For the first time, the Curiosity rover has found rock primarily made of iron on the Martian terrain. The meteorite has been named “Lebanon,” and is accompanied by a second smaller rock called “Lebanon B.” Curiosity snapped images of the meteorites on May 25 of this year.
The rover used its Remote Micro-Imager (RMI) of Curiosity’s Chemistry and Camera to take the pictures, which revealed unexplained cavities in the meteorites. The cracks may in fact be due to erosion targeting crystalline portions of the metal within the rock. An alternative hypothesis is that olivine crystals were, at some point, crevassed within the meteorite. Olivine crystals are frequently found in pallasites, a stony-iron type of meteorites which is theorized to take shape between the core and mantle in an asteroid.
Images of the newly-discovered rocks were taken on the 640th Martian day that Curiosity has undertaken an exploration of the surface of Mars. The rover’s Mast Camera (Mastcam) provided color to the detailed, high-resolution images taken in a circular fashion. The rock photographed, “Lebanon,” has a width of 2 meters, larger than “Lebanon B.”
Iron meteorites are most common type of the few meteorites found on the Martian surface. Iron rock may dominate because it is less likely to erode. On Earth, stony meteorites are more frequently found — about 5.7% of all fallen meteorites are stony. However, it is not unusual to spot an iron meteorite.
Composed of an iron-nickel alloy called meteoric iron, iron meteorites form from the cores of planetesimals. The rock has been associated with M-type asteroids because it has a similar spectrum of visible and infrared wavelengths. The asteroids, smashed to pieces through collisions, produce fragments of iron, which account for about 90% of all meteorites.
Iron meteorites are much denser than stony meteorites and are known to be the largest of its type.