There's one new mission and two promoted ones in this month's roundup: I've added JAXA's Akatsuki Venus Climate Orbiter for the first time, and both Hayabusa and Rosetta have been promoted from the "quietly cruising" section. Akatsuki is scheduled to launch May 17, Hayabusa's approaching its Earth sample return on June 13, and Rosetta is approaching its asteroid Lutetia flyby on July 10. The other main event to look forward to is a close flyby of Enceladus on May 18 that should result in more spectacular images of the moon. On to the details:
In the inner solar system:
The MESSENGER spacecraft is cruising along, with less than a year remaining until Mercury orbit insertion (which is planned for March 18, 2011). In preparation for the orbital mission, the mission is running through numerous simulations of typical -- and not-so-typical -- scenarios for operating the spacecraft. Venus Express has successfully concluded its atmospheric drag experiments, in which the spacecraft's reaction wheels were used as sort of sensors for the density of the atmosphere. The solar panels were titled in various ways to the direction of Venus Express' motion, sometimes making the spacecraft into a big windmill, sometimes into a big paddlewheel, and the amount of torque that was required to maintain the spacecraft's orientation was carefully recorded. Venus Express is not the first do to these sorts of experiments at Venus; the first experiments were done by Magellan, and helped establish the possibility of using aerobraking to modify a spacecraft orbit. But the Venus Express experiments are different because, at the time of the aerodrag experiments, Magellan was a sick old spacecraft with no data recording capability; Venus Express is, if not young, at least in very healthy middle age, and does not need to maintain Earth pointing to relay data as it performs its experiments. This is actually the fourth aerodrag campaign Venus Express has performed; there will be two more, in October of this year and later next year. According to Venus Express's Don Merritt, "We're trying to work out the techniques while also seeing how the results compare to models of the atmosphere. What we are not trying to do is change the orbit. If our extension is approved for operations in 2013 and 2014, we'll use what was learned in the drag campaign to then use a much higher level of drag (drop lower into the atmosphere) to significantly change the orbit. Slowing down via aerodrag at pericenter will allow us to significantly reduce the apocenter to a yet undetermined level." JAXA's Akatsuki and IKAROS are scheduled to launch on May 17. Akatsuki will have a quick cruise to Venus, arriving in December for a 2-year orbital mission focused primarily on Venus' atmosphere. It will have an equatorial orbit, in contrast to Venus Express' polar orbit.
Lunar Reconnaissance Orbiter is busily mapping the Moon from its science orbit. There have been some very cool image releases from the LROC team lately. I particularly liked the Craters on the Schrodinger pyroclastic cone one, and also the cool craters in "Each crater tells a story." There are lots more captioned LROC images available, and the laser altimeter team is releasing a new image every week. JAXA's Hayabusa is rapidly approaching Earth for its June 13 sample return. Last month, Japan and Australia formally reached an agreement that will allow JAXA to land the sample return capsule in the Woomera Prohibited Area in south-central Australia. They announced yesterday that the spacecraft was given a "go" signal for Trajectory Correction Maneuver 1 at 19:00 JST (10:00 UTC), which is a few days ahead of the schedule According to that (now outdated) schedule, there should be one more maneuver this month, around May 29. At the end of this month the spacecraft will still be aimed at a point off of Earth's disk. As of today, Hayabusa is 18,100,000 kilometers from Earth, approaching us from the constellation of Cancer.
