What's up in the solar system, May 2016 edition: Good news in cruise for Juno and ExoMars Trace Gas Orbiter
May 2016 will be yet another month of fairly routine operations across the solar system -- if you can ever use the word "routine" to describe autonomous robots exploring other planets. I count 19 spacecraft carrying out 17 active science missions: Akatsuki, Lunar Reconnaissance Orbiter, Chang'e 3, possibly Chang'e 5 T1, ARTEMIS, Odyssey, Opportunity, Mars Express, Mars Reconnaissance Orbiter, Curiosity, Mars Orbiter Mission, MAVEN, Dawn, Rosetta, Cassini, New Horizons, and the Voyagers. Meanhile, Hayabusa2, ExoMars Trace Gas Orbiter, and Juno are cruising toward their destinations. ExoMars' cruise to Mars has started smoothly, and Juno is only two months away from Jupiter orbit insertion, this summer's most anticipated event. Closer to home, many of us stuck on Earth will have an opportunity to witness a rare transit of Mercury across the Sun on May 9. And sometime soon, the world should receive the first public release of data from the Pluto encounter phase of the New Horizons mission.
Before I get into further detail, here's Olaf Frohn's summary diagram:
What's Up in the Solar System diagram by Olaf Frohn (updated for December 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)
May marks the last full month in space for Tim Kopra, Tim Peake and Yuri Malenchenko, three Expedition 47 crew members who launched to the International Space Station back in December. The trio recently received a two-week mission extension to June 18. Also currently aboard the station is NASA astronaut Jeff Williams, as well as cosmonauts Oleg Skriprochka and Alexey Ovchinin. The crew has started packing return cargo into SpaceX's CRS-8 Dragon, which arrived April 10. Dragon departs on May 11 and will splash down in the Pacific Ocean. Also potentially leaving this month is Orbital ATK's OA-6 Cygnus cargo craft, which arrived March 26. After Cygnus is released, an experiment called Saffire-1 will ignite a controlled fire aboard the spacecraft before it reenters Earth's atmosphere. Either later this month or in early June, flight controllers may inflate BEAM, the expandable habitat that was attached to the station's Tranquility module last month.
At least three international launches are planned in May, according to schedules posted at Spaceflight Now and RussianSpaceWeb. A Soyuz rocket launches a Russian navigation satellite from the Plesetsk Cosmodrome on May 21. Three days later, another Soyuz blasts a pair of European navigation satellites into orbit from French Guiana. Finally, on May 28, a Proton rocket carries a commercial communications craft into space from Baikonur.
Inner Solar System
Akatsuki is finally in its science orbit, doing science! I'm planning a more detailed update on what Akatsuki is doing; in the meantime, here's a lovely photo of nightside clouds taken with an infrared camera. From its long orbit Akatsuki should be able to get lots of photos like this, watching cloud dynamics.
Venus' glowing nightside from Akatsuki
Akatsuki took this photo of cloud patterns on the nightside of Venus on March 25, 2016 from a distance of about 100,000 kilometers. The IR2 camera sees at a wavelength of 2.26 microns, a wavelength at which Venus' hot lower atmosphere radiates. This infrared light is blocked by clouds in some places but not others, yielding an image of the clouds in silhouette. When combined with data from other wavelengths and more images taken over time, Akatsuki scientists will be able to watch the three-dimensional motion of Venus' atmosphere.
Lunar Reconnaissance Orbiter is still actively exploring the Moon. Last month they issued a press release about new work based on Lunar Reconnaissance Orbiter data on lunar swirls, odd features thought to be related to magnetized lunar crust that interacts with the solar wind. What I thought was most interesting about the release is that the lead authors on the two newest papers -- Brett Denevi and Amanda Hendrix -- are women who I think of as working on other worlds (Brett on Mercury, and Amanda on Saturn's icy moons). It's pretty neat, in planetary science, how experience with working on certain kinds of physics or observation techniques on one world can take you to totally different parts of the solar system.
I just realized that I've been neglecting to include Mars Orbiter Mission in these updates. Unfortunately, I don't have any information on its recent status. A news release from the mission yesterday concerned a paper that was released in March, and the official Twitter and Facebook pages have been quiet since December. I hope someday to see public release of archival data from its color camera!
