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Deep Space Digest – June 20
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Plenty of news to go around this update, from MESSENGER to New Horizons and most missions in between.

In the News:

MESSENGER

MESSENGER began its low-altitude campaign on June 17, ironically by raising its orbit. The gravitational effects of the Sun are slowly causing MESSENGER’s lowest point above Mercury to fall towards the surface, so operators have to periodically reboost the spacecraft to prevent it from crashing into the surface. The June 17 reboost was the first of four, and raised the lowest point of MESSENGER’s eccentric orbit from 114 km (71 miles) to 155 km (96 miles). The remaining three burns are scheduled for September, October, and January, after which MESSENGER will have run out of propellant for reboosting. Mission end is now slated for March 2015.

During this phase of the mission, MESSENGER will drift closer to the surface, allowing extremely high resolution images for regions of interest. The low altitudes will also allow gravitational measurements of the enormous fault scarps that scar the surface, allowing scientists to unravel the mechanics behind their formation.

Time since launch: 3608 days
Total elapsed time in Mercury orbit: 1190 days
Light travel time to Earth: 4 minutes, 37 seconds

 

Venus Express

Venus Express’s aerobraking campaign kicked into high gear this week. In a blog update on June 18, the ESA declared the ‘walk-in’ phase of the campaign complete. Currently, Venus Express is only 136km (85 miles) above the blistering Venusian surface at closest approach. Atmospheric drag will pull the probe down an additional 1km per week. By the time the aerobraking campaign wraps up on July 11, Venus Express will be flying approximately 132 km (82 miles) above the surface. This will be the lowest an orbiting spacecraft at Venus has flown and survived, beating out the record of 139km (86 miles) set by NASA’s Magellan in 1994.

The ESA also published an excellent summary of the science operations that Venus Express will be conducting during the aerobraking mission.

Time since launch: 3146 days
Time elapsed time in Venus orbit: 2993 days
Light travel time to Earth: 11 minutes, 2 seconds

Chang’e 3/Yutu

Chinese news agency Xinhua published an article about the health of Chang’e 3 and Yutu on May 28. Li Benzheng, deputy commander-in-chief of China’s lunar exploration program, reported that the rover was not in good health. “With each lunar night, the functionality of Yutu is weakened,” Li was quoted as saying. Despite the poor health of the rover and lander, Yutu participated in a digital torch relay for the Summer Youth Olympic Games on June 19. Live video of the rover served as a backdrop for the games’ mascot during the torch relay.

China’s space agency donated a replica of the Yutu rover to the UN’s aerospace bureau in Vienna, Austria on June 13.. The replica now resides at the Vienna International Center.

Time since launch: 202 days
Time since landing: 189 days

 

Opportunity

Opportunity continues to explore the Pillinger Point area on the western rim of Endeavor Crater. The rover has been plagued by warm resets over the past couple weeks. These resets are caused by errors in writing to the rover’s flash memory, which prevent the proper execution of commands sent to the rover. If the command is not recognized, the rover pauses and waits for a new set of instructions. The warm reset problem has disrupted Opportunity’s “touch-and-go” operations. Touch and go is a two sol command sequence, in which the first day is spent observing a target with the APXS and microscopic imager, and the second day is spent driving to the next target.

The rover experienced warm resets on May 31, June 4, and June 10, all of these resets affecting the driving sol of Opportunity’s command sequence. Despite the resets, Opportunity had three drives of over 15 meters during the update period. Aside from the flash memory problem, the rover is in good health.

Time since launch: 4002 days
Total elapsed time on Mars: 3697 sols (3799 Earth days)
Total roving distance: 39.49km (24.53 miles)
Light travel time to Earth: 7 minutes, 37 seconds

 

Curiosity

On June 3, Curiosity observed a transit of Mercury across the Sun. Although the small apparent size and the comparatively low resolution of Curiosity’s panoramic camera made the event look unimpressive, it was a historic first from the surface of Mars. The rover is still making a dash for the base of Mt. Sharp. Images taken by the rover’s panoramic imager on June 19 show the foot of the mountain, as well as the rim of Gale Crater in the distance.

On June 22, Curiosity will celebrate the end of its first Martian year, having spent 668 sols working in Gale Crater. This also marks the end of Curiosity’s primary mission and the beginning of the first extended mission.

