A Great Day for Engineering

Todd BarberTodd Barber, Cassini Lead Propulsion Engineer (bio)

Hello again from the other side of Enceladus!  I’m happy to report that the engineering teams are very pleased this morning with this historic Enceladus flyby.  I attended a 9 am weekly meeting regarding engineering subsystem status, and all engineers reported a very nice flyby.  The team includes attitude control, command and data subsystem, power, propulsion, thermal, fault protection, and telecommunications engineers.  Our telecom guy brought in some nice pastries from his favorite European bakery to help celebrate another successful Cassini encounter.  Just before the meeting, I did manage to find five minutes to look at the latest Enceladus images from the flyby–they’re breathtaking!  Makes all of the hard work seem more than worthwhile.

We’d love to celebrate this engineering success, but as I mentioned in a prior blog, the show must go on.  We did open the main-engine cover successfully last night, which is vital for today’s main-engine maneuver.  Around 5:30 pm PDT, as seen on the third rock from the sun, Cassini will fire its main engine for about seventeen seconds.  So, as our science teams digest a treasure trove of new data, the engineering teams are looking forward to a thrilling Titan low-altitude flyby in a few weeks.  This friendly give-and-take between science and engineering isn’t always easy, but it’s truly wonderful how the teams support each other and pull off things that seem impossible.  I’m honored to be a part of this world-class team, and I thank you for your continued support of Cassini!


Visiting the Icy Outpost of Enceladus

Carolina Martinez

Carolina Martinez, JPL News Team

As we head into the close brush with the geysers of Enceladus, scientists, engineers and the public can come along on the ride as we count down to this amazing flyby, Cassini’s closest flyby yet of any of Saturn’s moons. On this blog we’ll post regular updates directly from the science and spacecraft teams.

Enceladus jumped to the top of scientists’ short list of places to look for life when the mission discovered giant geysers ejecting water-ice crystals and gas into space.  Few people know that Michele Dougherty of Imperial College London and principal investigator on the Magnetometer instrument was the one who pushed to have Cassini’s flyby altitude of 1,300 kilometers lowered to just 175 kilometers during the third Enceladus flyby on July 14, 2005.
This was after two flybys of Enceladus in February and March 2005.  Magnetometer data from those flybys showed strange things going on in the magnetic field lines.  Michele and others thought if they could just come close enough, they might be able to figure out what was happening.  She and others convinced the project to change the flyby altitude and lower it substantially. Not an easy task as these things are planned months in advance, but with a little luck and a lot of work everything fell into place and the team went closer.  Lo and behold, the little moon, the brightest in the solar system, was active, and geysers of water and vapor were erupting from mysterious hot spots at the moon’s south pole. 
You can see the original news release on the Magnetometer discovering an atmosphere around Enceladus at: https://www.nasa.gov/mission_pages/cassini/media/cassini-031605.html
For a timeline of Enceladus discoveries, and a  mission description with flyby details put together by Amanda Hendrix, Cassini scientist on the Ultraviolet Imaging Spectrograph (UVIS), see our media page:  

While you’re there, check out the preview video, Taking the Plunge. 
Oh and a real nice Enceladus interactive that lets you leapfrog from place to place all over the little moon is now online: http://saturn.jpl.nasa.gov/multimedia/flash/Enceladus/enceladus.html
Stay tuned for exciting events ahead. 

Trying to Be Patient

John SpencerJohn Spencer, Cassini Scientist on the Composite Infrared Spectrometer (bio)

Yeah!  We made it!  I wasn’t too worried about the plume passage, as I wrote yesterday, but it was still wonderful to hear last night that Cassini had contacted Earth and was sending home its precious cargo of Enceladus data.  Not only did we survive, which was never much in doubt, but the spacecraft was healthy and the data were looking good.  This morning, the beautiful images of Enceladus posted on the Cassini raw image Web site provided further confirmation that things had gone well.  And there was more welcome news from the folks at Goddard Spaceflight Center in Maryland, where our Composite Infrared Spectrometer (CIRS) instrument was built and is operated.  The CIRS data have been collected from the Deep Space Network, compiled at JPL, transferred to Goddard, and everything looks as expected.  The data are now going through the time-consuming calibration process, converting the raw bits into spectra that will reveal some of the secrets of the active south polar region.  We should be able to transfer the calibrated data to Boulder and start work on it in an hour or two–I can’t wait!

