If you're familiar with the pockmarked landscape of Mars, you'll know that the Red Planet gets hit by meteorites a lot. So it stands to reason that you'll likely find the occasional ex-space rock just sitting out there on the surface, particularly if your primary task is to constantly look down. And it just so happens we have a robotic geologist that has been getting intimate with Mars rocks since 2012 and it has just found a new rock beyond Mars.

The meteorite was discovered in imagery taken by Curiosity's Mastcam on sol (day) 1503 of its mission (Oct. 28) and followup studies by the rover's ChemCam on Oct. 30 revealed the object's strange, melted structure (pictured below). Curiosity is currently climbing the slopes of Mount Sharp (Aeolis Mons) in the center of Gale Crater after leaving the geologically fascinating region of "Murray Buttes." 

University of Arizona planetary scientists believe that it is a metallic nickel-iron rich meteorite, which are commonly found on Earth. This Martian example has been nicknamed "Egg Rock" by the Curiosity mission team. 

The interesting thing about meteorites on the Martian surface is that they are not subject to some of the aggressive weathering terrestrial meteorites are. Mars' atmosphere is very dry, limiting the amount of moisture that can degrade the pristine material. These factors help to preserve the meteorite material for indefinite periods, particularly if they are metal-rich.

Also, as the Mars atmosphere is so thin, compared with Earth's hefty atmospheric gases, Mars meteors will more likely hit the ground as meteorites and not completely burn up. Therefore future human meteorite hunters would want to consider field trips to Mars to collect these treasures as they hold many clues to the composition of ancient asteroids that formed when the solar system was young. 


Curiosity's ChemCam's Remote Micro-Imager (RMI) took this image of 'Egg Rock" on Oct. 30


Due to their comparative abundance on the surface, future Mars colonists may also seek out meteorites such as these so precious metals can be extracted and used for industrial processes. Although the increased risk of more frequent meteorite strikes will be a problem, the reward could be a potential goldmine of rare metals that can be found on or near the surface. Why mine asteroids when you can extract asteroid chunks from the Martian dirt?

Though obviously a rare find for our robotic explorer, this certainly isn't the first meteorite that's been found on the Martian surface. For example, in 2014 the 6-wheeled rover spotted a huge 2 meter-wide meteorite sticking out of the Martian regolith. Mars Exploration Rovers Opportunity and Spirit have also been pretty successful meteorite hunters

As both Curiosity and Opportunity continue to explore the Martian surface, it will be interesting to see how many more space rocks they find, potentially providing an estimate of how many meteorites may be accessible to our future Martian explorers to find.

Quelle: Seeker


Update: 5.11.2016


Colorized view of a meteorite on Mars from the ChemCam instrument on NASA's Curiosity Mars rover
Mars image from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover
The dark, golf-ball-size object in this composite, colorized view from the ChemCam instrument on NASA's Curiosity Mars rover is a nickel-iron meteorite, as confirmed by analysis using laser pulses from ChemCam on Oct. 30, 2016. The grid of bright spots on the rock resulted from the laser pulses. Credit: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS/MSSS
› Full image and caption

Laser-zapping of a globular, golf-ball-size object on Mars by NASA's Curiosity rover confirms that it is an 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. 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 Oct. 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, at the Research Institute in Astrophysics and Planetology (IRAP), of France's National Center for Scientific Research (CNRS) and the University of Toulouse, 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 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 Horton Newsom of the University of New Mexico, Albuquerque. "Mars may have sampled a different population of asteroids than Earth has."

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. Egg Rock may have fallen to the surface of Mars many millions of years ago. Researchers 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.

Egg Rock was found along the rover's path up a layer of lower Mount Sharp called the Murray formation, where sedimentary rocks hold records of ancient lakebed environments on Mars. The main science goal for Curiosity's second extended mission, which began last month, is to investigate how ancient environmental conditions changed over time. The mission has already determined that this region once offered conditons favorable for microbial life, if any life ever existed on Mars.

Curiosity was launched five years ago this month, on Nov. 26, 2011, from Cape Canaveral Air Force Station, Florida. It landed inside Gale Crater, near the foot of Mount Sharp, in August 2012. 

The rover remains in good condition for continuing its investigations, after working more than twice as long as its originally planned prime mission of about 23 months, though two of its 10 science instruments have recently shown signs of potentially reduced capability. The neutron-generating component of Curiosity's Dynamic Albedo of Neutrons (DAN) instrument, designed for working through the prime mission, is returning data showing reduced voltage. Even if DAN could no longer generate neutrons, the instrument could continue to check for water molecules in the ground by using its passive mode. The performance of the wind-sensing capability from Curiosity's Rover Environmental Monitoring Station (REMS) is also changing, though that instrument still returns other Mars-weather data daily, such as temperatures, humidity and pressure. Analysis is in progress for fuller diagnosis of unusual data from DAN, which was provided by Russia, and REMS, provided by Spain.

Quelle: NASA