In recent weeks, as NASA's Mars Exploration Rover Spirit has driven
through the basin south of "Husband Hill," it has been traversing mainly
sand and dune deposits. This week, though, Spirit has been maneuvering
along the edge of an arc-shaped feature called "Lorre Ridge" and has
encountered some spectacular examples of basaltic rocks with striking
textures. This panoramic camera (Pancam) image shows a group of boulders
informally named "FuYi." These basaltic rocks were formed by volcanic
processes and may be a primary constituent of Lorre Ridge and other
interesting landforms in the basin.
Spirit first encountered basalts at its landing site two years ago, on a
vast plain covered with solidified lava that appeared to have flowed
across Gusev Crater. Later, basaltic rocks became rare as Spirit climbed
Husband Hill. The basaltic rocks that Spirit is now seeing are interesting
because they exhibit many small holes or vesicles, similar to some kinds
of volcanic rocks on Earth. Vesicular rocks form when gas bubbles are
trapped in lava flows and the rock solidifies around the bubbles. When
the gas escapes, it leaves holes in the rock. The quantity of gas bubbles
in rocks on Husband Hill varies considerably; some rocks have none and
some, such as several here at FuYi, are downright frothy.
The change in textures and the location of the basalts may be signs that
Spirit is driving along the edge of a lava flow. This lava may be the
same as the basalt blanketing the plains of Spirit's landing site, or it
may be different. The large size and frothy nature of the boulders around
Lorre Ridge might indicate that eruptions once took place at the edge of
the lava flow, where the lava interacted with the rocks of the basin
floor. Scientists hope to learn more as Spirit continues to investigate
these rocks.
As Earth approaches the Chinese New Year (The Year of the Dog), the Athena
science team decided to use nicknames representing Chinese culture and
geography to identify rocks and features investigated by Spirit during
the Chinese New Year celebration period. In ancient Chinese myth, FuYi
was the first great emperor and lived in the east. He explained the
theory of "Yin" and "Yang" to his people, invented the net to catch fish,
was the first to use fire to cook food, and invented a musical instrument
known as the "Se" to accompany his peoples' songs and dances. Other rocks
and features are being informally named for Chinese gods, warriors,
inventors, and scientists, as well as rivers, lakes, and mountains.
Spirit took this image on the rover's Martian day, or sol, 731 (Jan. 23,
2006). This stereo view combines images from the two blue (430-nanometer)
filters in the Pancam's left and right "eyes." The image should be viewed
using red/blue stereo glasses, with the red over your left eye.