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The Planetary Society Blog
By Emily Lakdawalla
Home, sweet home for Spirit
Feb. 8, 2006 | 09:43 PST | 17:43 UTC
Spirit has finally arrived at the site called "Home Plate," and what can I say about it but WOW!
To give you a little context, here is Spirit's traverse map up to sol 742. There are several easy-to-spot features on Spirit's traverse maps. There is the dark spot of Bonneville crater near the top; the lumpy shape of the Columbia Hills at the right side; the very dark splotch of sand dunes called "El Dorado" at the south end of the hills; and, finally, a vaguely pentagonal-shaped, light-colored spot with very sharp edges near the lower right. That lower right spot is called Home Plate. (For those of you who are not familiar with the American sport of baseball, the starting "Home Plate" position for a batter in baseball is a similarly shaped rubber mat -- the other three bases are square. Several of the Mars Exploration Rover scientists are big baseball fans.) Spirit traverse map from Sol 1 to Sol 742This image shows the route that Spirit has driven inside Gusev Crater from sol 1 to 742 (February 2, 2006). The underlying image is a mosaic of images from the Mars Orbital Camera (MOC) on the Mars Global Surveyor orbiter. The scale bar at lower left is 500 meters (0.31 mile). As of Sol 742, the rover had driven a total of 6,430 meters (4.00 miles). Credit: NASA / JPL-Caltech / MSSS / USGS / NMMNHS |
That light-colored, sharp-edged Home Plate has beckoned at the science team for a long time. Its sharp edges promised the possibility of an interesting contrast in rock type, and as far as they have been able to see from a distance it looked like a raised, flat plateau. To a geomorphologist, that kind of shape suggests two things: layered rocks, and steep sides that may cut across those layers. Well, the geomorphologists have finally gotten their close views and, again, wow. Here's what Home Plate looked like from the Pancam on sol 743: Spirit's position at Home Plate on sol 746Spirit approached "Home Plate" on sol 743 and captured this color panorama of the elevated plateau. It then rolled toward the layered rocks over the next three sols. Two artist's renderings of the rovers are inserted into the panorama to show Spirit's position when it acquired panoramic views on sol 746. By the end of sol 746, it had settled in to study the layered rocks with its instrument deployment device. Credit: NASA / JPL / Cornell / Doug Ellison / Nico Schmidt |
Look at all those layers! They drove over to the steepest part by sol 746, and here's the view from there:Spirit's view of Home Plate at the end of sol 746Credit: NASA / JPL / Cornell / Tesheiner |
Look at all those fine laminations! I cannot wait to see what the mineralogy tells us about these rocks. You can get fine laminations in volcanic or windblown deposits, of course, so there's no celebrating yet -- but these are the best candidates I've yet seen for those crater-filling lakebed deposits that Spirit landed in Gusev Crater to see. Do click on this one to enlarge so you can see the variety of different thicknesses and kinds of layers in these rocks. They are tremendous. Spirit appears to be settling in to this spot for the duration, and according to the Pancam tracking database it appears that their next plan is to perform a very large Microscopic Imager mosaic of the rocks in front of the rover.
Finally, I'll leave you with this comparison. Look at that panorama, of Home Plate on sol 746, and then see this one, from Opportunity.Opportunity panorama: "Burns Cliff," sols 287-294Opportunity scrambled slowly across the steeply sloped wall of Endurance Crater to reach "Burns Cliff," a vertical pile of finely layered rocks that was irresistible to the rover sceintists. From this precarious position it captured a 7-color panorama from sols 287 to 294 (November 13 to 20, 2004). The bulging appearance of the wall is due to Spirit's very close position to it; in reality the view spans about 180 degrees and the wall is gently concave. For the full-resolution image, visit the Pancam website. Credit: NASA / JPL / Cornell |
I would argue that, to a first appearance, Home Plate looks a lot more like what they've been seeing at Opportunity's landing site than anything they've ever seen at Spirit's. Still, understanding the mineral composition of these rocks, and how those minerals are assembled into the rocks, will be necessary before they can figure out how the Home Plate rocks were made, and the minerals are very unlikely to be the same at Spirit's site as they are at Opportunity's. I'm looking forward to this phase of Spirit's exploration of Gusev Crater!
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