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Deep Space Digest – September 12

Yutu celebrates a holiday, Curiosity arrives at Mt. Sharp, Opportunity formats its memory, Rosetta explores 67P, and Cassini studies Saturn’s atmosphere.


In the News:


Chang’e 3/Yutu

For China’s Mid-Autumn Day festival, the Chinese government released a new panorama from the Yutu rover, which shows the final resting location of the rover, which lost the ability to move after a control failure in January. Despite the failure, the rover is still in active communication with its Earthside controllers and still performing science with instruments not affected by the control failure.

On September 5, results of an investigation into the control failure were released. The rover’s designer believes that the rover was damaged by the larger than expected rocks that were present at the landing site. The likely cause is a short circuit in the wiring that powered the rover’s wheels after a collision. The power surge caused by the short circuit then damaged the rover’s control system.

Time since launch: 285 days
Time since landing: 272 days



On September 11, Curiosity’s operators announced that the rover had arrived at Mt. Sharp, after reaching an outcrop of rock that belongs to the lowest layer of the mountain. Curiosity is reaching the outcrop, dubbed Pahrump Hills, after a short delay due to a route that took it through perilously thick sand. The rover was forced to reroute around the sand trap, on higher terrain that was more damaging to its wheels. Fortunately, it appears that the worst of the terrain is behind Curiosity, as the path ahead seems to be a lot more smooth. Here’s a panoramic view of Mt. Sharp’s slopes, covering an area named Amargosa Valley. The Pahrump Hills outcrop, at which Curiosity will be stopping to examine in fine detail, is located just above the scale bar.

The ascent’s starting point was changed to Pahrump Hills earlier this year, after a closer look at MastCam and Mars Reconnaissance Orbiter images showed that the location was as scientifically valid as the previous goal at a location named Murray Buttes. The decision shaved roughly two kilometers and several weeks of travel off of Curiosity’s journey. Jennifer Trosper, Curiosity’s Deputy Project Manager noted in a press release: “The wheels issue contributed to taking the rover farther south sooner than planned, but it is not a factor in the science-driven decision to start ascending here rather than continuing to Murray Buttes first. We have been driving hard for many months to reach the entry point to Mount Sharp, Now that we’ve made it, we’ll be adjusting the operations style from a priority on driving to a priority on conducting the investigations needed at each layer of the mountain.”

Time since launch: 1024 days
Total elapsed time on Mars: 748 sols (768 Earth days)
Light travel time to Earth: 11 minutes, 56 seconds
Total roving distance: 9.54km (5.93 miles)


Opportunity shut down operations on August 20th to begin preparations for a flash memory reformat. The rover’s flash memory had been experiencing frequent resets, which lead to partial or total science data losses approximately once a week. The rate skyrocketed in mid-August, with shutdowns on the 15th, 16th, and 19th which lead NASA to make the decision to reformat. While the procedure is a delicate operation, it has been deployed successfully on Opportunity’s twin Spirit. In 2009, a similar problem plagued the Spirit rover, and was solved by reformatting the rover’s flash memory. To read about the process of reformatting the flash memory system, check out this article by the JPL. The flash memory was successfully reformatted on September 4.

Shortly before the rover stopped operations last month, it collected images to produce a panorama of its surroundings on the western rim of Endeavor Crater. The panoramic image it collected shows the rover’s tracks over 700m away, produced during operations early in the summer. With the reformat complete, the rover will continue to head south, toward an outcrop of clay minerals identified in a location named Marathon Valley.

Time since launch: 4090 days
Total elapsed time on Mars: 3780 sols (3884 Earth days)
Total roving distance: 40.69km (25.28 miles)
Light travel time to Earth: 11 minutes, 56 seconds



On September 10, Rosetta settled into its global mapping orbit, a roughly circular orbit that lies only 30km from the surface of Churuymov-Gerasimenko. The mapping orbits consist of three phases, punctuated by orbital maneuvers. The first mapping orbit will spend 7 days watching the comet’s sunrise line, a position ideal for mapping small variations in topography. Next week, Rosetta will perform a small thruster burn to map the comet’s day side. After another 7 days, Rosetta will begin mapping the night side of the comet, looking for thermal variations.

While the detailed mapping phase is only beginning, the preliminary surveys of the surface have already begun to reveal the nature of the surface. On August 25, the Rosetta team used the available imagery to narrow down the number of landing sites for the Philae lander to just five. On September 5, the Alice ultraviolet spectrometer took its first look at the comet. That look revealed that the comet’s surface is extremely dark in the ultraviolet, with no trace of water ice (which is very bright in UV) to be found. On September 8, the Rosetta team released the first geological map of the comet’s surface, which split the comet into regions of distinct topography. Rosetta’s VIRTIS instrument has shown that 67P’s surface is probably a dusty, loosely packed layer that has had all of its water burnt off by the heat of the Sun. It has also been seeing hints of complex organic compounds that are commonly found in a class of meteorite known as carbonaceous chondrites. This early phase of science operations is just a hint at the wealth of data Rosetta will return as it nears the Sun.

