NASA has solved the mystery of the "Martian jelly doughnut." First seen by the Mars Exploration Rover Opportunity on January 8, the 1.5-in (4 cm) wide, white-rimmed, red-centered rock that resembles a piece of pastry seemingly appeared out of nowhere, but the space agency now says that it's actually a rock fragment dislodged by the rover's passing.

The "jelly doughnut," also known as Pinnacle Island, made its appearance when it showed up in an image sent by Opportunity where nothing was present four days earlier. It looked a bit as if a fungus had suddenly grown from the Martian soil and prompted a law suit in a California court by science writer Rhawn Joseph, who claimed that the rock was a living organism that NASA refused to investigate properly.

However, far from being dramatic proof of life on the Red Planet, new images indicate that Pinnacle Island is a fragment of a rock that one of Opportunity's wheels struck which broke off and rolled downhill.

"Once we moved Opportunity a short distance, after inspecting Pinnacle Island, we could see directly uphill an overturned rock that has the same unusual appearance," says Opportunity Deputy Principal Investigator Ray Arvidson of Washington University in St. Louis. "We drove over it. We can see the track. That's where Pinnacle Island came from."

In the interests of thoroughness, Opportunity examined Pinnacle Island and found it contained high levels of water soluble manganese and sulfur, indicating a wetter environment in the ancient past. "This may have happened just beneath the surface relatively recently," Arvidson says. "Or it may have happened deeper below ground longer ago and then, by serendipity, erosion stripped away material above it and made it accessible to our wheels."

Opportunity is now headed south to study an exposed section of rock higher up the slope in the direction of a ridge called the McClure-Beverlin Escarpment in honor of engineers Jack Beverlin and Bill McClure, who saved the Mariner 6 Mars probe from destruction on liftoff on February 14, 1969.

The sudden appearance of the "jelly doughnut" (Image: NASA)

This maneuver is the first that Opportunity has made in a month as it waited out a spell of bad weather. According to NASA, part of the reason for this move is to place the rover's solar panels at better advantage as the Martian southern hemisphere passes its winter solstice. Nursing Opportunity's power supply is of considerable importance to NASA due to the rover operating over a decade past its design life.

"We are now past the minimum solar-energy point of this Martian winter," said Opportunity Project Manager John Callas of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "We now can expect to have more energy available each week. What's more, recent winds removed some dust from the rover's solar array. So we have higher performance from the array than the previous two winters."

Launched on July 7, 2003, Opportunity is the second and final Mars Exploration Rover and twin of the now defunct Spirit rover. It landed on January 25, 2004, three weeks after Spirit, in the Meridiani Planum region of Mars for a mission scheduled to last 90 Martian days, but ten years later, it's still going strong. It continues to study Martian soil and provide surface calibration for orbital observations by the Mars Reconnaissance Orbiter, and has traversed about 25 mi (40 km), making it one of the most well-traveled rovers in history.

Source: NASA

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