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What's up in solar system exploration: August 2015 edition

Posted by Emily Lakdawalla

10-08-2015 19:31 CDT

Topics: Mars Orbiter Mission (MOM), Cassini, Lunar Reconnaissance Orbiter, Akatsuki (Planet-C), Voyager 1 and 2, Dawn, MAVEN, Chang'E program, Curiosity (Mars Science Laboratory), Mars Reconnaissance Orbiter, Rosetta and Philae, Opportunity, Mars Express, mission status, Mars Exploration Rovers, Juno

My summer vacation is over. It's time to tear my gaze away from the beach and look upward at the twenty-something planetary spacecraft exploring targets beyond Earth right now. What's going on up there? As ever, Olaf Frohn's diagram provides a helpful summary:

What's Up in the Solar System diagram by Olaf Frohn (updated for September 2016)

Olaf Frohn

What's Up in the Solar System diagram by Olaf Frohn (updated for September 2016)
A diagram, updated once a month, of active space missions traveling beyond Earth orbit. Contains links to past diagrams.

The innermost solar system is a little thin right now. With MESSENGER's demise earlier this year, no active mission is exploring either Mercury or Venus. JAXA's Akatsuki is on the way, hoping to enter orbit in December. Recall that Akatsuki lost its main engine during its first orbit insertion attempt, and has since vented all the fuel that that engine would have used in order to reduce its mass, making it possible for the spacecraft to return to Venus and attempt a second orbit insertion using only the attitude control jets. They posted some happy news last week: on August 4, Akatsuki performed a crucial deep-space course correction maneuver successfully. The maneuver placed Akatsuki on a course that will optimize its ability to perform science if it enters orbit at Venus as hoped.

I don't generally mention the Sun-observing missions in my What's Up updates because I'm biased toward planets. I don't usually mention Earth observing ones because there are too many to keep track of. But I have to make an exception for DSCOVR, which is technically an Earth/Sun mission but proved last week that it's more than capable of making observations of the Moon as well. Wow.

DSCOVR views the Moon crossing Earth

NASA / NOAA

DSCOVR views the Moon crossing Earth
NASA's Earth Polychromatic Imaging Camera (EPIC) aboard the Deep Space Climate Observatory (DSCOVR) satellite captured this unique view of the Moon as it moved in front of the sunlit side of Earth last month. This view shows the fully illuminated “dark side” of the moon that is never visible from Earth.

These images were taken between 3:50 p.m. and 8:45 p.m. EDT on July 16, showing the moon moving over the Pacific Ocean near North America. The North Pole is in the upper left corner of the image, reflecting the orbital tilt of Earth from the vantage point of the spacecraft.

The animation is cool but it's also well worth looking at the still version in order to study its features better. What a beautiful view of the lunar farside! The color is lovely. Note the subtle darkening that marks the south pole-Atiken basin, one of the solar system's largest impact structures.

Earth and Moon from DSCOVR

NASA / NOAA / Ian Regan

Earth and Moon from DSCOVR
NASA's Earth Polychromatic Imaging Camera (EPIC) aboard the Deep Space Climate Observatory (DSCOVR) satellite captured this unique view of the Moon as it moved in front of the sunlit side of Earth last month. This view shows the fully illuminated “dark side” of the moon that is never visible from Earth. Ian Regan processed this version of the image to account for the Moon's motion.

Up at the Moon, Lunar Reconnaissance Orbiter is still reliably returning data. The camera system has returned more than 1.5 million images now, and is still going strong. And against all odds, the Yutu rover is still in radio contact with Earth, even though it's unfortunately been immobile since January 2014.

Mars remains the most active spot beyond Earth in the solar system. This week, Mars Reconnaissance Orbiter reaches its 10th anniversary of service in space, but it's far from the oldest spacecraft in orbit at Mars; Mars Express and Mars Odyssey are still at work up there. Mars Orbiter Mission has ventured into an extended mission and is still returning photos, though apparently none of the full-disk images in a variety of phases that I had hoped for from its 4-Megapixel color camera. Even Mars' newest resident, MAVEN, is three-quarters of the way through its one-year primary science mission, which began on November 16, 2014. MAVEN's mission will undoubtedly be extended long beyond that, as it will be needed to support surface missions if and when Odyssey and Mars Reconnaissance Orbiter eventually fail.

Both Opportunity and Curiosity have been very active lately. Opportunity has finally reached Marathon Valley, a site identified from orbit to have signs of clay chemistry. The team is excited about the science prospects even though the rover's memory problems persist. A. J. S. Rayl has all the details on Opportunity's status in her latest MER Update. Enjoy this recent late-afternoon view from Marathon Valley:

Opportunity Sol 4087: Afternoon in Marathon Valley

Data: NASA / JPL / Cornell U. Processing: James Canvin

Opportunity Sol 4087: Afternoon in Marathon Valley
A wonderful low sun, late afternoon, view looking to the north side of Marathon Valley and beyond.

