Animation of the Jupiter Europa Orbiter's Four Io Flybys

Yesterday, while finishing up work on the Exploration of Io article on Wikipedia and looking for a graphic for the Jupiter Europa Orbiter (JEO), I noticed that a SPICE trajectory file for JEO had been posted online. The Jupiter Europa Orbiter is NASA's portion of the Europa/Jupiter System Mission approved last year. I can use the SPICE kernel to display the position of the spacecraft at a given time in Celestia.  The trajectory file covers the Jupiter tour portion of the current mission baseline, though obviously a number of factors between now and the arrival of JEO at Jupiter will cause changes to this baseline, including changes in the launch date (assumed as February 2020 with an arrival at Jupiter in December 2025).  So, as of right now, these provide more of an example of the types of flybys JEO can perform at Io.

I've created a little video and uploaded it to Youtube with animations from Celestia simulating each of the four Io flybys in the current tour.  You can see some of the highlights from each encounter, though note that no science is planned for the first encounter (Io-0) as it takes place right before JEO's all-important, Jupiter Orbital Insertion burn.  For Io-1, on July 9, 2026, JEO passes almost directly over the Amirani plume, and depending on how high gases from the volcano reach, it could directly sample the composition of it.  JEO can also image the north polar region of Io from an oblique angle. However, Amirani's plume is ~75 km tall, while the altitude for Io-1 is 300 km.  For Io-2, on September 3, 2026, JEO should be able to image the Pele volcano and south polar region at high resolution. In the latter case, this is the section not covered by Voyager 1 at medium resolution.  The Zamama, Marduk, Prometheus, and Pele plumes will also be visible along the bright limb near C/A.  Finally, for Io-4, JEO will pass directly over Tohil Mons providing a chance to obtain laser altimetry over a mountain we have pretty good stereo coverage already, providing a useful comparison.

I wrote up a more detailed article on the potential science from each of these encounters last February.



I hope you all enjoy!  I should point out that this video was uploaded at 720p so you can view it in high-definition, and this definitely works better if you view it full screen.

Link: Animation of the Jupiter Europa Orbiter's Four Io Flybys [www.youtube.com]

Animation of Galileo's I24 Flyby of Io

Over the last few days we've been looking back at the Galileo's October 11, 1999 flyby of Io that occurred ten years ago this past Sunday.  We've looked at the planning that went into the science observations as well as some of the issues encountered during flyby.  Today, I wanted to present a video I created using Celestia and edited in Adobe Premiere Pro.  This combines a simulation of the flyby with some of the actual data that was returned during each observation.  And by ALL MEANS, full-screen this video!

The music used in this video is by _Ghost from ccMixter.com.  The two samples used, Ice and Chilli and Low (Ghostrust Reflection), are available under the Creative Commons NonCommercial Sampling Plus 1.0 license.



I had hoped to have this animation done yesterday, but what are you going to do? I hope you all enjoy!

Link: Galileo's I24 Flyby of Io [www.youtube.com]

July 22 Eclipse of Io by Ganymede

Later this morning, Io's trailing hemisphere will experience a total solar eclipse when Ganymede passes between Io and the Sun. The eclipse runs roughly from 13:34 to 13:39 UTC (14:08-14:14 UTC as seen from Earth). The video below was created in Celestia and shows the eclipse both from above Io, showing the shadow of Ganymede cross Io's surface, and from the surface of Io, showing Ganymede pass in front of the Sun.


Computer Animation of the total eclipse of the Sun by Jupiter's moon Ganymede over the trailing hemisphere of Io on July 22, 2009. First half shows a view from 4500 miles above Io's trailing hemisphere. Second half zooms in on the sun from an unnamed volcanic pit showing the total eclipse. The animation runs from 13:30 to 13:40 UTC on July 22, 2009.

EDIT 07/22/2009 10:06 AM: Fixed the title of the article, changing Jupiter to Ganymede. Obviously, a Jupiter eclipse is nothing special. A Ganymede one is.