RSS Feeds and More

Carolina MartinezCarolina Martinez, JPL News Team

Thank you to all for the wonderful comments of encouragement on this new blog.  We hope we can live up to your expectations and it’s wonderful to read all the well-wishes.  For those who’d like to get updates via the RSS feed, click here to get updates directly to your computer.  You’ll find the RSS icon in the light gray panel near the top – near where it says Enceladus-flyby-Mar2008. The RSS feed is for all NASA blogs, not just this one.  Thanks for all the inputs as well, we’ll try to incorporate this feedback on future blogs.  When you submit a comment, please keep comments on the subject of this blog and please do not include links to other sites.

A preview of what’s to come . . . later today Todd will join us to tell us what the spacecraft and navigation teams are up to and we hope to post some Optical Navigation images today.  John and/or Amanda are writing up more details on plume hazards.  Meanwhile, Amanda’s at the Lunar and Planetary Society Conference and will be reporting briefly from there.  Speaking of the LPSC, there are lots of Cassini results being presented there; to get summaries on those abstracts check out this feature.

Raw (Unprocessed) Images In

Carolina MartinezCarolina Martinez, JPL News Team

To see all of the raw images go to this Web site and click on the “latest images” icon or select Enceladus as the target: http://saturn.jpl.nasa.gov/multimedia/images/raw/index.cfm

Below is a selection of different views.

Our blog team is still poring over their data but I’m sure they will check in soon. Todd will have a spacecraft checkout report and Amanda and John will fill us in on their reaction to seeing their data come in.  We will also have a post from Linda on all the questions they hope to answer from their treasure trove of goodies.


Enceladus – Then and Now

Linda SpilkerLinda Spilker, Cassini Deputy Project Scientist

As the hours tick down and Cassini gathers data during our closest flyby yet of Enceladus I am thinking about the two Voyager flybys of the Saturn system that took place over 25 years ago.  How in the world did we miss the Enceladus plumes back then???

In a nostalgic mood, I am looking over some of my old Voyager timelines today.  (Yes, I actually kept all of my old timelines from each Voyager flyby)!  I see that we took pictures of Enceladus during the first Voyager flyby in 1980, discovering a tiny, sparsely cratered world at the heart of the E ring. I remember wondering how such a tiny moon could create such a huge, tenuous ring.  That mystery was one of the puzzles left for Cassini to solve.  Remember that Cassini is in orbit around Saturn so we do multiple flybys, but the Voyagers only flew by Saturn, and each only had one encounter with Enceladus in their itinerary.

Enceladus< This view of Enceladus was taken by Voyager 2 in 1981.

My timelines show that we planned to take more pictures of Enceladus during the Voyager flyby in 1981.  Alas, the Voyager 2 scan platform containing the cameras and spectrometers stuck just as we flew close to Saturn, and the observation of our outbound pictures and spectra of Enceladus (and everything else!) were never made.  I remember feeling sad about how much unique data we wouldn’t get on that fateful day and the days that followed.  What discoveries remained for some other lucky scientists to make, I wondered?  Little did I know that I would be one of those lucky scientists! Good thing Cassini is there to keep an eye on Enceladus!

Flyby Complete – Scroll for 'Enceladus Data Back on Earth'

Carolina Martinez Carolina Martinez, JPL News Team

Here is a video clip of the Cassini mission control area with Grant Eller, mission control engineer at the helm, confirming with the Deep Space Station in Goldstone, California that data has begun transmitting from Cassini to Earth. Play clip 

Here is a clip of fellow blogger Todd Barber: Play clip

Follow this link to download high-resolution, broadcast-quality clips: https://www.nasa.gov/mission_pages/cassini/media/enceladus-clips-20080312.html

