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Curiosity wiggles wheels to prepare for first drive on Mars

LOS ANGELES, Aug. 22 — Curiosity rover has wiggled its four corner wheels to prepare for its first drive on Mars, NASA' s Jet Propulsion Laboratory in Pasadena, California announced Tuesday.

JPL said the six-wheeled rover wiggled its four corner wheels side to side for the first time on Mars Tuesday as a test of the steering actuators on those wheels.

This was critical preparation for Curiosity's first drive on Mars.

"Late tonight, we plan to send Curiosity the commands for doing our first drive tomorrow," said Curiosity Mission Manager Michael Watkins of JPL.

"We wanted to test the steering, because otherwise we would be driving in whatever direction we landed in," Watkins explained during a teleconference Tuesday.

Watkins said the commands will be sent up Tuesday night for a drive of just a few yards (meters), incorporating a turn to the right and a backing-up maneuver. That initial movement should occur "in the middle of the night our time" and last about a half-hour, he said.

The six-wheeled rover has a versatile steering system, with two front and two rear wheels that can be independently twisted so much that the car-sized, one-ton vehicle pirouettes in place.

The two middle wheels can push as well, but they are not built for turning.

Each wheel measures 20 inches (50 centimeters) in diameter, which is about the size of an automotive tire, according to JPL.

Successful driving is the key to Curiosity's two-year, 2.5 billion-dollar mission, because its ultimate goal is to reach the flanks of a 3-mile-high mountain within the crater, known as Aeolis Mons or Mount Sharp, which is about 12.5 miles (20 kilometers) away, Watkins said.

Once the rover is fully into its drive mode, it's expected to trek up to the length of a football field (100 meters) in a day.

Curiosity's first destination is an intersection of three geological formations about a quarter-mile (400 meters) from the landing site, known as Glenelg, according to JPL.

The rover is due to spend the next couple of months checking out that area, and then it will turn its wheels toward Mount Sharp.

That's where scientists expect to read the geological history of Mars over the course of billions of years, as recorded in the layers of rock going up the mountainside.

Those readings could show how habitable the planet might have been at different epochs, JPL said.

JPL also announced Tuesday that Curiosity has been investigating the Martian weather around it and the soil beneath it, as its controllers prepare for the car-size vehicle's first drive on Mars.

The rover's weather station, provided by Spain, checks air temperature, ground temperature, air pressure, wind and other variables every hour at the landing site in Gale Crater, JPL said.

On a typical Martian day, or "sol," based on measurements so far in the two-week old mission, air temperatures swing from 28 degrees to minus 103 degrees Fahrenheit (minus 2 to minus 75 Celsius), according to JPL.

Ground temperatures change even more between afternoon and pre-dawn morning, from 37 degrees to minus 132 degrees Fahrenheit (3 to minus 91 Celsius).

"We will learn about changes from day to day and season to season," said Javier Gomez-Elvira of the Centro de Astrobiologia, Madrid, Spain, principal investigator for the suite of weather sensors called the Rover Environmental Monitoring Station with JPL.

An instrument provided by Russia is checking for water bound into minerals in the top three feet (one meter) of soil beneath the rover.

It employs a technology that is used in oil prospecting on Earth, but had never before been sent to another planet.

"Curiosity has begun shooting neutrons into the ground," said Igor Mitrofanov of Space Research Institute, Moscow, principal investigator for this instrument, called the Dynamic Albedo of Neutrons, or DAN.

"We measure the amount of hydrogen in the soil by observing how the neutrons are scattered, and hydrogen on Mars is an indicator of water," JPL quoted Mitrofanov as saying in a statement.

The most likely hydrogen to be found in shallow ground of Gale Crater, near the Martian equator, is in hydrated minerals, JPL said.

These are minerals with water molecules, or related ions, bound into the crystalline structure of rocks.

They can tenaciously retain water from a wetter past after all free water has gone, according to JPL. (PNA/Xinhua)


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