Spirit has surveyed rocks at Gusev exploration site that are solidified from lava as shown in this approximate true color image. Image Credit: NASA/JPL-Caltech/Cornell
Hardened Lava Meets Wind on Mars
NASA's Mars Exploration Rover Spirit used its microscopic imager to capture this spectacular, jagged mini-landscape on a rock called "GongGong." Measuring only 3 centimeters (1.2 inches) across, this surface records two of the most important and violent forces in the history of Mars -- volcanoes and wind.
GongGong formed billions of years ago in a seething, stirring mass of molten rock. It captured bubbles of gases that were trapped at great depth but had separated from the main body of lava as it rose to the surface. Like taffy being stretched and tumbled, the molten rock was deformed as it moved across an ancient Martian landscape. The tiny bubbles of gas were deformed as well, becoming elongated. When the molten lava solidified, the rock looked like a frozen sponge.
Far from finished with its life, the rock then withstood billions of years of pelting by small sand grains carried by Martian dust storms that sometimes blanketed the planet. The sand wore away the surface until, little by little, the delicate strands that enclosed the bubbles of gas were breached and the spiny texture we see today emerged.
Even now, wind continues to deposit sand and dust in the holes and crevices of the rock.
Similar rocks can be found on Earth where the same complex interplay of volcanoes and weathering occur, whether it be the pelting of rocks by sand grains in the Mojave desert or by ice crystals in the frigid Antarctic.
GongGong is one of a group of rocks studied by Spirit and informally named by the Athena Science Team to honor the Chinese New Year (the Year of the Dog). In Chinese mythology, GongGong was the god-king of water in the North Land. When he sacrificed his life to knock down Mount BuZhou, he defeated the bad Emperor in Heaven, freed the sun, moon and stars to go from east to west, and caused all the rivers in China to flow from west to east.
Spirit's microscopic imager took this image during on the rover's 736th day, or sol, of exploring Mars (Jan. 28, 2006). The rock lies in the "Inner Basin" between "Husband Hill" and "McCool Hill" in Gusev Crater. Spirit acquired the image while the rock was fully shadowed, with diffuse illumination mostly from the top in this view.
Image credit: NASA/JPL-Caltech/Cornell/USGS
And...
Home Plate has been a target for Spirit since shortly after the robot landed on the red planet in January 2004. The feature stood out in overhead images taken by Mars Global Surveyor's Mars Orbiter Camera. It stood out as a bright, nearly circular spot in the Columbia Hills region, Crumpler explained.
I think it is amazing that for over 700 Martian days the rover has been in operation, when it was originally designed for 90 days of use, after which it was expected to be useless.
"But that's purely conjecture at this point ... a working hypothesis," Squyres said. "Everything is on the table until we've gotten more data down."
It's been a while since I studied geology, but those rocks definitely look extrusive. They look a lot like aa. I like the high resolution image because you can almost imagine that when it wasn't as weathered that you could see where volcanic gasses were trapped before expanding and escaping at the surface. It should be interesting to see how lava with a high quantity of trapped gases develops on Mars as compared to the Earth. With the lower atmospheric pressure I would expect that gas bubbles in rocks would be much larger and the jaggedness that starts on the surface of a rock would extend much deeper.
Latest panoramic camera pictures from Spirit at Homeplate are here: http://marsrovers.jpl.nasa.gov/gallery/all/spirit_p748.html
Do you have a working link for this article?
Mark
That third rock in the upper left corner looks like the baseball cap I lost when I was a kid and I could swear one of those "rocks" is my missing sock.
I think we now know where missing socks and hats go.
Left Navigation Camera Non-linearized Full frame EDR acquired on Sol 753 of Spirit's mission to Gusev Crater at approximately 12:49:08 Mars local solar time. NASA/JPL