Emily LakdawallaApr 04, 2016

What's up in solar system exploration: April 2016 edition

Welcome to my monthly inventory of the 20-plus spacecraft actively exploring our solar system. This month (actually, today), Cassini had a relatively close flyby of Titan, and New Horizons will observe a very distant Kuiper belt object named 1994 JR1. Akatsuki has just fine-tuned its orbit around Venus, and Hayabusa2 has begun an 800-hour ion engine thrusting phase to steer it toward near-Earth asteroid Ryugu. On Mars, Curiosity has just about finished its traverse of the Naukluft plateau, and Opportunity has performed its steepest-ever climb and witnessed one of the biggest dust devils of the mission. Juno is only 92 days away from Jupiter arrival. Before I get into further detail, here's Olaf Frohn's summary diagram:

Earth Launches and Landings (contributed by Jason Davis)

On board the International Space Station, Expedition 47 continues with NASA astronauts Tim Kopra and Jeff Williams, ESA astronaut Tim Peake, and the cosmonaut trio of Yuri Malenchenko, Oleg Skriprochka and Alexey Ovchinin. Kopra remains in command until his departure in June. There are no planned spacewalks. The crew welcomes its third cargo flight in three weeks this month, after SpaceX's CRS-8 mission launches April 8. This will mark a return to flight for Dragon, which has not flown since the loss of CRS-7 last year. In its unpressurized trunk, Dragon will be carrying an inflatable habitat testbed called BEAM that will be installed on the station's Tranquility module, node 3. BEAM will be unpacked and berthed either in late April or early May.

The only other expected U.S. launch is another SpaceX Falcon 9, carrying the JCSAT 14 communications satellite. Space Systems Loral, which designed and built the spacecraft, delivered it to Cape Canaveral last month.

Russia launches three rockets in April, according to RussianSpaceWeb.com and Spaceflight Now. On April 22, a Soyuz launches Sentinel 1B, a European Earth observation satellite, from French Guiana. A day later on April 23, an Intelsat communications satellite rides a Proton rocket to orbit from Baikonur, Kazakhstan. And on April 25, Russia hopes to activate its new launch site at the Vostochny Cosmodrome in the country's Far East region. For that mission, a Soyuz rocket will carry a spacecraft dubbed the Mikhail Lomonosov into orbit. The satellite is equipped with scientific instruments to study cosmic rays and other high-energy phenomena. 

Finally, India may launch its IRNSS 1G navigation satellite this month. The flight was originally scheduled for March but was delayed.

Inner Solar System

At Venus, Akatsuki has just performed a 15-second burn to adjust its orbit around Venus. Apart from that, it is easing into science operations. Other recent tweets from the official Twitter account have concerned the performance of radio occultations: As the spacecraft's orbit takes it behind Venus as seen from Earth, it broadcasts a radio signal to a ground station on Earth; the attenuation and refraction of the beam provides data one the atmosphere of Venus.

Earth's Neighborhood

Lunar Reconnaissance Orbiter is keeping on, keeping on. Last month they released this gorgeous oblique view of Chappy crater on the Moon. The blog entry accompanying the release says that the crater is just a little bit larger than Meteor crater in Arizona, but Chappy is a lot better preserved. Most of the visible ejecta blanket formed as a "ground hugging flow", while impact melt forms the "dark, lacy, discontinuous crust" immediately around the rim.

I got a bit of a Chang'e 3 and Yutu update at the Lunar and Planetary Science Conference, where Zou Yongliao gave an overview of Chinese space exploration plans during lunch on Tuesday, March 22. He confirmed that Chang'e 3 is still doing science from the surface of the Moon. He said that of the eight science instruments launched to the Moon on the mission, only one was still working: the ultraviolet telescope on the Chang'e 3 lander. It has downlinked 180,000 images to date.

Chang'e 5 T1 is still active at the Moon, having completed (as of March 1) more than 4100 orbits. There are a couple of Chang'e 5 T1 images of the lunar surface in the same article.

I don't have any updates on ARTEMIS beyond what I wrote in February, or on the status of the other active Chang'e spacecraft.

Near-Earth Asteroids

On March 22, Hayabusa2 began continuous operation of its ion engines to adjust its orbit to match that of asteroid Ryugu. So I've shifted Hayabusa2's position in this monthly post from "near Earth" to "near-Earth asteroids!" This period of ion engine operation is planned to last about 800 hours, completing in mid-May. Haybusa2 will have three periods of continuous ion thrusting between now and its June or July 2018 arrival at Ryugu. A little more information is available on the JAXA "fanfun" site.

On the Way to Mars

ExoMars Trace Gas Orbiter launched successfully last month. Here's a cool time-lapse video of the process of final assembly and launch. The mission appears to be going well so far, with the spacecraft healthy. But photos taken from Earth shortly after the launch show that ExoMars may have narrowly averted a launch disaster: the Briz-M upper stage of the launch vehicle evidently broke up shortly after separating from the spacecraft, before completing the rocket burn that would have sent it into its graveyard orbit around the Sun. Anatoly Zak reports the details in an article for Popular Mechanics.


I don't yet have any updates on Odyssey in its new 06:45 sun-synchronous orbit, but with a spacecraft of Odyssey's age, no news is good news. The THEMIS images are still coming in on a regular basis.

There was little news from Mars Express this month, perhaps because ESA was busy with the successful launch of ExoMars Trace Gas Orbiter! The Mars Webcam has been active, with the most recent images dating to March 26. The HRSC team released one captioned image last month, a gorgeous frosty view of the western edge of Hellas basin.

