Constraining ages of surface features on rocky objects in the Solar System provides fundamental insights about the flux of impactors through time (including the putative Late Heavy Bombardment), rates of tectonic and volcanic processes, and temporal context for detected organic compounds. Spaceflight instrumentation is being developed to characterize these ages in situ. An LA-ICPMS is suggested as a candidate for a planetary chronology mission, with Mars as a case study; the capability of the technique to measure Rb and Sr isotopic signatures in geological samples with adequate accuracy within the 200 Myr (2σ) precision benchmark presented in NASA’s Technology Roadmap is tested. Data are presented that reports on these metrics for 87Sr/86Sr ratios, and a Monte Carlo simulation models synthetic isochrons to evaluate the accuracy and precision limitations of this method. A minimum of 10 data points per sample is suggested to meet the NASA benchmark.