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Deep Space Digest – July 4
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Venus Express dives deeper, Opportunity spies a moon, Curiosity hits paydirt, Cassini looks at rings, and New Horizons uses Hubble (by way of Earth).

In the News:

Venus Express

Venus Express’s aerobraking campaign is entering its final week. According to a June 27 update on the ESA’s Rocket Science blog, the aerobraking maneuvers have already shortened Venus Express’s orbits by 20 minutes. The spacecraft seems to be holding up well – although the solar panels are heated by nearly 70C (126F) during each aerobraking pass, the design of aerobraking mode keeps the panels at a comfortable 10-15C (50-60F) at their hottest. This comes at the risk of thermal shock breaking the solar panels.

As of July 2, Venus Express is coming within 131km (81 mi) of the surface at its closest, following a maneuver that lowered its pericenter by 0.8km. This is 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.

Time since launch: 3160 days
Time elapsed time in Venus orbit: 2907 days
Light travel time to Earth: 11 minutes, 43 seconds

Opportunity

Having wrapped up work in the Pillinger Point area, Opportunity has continued south along the western rim of Endeavor Crater. “Touch and Go” activities continue, as Opportunity will sit in one spot to collect data on a target rock for one day, then spend the next moving to another target. The solar panels are continuing to generate abundant energy, allowing the rover to conduct night-time observations of Phobos, Mars’s innermost moon. While the cameras snap away at Phobos, Opportunity’s APXS instrument is collecting atmospheric argon measurments.

The flash memory resets that plagued Opportunity during the last update period seem to have tapered off. Only one reset occurred during this time period, on June 14. The rover remains in good health.

Time since launch: 4016 days
Total elapsed time on Mars: 3712 sols (3813 Earth days)
Total roving distance: 39.59km (24.60 miles)
Light travel time to Earth: 8 minutes, 23 seconds

 

Curiosity

Scientists released preliminary results of a ChemCam target that Curiosity examined at The Kimberley waypoint. The observations are interesting, because they indicate that the sediments contain potassium and sodium feldspar minerals. These two minerals generally form in granitic rocks. All of the igneous rocks that have been studied to date on Mars are basalts, which generally lack these minerals. This makes the source of the sediments at The Kimberley something of a mystery, as no granitic outcrops are known in the area of Gale Crater. While at The Kimberley, Curiosity took a self-portrait which NASA released on June 24.

To celebrate Curiosity’s first Martian year, the mission team planned Women’s Day on June 26. During Women’s Day, 76 of Curiosity’s 102 operational positions were staffed by women. “I see this as a chance to illustrate to girls and young women that there’s not just a place for them in technical fields, but a wide range of jobs and disciplines that are part of the team needed for a project as exciting as a rover on Mars,” said Colette Lohr, a JPL engineer who was in charge of developing Curiosity’s science plans as part of Women’s Day.

During a drive on June 27, Curiosity left its landing ellipse. The landing ellipse was a 20X25km zone of uncertainty for Curiosity’s initial landing. Curiosity landed about 5km from the southern edge of the landing ellipse. Incidentally, Curiosity seemed hesitant to leave the landing ellipse. Ken Herkenhoff, a Curiosity mission scientist, wrote “”After traversing 82 meters the rover stopped because it determined that it was slipping too much. Coincidentally, the rover stopped right on the landing ellipse, a major mission milestone!”

Time since launch: 966 days
Total elapsed time on Mars: 678 sols (697 Earth days)
Light travel time to Earth: 8 minutes, 23 seconds

 

Rosetta

Rosetta is continuing to close in on 67P/Churyumov-Gerasimenko. As the comet approaches, Rosetta needs to slow down enough to be captured by the comet’s small gravitational field. The probe performed a burn on July 2 that slowed it down by 59 m/s relative to 67P and took roughly 90 minutes to complete. Only 5 burns are now left before Rosetta falls into orbit around 67P, the next of which is scheduled for July 9. Interestingly, the exhaust from these burns is detectable by Rosetta’s mass spectrometer. A blog post detailing this can be found here.

As of today, Rosetta is less than 43,000 km (26,000 miles) from 67P, close enough for the comet to take up more than a single pixel in Rosetta’s narrow-angle camera. On July 3, the ESA released an animation showing the nucleus of 67P rotating on June 28. The probe is also getting close enough to begin learning about 67P’s water production rate – on June 4 Rosetta found that 67P was venting about two glasses of water (300mL) into space per second.

