Mars Exploration Rovers Update: Spirit Breaks More Records; Opportunity Digs a Trench

Mars driving records are falling at Gusev Crater, as the rover Spirit continues its steady progress towards the nearby crater nicknamed “Bonneville.” On Sol 43, which ended on the morning of Monday, February 16, Spirit drove 19 meters (62.3 feet) in the morning and another 8.5 meters (27.9 feet) in the afternoon. The total drive of 27.5 meters (90.2 feet), breaks the Mars one day drive record of 24.4 meters (80 feet), set by Spirit only 7 sols ago. The previous record holder Sojourner, rover of the 1997 Mars Pathfinder mission, had managed no more than 7 meters (23 feet) in a single sol.

On sol 44 Spirit added another 21.6 (70.9) to its Mars mileage, bringing the total to 108 meters (354 feet) – another record. Sojourner had traveled a total of only 102 meters (334 feet) during its entire 12 active weeks on Mars.

At every stop along the way Spirit unfolds its long arm known as IDD (“Instrument Deploying Device”) and studies the rocks and the dusty surface in its vicinity. Despite its impressive progress, however, the rover still has a long way to go before reaching “Bonneville,” its primary target. According to Dr. Ray Arvidson, the deputy Principal Investigator for the Athena science payload, it will take the rover about 12 more sols to cover the remaining 245 meters (800 feet) to the crater’s rim. Once there, depending on the steepness of the slopes and nature of the ground, Arvidson and his colleagues will decide whether it is safe for the rover to enter the crater, or whether it will only travel around its edge.

Scientists hope to learn a great deal from studying “Bonneville” explained Arvidson. The impact that created the crater tore through the upper crust of the Martian surface, and exposed the hidden layers beneath. If those hidden layers are indeed accessible to Spirit’s scientific instruments, as scientists hope, they could provide important clues to the geological history of the region.

Meanwhile, at Meridian Planum, Spirit’s twin Opportunity spent its 24th sol on Mars digging a trench in the dusty surface. Since the rover lacks any specialized digging equipment, mission controllers instructed Opportunity’s front right-hand wheel to spin by itself, while the rover remained planted firmly in place. Much like a car spinning its wheels in deep sand, the rover dug itself a hole. It then backed up a bit and repeated the procedure once more, excavating another hole next to the first one, and then one more after that. The end result was a trench, 50 centimeters (20 inches) long, 20 centimeters (8 inches) wide, and as much as 10 centimeters (4 inches) deep.

In the next few sols scientists will use the trench to investigate the structure and composition of the ground below the visible surface. But even before undertaking the detailed studies, the very appearance of the trench gave investigators something to ponder. Contrasting sharply with the grayish tones of landscape around it, large portions of the bottom of the trench appear shiny and reflective. “We don’t yet know what this is,” said Dr. Robert Sullivan of Cornell, a member of the rovers’ science team. “It could be a different substance from what we see on the surface, or it could be fine dust particles packed tightly together by the weight of the rover.” Whatever the case may be, scientists are sure to find out in the next few sols as Opportunity’s long arm with its numerous instruments studies the bottom and sides of the trench.