Madicken Munk Brett Davidheiser-Kroll Nicholas H. Warner Sanjeev Gupta Rachel Slaybaugh Patrick Harkness Darren Mark Leah E. Morgan 2017 <p><span>The chronology of the Solar System, particularly the timing of formation of extra-terrestrial bodies and their features, is an outstanding problem in planetary science. Although various chronological methods for </span><i>in&nbsp;situ</i><span> geochronology have been proposed (e.g., Rb-Sr, K-Ar), and even applied (K-Ar), the reliability, accuracy, and applicability of the </span>⁴⁰<span>Ar/</span>³⁹<span>Ar method makes it by far the most desirable chronometer for dating extra-terrestrial bodies. The method however relies on the neutron irradiation of samples, and thus a neutron source. Herein, we discuss the challenges and feasibility of deploying a passive neutron source to planetary surfaces for the </span><i>in&nbsp;situ</i><span> application of the </span>⁴⁰<span>Ar/</span>³⁹<span>Ar chronometer. Requirements in generating and shielding neutrons, as well as analysing samples are described, along with an exploration of limitations such as mass, power and cost. Two potential solutions for the </span><i>in&nbsp;situ</i><span> extra-terrestrial deployment of the </span>⁴⁰<span>Ar/</span>³⁹<span>Ar method are presented. Although this represents a challenging task, developing the technology to apply the </span>⁴⁰<span>Ar/</span>³⁹<span>Ar method on planetary surfaces would represent a major advance towards constraining the timescale of solar system formation and evolution.</span></p> application/pdf 10.1111/ggr.12170 en Wiley Instrumentation development for In Situ 40Ar/39Ar planetary geochronology article