Time since launch: 3777 days
Current distance from 67P/Churyumov-Gerasimenko: ~43,000 km (~26,000 miles)
Current distance from Earth: 415 million km (258 million miles); light travel time: 23 minutes 5 seconds

 

Cassini

Cassini had a very busy couple of weeks during this update period. June 18 brought Cassini near Titan for the T-102 flyby, during which the planned (and complicated) radio experiment was successfully executed. On June 19, after watching Titan recede in its rearview mirror, Cassini took infrared images of Saturn’s rings to learn about their composition. The next day, Cassini looked for Saturn’s shadow on the huge, distant Phoebe ring. Once that observation was complete, Cassini took a short break to watch a star emerge from behind Saturn (useful for figuring out a density profile of the atmosphere) and to image Enceladus’s geysers.

On June 22, Cassini took a series of images of Saturn’s F-ring, following the ring’s material as it completed a full 15 hour orbit around the planet. Cassini scientists plan to compile these images into a movie for release in the near future. After completing that series of observations, Cassini again took infrared images of Saturn’s rings. At the same time another instrument, VIMS, watched as a star passed behind Saturn’s rings. These observations will help build a better picture of ring particle density distribution.

Time since launch: 6107 days
Total time at Saturn: 3656 days
Light travel time: 1 hour, 17 minutes

 

New Horizons

Results for the preliminary Hubble search for a post-Pluto encounter target were released this week. Hubble is an overbooked telescope, and the last minute search for a target were squeezed into the schedule with a pilot program. The New Horizons team was granted small bits of observing time over two weeks to look for a Kuiper Belt Object (KBO) back in June, with the promise of more observing time if they turned up two or more KBOs. Their initial searches bore fruit, and two new objects were discovered. It is still unclear whether these objects could be visited by New Horizons in the future, so the New Horizons team will use their additional time with the Hubble to find more possible targets.

Time since launch: 3089 days
Current distance from Pluto: 447 million kilometers (277 million miles)
Current distance from Earth: 4.30 billion kilometers (2.67 billion miles); light travel time: 3 hours, 59 minutes

 

Other missions:

MESSENGER

MESSENGER is continuing its low-altitude imaging campaign, the final phase of its mission. During this phase it will make passes within 25 miles of Mercury’s north pole, producing images with resolution greater than 10m/pixel. Fuel to maintain the spacecraft’s orbit will run out late this year, and MESSENGER will crash into Mercury sometime during March 2015.

Time since launch: 3622 days
Total elapsed time in Mercury orbit: 1204 days
Light travel time to Earth: 5 minutes, 42 seconds

 

Chang’e 3/Yutu

Chang’e 3 and Yutu have been in hibernation at their landing site at Mare Imbrium. Local sunrise will occur on July 5. Yutu has been crippled with a mechanical problem that prevents it from storing its instruments and heating itself properly during hibernation. Chinese scientists have reported that the rover is weaker and weaker with each hibernation period, so it remains to be seen if it has survived another lunar night.

Time since launch: 216 days
Time since landing: 203 days

 

MAVEN

Currently en route to Mars, where it will arrive on September 22, 2014.

Time since launch: 228 days
Current distance from Mars: 20.7 million kilometers (12.9 million miles)
Current distance from Earth: 130.1 million kilometers (80.9 million miles); light travel time: 7 minutes, 14 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: 241 days
Current distance from Mars: 21.2 million kilometers (13.2 million miles)
Current distance from Earth: 129.9 million kilometers (80.7 million miles); light travel time: 7 minutes, 13 seconds

 

Dawn

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

Time since launch: 2459 days
Time since Vesta departure: 654 days
Current distance from Ceres: 9.3 million kilometers (5.8 million miles)
Current distance from Earth: 343 million kilometers (212 million miles); light travel time: 18 minutes 55 seconds

 

Juno

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

Time since launch: 1059 days
Current distance from Jupiter: 346 million kilometers (215 million miles)
Current distance from Earth: 603 million kilometers (375 million miles); light travel time: 33 minutes, 33 seconds

 

Voyager 1

Time since launch: 13,452 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: 13,468 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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