What's up in the solar system, August 2016 edition: Juno to get Jupiter close-ups, Rosetta descending, road-tripping rovers
Welcome to your solar system exploration update for the month of August, 2016! The thing I'm most excited about this month: we'll finally see JunoCam's first high-resolution images of Jupiter. We'll also see OSIRIS-REx making progress toward its September 8 launch. Both rovers are road-tripping at Mars, while ExoMars Trace Gas Orbiter has completed a major mid-course correction ahead of its October arrival. Rosetta is at the beginning of the end of its mission, saying farewell to Philae and shifting into lower orbits. New Horizons is getting very close to the end of transmitting all its Pluto data, plus a new pile of data on distant Kuiper belt objects. Read on for more detailed updates on these and all the other active missions exploring our solar system. But first, here's Olaf Frohn's chart of active space missions.
What's Up in the Solar System diagram by Olaf Frohn (updated for September 2018)
A diagram, updated once a month, of active space missions traveling beyond Earth orbit. Contains links to past diagrams.
Earth Launches and Landings (contributed by Jason Davis)
The SpaceX Dragon capsule that arrived at the International Space Station on July 20 will remain berthed to the orbital laboratory all month, departing on August 29. In mid-August, astronauts Jeff Williams and Kate Rubins will suit up for a spacewalk to install a new docking adapter currently stored in Dragon's unpressurized trunk. As early as August 22, Orbital ATK plans to send its re-engineered Antares rocket on a return-to-flight mission, blasting a Cygnus cargo craft on its way to the ISS.
As of July 19, Akatsuki has spent a year in orbit at Venus -- a Venus year in orbit, that is (243 Earth days). JAXA posted a brief update on the mission with a pile of photos from its different cameras. Some of the photos look like ones I've seen before, but this one -- taken with a camera that sees in a near-infrared wavelength of 2.26 microns -- is really unusual.
ISAS / JAXA
Venus' clouds in the near-infrared
Akatsuki took this photo of Venus' nightside with its 2-micron camera (at a wavelength of 2.26 microns) on April 26, 2016, from an altitude of 76,000 kilometers. The clouds are backlit by thermal emission from the lower atmosphere.
This month, new moon is on August 2 and full moon is on August 18. I don't have much news from Lunar Reconnaissance Orbiter, but it's actively surveying the Moon. It's always worth checking the LROC website for the latest images. A recent update on Chang'e 3 states that the Chinese lander has just gone to sleep for the lunar night, its 33rd. As usual, I'm not sure about the status of Chang'e 5 T1.
I got an update on the pair of ARTEMIS spacecraft from project scientist David Sibeck: "Although the ARTEMIS instruments were not designed to measure molecular ions, their observations have been used to infer the presence of heavy molecules (N2+, NO+, and O2+) from Earth at lunar distances....Simulation work shows that they drifted out of the Earth’s radiation belts and got entrained in the flow of solar wind plasma that had entered the Earth’s outermost magnetosphere, thence were swept antisunward to the Moon. Apparently they are a regular feature at, and can influence the lunar environment." I'll have a bit more about this in a future blog post. In the meantime, enjoy this artwork of ARTEMIS near the lunar wake.
NASA / GSFC / UCLA
Artist's impression of an ARTEMIS spacecraft near the lunar wake
This is the first appearance in a "What's Up" post of the OSIRIS-REx mission, due to launch on September 8. (It's still in "Earth's Neighborhood" and will be for a little while after its launch, after which I'll shift it to "Near-Earth Asteroids.") The spacecraft is in Florida and undergoing final assembly and testing; there are several crucial reviews taking place with much to make sure that the spacecraft is really ready to launch safely.
Summer 2016 was the last opportunity for Earth-based observers to obtain data on asteroid 162173 Ryugu before the arrival of Hayabusa2. This photo, taken by the FORS2 instrument on the 8.2-meter Antu telescope, was part of a series of observations designed to pin down its rotation period (either 3.8 or 7.6 hours) and pole orientation. More information
Mars passed through the northern autumnal equinox on July 4, so the north pole is entering winter darkness and the days are getting longer and warmer at the southern hemisphere landing sites of the two Mars rovers.