On the other side of Mars, Curiosity has finally been permitted to drill again after concerns about a short circuit in its drill vibration mechanism, and has taken a bite out of Buckskin. I'll have much more detail to report on Curiosity's recent activities later this week. But I can't wait to share this photo, a new self-portrait. Curiosity takes self-portraits -- time permitting -- to document drill locations. But they developed a new, lower angle for this one -- a Sojourner's-eye view of Curiosity.

Curiosity MAHLI self-portrait, sol 1065

NASA / JPL-Caltech / MSSS / James Sorenson

Curiosity MAHLI self-portrait, sol 1065
Curiosity captured this on Sol-1065 (August 5th, 2015) using its MAHLI camera on the end of the arm to mark its 3rd year on Mars.

Moving beyond Mars, it's going to be a really thrilling month for the Rosetta mission, as comet 67P/Churyumov-Gerasimenko is passing through perihelion on August 13.  (That's a particularly informative web page, but you need to make sure to click the little box that says "Continue" below the main text to unhide the lengthy FAQ section.) Meanwhile, the first release of science data from several of its instruments finally happened, including OSIRIS images -- but only through June 12, 2014, when the comet was still just a fuzzy speck. Still, I'm delighted to see any OSIRIS data at all; it took four years for the Mars flyby data to be released. A fourteen-month lag is a major improvement! They also ingested all of OSIRIS' cruise data into ESA's Archive Image Browser, which makes it much easier to browse the Earth, Mars, and asteroid flyby data than it used to be. Finally, they added a "comet escort phase" album of Navcam images to the browser, covering January 8-14, 2015.

A special issue of Science came out with first results from the comet lander Philae on July 31, which I have not yet had time to read. You can download the papers for free from here. For past special science issues from other missions, such links only worked for a week, so download them all now even if you don't have time to read for a while. Unfortunately, the web story accompanying the announcement of the Philae science results contains no further happy news on Philae's status; as far as I can find on the ESA website, Philae was last heard from on July 9. That's partially due to the shape of Rosetta's orbit, though; a Philae tweet dated July 27 indicates it would be two weeks until there would be a new opportunity for communication. So there's still plenty of reason for hope.

Dawn is currently in transition between orbital altitudes at Ceres. It began moving from Survey orbit at 4400 kilometers to High-Altitude Mapping Orbit at 1470 kilometers on June 30, but almost immediately went into safe mode due to a problem with the gimbaling mechanism on ion engine number 3. As Marc Rayman explains in his Dawn Journal, mission controllers switched to ion engine number 2 and resumed the work of shifting the orbit; it should arrive in HAMO in a few days.

I don't have much of any news on Hayabusa2, but at this early phase of its mission to 1999 JU3, no news is good news. Here's an entertaining recent tweet from the official account:

Juno is not doing science yet, but it's less than a year away from orbital insertion now. I've learned that some of the changes that they made to their orbital plan at Jupiter had to do with concerns over the spacecraft's going into safe mode during the Earth flyby -- twice. Jupiter is going to be interesting...

Cassini's recent activities have included lots of encounters with icy moons. A particularly close one is coming up in a week, when it will zoom past Dione at an elevation of only 474 kilometers. Although the camera will be imaging, the primary focus of the Dione flyby is gravity science; as Jason Perry explains in his Cassini Looking Ahead article for Rev 200, the science team is interested in determining whether Dione's relatively dense interior is differentiated into an icy mantle or rocky core, or not. Cassini will follow the Dione flyby with more distant imaging of Tethys and Enceladus. Later on this year, there will be three close Enceladus flybys: two in October, and one in December. These flybys are all exciting, but they're all bittersweet; increasingly, the mission is doing its last close flyby of target X, Y, or Z. The spacecraft will shift its orbit to an inclined one -- making close flybys of moons rare -- in January. The mission will come to an end in about two years, on September 15, 2017.

There are no spacecraft exploring or cruising to Uranus and Neptune, so next we skip on out to New Horizons, which is (as of the moment that I write this text) nearly 33 million kilometers beyond Pluto, a distance that increases at pretty much the same rate that it did before the flyby -- about 1.2 million kilometers a day. While I was on vacation, only a few new photos appeared on the raw image website, the first five pictures from Departure Phase 1. That's because we're in a planned image drought period, when New Horizons is transmitting the so-called "low-speed" data set and all the spacecraft telemetry. According to what I was told before the Pluto flyby, image transmission will not begin again until September 15. Images that arrive before close of business on September 15 will be released on September 18; anything that comes in the week after that will be released September 25. However, it was also hinted to me that New Horizons might possibly be commanded to return an image or two between now and then. We can hope, but don't expect anything until late September.

