Field Report from Mars: Sol 4119 - August 26, 2015

Opportunity is moving down into a large valley that cuts through the rim of Endeavour crater. The valley is somewhat like a chute directed  into the crater floor, which is a long ways below—so it is somewhat scary, but also pretty interesting scenery. The valley floor is of interest because we have evidence from orbital remote sensing that there is some alteration of the rock mass here. We would like to understand the geologic setting of the alteration and how it occurs in the outcrops. Of course, the whole point of the investigation is the fact that alteration like the type we are seeing requires a lot of water, and we want to know when it was there and how it moved through the rocks. Then we can get a better idea of how water may have played a role in the environment on early Mars. The crater rim is very eroded, so there was water all right.

Here is the current total traverse from the landing site. This is a drive of over 25 miles (40 km). We are well into our 11th year operating on Mars. The line ends at a notch on the rim of Endeavour crater that we have named Marathon Valley (after the marathon distance traveled getting here).

This is an overhead zoom into the area where Opportunity is right now. We are working our way into the valley and hope to do a circuit near the base of the north valley wall before about November. After that we will need to scurry over to the south side for better winter power with the solar arrays. The green line outlines the area where we see alteration based on orbital remote sensing—it outlines the prospecting area, which is what we are doing, basically: prospecting.

At this location the main activity is an examination of the outcrop on  the valley floor, but a few panoramas have been acquired while sitting here. Here is a view of the rover setting with respect to surroundings as seen in some of those panoramas. The large mass of dark rocks upslope is a target of interest. It corresponds to the large shadowed slope on the left side of the second image above. The view is upslope to the northwest and the crater rim. So yes, we have dropped into the crater-inside side of the rim.

The view downslope gives you an idea of the rather steep slope. Good thing we have good brakes! Off in the distance is the far rim of Endeavour crater, a good 13 miles (22 km) away.

This is a quick look at some of the panorama from the current setting. I have taken the color Pancam data acquired from this location and placed it on top of the Navcam image mosaic. The various white lines map out a few things that we are trying to track. The two circles to the north at 22 and 27 m distance may be the next drive targets. Haven't decided yet because we are waiting for more Pancam results before we pick a target. The circles marked "sta 4, 5, 6" are places that we plan to examine as we do a drive along the north wall of the valley. This is a geologically complicated area and we hope to get a better sense of the structure with a good walk-about. Nice view of the distance from here anyway.