Is there anything that rover can’t do?

In a wonderful stroke of celestial luck, the Mars Science Laboratory (MSL) was able to observe a partial solar eclipse on Sept. 13, around five weeks after landing on the Red Planet. Of course, it wasn’t a terrestrial solar eclipse — where the Earth’s moon blocks sunlight — this was an eclipse between one of Mars’ moons and the sun.

In the photo above — one of a series of photos snapped by the rover’s Mastcam camera — a small chunk of the solar disk appears to be missing. That would be the silhouette of Phobos, Mars’ largest natural satellite, interrupting an otherwise perfectly sunny Mars day.


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Phobos is small, measuring only 27 kilometers (17 miles) across at its widest point. It orbits Mars around 6,000 kilometers (3,700 miles) above the surface. Mars has a second, smaller moon called Deimos that orbits the planet nearly four times further away. It is believed that these two dinky, dusty satellites didn’t originate from Mars itself, they are more likely interloping asteroids that were captured by Martian gravity.

Curiosity mission managers have been planning for the partial eclipse — or “transit” — for some time and they hope to command the rover to point skywards for future astronomy opportunities. “Actually, there are I think three opportunities in the next month or so where we’ll image those transits,” said Jennifer Trosper, of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “They’re neat opportunities to see a unique scientific observation.”

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The Mastcam — that has, until now, been snapping some wonderful color views of the Martian landscape — is very sensitive, so to avoid damage to its sensors, a neutral density filter had to be used. The sunlight intensity could therefore be lowered by a factor of 1,000.

Trosper added that similar photographs have been snapped by NASA’s Spirit and Opportunity rovers.

In a bid to understand the nature of the two mysterious Mars moons, observations like these are important for scientists to analyze Phobos and Deimos’ orbital evolution. But despite the science, as pointed out by’s Mike Wall, “…the gee-whiz factor may be reason enough by itself to point Mastcam skyward.”

So, besides being a well equipped geologist, chemist, explorer and photographer, Curiosity is also an astronomer. It’s hard not to love that six-wheeled robot.

Image credit: NASA/JPL-Caltech. Brightness/contrast corrected