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Deep Space Digest – August 15

Chang’e 5 news, Curiosity meets a sand trap, Opportunity on the move, Rosetta reaches a comet, and Cassini scans Saturn’s magnetosphere.

Apologies for the late update this week.

In the News:

Chang’e 3/Yutu

Yutu and its Chang’e 3 rover apparently continue to return data. The Yutu rover suffered a crippling failure in January, leaving it unable to move. The big news regarding China’s Chang’e program is that China has confirmed the mission plan for Chang’e 5. The land on the Moon, collect a sample, and return it to Earth. The Chinese news agency Xinhua also reports that the country is readying an orbiter that will launch later this year that will test out the high-speed atmospheric reentry before Chang’e 5’s design is finalized.

Time since launch: 258 days
Time since landing: 245 days


Curiosity has had trouble making progress towards the foothills of Mt. Sharp over the last couple of weeks. Although it survived a traverse of difficult caprock terrain called Zabriskie Plateau with little damage, the rover has since run into difficulty maneuvering in Hidden Valley, the next leg of its route. The valley has a sandy floor, leading to excessive wheel slippage. After the slippage was noticed, Curiosity backed up, retracing its route into Hidden Valley.

The difficulty in moving has led the rover’s operators to abandon their original plan of examining the Pahrump Hills outcrop. This outcrop is believed to the be basal layer of the sedimentary sequence that makes up the Mt. Sharp massif. The Pahrump Hills are key to linking the geology Curiosity has examined so far, which is believed to predate the formation of Mt. Sharp, and the subsequent sedimentation that formed the mountain. Fortunately, it appears that a small outcrop (named Bonanza King) of the Pahrump Hills formation is within reach of Curiosity. Today, JPL announced that Curiosity will drill into the Bonanza King outcrop in lieu of closer examination of Pahrump Hills.

Time since launch: 995 days
Total elapsed time on Mars: 719 sols (737 Earth days)
Light travel time to Earth: 10 minutes, 39 seconds
Total roving distance: 9.14km (5.68 miles)


Opportunity is working its way south along the western rim of Endeavor Crater. Its target is a small notch in the crater’s rim that the rover’s operators refer to as “Marathon Valley”. The rocks at Marathon Valley appear to have a large amount of clay that formed in freshwater. Opportunity began August wrapping up detail work at an outcrop named “Fairweather”, which the rover’s operators decided was interesting enough to backtrack 30 meters to explore in more detail. A panorama of the outcrop area can be seen here. While at Fairweather, the rover took several APXS measurements, as well as a panorama of the area. Once work was finished there on August 5, the rover turned south again.

On August 7, the Opportunity team decided the next waypoint on the rover’s journey would be an outcrop dubbed “Wdowiak Ridge”. However, that evening the rover suffered a flash memory reset which stalled the rover until August 9. Once control was restored, Opportunity spent the next two days performing a “touch and go” routine. Finding no other targets of interest in the immediate area, the rover spent the next two days performing two long drives to reach Wdowiak Ridge.

Time since launch: 4058 days
Total elapsed time on Mars: 3754 sols (3855 Earth days)
Total roving distance: 40.63km (25.25 miles)
Light travel time to Earth: 10 minutes, 39 seconds



On August 6, Rosetta successfully executed the final thruster burn necessary to match speed with Comet Churyumov-Gerasimenko. The probe is currently performing stationkeeping maneuvers that allow it to survey the comet’s surface from a number of different angles. This surveying process is necessary to find a safe but interesting landing spot for its Philae lander to examine beginning in November. Already, the survey is turning up interesting features on the comet’s surface (which I’ve written about here), which are evidence that the comet’s surface is a very active place.

