Two months into its road trip to Mount Sharp, NASA's Mars rover Curiosity paused and pointed its cameras skyward as the planet's larger moon Phobos sailed in front of the sun.
NASA released a trio of Curiosity's pictures on Thursday, taken three seconds apart on Aug. 17 and showing the solar eclipse - the sharpest eclipse images ever taken from Mars.
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Viewed from the planet's surface, Phobos does not fully cover the sun, so this type of eclipse is known as a "ring" or "annular" eclipse.
"It was even closer to the sun's center than predicted, so we learned something," Curiosity scientist Mark Lemmon, with Texas A&M University, said in a NASA press release.
"This event occurred near noon at Curiosity's location, which put Phobos at its closest point to the rover, appearing larger against the sun than it would at other times of day," Lemmon said.
"This is the closest to a total eclipse of the sun that you can have from Mars," he added.
Curiosity touched down inside a giant impact basin near the planet's equator last August for a two-year mission to assess if the planet most like Earth in the solar system has - or ever had - the ingredients to support and preserve life.
The rover spent the first part of its mission in an area known as Gleneg and found chemistry suitable for life in its first rock drill sample. Two months ago, it turned around to begin the long trek to its primary target, a 3-mile high mountain of layered sediment known as Mount Sharp.
This week, Curiosity used its auto-navigation system for the first time. The system lets the rover plot its own path based on analysis of images.
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First, Curiosity takes several sets of stereo pairs of images. Then, the rover's computer processes the information to map any geometric hazard or rough terrain, NASA said in a press release.
"The rover considers all the paths it could take to get to the designated endpoint for the drive and chooses the best one," NASA said.
Curiosity used its auto-nav on Tuesday for a 33-foot test drive. The system should allow for a somewhat speedier transit to Mount Sharp, some 4.5 miles away.
Image: Curiosity moonlighting as astronomer, catches a glimpse of Phobos eclipsing the sun. Credit: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M