Curiosity Rover’s Eclipse Pictures Hold Clues to Red Planet’s Past

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SEATTLE — Photos of several partial solar eclipses snapped recently by NASA’s Mars Science Laboratory rover may help scientists better understand the red planet’s interior structure and composition, researchers say.

The 1-ton Curiosity rover captured Mars’ tiny moon Phobos taking a nibble out of the sun’s disk Sept. 13. Several days later, it watched additional partial eclipses caused by the moons Phobos and Deimos.

Scientists will use these photos to nail down the orbits of Phobos and Deimos precisely and to determine how much they have changed over the last few years, researchers said. This information, in turn, could yield key insights about the interior of Mars, which remains largely mysterious.

“We can’t go inside Mars, but we can use these to tell how much Mars is deformed when the moons go by,” Curiosity science team co-investigator Mark Lemmon of Texas A&M University told reporters Sept. 19. “So we measure the transits very precisely, we get information on Mars’ interior structure.”

Phobos is just 22 kilometers wide on average, and Deimos is even smaller. Many scientists think both satellites are asteroids that were captured by the red planet’s gravity long ago.

Neither moon will be in its current orbit forever. Deimos, which whips around Mars every 30 hours or so, is speeding up, while Phobos is slowing down in its eight-hour orbit. Scientists think Mars’ gravity will probably destroy Phobos, perhaps in the next 10 million to 15 million years or so.

“It will work its way in at some point and get so close that tidal forces from Mars will very likely break it up before it does start grazing the atmosphere and come down,” Lemmon said. “So Mars may briefly have a ring system.”

The Curiosity team has been doing more than just skywatching since landing the $2.5 billion robot inside Mars’ huge Gale Crater on Aug. 5. Researchers have thoroughly vetted Curiosity and its 10 science instruments, which are designed to help the rover determine if the Gale area could ever have supported microbial life.

Curiosity has also hit the road recently, traveling a total of about 290 meters from its landing site as of Sept. 19. The rover now sits about 200 meters from its first major science destination, a site called Glenelg where three different types of martian terrain come together.

But Curiosity will spend the next several days more or less stationary, gearing up to perform its first contact science operations on a pyramidal rock that mission scientists have named “Jake Matijevic,” after a rover team member who died shortly after Curiosity landed.

The rover will investigate the 25-centimeter-high rock with its Alpha Particle X-Ray Spectrometer, which measures elemental composition, and its Mars Hand Lens Imager close-up camera. Both instruments sit at the end of Curiosity’s 2.1-meter robotic arm.

Curiosity will also zap the Jake Matijevic rock with the laser on its ChemCam instrument, which reads rock composition from the vaporized bits, scientists said.

While researchers are looking forward to reaching Glenelg, Curiosity’s ultimate destination is the base of Mount Sharp, the 5.5-kilometer mountain rising from Gale Crater’s center. Mars-orbiting spacecraft have spotted signs that Mount Sharp’s foothills were exposed to liquid water long ago.

Mount Sharp’s interesting deposits lie about 10  kilometers away. Curiosity — which is covering about 30 meters on a big driving day but should eventually bump that up to 100 meters or so — could be ready to head toward Mount Sharp around the end of the year, rover scientists have said.