Conceptual Design of an In Situ K-Ar Isochron Dating Instrument for Future Mars Rover Missions

抄録

Age is one of the most important observables in planetary science. Although a sample return mission will provide accurate radiometric age measurements, it may not be launched very often because of its high cost. Thus, in situ radiometric age measurements with a one-way landing mission is very important. We are developing an on-site K–Ar isochron dating instrument for such a mission. This instrument is intended to measure K and Ar abundances with laser-induced breakdown spectroscopy and noble gas mass spectrometry, respectively. In this study, we propose an in situ dating package using mostly flight-equivalent components and a small number of components currently under development by our team. The geochronology instrument suite will contain a pulse laser, a spectrometer, a re-sealable vacuum chamber, a time-of-flight mass spectrometer, and a sample handling system using parallel link arms. Our assessment estimates that such an in situ geochronology package for measuring K–Ar crystallization age with 10–15% of accuracy for rocks with 3 Ga of age would be approximately 240 mm × 240 mm × 400 mm in size and 12.5 kg in mass.