What’s that musket ball doing on Mars?

Certainly catches the eye, doesn’t it? The spherical rock was photographed on September 11, 2014 by the Curiosity rover. It’s about a half-inch across and according to NASA scientists probably a concretion. Credit: NASA/JPL-Caltech/MSSS

It looks ever so much like an early 18th century musket ball, but the chances of soldiers traipsing around Mars a couple hundred years ago seems unlikely. Even if it’s the god of war. NASA’s Curiosity rover snapped this photo during a routine round of landscape imaging on September 11th.

There’s nothing like seeing a near-perfect sphere on another planet to make you sit up and wonder. First off, it’s not as big as you might think, measuring just under 1/2 (1 cm) in diameter or about the size of a marble. Second, we’ve seen spheres on Mars before – zillions of them!

Tiny “blueberries” in the Martian soil near the rock outcrop at Meridiani Planum called Stone Mountain. While other ideas have been proposed for their formation, water trickling through rocks to build concretions remains a strong possibility. Credit: NASA/JPL

The Mars Opportunity rover found countless spheres, nicknamed Martian “blueberries”, during  its exploration of Meridiani Planum. If you could hunker down for a look, they’d remind you of BBs from a  BB gun with diameters of .16 to .24 inches (4-6 mm). The spheres contain large amounts of hematite, an iron-bearing mineral, that most likely originated as concretions in layers of sedimentary rock that have since eroded away.

Groundwater moving through porous rocks can dissolve iron-containing minerals which then precipitate out as small, compact spheres. Concretions on Earth, such as Moqui balls and Kansas Pop Rocks, are considerably larger than the Martian variety, but that may be due to the different environments of the two planets. 

So our mystery sphere is probably a larger-than-usual concretion, freed from its rock stratum by wind and perhaps water erosion and now served up on a plate for Curiosity’s and eyes.

To view more pictures of the weird sphere, click HERE and scroll down toward the bottom for the Mastcam color images.

Planets, moon gather at dusk / Curiosity chews into Mt. Sharp

The crescent moon and Saturn twist the night away this evening September 27, 2014. Catch the pair low in the southwestern sky 1-2 hours after sunset. Further east, Mars joins Antares in conjunction. Stellarium

Space weather experts are forecasting a minor G1 geomagnetic storm with possible auroras across the northern U.S. and southern Canada this evening.

While you’re out watching for that telltale green arc in the north, take a few minutes to face the opposite direction. Low above the southwestern horizon you’ll find the crescent moon parked near the planet Saturn. It may be our last chance to see the planet with ease. Saturn’s been sinking into the west for some time. Tonight’s moon will guide you right to it.

A little more than a fist to the left or east of Saturn, Mars will be in conjunction with its colorful friend Antares (both are red-hued) only 3.1º to its north. Both star and planet shine at magnitude +1 though Mars is officially a hair brighter. Can you see the difference?

Photo from the Mars Hand Lens Imager (MAHLI) camera on Curiosity shows the first sample-collection hole drilled in Mount Sharp, the layered mountain that is the science destination of the rover’s extended mission. The hole is 0.63 inch wide and about 2.6 inches deep and photographed from 2 inches away. Click to enlarge. Credit: NASA/JPL-Caltech

This week NASA’s Mars Curiosity Rover drilled and gathered its first rock sample from the base of Mt. Sharp in Gale Crater. The target rock formation, called Confidence Hills, lies on the Pahrump Hills outcrop at the base of the mountain. The rock is a mudstone and softer than any of the rocks previously sampled by the rover.

Mudstone rock outcrop where Curiosity got its first taste of Mt. Sharp (drill hole at top), the rover’s main science target during its time on Mars. Curiosity landed on the planet in August 2012. Credit: NASA/ JPL-Caltech, colorized by Bob King

“This drilling target is at the lowest part of the base layer of the mountain, and from here we plan to examine the higher, younger layers exposed in the nearby hills,” said Curiosity Deputy Project Scientist Ashwin Vasavada of JPL. Scientists hope to get a look at the first rock to underlie Mount Sharp to get a picture of the environment at the time the mountain formed and what led to its formation. Mount Sharp is composed of layered sediments, some of which appear to have been deposited by water several billion years ago.

