Nasa Mars Rover Curiosity: Wheel Wiggles but Wind Sensor is damaged

After wiggling its wheels in the Martian soil, the Mars rover Curiosity was pronounced fit to take its first test drive tomorrow.

But amidst the fanfare comes news of the rover's first science casualty.

During shakedown tests this week, the team discovered that a wind sensor on the rover's mast was damaged.

The instrument is basically an exposed circuit board attached to Curiosity's "neck" as part of the Rover Environment Monitoring Station, or REMS.

This weather station includes a suite of sensors that will measure wind speed and direction, temperature, air pressure, humidity and ultraviolet radiation throughout each day of the mission.

One of two wind sensors on REMS sent back nonsensical data. Inspections with Curiosity's cameras revealed that some of its wires are broken, and there's little hope of finding a workaround.

The team thinks the device could have been damaged in a hail of rocks during the rover's death-defying landing.

As the rover was being lowered to the ground on the Sky Crane, the plumes stirred up winds that tossed small rocks into the air. Those rocks came raining back down onto the rover's deck, where its neck-like mast was still folded down.

"Putting two and two together, we've come up with idea that some of these rocks could have fallen on the circuit boards and caused potential damage," said deputy project scientist Ashwin Vasavada in a news conference on 21 August.

"These are pretty fragile devices," Vasavada added. "That's the price we pay for flying the next generation of wind sensor."

It could have been worse. The damaged sensor was a backup, designed to get extra measurements when the wind was coming from directly behind the rover.

The other, forward-facing sensor is "working perfectly", says REMS principal investigator Javier Gomez-Elvira.

"We still have the capability to measure wind from the front, so we have almost all the capability that we had from the beginning."

Because Curiosity's nuclear power source keeps it warm at night and through the winter, REMS will give the first direct weather measurements throughout the entire Martian year, and the first measurements of a full Martian day since the Viking 1 lander stopped responding in 1982.

Monitoring the modern weather will also illuminate the planet's past. Gale Crater, where the rover landed, was carved out by wind billions of years ago, and the five-kilometre-high mountain at its centre was probably also shaped by wind.

More recently, wind sloshing back and forth in the crater's basin formed dark sand dunes that the rover will have to dodge to get to the mountain's foothills.