Two iron meteorites have been spotted by the Mars rover Spirit, mission scientists have announced. The finds are the first meteorites identified by Spirit, although its twin, Opportunity, discovered a similar space rock on the other side of the planet in January 2005.
Spirit photographed the rocks in April 2006, just after it parked at Low Ridge Haven, a northern-tilting slope that is serving as its home for the six-month-long Martian winter.
Advertisement
The rocks appear smoother and lighter in tone than surrounding rocks. They resemble the glossy, pitted meteorite 鈥� dubbed 鈥淗eat Shield Rock鈥� 鈥� that Opportunity found near its discarded heat shield.
Observations of that rock with Opportunity鈥檚 miniature thermal emission spectrometer (Mini-TES) showed it was very reflective 鈥� a telltale sign of an iron meteorite (see Metal chunk on Mars confirmed as meteorite). Now, observations by the Mini-TES on Spirit reveal the two suspect rocks are similarly reflective.
鈥淭hey鈥檙e very good reflectors,鈥� says mission member Ray Arvidson of Washington University in St Louis, US. 鈥淲e鈥檙e seeing the heat of the sky being reflected to Mini-TES. I don鈥檛 know how that can happen unless it鈥檚 a metal.鈥�
Drive-by meteorite
Iron meteorites make up just a few percent of the space rocks that would be expected to litter the Martian surface. But their appearance and spectral properties make them much easier to identify than the more common 鈥渟tony鈥� meteorites.
The meteorites are fragments of larger space rocks nudged out of the asteroid belt between Mars and Jupiter and into the Red Planet鈥檚 path. They survive on the surface because there are few geological processes on Mars that would bury them after they fall to ground, says Arvidson.
鈥淚t鈥檚 not surprising that we occasionally drive past a meteorite,鈥� he told New 杏吧原创. 鈥淢ars is a very old surface and the erosion rates are relatively small, so we should expect these things to collect and be exposed for our viewing.鈥�
Features observed at Spirit鈥檚 winter haven are being named after research stations and place names in Antarctica. So the two rocks have been dubbed 鈥淎llan Hills鈥� 鈥� for a site where many meteorites are found in the Antarctic ice 鈥� and Zhong Shan, an Antarctic base established by China in 1989.