Time since launch: 938 days
Total elapsed time on Mars: 666 sols (683 Earth days)
Light travel time to Earth: 7 minutes, 37 seconds

 

Rosetta

On June 17, Rosetta closed to within 200,000 km (124,000 miles) of Comet 67P/Churyumov-Gerasimenko. The following day, Rosetta performed the third and final of its “big burns”, this time with the goal of changing the probe’s velocity by 89 m/s. The burn took about 2 hours and 15 minutes to complete, and reduced its speed relative to 67P to around 200 m/s. Although the big burns are now complete, Rosetta has a series of smaller burns scheduled between now and August 6, the projected arrival date at 67P.

During the approach phase, Rosetta has been observing 67P. Curiously, activity on the comet seems to have declined in the month since Rosetta last looked. Observations on June 4 turned up no sign of the dust cloud that was forming around the comet in early May, and the nucleus itself has faded somewhat.

Time since launch: 3763 days
Current distance from 67P/Churyumov-Gerasimenko: ~162,000 km (100,000 miles)
Current distance from Earth: 434 million km (269 million miles); light travel time: 24 minutes 6 seconds

 

Cassini

For the first half of this update period, Cassini continued to observe Saturn’s auroras with its ultraviolet imaging spectrograph (UVIS) instrument, performing observations on May 28-30 and again on June 4-5. Short observations of Titan were performed May 28-June 6. The main event of this flyby period was a flyby of Titan (T-102) on June 18, at a distance of 3659 km (2274 miles). The radio experiment that was performed on the T-101 flyby was repeated again, this time attempting to catch reflections of Cassini’s radio transmissions off of Kraken Mare, a hydrocarbon lake near Titan’s north pole that is nearly the size of Lake Superior.

Another experiment, a radio occultation event (in which Cassini passes behind Titan from Earth) attempted to collect an extremely detailed temperature and density profile of Titan’s atmosphere. For an idea of the difficulty involved, have a look at this NASA story which details the experiment.

Time since launch: 6093 days
Total time at Saturn: 3642 days
Light travel time: 1 hour, 16 minutes

 

New Horizons

New Horizons is in good health following its May 29-30 dry run of next year’s Pluto flyby. The main news concerning the mission is that Hubble will be involved in finding a post-Pluto flyby target for the spacecraft. A citizen science campaign, Ice Hunters, failed to turn up a Kuiper Belt Object (KBO) that was reachable by New Horizons. Subsequent searches by ground-based telescopes were hampered by bad weather, leaving Hubble as a last resort for finding a suitable target for New Horizons to visit following its July 2015 flyby of Pluto. The first raw images from Hubble’s search were beamed back to Earth on June 16.

Time since launch: 3075 days
Current distance from Pluto: 492 million kilometers (305 million miles)
Current distance from Earth: 4.28 billion kilometers (2.66 billion miles); light travel time: 3 hours, 58 minutes

 

Other missions:

MAVEN

Currently en route to Mars, which it is expected to reach September 22, 2014.

Time since launch: 214 days
Current distance from Mars: 24.4 million kilometers (15.2 million miles)
Current distance from Earth: 113.4 million kilometers (70.5 million miles); light travel time: 6 minutes, 19 seconds

 

Mangalyaan-1

ISRO directed Mangalyaan-1 to perform a small course correction maneuver on June 11. The correction burn took only 16 seconds for the spacecraft to perform. India’s first Mars mission is currently en route to the Red Planet, which it is expected to reach September 24, 2014.

Time since launch: 227 days
Current distance from Mars: 25.1 million kilometers (15.6 million miles)
Current distance from Earth: 113.3 million kilometers (70.4 million miles); light travel time: 6 minutes, 18 seconds

 

Dawn

Currently en route to the asteroid Ceres, which it is expected to reach in February 2015.

Time since launch: 2445 days
Time since Vesta departure: 640 days
Current distance from Ceres: 10.4 million kilometers (6.5 million miles)
Current distance from Earth: 315 million kilometers (196 million miles); light travel time: 17 minutes 26 seconds

 

Juno

Currently en route to Jupiter, which it is expected to reach in August 2016.

Time since launch: 1045 days
Current distance from Jupiter: 354 million kilometers (220 million miles)
Current distance from Earth: 576 million kilometers (358 million miles); light travel time: 32 minutes, 2 seconds

 

Voyager 1

Time since launch: 13,438 days
Current distance from Earth: 19.05 billion kilometers (11.84 billion miles); light travel time: 17 hours, 39 minutes

 

Voyager 2

Time since launch: 13,454 days
Current distance from Earth: 15.61 billion kilometers (9.70 billion miles); light travel time: 14 hours, 28 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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