HIGH RESOLUTION, AVALANCHE DIODE X-RAY SPECTROMETER FOR PLANETARY EXPLORATION

ONE OF THE MOST EXCITING GOALS OF THE NASA SPACE PROGRAM IS TO LAND A VEHICLE ON MARS AND CONDUCT PHYSICAL AND CHEMICAL MEASUREMENTS OF THE MARTIAN SURFACE. OF THE VARIOUS ANALYTICAL TECHNIQUES BEING CONSIDERED FOR THE LANDER MISSION, X-RAY FLUORESCENCE ANALYSIS OFFERS THE POSSIBILITY OF PROVIDING THE IN-SITU INFORMATION ABOUT THE CHEMICAL COMPOSITION OF THE PROSPECTIVE SAMPLES WHICH WILL BE SELECTED FOR THE TRIP BACK TO EARTH. A KEY ASPECT OF ADAPTING THE TECHNIQUE FOR THE LANDER MISSION WILL BE THE AVAILABILITY OF A PRACTICAL, HIGH RESOLUTION, LOW ENERGY X-RAY DETECTOR. AN IDEAL CANDIDATE FOR SUCH A DETECTOR IS THE LARGE AREA, SILICON AVALANCHE PHOTODIODE RECENTLY DEVELOPED AT OUR COMPANY. THIS DETECTOR, WHICH OPERATES AT OR SLIGHTLY BELOW ROOM TEMPERATURE, CAN, IN PRINCIPLE, MEET ALL OF THE PERFORMANCE REQUIREMENTS FOR THIS ASPECT OF THE MISSION. THIS PROPOSAL DISCUSSES THE RESEARCH NEEDED TO IMPROVE THE RESOLUTION OF THESE EXCITING NEW DETECTORS AND WORK IS PROPOSED ON BOTH THE SILICON DIFFUSION PROCESS AND THE DESIGN OF THE DEVICE STRUCTURE. WHEN COMPLETED, THE NEW SPECTROMETER SHOULD BE HAVE A VERY WIDE RANGE OF APPLICATION NOT ONLY FOR NASA MISSIONS, BUT ALSO FOR MANY OTHER FIELDS OF SCIENCE AND INDUSTRY AS WELL.