Rover tools tested as science mission looms

This image from the Mars Hand Lens Imager (MAHLI) on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT).

This image from the Mars Hand Lens Imager (MAHLI) on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). Photos courtesy of NASA

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The NASA Mars rover Curiosity used its left Navigation Camera to record this view of the step down into a shallow depression called "Yellowknife Bay."

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General area in Yellowknife where first drilling operation will take place. The sinuous rock feature in the lower center of this mosaic of images recorded by the NASA Mars rover Curiosity is called "Snake River."

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This image from the Mars Hand Lens Imager (MAHLI) on NASA's Mars rover Curiosity shows details of rock texture and color in an area where the rover's Dust Removal Tool (DRT) brushed away dust that was on the rock.

Just over five months ago, the Mars Science Laboratory rover, Curiosity, landed in Gale Crater on Mars.

Gale Crater was the chosen landing site because of the mountain of layered materials within the crater. Studying these sedimentary layers will tell the story of what Mars was like in the past.

Gale Crater was formed by a meteor impact about 3.5 to 3.8 billion years ago. This impact punched a 96-mile-diameter hole in the terrain and ejected rocks and soil around the crater. There may have been a lake here billions of years ago that filled the crater with sediments.

The Martian winds, over time, then carved the 3.4-mile-high mountain Aeolis Mons, informally named “Mount Sharp” after geologist Robert P. Sharp. This mountain is higher than Mount Rainier rises above Seattle, or over three times higher than the depth of the Grand Canyon. Gale covers about the same area as Connecticut and Rhode Island combined.

Water is a key ingredient of life as we know it, so current exploration of Mars is searching for signs of water. The layers of Mount Sharp contain minerals called clays and sulfates. Clays and sulfate minerals form in water under different conditions, so the history of water at Gale is recorded in its rocks. This history will give us clues to whether Mars ever could have been a habitat for life.

Curiosity landed on a relatively flat area between the crater wall and Mount Sharp, and it has been making its way to the base of Mount Sharp over the past five months. It has traveled about 2,303 feet (0.44 miles) from the landing site to its current location in a shallow depression called “Yellowknife Bay.” This depression is a flatter and lighter-toned type of terrain from what was crossed in the first four months.

While at Yellowknife Bay, two new tools are being tested for the first time, the Dust Removal Tool and the Drill.

The DRT can be used to remove dust and loose material off of rock surfaces. Most of the surfaces are covered with a reddish-brown dust that needs to be removed before Curiosity can get a good look at the rock below the dust. This will allow scientists to determine if the rock is worth drilling to sample its inner composition.

The DRT is mounted to the turret of the robotic arm. It cleans the rocks using two stainless steel wire brushes that are rotated by a single actuator. The robotic arm has to be set to the correct standoff position before the brushes are activated. The minimum area cleaned is a circle about two inches in diameter. The DRT was used for the first time last Sunday.

Cleaning the surface also removes surface contaminants that might confuse samples taken from deeper in the rock with the hammer drill. Curiosity is the first Mars rover to carry a drill to explore the inside of rocks.

The drill is also mounted on the turret at the end of the robotic arm. It is designed to drill into rocks and collect materials for analysis by the chemical and mineral sensors inside the rover. The drill will extract a powder-like material from the interior of the rock to be used for the analysis.

The engineers are looking for a suitable rock at Yellowknife for the drill’s first use. Once a rock is selected, the test should be completed in the next few weeks. This will be the last of the instruments to be tested and used.

With the completion of this test, most of Curiosity’s systems will have been vetted and be operational. This marks an important transition in the mission, as the engineers who have carried out preplanned activities to test the rover’s systems and operations hand over the keys to the science team, who will now take the lead in determining the daily activities. Curiosity is ready to begin its real science mission.

Marty Scott is the astronomy instructor at Walla Walla University, and also builds telescopes and works with computer simulations. He can be reached at marty.scott@wallawalla.edu.

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