Fish-eye view taken with Curiosity’s front hazcam showing the drill at work on the Confidence Hills target at the base of Mount Sharp September 24, 2014. The rock surface is webbed with cracks. Click to enlarge. Credit: NASA/JPL-Caltech, colorized by Bob King

NASA will put the breaks on Curiosity now that it’s reached its prime science destination after traveling 5 miles (8 km) since touching down on Mars August 6, 2012. Next, the rover will deliver a powdered rock sample into a scoop on it arm, where the soil’s texture will be scrutinized to access whether it’s safe for further sieving, portioning and delivery into Curiosity’s internal laboratory instruments without clogging hardware.


Drum roll please … Curiosity takes first-ever pix of asteroids from Mars!

The Curiosity rover captured the first image of asteroids from the surface of Mars. Also included in the image are separate photos of Mars’ moon Deimos in a circular, exposure-adjusted inset and square insets at left from other images the same night of its second moon Phobos as well as Jupiter and Saturn. Credit: NASA/JPL-Caltech/MSSS/Texas A&M

Dang! NASA’s Curiosity rover beat me to it by just one day, spotting the asteroids Ceres and Vesta from the surface of Mars on Sunday April 20. Me? I caught them later that night from a comfortable location on Earth with a pair of 8×40 binoculars.

The rover aimed its high-resolution mast camera skyward to take the first-ever photos of the largest (Ceres) and brightest (Vesta) asteroids. Both objects are destinations of NASA’s Dawn Mission as we learned in this recent blog. The photo shows trailed images of both – it was a 12-second time exposure – and Mars’ smaller moon Deimos. The others were added to make a composite. While it looks like it was taken with a mobile phone, it’s one of very few photos taken of the night sky from another planet.

Original mastcam photo of Ceres, Vesta and much brighter Deimos, the smaller of Mars’ two moons. Credit: NASA

The two asteroids and three stars would be visible to someone of normal eyesight standing on Mars. Specks are effects of cosmic rays striking the camera’s light detector. Given that Mars is located closer to the asteroid belt than Earth, I checked the brightness of Ceres and Vesta. Interestingly, both are located in the constellation Virgo just as they are from our own planet right now, but their brightnesses differ. Vesta shines at magnitude +4 (+5.8 from Earth), making it a relatively easy naked eye object from the Martian ‘countryside’. Ceres is currently magnitude +7 from home but magnitude +5.8 and dimly visible with the naked eye from Mars.

Thinking about it a minute, it shouldn’t surprise us that both asteroids are traveling together in the same constellation as seen from both planets. Can you guess why? Remember that Mars was at opposition earlier this month and lined up with Earth on the same side of the sun. That alignment means that we both look out at virtually the same “springtime” constellations in our respective night skies AND look in nearly the same direction when viewing Ceres and Vesta. If Mars was on the opposite side of the sun, Martians would have to look in the opposite direction of the sky to see them.

Curiousity took this fisheye photo with its front hazcam on April 24, 2014 from the Kimberley showing one of the three hills, likely Mt. Remarkable. Credit: NASA/JPL-Caltech

“This imaging was part of an experiment checking the opacity of the atmosphere at night in Curiosity’s location on Mars, where water-ice clouds and hazes develop during this season,” said camera team member Mark Lemmon of Texas A&M University, College Station. “The two Martian moons were the main targets that night, but we chose a time when one of the moons was near Ceres and Vesta in the sky.”

We love it and wouldn’t complain if you guys shot more nighttime stuff. How about a sequence of images of the rising Earth or a longer time exposure showing star trails with the landscape faintly illuminated by the light of Phobos and Deimos?

Curiosity rover revels in ravishing rocks at ‘the Kimberley’

A view of Curiosity’s new digs called ‘the Kimberley’, named for a wilderness region in Western Australia. Taken on April 11 it shows tilted sandstones separated by windblown sands. The hilly rim of Gale Crater is seen in the distance. Click to enlarge. Credit: NASA/JPL-Caltech

NASA’s one-ton Curiosity rover has beamed back thousands of photos of amazing landscapes within Gale Crater since landing in August 2012. And that’s after driving only 3.8 miles, probably the distance to the nearest grocery store for many of us.