Which brings us to the last, distant travelers, the Voyagers. They're still traveling, roughly three times farther from the Sun than New Horizons is, well beyond the outer edge of the Kuiper belt. To answer a frequently-asked question, the two Voyagers will always and forever be farther from the Sun than New Horizons, even though all three are on escape trajectories and lightweight New Horizons left Earth faster. The Voyagers gained more velocity from their multiple giant-planet gravity-assist flybys than New Horizons, which only received one boost, from Jupiter. (Pluto is too small to have affected New Horizons' velocity substantially.) In fact, it's not clear that New Horizons will still be communicating with Earth by the time it reaches the region of space that the Voyagers are now exploring, the boundary between the heliosphere and the interstellar medium. But there is a lot to learn from New Horizons as it probes the region between Pluto and its eventual last-contact point, wherever that might be.

 
See other posts from August 2015

 

Or read more blog entries about: Mars Orbiter Mission (MOM), Cassini, Lunar Reconnaissance Orbiter, Akatsuki (Planet-C), Voyager 1 and 2, Dawn, MAVEN, Chang'E program, Curiosity (Mars Science Laboratory), Mars Reconnaissance Orbiter, Rosetta and Philae, Opportunity, Mars Express, mission status, Mars Exploration Rovers, Juno

Comments:

UniversalHome: 08/11/2015 12:58 CDT

Thank you for your insightful summary -- welcome back, you were missed. I look forward to the Juno mission as I would like to know more about Jupiter and its system of natural satellites. Increasingly, however, I look upon Mars as almost a cosmic analog of Earth within our own Solar System. The Martian scene above looks very similar to scenes from the American Southwest. It's hard to resist the idea that Mars beckons as humanity's next planetary home. Thanks again for the update.

masanori: 08/11/2015 01:57 CDT

The dates on which Akatsuki performed manoeuvre were 17th, 24th, 31st July, not on 4th August. All the 3 dates were the planned dates, which means the mission team divided the needed burn into three in advance, while they were also ready to do the 4th burn if needed after the 3rd. After the 1st one, I happened to have an occasion to talk with one of the mission team members who told me that the result of the 1st one was what they wanted, which was a very good news because the four thrusters which were used had not had experience of keeping burning for such long duration and also these thrusters are the first choice to use when trying to enter the Venus orbit. BTW thank you very much NASA for their help with DSN on these trajectory correction manoeuvres of Alatsuki. Thanks in advance on the day Akatstuki tries again, on 7th Dec 2015.

masanori: 08/11/2015 01:59 CDT

Additional, maybe unneeded comment: As I see/hear informations from JAXA in both Japanese & English these days, it's not rare to notice the difference in what they say. The worst one among these days is the post-launch press conference of Hayabusa2. A staff, who was doing a role of turning what both DLR's & CNES's officials said into Japanese language, kept on NOT telling most of what DLR's & CNES's officials said and kept on adding/telling what DLR's & CNES's officials DID NOT say, without informing that it's this staff's comments. Another bad example is that BepiColombo's team member from ESA mentioned on (original) English version about JAXA's reducing of budget on planetary science, but on Japanese version JAXA changed it into budget about space science in general (I suspect JAXA HQ might have not wanted this fact to be highlighted to the citizen). As for Akatsuki, what the mission team did by 4th August 5:30pm is different on JAXA's news between Japanese version http://www.isas.jaxa.jp/j/topics/topics/2015/0805.shtml and English version http://global.jaxa.jp/projects/sat/planet_c/ Thus, I think this tells how much preciously or poorly JAXA is treating the citizen/taxpayers and the international viewers/readers.

LocalFluff: 08/11/2015 04:04 CDT

I want to add Gaia space telescope to this great review. It's main tasks are not very "planetary", but it is expected to find exoplanets. And most interestingly, the data is being searched for lucky microlensing events that could reveal Oort Cloud objects! I don't think any OCO on a non-cometary trajectory has ever been discovered. Since microlensing doesn't depend much on the properties of the object revealed, the data should be statistically very representative. So maybe with only a handful detections one can say alot about the size and direction of Oort Cloud objects in general. And maybe note whether the cloud really is spherical or denser in some directions. And when one knows where to look, maybe for once microlensing events can be followed up by powerful telescopes? We should see some science results soon, Gaia has made more than a solar revolution by now, which must be key to its parallax measurement. ESA missions are often much more media quite than NASA missions. They foolishly keep the data secret until the interested public forgets about its existence.

donlevone: 08/11/2015 12:38 CDT

Have you look carefully the new global map of pluto, Emily? Kupe vallis in Voyager terra. There is a hi-resolution data there. It looks like they have more pictures on the ground but they have not released them. I read somewhere that the spacecraft will take very hiresolution line of pictures. It was in some of the papers you shared... Will we have to wait for them until September? :( . Sorry for my english

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