Rosetta also released a selfie, taken by cameras onboard the Philae lander. The image shows one of Rosetta’s solar panels, with the comet in the far background.

Time since launch: 3885 days
Time since arrival at 67P/Churyumov-Gerasimenko: 37 days
Current distance from Earth: 434 million km (272 million miles); light travel time: 24 minutes 17 seconds



Cassini’s August 21 encounter with Titan studied the moon’s northern polar lakes, especially Kraken Mare, a body of liquid methane and ethane where a mysterious patch of “land” disappeared between subsequent passes last year. After the flyby was complete, Cassini turned its attention back to Saturn. On the 27th and 28th of August, the spacecraft made maps of Saturn’s atmosphere, first with the Ultraviolet Imaging Spectrometer (UVIS), then with the Composite Infrared Spectrometer (CIRS). After the global maps of Saturn were made using these instruments, CIRS made a series of point observations on August 29, September 3, 5, and 7. On September 1, the Visual and Infrared Mapping Spectrometer (VIMS) spent 36 hours making taking images for a time-lapse movie of clouds in Saturn’s northern hemisphere.

Between atmospheric observations of Saturn, Cassini spent time watching for short-lived clouds above the polar lakes on Titan. It also studied two of Saturn’s more far-flung moons, Thrymr (named after a frost giant of Norse myth) and Kiviuq (named after a heroic wandering shaman in Inuit mythology). Thymr was imaged with Cassini’s visible light cameras on August 30, at a distance of over 20 million kilometers. Kiviuq was also imaged with the visible light cameras, as well as the UVIS on September 8.

Time since launch: 6170 days
Total time at Saturn: 3726 days
Light travel time: 1 hour, 26 minutes


Other missions:


MESSENGER is currently orbiting Mercury. The mission is in its final year of operation, but is using its slowly decaying orbit to obtain spectacular views of the planet’s north polar region.

Time since launch: 3695 days
Total elapsed time in Mercury orbit: 1274 days
Light travel time to Earth: 9 minutes, 17 seconds


Venus Express

Venus Express is currently orbiting Venus. After the aerobraking campaign ended last month, the spacecraft was successfully reboosted into a higher orbit. While this orbit will slowly decay over the coming months, Venus Express is expected to continue regular science operations until December.

Time since launch: 3230 days
Time elapsed time in Venus orbit: 2977 days
Light travel time to Earth: 13 minutes, 56 seconds



MAVEN is now less than two weeks from arrival at Mars. Arrival will be on September 22.

Time since launch: 298 days
Current distance from Mars: 2.7 million kilometers (1.7 million miles)
Current distance from Earth: 213 million kilometers (132 million miles); light travel time: 11 minutes, 49 seconds


Mars Orbiter Mission

India’s first Mars mission is now less than two weeks from arrival at Mars. Arrival will be on September 24, 2014.

Time since launch: 311 days
Current distance from Mars: 3.2 million kilometers (2.0 million miles)
Current distance from Earth: 213 million kilometers (132 million miles); light travel time: 11 minutes, 48 seconds



Currently en route to the asteroid Ceres, where it will arrive in February 2015.

Time since launch: 2520 days
Time since Vesta departure: 715 days
Current distance from Ceres: 4.8 million kilometers (3.0 million miles)
Current distance from Earth: 479 million kilometers (297 million miles); light travel time: 26 minutes 32 seconds



Currently en route to Jupiter, where it will arrive in August 2016.

Time since launch: 1129 days
Current distance from Jupiter: 313 million kilometers (195 million miles)
Current distance from Earth: 669 million kilometers (416 million miles); light travel time: 37 minutes, 13 seconds


New Horizons

New Horizons is now less than a year away from its flyby of Pluto, which will occur on July 14, 2015.

Time since launch: 3145 days
Current distance from Pluto: 364 million kilometers (226 million miles)
Current distance from Earth: 4.48 billion kilometers (2.78 billion miles); light travel time: 4 hours, 9 minutes


Voyager 1

Time since launch: 13,520 days
Current distance from Earth: 19.30 billion kilometers (12.00 billion miles); light travel time: 17 hours, 53 minutes


Voyager 2

August 25th marked the 25th anniversary of Voyager 2’s flyby of Neptune, its final planetary encounter before leaving the Solar System.

Time since launch: 13,536 days
Current distance from Earth: 15.77 billion kilometers (9.80 billion miles); light travel time: 14 hours, 37 minutes

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About The Author
Justin Cowart
Justin Cowart is a geologist interested in Earth and Solar System history. As a geologist, he spends hist time looking at the ground, but in his free time he looks to the skies as an amateur astronomer.

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