The Kimberley seen from orbit with the rover’s path highlighted. Curiosity rolled into the new location around the 589th Martian day or “sol”. Scientists selected the area based on pictures and studies made from orbit showing it to be rich in different rock types all exposed in the same location. Credit: NASA/JPL-Caltech

Earlier this month, the rover entered the Kimberley, a rise within the crater dotted with three buttes – Mounts Remarkable, Joseph and Christine – that exposes several varieties of rock scientists are eager to study. The area will be the focus of exploration for weeks to come before Curiosity resumes its journey to the slopes of Mount Sharp, a broad peak that rises 3 miles (5 km) from the crater’s floor.

Sandstones on Mars near the Kimberley photographed on March 29, 2014. Click to enlarge. Credit: NASA/JPL-Caltech

The Kimberley is strewn with some of the most beautiful sandstones yet seen on Mars. Sandstones form when water or wind carries along grains of sand until depositing them in a layer at the bottom of a stream or on the ground as in a desert. Minerals within the pore spaces between the sand grains cement the grains together to create sandstone. Sometimes layers of deposited sand can build up one atop another helping to further compact the material into stone.

Differing degrees of resistance to erosion result in a stair-stepped pattern visible in this photo taken 1/4 mile northwest of the Kimberley on Feb. 25, 2014. Steeper steps result from more resistant rock, so the flat, tan surface (foreground) is a weakly resistant sandstone. The small steps to the right center are a bit more resistant, and the steeper steps near the top of the scene are even more resistant. Click to enlarge. Credit: NASA/JPL-Caltech/MSSS

Cement materials vary greatly. Clay minerals build sandstones that crumble with a rap of a hammer and more quickly erode in the Martian winds. Quartz cement creates a tougher rock more resistant to erosion. If you’ve ever marveled at the sight of a western, canyon-filled landscape, you’re seeing the varying resistance of sandstone to erosion at work. The same thing happens on Mars:

Another spectacular view of tipped and tilted sandstones with Mt. Remarkable in the distance photographed on April 11, 2014. Click to enlarge. Credit: NASA/JPL-Caltech

“A major issue for us now is to understand why some rocks resist erosion more than other rocks, especially when they are so close to each other and are both likely to be sandstones,” said Michael Malin of Malin Space Science Systems, San Diego. Malin added that variations in cement material of sandstones could provide clues to different types of wet environmental conditions in the area’s history.

Curious furrows are seen in the foreground in this photo taken at the Kimberley on April 3, 2014. Click to enlarge. Credit: NASA/JPL-Caltech/MSSS

At Yellowknife Bay, Curiosity’s last major waypoint, erosion had exposed both sandstones and a lower layer of mudstone that was once part of an ancient lake bottom. The rover will be tooling around the Kimberley for a while – why not join the exploration by periodically checking out the Mars raw image archive?

A conglomerate rock formation at the Kimberley formed of boulders and rocks that were transported from elsewhere – by river or glacier for instance – and cemented together. Click to enlarge. Credit: NASA/JPL-Caltech/ MSSS

Curiosity wheel tracks seen from orbit / How do you drive a rover anyway?

Two parallel tracks left by the wheels of NASA’s Curiosity Mars rover cross rugged ground in this photo taken on Dec. 11, 2013 from orbit. At the time, it had driven about 2.86 miles (4.61 km) since its August 2012 landing in Gale Crater. Click to enlarge. Credit: NASA/JPL-Caltech/Univ. of Arizona

Photos taken by the Curiosity rover’s cameras often leave the impression of a wide-open, easily navigable landscape. Sure there are plenty of rocks to avoid, but the way ahead toward Mt. Sharp looks clear, right? Maybe not so much once you get an orbital perspective.

Curiosity driver Jeng Yen. Credit: NASA

NASA recently released photos taken by the Mars Reconnaissance Orbiter showing Curiosity’s zigzagging tracks across surprisingly rugged, up-and-down terrain. The rover is slowly moving from a bright dust-covered area to a region with a darker surface, where windblown sand scours the surface relatively free of dust.

Studying the images I gained a new appreciation for the work done by the Jeng Yen and the team of Curiosity drivers.

Yen, who’s worked at the Jet Propulsion Lab since 1998, has successfully developed rover models and simulation methods used by the Spirit and Opportunity rovers during their explorations of Mars. He also pilots the Curiosity rover.

Driving a robot car remotely from a distance of 117 million miles resembles playing a video game but only after you’ve done a lot of homework. After mission scientists choose a target, Yen uses pictures taken by Curiosity along with an elevation map of the region created with data gathered from the Mars orbiter to plot a safe path to the target area.