In the first half of April, Opportunity's science and engineering teams conducted a "mini walkabout" of Marathon valley, looking for sites for in-situ investigation. It's now investigating the first of those sites, "Pierre Pinaut," but has been slowed down a bit by a couple of anomalies with the Microscopic Imager. Things seem to be okay, though, and the power situation is very good, with more than 600 watt-hours being generated all month. The latest atmospheric opacity number is heading upward, though, which I hope is not a warning of dustier skies in May. Check out these and other updates at the Opportunity website.
Rosetta's science is getting better all the time as it continues to watch comet Churyumov-Gerasimenko change. Last month, the mission released some maps showing how the color of the comet changed between August and November of 2014. No previous mission has orbited a comet, and no previous comet has been seen by a spacecraft more than twice, so Rosetta's long-term survey is going to be scientifically revolutionary. Meanwhile, the formal release of Navcam images has slowly but steadily been catching up with the present, and the latest Navcam image releases were taken only 6 weeks ago. That's pretty extraordinary. The Rosetta mission will come to an end in only 5 months, at the end of September.
Dawn is now orbiting Ceres at the lowest altitude it'll ever achieve: an average 385 kilometers. Last month, principal investigator Chris Russell told reporter Govert Schilling that the mission was considering targets beyond Ceres for an extended mission, surprising many (by which I mean to say, this was a huge surprise to me). The latest Dawn Journal reports that Dawn's remaining two reaction wheels continue to work fine and that the mission has done a good job husbanding hydrazine, but the remaining fuel is still expected to last only partway through 2017 even if the reaction wheels stay 100% healthy. Check the Photojournal for the latest images! Here's a lovely photo mosaic of Haulani crater:
NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / PSI
Haulani Crater at LAMO
This image is a mosaic of views that NASA's Dawn spacecraft took in its low-altitude mapping orbit (LAMO), at a distance of 385 kilometers from the surface of Ceres. In the center is Haulani Crater, which has a diameter of 34 kilometers.
Juno is now just 63 days and about 38 million kilometers from Jupiter. Amateur astronomers continue to pour images into the JunoCam image database to help the team plan future imaging. Jupiter was at opposition in March, so the quality of amateur astronomer images peaked then; images are still excellent now, but as we approach summer, the quality of Earth-based Jupiter images will be declining precipitously. Junocam is not a very high-resolution camera, but after orbit insertion for a couple of months, its images will be better than the ones we can get from Earth.
Cassini is just about at periapsis of Rev 235, headed for its 120th flyby of Titan. This flyby is devoted to a radio occultation experiment, where Cassini will watch radio signals from Earth pass through Titan's atmosphere. Closest approach happens at a close altitude of 971 kilometers. (Cassini does closer flybys of other icy moons, but Titan's atmosphere keeps Cassini at arm's length.) The flyby will also boost the inclination of Cassini's orbit from 27.8 to 35.3 degrees. The Cassini mission website has just been redesigned, and the new version of the raw images page has better filtering than it did previously.
New Horizons has downlinked quite a lot of good LORRI data from the "core" phase of the encounter in the last month, including several new views of Hydra and Nix, while also filling in much more of the Pluto and Charon approach sequence. Visit my LORRI data summary page and look for the yellow-highlighted images to see all the new stuff. This one is one of the last that New Horizons took showing Pluto and Charon in the same LORRI frame, a high-resolution view of the face of Pluto we didn't see up close during the flyby. Meanwhile, I'm eagerly awaiting the first release of data from New Horizons to the Planetary Data System; my understanding was that they were supposed to release data returned to Earth as of July 31, 2015 in April, but I haven't seen the data release yet. The data should show up at the Small Bodies Node of the PDS and possibly also at the Ring-Moon Systems Node. There have been two nice blogs on geologic mapping of Pluto published in the last month, one by Oliver White and one by Ross Beyer. Check their science images gallery for the latest interpretation of New Horizons images!
Finally, the Voyagers are still going, going, going. Voyager 1 is at 134.9 AU from the Sun, and Voyager 2 is at 111.1 AU.