Last month Mars Reconnaissance Orbiter celebrated 10 years in orbit. You can watch a webcast lecture on the anniversary occasion here. The latest weather report from MARCI includes "water-ice clouds associated with the aphelion cloud belt" but little dust storm activity, and "storm-free skies" for both rovers. Don't forget to check the HiRISE website regularly for image updates. This one shows what may be salt deposits just one crater over to the west of Curiosity's landing site.

I don't have any news on the status of MAVEN, but last month a team of scientists published an article in Geophysical Research Letters summarizing MAVEN's observations of the effects of comet Siding Spring on Mars' magnetosphere. A related press release provides a good summary of the work. MAVEN's next two deep-dip campaigns have now been planned for early June and late July of this year.

The rover drivers have been having a good time trying to roll Opportunity up a steep hill to reach an outcrop on Knudsen Ridge named Pvt. Whitehouse. At one point, the rover was pushing 32 degrees of tilt. Unfortunately, despite the drivers' best efforts, they weren't able to reach the rock target, so they backed Opportunity down the hill and are now attempting a different spot. A benefit of this article being late is that I'm publishing it after A. J. S. Rayl's monthly MER Update, which gives you all the details. The steep slopes and high elevation of Opportunity's recent travels have produced some spectacular views, including this photo, one of the best dust devil images I've seen from the mission. Here's an even cooler version, in 3D, and here's a fanciful panorama version.

On the other side of Mars, Curiosity is almost all the way across the Naukluft plateau. Driving has been a bit of a challenge, with a few drives stopping short as the rover's rocker-bogie suspension system tilts to accommodate the bumpy ground. Unlike Opportunity, it's not regional tilt, but local roughness that has been triggering drive faults. But they've made steady progress and will soon be driving down from the plateau and approaching the edge of the Murray Buttes. While up on the plateau, they took a moment to investigate the part of the CHIMRA mechanism that faulted at Namib dune. This photo shows the CHIMRA tunnel wide open -- a huge relief to me! There is a science team meeting this week, which usually limits science a bit, ironically, but the priority right now is driving. I plan to post an update about the drive across the Naukluft plateau next week.

Beyond Mars

Rosetta has just traveled farther from comet Churyumov-Gerasimenko than it has been for a long time. According to a recent update in the ESA blog, "Rosetta embarked on an excursion around 1000 km in the anti-sunward direction to study the wider coma, tail and plasma environment of Comet 67P/Churyumov-Gerasimenko." When they say "anti-sunward," they aren't kidding; Rosetta got this gorgeous photo of the comet at very high phase, with the Sun nearly behind it, backlighting the plumes. (The Sun is out of the frame, above the comet nucleus.) On March 30, Rosetta reached the 100-kilometer mark, and it's now headed closer again, planning a zero phase observation (the opposite of this one, with the Sun directly behind the spacecraft) from an altitude of 30 kilometers.

Dawn is now orbiting Ceres at the lowest altitude it'll ever achieve: an average 385 kilometers. I don't have a lot to add beyond the report I filed from the Lunar and Planetary Science Conference last week: They've completed a global monochrome map from their low altitude, and are now filling in color, stereo, and especially spectrographic data as they continue to pursue the priority activities of the lowest orbit, neutron spectrometry and gravity science. Check the Photojournal for the latest images!

Juno is now 92 days and about 32 million kilometers from Jupiter. Amateur astronomers continue to pour images into the JunoCam image database to help the team plan future imaging. Damian Peach emailed me this photo, taken on March 18, of Juno's target. I swear Damian has a secret spacecraft that he's using to take these incredible pictures. Juno's pictures will be even better, and from unusual angles, but I want to take a moment to convey my respect and thanks to the worldwide community of amateur astronomers that are keeping an eye on Jupiter and sharing their photos with the world. No brief spacecraft mission can replicate the constancy and frequency of the amateurs' monitoring.

Cassini has just passed through periapsis of Rev 234, headed for its 119th flyby of Titan. (Holy cow, 119.) This flyby is special, the Cassini website states, because "It is the only flyby in the mission where the Ultraviolet Imaging Spectrograph (UVIS) and the Ion and Neutral Mass Spectrometer (INMS) will observe Titan's atmosphere simultaneously at the same latitude." Closest approach happens at a close altitude of 990 kilometers. (Cassini does closer flybys of other icy moons, but Titan's atmosphere keeps Cassini at arm's length.) Apart from the scientific value of the flyby, it will also boost the inclination of Cassini's orbit from 20.6 to 27.8 degrees.

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New Horizons had a very busy week at the Lunar and Planetary Science Conference two weeks, although I was so busy with Ceres and Mars that I didn't attend many of the New Horizons team talks. Fortunately, they continue to release captioned images every Thursday, like this one of a now-frozen, possibly-once-fluid nitrogen lake on Pluto. There is also an excellent series of blogs from the New Horizons team that I don't think is getting enough attention. The past month's offerings have included Pluto mapping by Ross Beyer; one on the "snakeskin" terrain, by Orkan Umurhan; and one on Pluto's polygons, by Katie Knight. Meanwhile, the spacecraft continues to downlink data from its July flyby. The next target they plan to observe is 1994 JR1, some time this month.

Finally, the Voyagers are still going, going, going. Voyager 1 is at 134.6 AU from the Sun, and Voyager 2 is at 110.8 AU.

The Time is Now.

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