NASA’s Curiosity Mars rover (lower left) and tracks left by its driving appear in this portion of a Dec. 11, 2013, observation by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. The wheel tracks are about 10 feet (3 m) apart. Click to enlarge. Credit: NASA/JPL-Caltech/Univ. of Arizona

Next, he creates a drive sequence of various turns and moves to follow the plotted path and then simulates the path using special software. Finally, any potential obstacles are discovered – and avoided – by examining the route with stereo imagery.

View from Curiosity’s navigational camera on Jan. 8, 2014. The open landscape is deceptive. There are slopes and other obstacles for which detailed elevation data and 3D modeling are needed to navigate the terrain safely. Click to enlarge. Credit: NASA/JPL-Caltech

Then he does it all over again and makes his request from the science and engineering teams to move to the target. If approved, Yen gets comfortable and toggles Curiosity along its chosen way. Seeing the photos stream back to Earth is the favorite part of his job.

Future Mars rover drivers? The Duluth East robotics team pilot their robot named “Archie” to pick up inner tubes and place them on pegs during a competition. Credit: Bob King

While we can be sure there’s a lot of hard work involved, Yen and colleagues must enjoy the immense satisfaction of exploring another planet in real time. With the tremendous surge recently in high school robotics programs and competitions, a career goal of becoming a rover driver on Mars or the moon can’t help but inspire.

Note: Source for information on Jeng Yen’s rover piloting skills HERE.


Mars a tough place for a country drive – Curiosity’s wheels look like heck

Close up of one of Curiosity’s wheels photographed on Dec. 22 shows plenty of dings, small holes and one big tear. Click to see the damage up close. Credit: NASA/JPL-Caltech/MSSS

More than a year’s worth of puttering around on Mars has done a number on the Curiosity rover’s six aluminum wheels. Look at all those dings, pits and holes.

Would you drive your car on this? View of Curiosity’s surroundings on Dec. 20, 2013. Credit: NASA/JPL-Caltech/MSSS

“Dents and holes were anticipated,” said Jim Erickson, project manager for the NASA Mars Science Laboratory Project, which operates Curiosity,” but the amount of wear appears to have accelerated in the past month or so. It appears to be correlated with driving over rougher terrain. The wheels can sustain significant damage without impairing the rover’s ability to drive.”

To that end, the project team is looking toward minimizing the amount of driving Curiosity will do over rugged terrain. Its recent travels have taken it over numerous sharp rocks embedded in the Martian soil as it tracks toward Gale Crater’s central peak Mt. Sharp.

Engineers ready Curiosity – and its brand new set of aluminum wheels – before launch last year. Credit: NASA

Curiosity’s wheels are 19.6 inches (50 cm) in diameter or bigger than a car tire and each has its own motor, making the rover a full-fledged “six-wheel drive” vehicle that can get itself out of many a tight spot. The rover can even do a full 360-degree turn in place. About the only thing the engineers didn’t consider was a spare.

Curiosity Rover update: Stalking the stony plains of Mars

A peek through the scraped and dinged up wheels of the Curiosity Rover taken with the close-up Mars Hand Lens Imager (MAHLI) camera Nov. 30, 2013. Credit: NASA/JPL-Caltech

I enjoy kicking back and looking over photos taken from other planets. There’s no better way to leave the Earth behind – if only for an hour – than digging through the archives. One of my favorite hangouts is the Mars Curiosity Rover raw image page. If you’ve followed this blog for a while, you already know how much I like sharing my favorite finds.

A field of little rocks embedded in soil photographed on Nov. 30. It’s currently mid-autumn in Mars’ southern hemisphere. Credit: NASA/JPL-Caltech

Curiosity landed at 4.5 degrees south latitude inside Gale Crater, placing it firmly in planet’s equatorial zone. Since the tilt of Mars’ axis is 25.2 degrees, nearly the same as Earth’s, the noonday sun is always high in the sky at Curiosity’s location just as it is for folks living near Earth’s equator.  Would that the temperature would follow suit. Average daily temperatures in Gale Crater have ranged from -20 F (-29 C) during the day to -120 F (-85 C) at night in recent weeks.