I don't have much news on Mars Odyssey or Mars Express. It's always worth looking at the THEMIS and VMC images. I don't have any updates on the Mars Orbiter Mission since June.
On the other side of Mars, it's sol 1415 for Curiosity and the rover has been driving steadily south since sol 1369. Curiosity has traveled more than 500 meters south of the last drill site, Oudam. More importantly, over that distance, Curiosity has traveled upward through the rock record by about 25 meters of elevation. That means it's time to drill again, to keep up a systematic survey of the mineralogy of the Murray formation as the rover travels up the stratigraphic section, so look for a new drill site in the next week or two. After that, it still has to drive another 500 meters or so to get beyond the first line of dunes, then another kilometer to cross an interdune region of bedrock, then another kilometer-plus of dune-threading before it will arrive at the next change in bedrock type. Throughout the driving, the views have been awesome:
NASA / JPL / James Sorenson
Murray Buttes, Curiosity sol 1414
Curiosity took this photo of some of the Murray Buttes to the south and west after a drive on sol 1414 (July 29, 2016).
This month, Rosetta will shift into a series of elliptical orbits that will bring it progressively closer to the comet, in preparation for the mission's end on September 30. As mentioned on this blog earlier, the spacecraft is shutting down nonessential systems because of declining solar power; one of those nonessential systems was the package that had been used to communicate with the silent Philae lander. Last month the Rosetta blog hosted an interesting article about the origin of comets, based on research performed with Rosetta data. The latest NavCam release covers images taken through June 28. As always, check here for the latest NavCam image releases and here for the OSIRIS image of the day.
As far as I know, Juno is doing fine; it will reach the apojove on July 31, beginning "orbit 1." It will spend almost all of August approaching Jupiter, speeding up all the way, until it executes its first close encounter with the planet with all its instruments firing at Perijove 1 on August 27. Once Juno returns the data to Earth, we should see the closest-ever images of Jupiter's clouds, and stunning pole-on views of the planet. I can't wait. JunoCam should have been shooting images continuously since July 9. After that, we're headed toward conjunction on September 26, a period when Juno will not be permitted to do much science or other activity. The science mission begins on November 9. Don't forget to visit the JunoCam website to discuss features visible in amateur astronomers' Jupiter images.
Cassini will reach apoapsis on July 30, beginning its Rev 239. There will be a targeted flyby of Titan on August 10, which will be used for gravity science, an opportunity to detect Titan's subsurface ocean. The 1600-kilometer flyby will raise Cassini's orbit inclination even more, to a very high 53.5 degrees. These high-inclination orbits are designed for studies of the rings; Cassini will be looking at "propellers" in the rings, and also observing several bright stars pass behind the rings. It will shoot a color portrait of the lit rings on August 6, and search for meteor impacts onto the C ring(!) on August 9. As always, check the raw images page for the latest views from Cassini's cameras.
I have a couple of updates on New Horizons. According to Kim Ennico they currently expect to complete the process of returning all the data from the Pluto encounter in late October or early November, but of course that depends on the schedule with the Deep Space Network and things could change. Meanwhile, they've had "a busy July" acquiring new data, according to John Spencer. He told me they've been "doing post-Pluto calibration observations of stars and so on during a brief 3-axis period, but also looking at KBOs Quaoar, 1994 JR1, Ixion, and 2002 MS4, plus Centaurs 2010 JJ124 and Chiron to get phase curves (though we don't expect to actually detect the Centaurs unless they have strongly forward-scattering rings, which is what the observations are designed to test)." The spacecraft has to be in 3-axis stabilization mode to be able to do these kinds of observations. The spacecraft has now returned to spin-stabilized mode, in which they can't point cameras but they can double their downlink rates. They'll remain spin-stabilized until January 2017, when they'll observe more Kuiper belt objects. For more on New Horizons, check out the latest team blog posts: one by Fran Bagenal on her 26 years of involvement in a Pluto mission; one by Anne Verbiscer on studying the opposition effect; and one by Cathy Olkin and Eddie Weigle on commanding spacecraft instruments.
Finally, the Voyagers are still going, going, going. Voyager 1 is at 135.7 AU from the Sun, and Voyager 2 is at 111.8 AU.