Curiosity rover spots rare ‘Egg Rock’ on Mars
WASHINGTON: A globular, golf-ball-size object discovered by Nasa’s Curiosity rover on Mars has been confirmed as a rare iron-nickel meteorite fallen from the Red Planet’s sky.
Iron-nickel meteorites are a common class of space rocks found on Earth, and previous examples have been seen on Mars, but this one, called Egg Rock, is the first on Mars examined with a laser-firing spectrometer, Nasa said.
To do so, the rover team used Curiosity’s Chemistry and
Camera (ChemCam) instrument. Scientists of the Mars Science Laboratory (MSL) project, which operates the rover, first noticed the odd-looking rock in images taken by Curiosity’s Mast Camera (Mastcam) at a site the rover reached by an October 27 drive.
“The dark, smooth and lustrous aspect of this target, and its sort of spherical shape attracted the attention of some MSL scientists when we received the Mastcam images at the new location,” said ChemCam team member Pierre-Yves Meslin, of National Centre for Scientific Research (CNRS) and the University of Toulouse in France.
ChemCam 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 the object.
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, 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 centre 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 Horton Newsom of the University of New Mexico in the US.
“Mars may have sampled a different population of asteroids than Earth has,” said Newsom. In addition, the study of iron meteorites found on Mars —including examples found previously by Mars rovers — can provide information about how long exposure to the Martian environment has affected them, in comparison with how Earth’s environment affects iron meteorites.