MessageToEagle.com - NASA's Mars rover Curiosity has driven up to a football-size rock that will be the first for the rover's arm to examine.

Curiosity is about 8 feet (2.5 meters) from the rock. It lies about halfway from the rover's landing site, Bradbury Landing, to a location called Glenelg.

In coming days, the team plans to touch the rock with a spectrometer to determine its elemental composition and use an arm-mounted camera to take close-up photographs.

Both the arm-mounted Alpha Particle X-Ray Spectrometer and the mast-mounted, laser-zapping Chemistry and Camera Instrument will be used for identifying elements in the rock. This will allow cross-checking of the two instruments.

The rock has been named "Jake Matijevic."

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'Jake Matijevic' Contact Target for Curiosity

The drive by NASA's Mars rover Curiosity during the mission's 43rd Martian day, or sol, (Sept. 19, 2012) ended with this rock about 8 feet (2.5 meters) in front of the rover. The rock is about 10 inches (25 centimeters) tall and 16 inches (40 centimeters) wide. The rover team has assessed it as a suitable target for the first use of Curiosity's contact instruments on a rock. The image was taken by the left Navigation camera (Navcam) at the end of the drive.
The rock has been named "Jake Matijevic." This commemorates Jacob Matijevic (1947-2012), who was the surface operations systems chief engineer for the Mars Science Laboratory Project and the project's Curiosity rover. He was also a leading engineer for all of the previous NASA Mars rovers: Sojourner, Spirit and Opportunity.
Curiosity's contact instruments are on a turret at the end of the rover's arm. They are the Alpha Particle X-Ray Spectrometer for reading a target's elemental composition and the Mars Hand Lens Imager for close-up imaging. Image credit: NASA/JPL-Caltech

Jacob Matijevic (mah-TEE-uh-vik) was the surface operations systems chief engineer for Mars Science Laboratory and the project's Curiosity rover. He passed away Aug. 20, at age 64. Matijevic also was a leading engineer for all of the previous NASA Mars rovers: Sojourner, Spirit and Opportunity.

The light-toned area is of special interest because it retains daytime heat long into the night, suggesting an unusual composition.

"As we're getting closer to the light-toned area, we see thin, dark bands of unknown origin," said Mars Science Laboratory Project Scientist John Grotzinger of the California Institute of Technology, Pasadena.

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Dark Bands Run Through Light Layers

This mosaic from the Mast Camera on NASA's Curiosity rover shows a close-up view looking toward the "Glenelg" area, where three different terrain types come together. All three types are observed from orbit with the High-Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. By driving there, Curiosity will be able to explore them.
One of these terrain types is light-toned with well-developed layering, which likely records the deposition of sedimentary materials. There are also black bands that run through the area and might constitute additional layers that alternate with the light-toned layer(s). The black bands are not easily seen from orbit and are on the order of about 3.3-feet (1-meter) thick. Both of these layer types are important science targets.
This mosaic is composed of images taken with the Mastcam 100-millimeter camera. Image credit: NASA/JPL-Caltech/MSSS

"The smaller-scale diversity is becoming more evident as we get closer, providing more potential targets for investigation."

Researchers are using Curiosity's Mast Camera (Mastcam) to find potential targets on the ground. Recent new images from the rover's camera reveal dark streaks on rocks in the Glenelg area that have increased researchers' interest in the area. In addition to taking ground images, the camera also has been busy looking upward.

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Phobos in Transit

Mars has two small, asteroid-sized moons named Phobos and Deimos. From the point of view of the rover, located near the equator of Mars, these moons occasionally pass in front of, or "transit," the disk of the sun. These transit events are the Martian equivalent of partial solar eclipses on Earth because the outline of the moons does not completely cover the sun (in contrast, Earth's moon does block the entire sun during a total solar eclipse). These eclipses, like those on Earth, occur in predictable "seasons" a few times each Mars year.
As part of a multi-mission campaign, NASA's Curiosity rover is observing these transits, the first of which involved the moon Phobos grazing the sun's disk. The event was observed on Martian day, or sol, 37 (September 13, 2012) using Curiosity's Mast Camera, or Mastcam, equipped with special filters for directly observing the sun. In a series of high-resolution video frames acquired at about three frames per second for about two minutes, the outline of part of Phobos blocked about five percent of the sun.
This animation shows the transit as viewed by the Mastcam 100-millimiter camera (M-100) in nine frames. Another version of the animation is available, consisting of 20 frames taken by the Mastcam 34-millimeter camera (M-34), which has about one-third the resolution of the M-100. In total, 256 frames were taken by the M-100 and 384 frames for the M-34.

Mastcam-34 animation
The transit was also observed by Curiosity's Rover Environmental Monitoring Stations (REMS) instrument, which saw about a five percent drop in the sun's ultraviolet radiation during the event.
Mission scientists use these events to very accurately determine the orbital parameters of the Martian moons. Phobos, for example, orbits very close to Mars and is slowly spiraling in to Mars because of tidal forces. These forces change the orbital position of Phobos over time, and accurate measurements of those changes can provide information about the internal structure of that moon and how it dissipates energy. Deimos orbits much farther away and is slowly spiraling out.
NASA's Mars Exploration Rover Opportunity will also attempt to observe a different set of Phobos and Deimos transits, seen from the other side of the planet, in Meridiani Planum. Image credit: NASA/JPL-Caltech/MSSS

On two recent days, Curiosity pointed the Mastcam at the sun and recorded images of Mars' two moons, Phobos and Deimos, passing in front of the sun from the rover's point of view. Results of these transit observations are part of a long-term study of changes in the moons' orbits. NASA's twin Mars Exploration Rovers, Spirit and Opportunity, which arrived at Mars in 2004, also have observed solar transits by Mars' moons.

Opportunity is doing so again this week.

"Phobos is in an orbit very slowly getting closer to Mars, and Deimos is in an orbit very slowly getting farther from Mars," said Curiosity's science team co-investigator Mark Lemmon of Texas A&M University, College Station. "These observations help us reduce uncertainty in calculations of the changes."

In Curiosity's observations of Phobos this week, the time when the edge of the moon began overlapping the disc of the sun was predictable to within a few seconds. Uncertainty in timing is because Mars' interior structure isn't fully understood.

Phobos causes small changes to the shape of Mars in the same way Earth's moon raises tides. The changes to Mars' shape depend on the Martian interior which, in turn, cause Phobos' orbit to decay. Timing the orbital change more precisely provides information about Mars' interior structure.

During Curiosity's two-year prime mission, researchers will use the rover's 10 science instruments to assess whether the selected field site inside Gale Crater ever has offered environmental conditions favorable for microbial life.

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