Ganymede Eclipse on Io Wednesday Morning

Tomorrow brings Io's most interesting eclipse this mutual event season as most of Io's trailing hemisphere (51° West-231° West) is plunged into darkness by Jupiter's largest moon, Ganymede. This is the culmination of a series of weekly eclipses by Ganymede on Io. With each weekly eclipse, the center of Ganymede's shadow appears further south on Io. Tomorrow, the center of Ganymede's shadow passes just north of Io's equator. The eclipse takes place tomorrow morning, July 15, between 10:45 and 10:50 UTC (3:45-4:50 MST) on Io. If you have a good telescope and want to try to observe this event, from Earth the penumbral shadow of Ganymede will reach Io at 11:19 UTC, totality will run from 11:21 to 11:25:28 UTC, and end of the eclipse comes at 11:27 UTC. The peak of the eclipse, as observed from Earth, comes at 11:23:14 UTC. The timing of this eclipse should make it a good observation target for observers in the western United States, western South America (like the European Southern Observatory), and Hawaii.

During the eclipse, Ganymede will appear 13' 17.2'' across in Io's sky (compared to our moon, which appears around 30' across in Earth's sky). The sun will appear 6' 19.9". Therefore, it is unlikely that the sun's corona would be seen during the eclipse except near the beginning and end. At its peak near Tol Ava Patera, the eclipse will last 1 minute and 55 seconds long.

For this eclipse, I've created a little fancier video using Celestia and Adobe Premiere. I think I am starting to get along with that latter software package...


Computer Animation of the total eclipse of the Sun by Jupiter's moon Ganymede over the trailing hemisphere of Io on July 15, 2009. First half shows a view from 4500 miles above Io's trailing hemisphere. Second half zooms in on the sun from east of Ra Patera showing the total eclipse. The animation runs from 10:40 to 10:55 UTC on July 15, 2009.

I have also created a nice map showing the area on Io that will experience this eclipse. You can download a full-res version here.

My post last year on this mutual event season should help provide some information on the science of these types of eclipse as well as occultations.

Notes from the Io Underground

Grrr... I hate when Mondays sneak up on you...

• The 111th Edition of the Carnival of Space is now online over at 21st Century Waves.
• Over the last few weeks, I have been presenting some of the mutual events in the Jupiter system, particularly solar eclipses on Io by either Ganymede or Callisto from the perspective of Io. However, a pair of amateur astronomers, John Sussenbach and Marc Delcroix, captured numerous observations of the solar eclipse on Io by Ganymede on June 24. Delcroix even plotted the brightness of Io versus time as the eclipse progressed. John Sussenbach also took a look at one of the the solar eclipses by Callisto on June 20.
• Plenty of important meetings related to the exploration of Io and the Jupiter system will be taking place this week. This includes a Europa/Jupiter System Mission Joint Science Definition Team (EJSM JSDT) meeting today, an Outer Planets Assessment Group (OPAG) meeting tomorrow, and the EJSM Instrument Workshop on Wednesday through Friday. I might be listening into the EJSM Instrument Workshop for at least some of the talks, but I haven't decided yet.
• Today's Astronomy Picture of the Day showing the volcano Arak Krakatoa erupting at night is pretty awesome. Definitely worth checking out.
• Van Kane has been keeping up with last week's Planetary Science Subcommittee and Decadal Survey Meetings. One of the key issues that seems to be coming to a head is the flat planetary science budget projected in the out years in the current budget proposal. This would cause increasing budget pressure on many projects, not only because of the lack of budget increases (resulting from the poor government revenues) and from cost overruns on some projects, including the albatross of planetary science, the Curiosity rover (née Mars Science Laboratory). According to Kane, Ed Weiler at the PSS meeting stated that there is not enough money in the Planetary Science Division budget projections to fund the Europa/Jupiter System Mission. As Kane stated in his blog, this is definitely bad news.
• Celestia version 1.6 was officially released late last week. Celestia is definitely one of the space simulator, particularly thanks to its support for NAIF Spice kernel files for spacecraft and planetary body trajectories and orientations. The software also has built-in video and screenshot support, which I often take full advantage of for this blog.
  

