The Potassium-Argon Laser Experiment (KArLE): In situ geochronology for planetary robotic missions

摘要

The Potassium (K) - Argon (Ar) Laser Experiment (KArLE) will make in situ noble-gas geochronology measurements aboard planetary robotic landers and rovers. Laser-Induced Breakdown Spectroscopy (LIBS) is used to measure the K abundance in a sample and to release its noble gases; the evolved Ar is measured by mass spectrometry (MS); and relative K content is related to absolute Ar abundance by sample mass, determined by optical measurement of the ablated volume. KArLE measures a whole-rock K-Ar age to 10% or better for rocks 2 billion years old (Ga) or older, sufficient to resolve the absolute age of many planetary samples. The LIBS-MS approach is attractive because the analytical components have been flight proven, do not require further technical development, and provide complementary measurements as well as in situ geochronology.