Be sure to look for Todd Barber’s post: “Enceladus Data Back on Earth!” Also, as some of you have probably noticed, some of the blog entries are out of order.  We apologize for this bug.  We are working on a solution, though, and appreciate the feedback. 
A lot of you have been posting really excellent questions, and the Cassini team has been really great about responding to them individually or responding to them through a blog entry…….but we haven’t had a chance yet to post all the answers to the blog.  I am working on pulling the questions and answers together and we plan to post that in the coming days, as time permits. 
That is it for today.  Check back tomorrow morning with new postings from our scientists and engineers.  Images are expected to hit the raw image site at around 5 a.m. PDT at: http://saturn.jpl.nasa.gov/multimedia/images/raw/index.cfm

Main Engine Cover Successfully Closed

Todd BarberTodd Barber, Cassini Lead Propulsion Engineer

Greetings again from Cassini engineering, as we are literally a day away from our date with destiny and a super-close Enceladus flyby. Another engineering event, critical for the health and safety of the spacecraft, has gone off without a hitch. Earlier this morning, around 4 am Pacific Daylight Time (PDT), we closed (or deployed, in our nomenclature) the main-engine cover. As we planned to head in closer to Saturn and Enceladus, we recognized the potential for a slight dust hazard, not uncommon during our multi-year orbital tour of the ringed planet. Even with minute dust grains, our delicate main-engine columbium coating could be damaged with hypervelocity impacts, so occasionally we have to deploy our “baby-carriage” cover to protect our twin main engines.

Our thermal control and devices team reports to me yet another successful deployment of the main-engine cover, an event that has taken place roughly three dozen times since launch over ten years ago. I can usually tell when this happens as a propulsion engineer because the closing of the cover helps to warm up the area around the engines, causing the temperature readings I monitor to increase. After the dust hazard is behind us, we’ll again open (or stow) the main-engine cover, although this will occur around 7 pm PDT on Wednesday. In other words, this event will occur after the thrilling E3 flyby, an important engineering event to be sure, but likely one that will be buried in the excitement of the prospect of new Enceladus science results mere hours away. 


John SpencerJohn Spencer, Cassini Scientist on the Composite Infrared Spectrometer (bio)

As I write this we are just minutes before closest approach.  The spacecraft is now completing the big turn to get its mass spectrometer and dust instruments facing forward, to best sample the plume as we fly through.  I have the simulator that we use for planning the observations open on my desktop, so I can ride along in my imagination as the flyby happens.  You can ride along too, using the cool CASSIE tool on the Cassini Web site http://saturn.jpl.nasa.gov/multimedia/CASSIE/ .  After closest approach, we’ll begin the temperature scans of the south pole.  Weeeeeee!

Cassies first screen

Optical Navigation Images

 Todd Barber, Cassini Lead Propulsion Engineer

Todd Barber Ok, folks, some readers have expressed additional interest in the Optical Navigation (op-nav) images of Enceladus we took on Sunday night.  They were posted within our raw image gallery , but I thought it would be a good idea to have them linked here.  If nothing else, these images remind us of the scientific thrills to come in a few short days!
Enceladus The Enceladus_no_zoom image (at left) shows the entire frame, with exposure times  optimized for Enceladus.  In this view, it is difficult to discern background stars. 

One can zoom in on this image of Enceladus, and that’s seen in the image Enceladus_zoom (the next image down).  These images, though intriguing and titillating, aren’t too useful for measuring the relative position of Enceladus.



< Enceladus_zoom

The next three images have a longer exposure time, in order to capture background stars.  Enceladus_stars_bg_noID may not win any photo contests, but all the important stuff is there — a brightly lit crescent Enceladus, background stars, and even some typically seen cosmic ray hits.  The stars seen in this image may seem very nondescript to you and me, but our op-nav experts know exactly which stars are which, thanks to excellent astrometry from orbiting telescopes like Hipparchos. 


< Enceladus-stars_bg_noID

The picture labeled Enceladus_stars_bg_withID identifies a few background stars seen in the prior image.
Enceladus < Enceladus-stars_bg_withID
Finally, Enceladus_stars_nobg_no/WithID just represents some quick-and-dirty image processing to remove the
artifact of horizontal banding seen in earlier images.
Enceladus < Enceladus_stars_nobg_no/WithID
The bottom line is our op-nav team helped nail Enceladus’ location within a few kilometers (or miles) with a
60-millisecond peek at Saturn’s orbiting ice ball. Not bad!