Although it has just arrived at the comet, the Rosetta team is already beginning to report some new discoveries. During the final approach phase, Rosetta’s Grain Impact Analyser and Dust Accumulator (GIADA) instrument detected dust strikes. Based on the instrument’s measurements, the team calculates that the dust grains being thrown into space by the comet are a few tens of microns (the width of a human hair) and a few hundreds of microns across. A summary of some of Rosetta’s other findings during the approach phase can be seen here.

Time since launch: 3857 days
Time since arrival at 67P/Churyumov-Gerasimenko: 9 days
Current distance from Earth: 410 million km (255 million miles); light travel time: 22 minutes 47 seconds



The first two weeks of August for Cassini were dominated by the Ultraviolet Imaging Spectrometer’s (UVIS) mosaic imaging project to document Saturn’s magnetosphere. UVIS measures oxygen trapped in Saturn’s magnetic field, allowing it to measure the shape and size of the magnetosphere. In between the scans, most of which took more than a day to complete, Cassini turned its electronic sensors towards Titan as part of a monitoring campaign, followed by short snapshots of Saturn to watch for emerging storm systems.

Cassini’s recent flybys of Titan have been acting to shorten its orbital period, as well as ratchet up its inclination with respect to Saturn’s equatorial plane. This week, its orbit was 31.9 days long and inclined nearly 50 degrees. However, on August 9, Cassini performed an orbital trim maneuver (OTM-387), designed so that subsequent Titan flybys will act to bring down the orbit’s inclination and allow close flybys of Enceladus beginning next year. The next flyby of Titan (T-104) will take place on August 21, and will focus on collecting radar imagery of the moon’s north polar region.

Time since launch: 6142 days
Total time at Saturn: 3698 days
Light travel time: 1 hour, 23 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: 3663 days
Total elapsed time in Mercury orbit: 1246 days
Light travel time to Earth: 11 minutes, 15 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: 3202 days
Time elapsed time in Venus orbit: 2949 days
Light travel time to Earth: 13 minutes, 20 seconds



MAVEN finished its cruise-phase instrument checkouts on July 17. The probe was placed into hibernation in preparation for orbital insertion on September 22, 2014.

Time since launch: 270 days
Current distance from Mars: 10.0 million kilometers (6.2 million miles)
Current distance from Earth: 183 million kilometers (114 million miles); light travel time: 10 minutes, 10 seconds


Mars Orbiter Mission

India’s first Mars mission is currently en route to the Red Planet, where it will arrive on September 24, 2014.

Time since launch: 264 days
Current distance from Mars: 10.5 million kilometers (6.5 million miles)
Current distance from Earth: 182 million kilometers (113 million miles); light travel time: 10 minutes, 8 seconds



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

Time since launch: 2492 days
Time since Vesta departure: 687 days
Current distance from Ceres: 6.3 million kilometers (3.9 million miles)
Current distance from Earth: 428 million kilometers (266 million miles); light travel time: 23 minutes 46 seconds



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

Time since launch: 1101 days
Current distance from Jupiter: 320 million kilometers (199 million miles)
Current distance from Earth: 660 million kilometers (410 million miles); light travel time: 36 minutes, 42 seconds


New Horizons

New Horizons is now less than a year away from its flyby of Pluto, which will occur on July 14, 2015. On August 13, New Horizons scientists at Johns Hopkins University released a time-lapse video taken by the LORRI imager onboard the spacecraft. The video shows Charon, Pluto’s largest moon orbiting the dwarf planet, and also captures the system’s “barycentric wobble”.

Time since launch: 3131 days
Current distance from Pluto: 396 million kilometers (246 million miles)
Current distance from Earth: 4.39 billion kilometers (2.73 billion miles); light travel time: 4 hours, 4 minutes


Voyager 1

Time since launch: 13,492 days
Current distance from Earth: 19.21 billion kilometers (11.94 billion miles); light travel time: 17 hours, 47 minutes


Voyager 2

Time since launch: 13,508 days
Current distance from Earth: 15.70 billion kilometers (9.76 billion miles); light travel time: 14 hours, 32 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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