A small globular object found by NASA’s Curiosity rover at the Murray Formation of lower Mount Sharp on Mars has been identified as an iron-nickel meteorite.
The smooth-surfaced rock at the center of this Oct. 30 image from Curiosity’s Mast Camera was examined by the rover’s ChemCam instrument and confirmed to be an iron-nickel meteorite. Image credit: NASA / JPL-Caltech / MSSS.
Iron-nickel meteorites are a common class of space rocks found on Earth, and previous examples have been seen on Mars, but this one is the first examined by Curiosity’s laser-firing spectrometer called ChemCam (Chemistry & Camera).
Curiosity mission scientists first noticed the dark, smooth-surfaced rock in images taken by Curiosity’s Mast Camera at a site the rover reached by an Oct. 27 drive.
This object, dubbed Egg Rock, is about 1.7 inches (4.3 cm) in diameter and may have fallen to the Martian surface many millions of years ago.
“The dark, smooth and lustrous aspect of this target, and its sort of spherical shape attracted the attention of some Curiosity scientists when we received the Mastcam images at the new location,” said ChemCam team member Dr. Pierre-Yves Meslin, from the University of Toulouse in France.
The smooth-surfaced object in this composite, colorized view from Curiosity’s ChemCam instrument shows a grid of shiny dots where ChemCam had fired laser pulses used for determining the chemical elements in the target’s composition. The analysis confirmed that this object is an iron-nickel meteorite. Image credit: NASA / JPL-Caltech / LANL / CNES / IRAP / LPG Nantes / CNRS / IAS / MSSS.
The ChemCam instrument found iron, nickel and phosphorus, plus lesser ingredients, in concentrations still being determined through analysis of the spectrum of light produced from dozens of laser pulses at nine spots on Egg Rock.
“The enrichment in both nickel and phosphorus at some of the same points suggests the presence of an iron-nickel-phosphide mineral that is rare except in iron-nickel meteorites,” Dr. Meslin said.
Iron meteorites typically originate as core material of asteroids that melt, allowing the molten metal fraction of the asteroid’s composition to sink to the center and form a core.
“Iron meteorites provide records of many different asteroids that broke up, with fragments of their cores ending up on Earth and on Mars,” said ChemCam team member Dr. Horton Newsom, from the University of New Mexico, Albuquerque.
“Mars may have sampled a different population of asteroids than Earth has.”
The mission scientists will be analyzing the ChemCam data from the first few laser shots at each target point and data from subsequent shots at the same point, to compare surface versus interior chemistry.