View of nearby ridge with either the rim of Gale Crater or the foothills of the crater’s central peak Mt. Sharp on Nov. 29. Credit: NASA/JPL-Caltech

Mars’ atmosphere is too thin and its surface too dry to hold onto heat very long. Once the sun is up, the air temperature warms rapidly but then plummets after sunset.  Still, -120 F isn’t all that bad. It’s still a tad warmer, at least for the moment, than -128.6 F (-89.2 C), the lowest temperature ever recorded on Earth at the (then) Soviet station at Vostok, Antarctica on July 20, 1983.

The wheels of the rover nudged a rock from its ancient resting place on Nov. 30, 2013. Credit: NASA/JPL-Caltech

It’s great to see Curiosity back up and running after engineers suspended science activities in mid-November when what appeared to be an internal short in its power source was discovered. Luckily the minor electrical problem didn’t affect the rover’s capabilities. Curiosity continues its trek to Mt. Sharp, the layered mountain at Gale Crater’s center, while at the same time examining powdered rock sample gathered six months ago.

Click on any image to see a much-enlarged version perfect for at-home exploring.

Image showing the foothills of Mt. Sharp in Gale Crater on Nov. 29, 2013. Credit: NASA/JPL-Caltech

Eroded rock layers photographed on Nov. 1, 2013. Credit: NASA/JPL-Caltech

Fang-like rock feature photographed on Nov. 2, 2013. Credit: Credit: NASA/JPL-Caltech

Abe Lincoln has Mars dust in his beard

After 14 months on Mars, Curiosity 1909 Lincoln cent is covered in a fine patina Martian dust and bits of soil. Photo taken on Oct. 2, 2013. Click to enlarge. Credit: NASA/ JPL-Caltech

When the Curiosity rover landed on Mars more than a year ago it brought with it an earthly artifact more than a century old – a 1909 Lincoln penny. For good luck? Maybe, but JPL engineers affixed the penny to the roving robot as a calibration target for its mobile, closeup camera named MAHLI (Mars Hand Lens Imager). While Abe’s looking a little dusty, his weathered face tells the story of 14 months on another planet.

The calibration target used by MAHLI to correct color casts in photos. The penny serves as a size reference. Credit: NASA/ JPL-Caltech

For MAHLI’s closeup pictures to accurately portray colors and brightness of the Martian landscape it needs a reference. The colored patches allow MAHLI to “white balance” or neutralize color casts common in digital images. The penny is a nod to the common practice by geologists of placing an object of known size in the frame to give the viewer a sense of scale.

Without something familiar in a picture as a reference, it’s hard to know the dimensions of things like soil grains and Mars pebbles.

Ken Edgett, principal investigator for MAHLI, bought the penny with his own money (coins in similar condition go for around $20 on eBay). Sure, mission planners could have used a standard ruler scale but opted instead for Edgett’s more poetic penny. NASA’s willingness to bend standard procedure to better connect with the public is a good thing.

The Mars penny all shiny before launch (left) and on Oct. 2. The coin is a 1909 VDB cent. The initials “VDB” of the coin’s designer, Victor David Brenner, are etched onto the reverse side. Credit: NASA/JPL-Caltech

But why a 1909 penny in particular? The Lincoln cent was first minted in 1909 to commemorate the centennial of President Lincoln’s birth. Curiosity was originally scheduled to launch in 2009, which happened to be the penny’s 100th anniversary. The connections across 200 years of time have an irresistible appeal to our romantic side.

Location of the calibration target and penny on the Curiosity rover. Credit: NASA

Delays pushed Curiosity’s launch date to 2011, but Lincoln kept his seat and now looks out across new territory every day.

The penny’s shine has disappeared beneath a fine coating of dust and bits of soil. I imagine NASA scientists wringing crucial data about the Martian atmosphere, winds and soil particle size as they study of the deposition of material on the coin’s face now and in the years ahead. Lincoln’s legacy reaches even to the Red Planet.

Countdown to Comet ISON Mars flyby

Beauty color photo of Comet ISON taken by astrophotographer Damian Peach on Sept. 24. ISON is a dusty comet. Much of that dust is blown back by light pressure from the sun to form the tail. Click to enlarge.

In just 4 days four Mars probes will focus cameras on Comet ISON as it makes its closest approach to the planet on Oct. 1. NASA’s Mars Reconnaissance Orbiter will study and photograph the comet from orbit on three days: Sept. 29, Oct. 1 and Oct. 2. Europe’s Mars Express orbiter, which began its ISON observing campaign on Sept. 21, will study the coma, the tenuous atmosphere that surrounds the comet’s icy nucleus. The probe will examine and photograph ISON through about October 5. As soon as photos are released, you’ll see them here.