30th Anniversary of the Voyager 2 Flyby of Jupiter

Thirty years ago today, on July 9, 1979, the Voyager 2 spacecraft encountered Jupiter from a distance of 650,000 kilometers about its cloudtops, marking the second Voyager project flyby of the planet. The encounter provided an opportunity to see the anti-Jupiter hemispheres of Ganymede and Callisto, to monitor changes on Jupiter and Io since the Voyager 1 encounter four months earlier, and to observe Europa up close for the first time.

Back in March, we took an extensive look at the Voyager 1 encounter with Jupiter and Io. The Voyager 1 flyby provided a revolution in our understanding of the giant planet and turned the four Galilean satellites from mere points of light we were only beginning to understand into four separate worlds, each with their own unique geologies. In particular, during the Voyager 1 encounter, active volcanism was observed on Io as well as a narrow ring around Jupiter.

For Io, the second Voyager encounter did not provide the same revolution in our understanding of that world; the clear star of the July 9 encounter was the cracked world of Europa. While Voyager 1 flew within 20,000 kilometers of Io on March 5, 1979, Voyager 2's trajectory kept the spacecraft outside Europa's orbit and, with Io on the other side of Jupiter during closest approach, Voyager 2 never came close than 1,128,000 kilometers of Io. However, the discovery of active volcanism on Io by Voyager 1 necessitated a change in the schedule of observations for the second encounter, including a 8-hour long sequence of images of a narrowing crescent Io as Voyager 2 receded from Jupiter. This prolonged observation sequence allows Voyager 2 to monitor volcanic plumes along Io's limb, including those at Amirani, Maui, and Loki. From observations such as these, Voyager 2 found that most of the plumes first observed by Voyager 1 were still active during the July 1979 encounter. Only Pele appeared to have shut down, though later observations by Hubble, Galileo, and other spacecraft seem to suggest that the Pele plume is intermittently active. Volund was not observed near the limb of Io during the Voyager 2 encounter, so it could not be determined if that plume was still active.

Earlier, Voyager 2 had observed Io while it was more illuminated by the Sun, like the image at left. The goal of these observation was to search for surface changes on Io as the result of volcanic activity between the two Voyager encounters. Among the changes observed were two new plume deposits surrounding Surt (probably active during a short, intense eruption in June 1979, but Surt was not viewed near the limb by Voyager 2 to see if it was still active) and Aten Patera. The presence of these changes from large plumes but without the observation of the plumes associated with them have led to the conclusion that large, Pele-type plumes tend to be short-lived compared to more persistent, smaller dust plumes like at Prometheus. Additional surface changes included a larger dark area within Loki Patera, the result of overturning of more surface area of the lava lake that covers much of Loki, and a change in the shape of the Pele plume deposit, from a heart shape to an oval. Subtle changes in the shape and intensity of the Pele plume deposit were also observed by Galileo in the late 1990s and early 2000s.

Of course, Io wasn't the only world Voyager 2 observed during its encounter 30 years ago. The star of the show was Europa. Europa was poorly observed during the previous Voyager encounter so this one really provided a great leap in our understanding of this icy world. Like Ganymede, Europa's surface was dominated by tectonic structures, ridges and dark, linear bands that criss-cross the surface. Unlike Ganymede, Europa's surface was found to be quite young with very few impact craters, though enough to show that the satellite's surface was much older than Io's. Spectral measurements suggesting a water ice surface, mass estimates between that of Io and Ganymede, and youth surface age soon led to the suggest that just beneath Europa's ice shell lay a liquid water ocean that today is a main focal point for exploration in the Jupiter system.

Voyager 2 never got the same amount of attention that the earlier Voyager 1 encounter did. During the same week, Skylab was slowly approaching its destruction over Australia, dampening press interest in the encounter, along with the perception that this encounter was covering similar territory as the previous one. But Voyager 2 provided an opportunity to follow up on the discoveries made by Voyager 1 by allowing for an adjustment to the observation plan, such as to monitoring Io's volcanic plumes and Jupiter's narrow ring system as Voyager 2 receded from the giant planet. Voyager 2 also allowed imaging scientists to fill out the global map of Ganymede and Callisto by observing their anti-Jovian hemisphere and providing the first close-up look of Europa. The Voyager 2 encounter unfortunately also began a 17-year gap in close-up spacecraft imaging of the Jupiter system. But Voyager 2 went on to bigger and better things, including doing followup observations of the Saturn system in August 1981 as well as our only encounters of Uranus and Neptune in 1986 and 1989, respectively.

