Murrili meteorite’s fall and recovery from Kati Thanda

Abstract

On November 27, 2015, at 10:43:45.526 UTC, a fireball was observed across South Australia by 10 Desert Fireball Network observatories lasting 6.1 s. An~37 kg meteoroid entered the atmosphere with a speed of 13.68 AE 0.09 km s −1 and was observed ablating from a height of 85 km down to 18 km, having slowed to 3.28 AE 0.21 km s −1. Despite the relatively steep 68.5°trajectory, strong atmospheric winds significantly influenced the darkflight phase and the predicted fall line, but the analysis put the fall site in the center of Kati Thanda-Lake Eyre South. Kati Thanda has meters-deep mud under its salt-encrusted surface. Reconnaissance of the area where the meteorite landed from a low-flying aircraft revealed a 60 cm circular feature in the muddy lake, less than 50 m from the predicted fall line. After a short search, which again employed light aircraft, the meteorite was recovered on December 31, 2015 from a depth of 42 cm. Murrili is the first recovered observed fall by the digital Desert Fireball Network (DFN). In addition to its scientific value, connecting composition to solar system context via orbital data, the recovery demonstrates and validates the capabilities of the DFN, with its next generation remote observatories and automated data reduction pipeline.

Mineralogy, petrology, geochemistry, and chronology of the Murrili (H5) meteorite fall: The third recovered fall from the Desert Fireball Network

“…This is compatible with the estimated radius of ~14 cm inferred by Sansom et al. (2020) from the photographic observations of the fireball, and the estimated radius of 15–20 cm from the cosmogenic radionuclide data.…”

“…It was recovered on December 31, 2015, <50 m away from the predicted fall line (Sansom et al. 2020).…”

“…Sansom et al. (2020) reported observations of a fireball lasting 6.1 s, entering the atmosphere with a speed of ~13.7 km s −1 at an altitude of 85 km, before slowing to ~3 km s −1 at an altitude of 18 km at the end of its luminous flight phase. From these observations, they determined that the meteoroid’s pre‐entry orbit had a semimajor axis of 2.521 ± 0.075 AU, an eccentricity of 0.609 ± 0.012, and an inclination of 3.32 ± 0.060°.…”

Dark-flight Estimates of Meteorite Fall Positions: Issues and a Case Study Using the Murrili Meteorite Fall

“…The most basic result is a fall linea ground plot showing a line giving fall positions for a given range of proposed masses. For the DFN, a wide range of masses are modeled, to aid in searching planning; generally this range is much larger than the expected uncertainty of the final mass, which is obtained from bright-flight modeling (Sansom et al 2020). This can be produced for multiple scenarios such as different assumed shapes or wind profiles, resulting in multiple fall lines.…”

“…The dimensions of the Monte Carlo scatter can be used to inform the likely width of the uncertainty in the fall line, which allows searchers to prioritize their activities in the most time-efficient manner. To highlight all the subtleties and complexity involved, we describe in detail the analysis related to the Murrili meteorite fall (Sansom et al 2020) below.…”