare unit from that mission with some slight modifications. The main improvement to the RAC has been the use of LED lamps. These have higher light output levels, consume less power and provide much better spectral characteristics for illuminating samples.

The photo at left shows technicians checking the mounting of the MPL RAC to the robotic arm. Note that in the image the RAC and the scoop are "upside-down" in regards to normal operation on the surface of Mars for the benefit of the personnel assembling it.

The RAC electronics is based on the design used for the Mars '98 MPL and Mars 2001 missions. A Frame Buffer Board (FBB) controls a CCD Readout Board (CRB) to provide command signals and clocking to the CCD in the RAC, and then capture the image data for download into the main computer onboard the spacecraft. The image data can be processed to correct known image defects and reduce its size prior to downlink back to Earth.

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