Southwest Research Institute | 2020 Feb 12
The early solar system was a chaotic place, with evidence indicating that Mars was likely struck by planetesimals, small protoplanets up to 1,200 miles in diameter, early in its history. Southwest Research Institute scientists modeled the mixing of materials associated with these impacts, revealing that the Red Planet may have formed over a longer timescale than previously thought.Modeling Early Mars ~ Credit: SwRI
An important open issue in planetary science is to determine how Mars formed and to what extent its early evolution was affected by collisions. This question is difficult to answer given that billions of years of history have steadily erased evidence of early impact events. Luckily, some of this evolution is recorded in Martian meteorites. Of approximately 61,000 meteorites found on Earth, just 200 or so are thought to be of Martian origin, ejected from the Red Planet by more recent collisions.
These meteorites exhibit large variations in iron-loving elements such as tungsten and platinum, which have a moderate to high affinity for iron. These elements tend to migrate from a planet’s mantle and into its central iron core during formation. Evidence of these elements in the Martian mantle as sampled by meteorites are important because they indicate that Mars was bombarded by planetesimals sometime after its primary core formation ended. Studying isotopes of particular elements produced locally in the mantle via radioactive decay processes helps scientists understand when planet formation was complete. ...
A Compositionally Heterogeneous Martian Mantle Due to Late Accretion ~ Simone Marchi et al
- Science Advances 6(7):aay2338 (12 Feb 2020) DOI: 10.1126/sciadv.aay2338