The European Mars Express has already began its studies of Comet ISON from Mars orbit on September 21. The probe is the first European craft to visit another planet. Credit: ESA

Both the Curiosity and Opportunity rovers will also be pressed into service to spy ISON from the ground during the same time. Seen from Mars, the comet should glow about magnitude 2.5-3, plenty bright to see with the naked eye if you could somehow wish yourself there.

Comet ISON will shine at around magnitude 3 low in the northern sky in the constellation Lacerta the Lizard from the Curiosity rover’s location. Maps made with Stellarium

Amateur and professional astronomers have been watching Comet ISON evolve since its discovery on Sept. 21, 2012. It began as a dim 15th magnitude patch of haze and brightened very slowly. Amateurs reported a nice uptick in activity beginning late this summer into early fall. ISON now shines at about magnitude 11.5-12 (still faint and requiring a telescope to see) and sports a short tail pointing to the northwest. I was able to see the tail and brighter coma in my 15-inch (37 cm) scope without difficulty about a week ago in a dark sky just before dawn.

Comet ISON tomorrow morning shortly before the start of dawn. The comet’s moving east near the border of the constellations Cancer and Leo. It’s both physically close to Mars and very near the planet in the sky. Because of glare from the moon, a large amateur telescope is still required to see the comet.

Time exposure photos show a classic beauty of a comet with a bright, compact head and elegant tail. According to NASA’s Comet ISON Observing Campaign site, astronomers consider ISON “somewhat more active” that a typical comet. It’s kicking out a lot of dust right now as the sun’s heat vaporizes ice on the comet’s surface. That’s why we see a substantial tail in recent photos. Any guesses as to exactly how bright ISON will become when it zips nearest the sun on Thanksgiving Day are just that … educated guesses.

Movie made from images taken by NASA’s Deep Impact probe in mid-Jan. 2013

Astronomers use formulas based on comet size, distance and dust production rate to come up with brightness predictions. ISON could rival Venus for a short time on Nov. 28 or be substantially fainter or brighter. If it survives its searingly close passage of 745,000 miles (1.2 million km) from the sun’s surface, it will likely become a beautiful sight for northern hemisphere skywatchers during the first half of December. Southern hemisphere observers will have their best views before closest approach.

Much depends on the the comet’s size, currently estimated at 1.8 miles (3 km), pretty typical for a comet. The bigger the iceball, the better the chance of surviving the sun’s battering. Let’s hope ISON keeps it together.

Curiosity snaps sharpest-ever photos of “ring of fire” eclipse on Mars

Phobos, the larger of the two Martian moons at 17 miles across (27 km), creates an annular or ring eclipse as seen through the telephoto eye of the Mars Curiosity rover on Aug. 17. Credit: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ.

Now that’s what I call crisp! NASA just released a series of high resolution pictures of Phobos transiting the sun on August 17. Taken with the 100mm telephoto lens mounted on Curiosity’s mast, they’re the sharpest ever of an eclipse from another world.

Curiosity paused during its drive toward Mt. Sharp and aimed its mast camera straight at the sun to make the sequence of views three seconds apart. Because the sun was nearly directly overhead at the time, Phobos was at its closest and biggest, covering the maximum amount of the sun’s disk as possible.

Sequence showing the sun before, during and immediately after an annular or “ring of fire” eclipse. This eclipse occurred on May 10, 1994 over central Illinois. Credit: Bob King

When one object passes in front of another but only blocks a small portion of it, astronomers call it a transit, but Phobos is big enough and its passage so central, this event is better described as an annular or ring eclipse. We have ring eclipses on Earth too, but because the moon is nearly spherical and much larger than Phobos, it leaves a much narrower “ring of fire”.

Two additional photos from the Phobos eclipse sequence showing the moon entering (left) and exiting the sun. Credit: NASA

Astronomers will measure the moon’s position as it moved across the sun to more precisely calculate Phobos’ orbit. As described in a recent blog, Phobos is gradually moving closer to Mars and will one day be broken to pieces. If you care to browse additional and original pix of the eclipse, check out this Curiosity raw image page and scroll down to the Mast Cam section.