OBJECTIVES: THE COSMOGENIC RADIONUCLIDE 129I (HALF-LIFE=1.57X10"7 YR) OFFERS THE POSSIBILITY OF EXTENDING THE TIME SPAN OVER WHICH COSMOGENIC RADIONUCLIDES CAN BE USED TO STUDY THE HISTORY OF EXTRATERRESTRIAL MATERIALS AND COSMIC RAYS. ITS HALF-LIFE FALLS BETWEEN THAT OF 53MN (3.7X10"6 YR) AND 40K (1.28X10"9 YR) A TIME FRAME RELEVANT TO THE EVOLUTION AND TRANSPORT OF METEORITE PARENT BODIES. THE GOALS OF THIS WORK: (1) TO STUDY EXPOSURE HISTORIES OF METEORITES BY EXTENDING THE RADIONUCLIDE TIMESCALE TO 10-30 MYR AND TO CONSTRAIN THE COMPLEX EXPOSURE HISTORIES OF LARGE STONY METEORITES; (2) TO ESTABLISH THE "LIVE" 129I-129XE EXPOSURE AGE DATING TECHNIQUE FOR IRON METEORITES; AND (3) TO STUDY SECULAR VARIATIONS OF THE COSMIC RAY FLUX OVER THE PAST 10"9 YEARS BASED ON IRON METEORITE EXPOSURE AGES.