* Astronomy

This pair of images from the panoramic camera on NASA's Mars Exploration Rover Opportunity served as initial confirmation that the two-year-old rover is within sight of "Victoria Crater," which it has been approaching for more than a year.

Engineers on the rover team were unsure whether Opportunity would make it as far as Victoria, but scientists hoped for the chance to study such a large crater with their roving geologist.



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Image credit: NASA/JPL-Caltech/MSSS/Cornell University

When scientists using orbital data calculated that they should be able to detect Victoria's rim in rover images, they scrutinised frames taken in the direction of the crater by the panoramic camera. To positively characterise the subtle horizon profile of the crater and some of the features leading up to it, researchers created a vertically-stretched image (top) from a mosaic of regular frames from the panoramic camera (bottom), taken on Opportunity's 804th Martian day (April 29, 2006).

The stretched image makes mild nearby dunes look like more threatening peaks, but that is only a result of the exaggerated vertical dimension. This vertical stretch technique was first applied to Viking Lander 2 panoramas by Philip Stooke, of the University of Western Ontario, Canada, to help locate the lander with respect to orbiter images. Vertically stretching the image allows features to be more readily identified by the Mars Exploration Rover science team.

The bright white dot near the horizon to the right of centre, labelled "Outcrop Promontory," (barely visible without labelling or zoom-in) is thought to be a light-toned outcrop on the far wall of the crater, suggesting that the rover can see over the low rim of Victoria. The northeast and southeast rims are labelled in bright green. Finally, the light purple lines and arrow highlight a small crater.

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This image from the Mars Orbiter Camera on NASA's Mars Global Surveyor highlights the Mars Exploration Rover Opportunity's approach toward "Victoria Crater."


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North is to the left. Opportunity's location at sol 804 (April 29, 2006) is marked, as are the left and right edges of Victoria's rim from the rover's point of view. The labelled "promontory" is a bright spot that scientists believe is an outcrop on the far side of the crater. Marked in light purple is a small, 35-meter crater.
Victoria Crater is 800 meters in diameter, about six times wider than "Endurance Crater," where Opportunity spent several months in 2004 examining rock layers affected by ancient water.

OPPORTUNITY UPDATE: 'Victoria' in View - sol 804-810, May 04, 2006:

Opportunity executed a three-sol examination of "Brookville" outcrop with tools on the robotic arm. This work included microscopic imaging, a brushing, 16 total hours of integrated data gathering with the Mössbauer spectrometer, and an overnight integration with the alpha particle X-ray spectrometer. Then Opportunity stowed its arm and drove 107 metres in three sols, reaching a point estimated to be 1,279 metres from "Victoria Crater." The team believes the rim of the crater is becoming visible in a vertically stretched image looking south.

Sol-by-sol summaries:

Sol 804 (April 28, 2006): This was the first sol of robotic arm work on Brookville. The rover took microscopic images, then brushed the target and followed with an afternoon data collection by the Mössbauer spectrometer. The rover observed a target called "Great Bend" with the miniature thermal emission spectrometer during the afternoon communication-relay session with NASA's Mars Odyssey orbiter.

Sol 805: Opportunity did morning atmospheric science and positioned the alpha particle X-ray spectrometer. The rover used that spectrometer on Brookville until taking morning images of Gila Bend using 13 filters of the panoramic camera.

Sol 806: On the final sol of arm work on Brookville, Opportunity changed tools to the Mössbauer spectrometer and completed an afternoon integration. At 7:00 p.m. local solar time, the team stopped the integration and Opportunity did a mini-deep sleep.

Sol 807: The panoramic camera took 13-filter images of the arm's brushing target. Then Opportunity drove for 30 minutes. After driving, the rover observed the surroundings from its new position with the navigation camera and looked in the drive direction with the panoramic camera.

Sol 808: Opportunity drove for an hour and 10 minutes in the compass direction of 150 degrees (south southeast), then took images from its new location. During the afternoon, the rover made observations with the thermal emission spectrometer and used the panoramic camera to check atmospheric clarity. It used the deep-sleep mode overnight.

Sol 809: Opportunity took another 1-hour-and-10-minute drive followed by imaging and atmospheric science during the Odyssey pass.

Sol 810 (May 5, 2006): The rover was directed to take rear-looking images with the navigation camera during the morning of sol 810 as part of plan uplinked on sol 809. The plan for uplink on sol 810 includes a 15-metre approach to a target for using the robotic arm's tools to inspect ripple banding during the weekend, plus post-drive imaging with the navigation camera and panoramic camera.

As of sol 809 (May 4, 2006) Opportunity has driven 7,575.51 metres.

Sol 806

Mars map showing where the Mars rover, Opportunity, landed on the Meridiani plain in January 2004.