For this post, I have posted some movies on Youtube created in Celestia showing the geometry of this encounter:

• Voyager 2 Trajectory through the Jupiter System
• Animation of Io as seen from Voyager 2 in July 1979
• Animation of Io as seen from Voyager 2 in July 1979 - Short Version
  

Over at UMSF, Paul Schenk, a planetary scientist at the Lunar and Planetary Institute in Houston, Texas, shared some of his memories of the Voyager 2 encounter.

Today's Eclipse of Io by Ganymede

Sorry I haven't covered the last two eclipses (June 24 and July 1), but taking a look at today's eclipse of Io by Ganymede we see as Ganymede's shadow is now reaching further south across Io's trailing hemisphere. The eclipse will take place in about 25 minutes from the time I am typing this, but you can still see an animation of it in the Youtube video I uploaded and embedded below:


Computer Animation of the total eclipse of the Sun by Jupiter's moon Ganymede over the trailing hemisphere of Io on July 8, 2009. First half shows a view from 7,317 km above Io's northern trailing hemisphere. Second half zooms in on the sun from the floor of Loki Patera showing the total eclipse. The animation runs from 07:30 to 08:20 UTC on July 8, 2009.

Today's Eclipses of Io by Callisto

Here are two videos showing today's total eclipses of the Sun by Callisto on Io's south polar region:


Computer Animation of the first of two total eclipses of the Sun by Jupiter's moon Callisto over the south polar region of Io on June 20, 2009. First half shows a view from 7,317 km above Io's southern trailing hemisphere. Second half zooms in on the sun from near Kurdalagon Patera showing the total eclipse. The animation runs from 04:10 to 04:56 UTC on June 20, 2009.


Computer Animation of the second of two total eclipses of the Sun by Jupiter's moon Callisto over the south polar region of Io on June 20, 2009. First half shows a view from 7,317 km above Io's southern trailing hemisphere. Second half zooms in on the sun from near Svarog Patera showing the total eclipse. The animation runs from 08:40 to 09:20 UTC on June 20, 2009.

An earlier partial eclipse occurred on June 19 over Io's southern leading hemisphere as well.

Eclipses of Io by Ganymede on June 16

Tomorrow (June 16), Io will experience three solar eclipses by its larger neighbor, Ganymede. Like those that took place last week, these eclipses are mostly visible over the north polar region of Io, though totality could be observed much further south than those last week (I say could because, obviously, no one is there to experience them). Luckily, thanks to software like Celestia, we don't have to let a little thing like a few hundred million kilometers stop us. Below is a video of an eclipse over the northern part of Io's anti-Jovian hemisphere that will take place in about three hours (1:08 am MST). Yes, like the nerd I am, I will watch it live on Celestia...

And completely off topic for a second, I know I have a few Iranian readers. All I want to say is good luck and stay safe! The world is pulling for ya!



In addition to this eclipse, there was an eclipse a few hours ago (5:52 pm MST) over the northern leading hemisphere and there will be one later on June 16 (3:39 pm MST) over the northern trailing hemisphere.

Another Total Eclipse by Ganymede Tomorrow

I completely forgot in my last post that there are TWO total solar eclipse by Ganymede tomorrow, in addition to the one around 08:50 UTC. The second, to occur around 18:50 UTC, will also cover the north polar region a little further to the west than the earlier eclipse, over the trailing hemisphere side of the north pole. Below is an animation of that eclipse:


Computer Animation of a second total eclipse of the Sun by Jupiter's moon Ganymede over the north polar region of Io on June 9, 2009. First half shows a view from 7,317 km above Io's northern trailing hemisphere. Second half zooms in on the sun from near the north pole showing the total eclipse. The animation runs from 18:30 to 19:15 UTC on June 9, 2009. This eclipse occurs nine hours after another total eclipse by Ganymede over a region to the east.