On to Mars:
Out at Mars, it's the end of the southern hemisphere autumn (Ls 85°), and the winter solstice will come on May 13. Today it is Mars Exploration Rover Spirit sol 2248 and Opportunity sol 2227. Last month, of course, Spirit went silent; that happened on sol 2210 (March 22). The orbiters continue to listen for signals from Spirit during scheduled passes, and the Deep Space Network also listens every day. But I'll likely have no Spirit news in these monthly updates for a while. Which is a bit sad, considering that if Spirit's still alive, she'll pass Viking Lander 1's Mars surface operations longevity record this month. As of the latest JPL update (dated April 21), Opportunity's solar panels were only putting out 247 Watt-hours, so doesn't have enough energy for daily driving; she's still managing a respectable couple hundred meters a week though. She is still driving south, but should be turning eastward toward Endeavour crater before long.Here is Eduardo Tesheiner's latest route map and Google Earth kml file for Opportunity. As I predicted last month, ESA's Mars Express mission has been very quiet following the fun of the Phobos flybys, but we know the spacecraft is still doing great because nearly every day, new images from the Mars Webcam show up. The current view is of a lovely half-phase Mars; I need to update my 64 views of Mars poster! There are two more seasons worth of Phobos encounters coming, with the closest encounters taking place on August 24, 2010 and January 9, 2011. Mars Reconnaissance Orbiter is humming along in normal science operations. The latest MARCI weather report mentions lots of local dust storm activity but clear skies for both solar-powered rovers. The latest captioned image releases from HiRISE include this really cool 3D anaglyph of collapse pits on a volcano named Arsia Mons, and this glorious view of layered rocks in Noctis Labyrinthus. NASA's Mars Odyssey remains the longest-lived spacecraft in orbit at Mars. You can see the latest from its THEMIS instrument here. I like this one showing a part of Candor Chasma, where landslides, tectonics, wind, and water all played equally important roles in shaping the landscape.
In the Asteroid Belt:
I've promoted ESA's Rosetta mission into the "active" crowd this month, as it is rapidly approaching its July 10 encounter with the asteroid 21 Lutetia. According to the most recent status report, the spacecraft is healthy, and will begin the navigation campaign for the flyby at the end of this month. They don't explain that in the status report but I assume that it means Rosetta will be starting its optical navigation of the asteroid, looking for its pinpoint of light against the background of stars, which the mission will use to update their understanding of the asteroid's position in its orbit. The Lutetia flyby is Rosetta's last planned scientific event before its May 2014 rendezvous with comet Churyumov-Gerasimenko.
NASA's Cassini was busy last month with close flybys of Titan, Dione, and one especially close flyby of Enceladus yesterday. That flyby was given over to radio science; there were no close images planned. But there will be images aplenty on May 18, when Cassini flies past Enceladus again, at an altitude of 201 kilometers. That's followed in short order by the 69th targeted flyby of Titan. That flyby will kick Cassini back up and out of the ring plane, ending the recent fun of icy moon flybys and mutual event images. It will also shorten Cassini's orbit to a 16-day period, which means it'll encounter Titan once per orbit again. The month begins on Cassini's rev 130 and ends at the beginning of rev 132.
The International Cometary Explorer remains on course for a return visit to Earth in 2014. When it does, ICE can be returned to a Sun-Earth L1 halo orbit, or can use multiple Earth swingbys to encounter Comet Wirtanen during its near-Earth apparition in December 2018. NASA's Dawn is now in the asteroid belt for good, and is steadily thrusting with its ion engines, patiently propelling itself toward a rendezvous with Vesta in July 2011. NASA's Deep Impact is cruising toward its November 4 flyby of comet 103P/Hartley 2. The latest status report, from March 3, doesn't say that there's anything out of the ordinary; they're preparing for the encounter. All systems on NASA's Stardust are "nominal" as less than a year remains until its flyby of comet Tempel 1. Closest approach will happen at 8:42 p.m. PST on February 14, 2011, or 04:42 February 15 UTC. They're currently working through a set of spacecraft tests in preparation for the encounter, including checks of both "sides" of the spacecraft electronics. Like most spacecraft, Stardust has redundant electronics, two complete sets that can be swapped should problems arise in a critical component. NASA's New Horizons has 15.37 AU to go to reach Pluto. It's still on course for a January to July 2015 encounter with the Pluto and Charon system. The spacecraft will wake up from a long hibernation this month, and be awake through June and into July. The wakeup period is "jam-packed" with activities, according to the mission's Twitter feed.
Finally, NASA's Voyager 1 and 2 spacecraft were still responding to commands from Earth as of March 10. Both have now crossed the "termination shock," where the solar wind slows down as it impinges upon the interstellar medium. Some other milestones to take note of this month, taken mostly from JPL's Space Calendar:
May 11-12: There is a conference on Nix and Hydra, Pluto's moons, on the fifth anniversary of their discovery (the anniversary is on May 15).