Carolyn Porco

Cassini Imaging Team Leader

As you can imagine, we Cassini imaging scientists have been bee-busy trying to understand what our recent images from this week's Enceladus flyby are telling us about the nature of the moon's south polar surface and sub-surface environments.

I can now report that, so far, we have successfully located the surface sources of the jets for which Enceladus has become renowned.

There is still much more to do to see if we can glean any information at all about the eruptive process itself from the geological characteristics we see on the surface.  But this, you have to admit, is a very good start!

Click here for our latest release.

Image left: Surface sources of some jets on Enceladus. Full image and caption

And click here for a similar image.

John Spencer

Cassini Scientist on the Composite Infrared Spectrometer (bio)

Click here to browse Cassini raw images site for Enceladus images

All sorts of emotions over the last couple of days.  Yesterday morning began with the great (but not surprising) news that our trusty spacecraft had successfully negotiated its latest and deepest- yet passage through the Enceladus plume, successfully executed its observations, and was starting to ship its cargo of data home.  There wouldn't be any calibrated data to look at for hours, so I focused for a while on something much more down-to-Earth: my wife Jane and I put in an hour harvesting produce at a local vegetable garden.   Searching through the luxuriant, dripping-wet foliage for green beans and tomatoes, Jane remarked, "Isn't it amazing what can happen on a planet that has water on it"?  That of course, is part of the reason why we're so excited to be exploring Enceladus--the geysers breaking through that intensely cold surface harbor heat, lots of it, maybe enough to melt the ice below the surface and, just maybe, enough to give Enceladus its own chance for life.  Maybe our new Composite Infrared Spectrometer (CIRS) observations of Enceladus' internal heat, now on their way home, could give us new clues about whether liquid water really does lurk beneath the surface.

Image left: This image shows our initial discovery, back in 2005,  that the south polar tiger stripe fractures were warm. Larger view

The rest of the day was an exercise in patience as we waited for the CIRS data to be calibrated at CIRS's home at NASA's Goddard Spaceflight Center in Greenbelt, Md., a complicated and time-consuming process.  By late afternoon, right before I had to leave for the evening, we got a nibble--a short sequence of data from the few minutes right after closest approach.  The processed data ended, tantalizingly, just before our planned stare at the active fracture Damascus Sulcus, which we hoped, if targeting was perfect, would give us perhaps our best-yet determination of the temperatures of the tiger stripe fractures.  But something bothered me--CIRS was operating in a mode that I didn't expect.  Had something gone wrong with the instrument commanding?  It was too late in the day to check with the folks in Maryland.  That worry preyed on my mind all evening, so this morning I pounced on the data as soon as I could, to run some more checks.  To my great relief, everything was fine--I had forgotten that we had planned to use that unfamiliar instrument mode for this unusual close-up observation.  Still, the rest of our data were still not calibrated, and I had to wait a bit longer.

In the meantime, there were the close-up ISS camera images to look at.  Like the other bloggers here, I was blown away by both the quality of the images, which were taken under very difficult 
circumstances, and by the bizarre landscape that they revealed.  Utterly stunning.  Hats off to the imaging team, particularly (as Bonnie and Carolyn also mentioned) to Paul Helfenstein, who sweated for months on the details of planning that sequence.

Then, finally, it was our turn--the Goddard team completed the CIRS calibration this morning, and I downloaded the data.  More nervousness, until the plots started coming up on the screen and showed a beautiful spike in the signal strength, right when we expected to be staring at Damascus.  It was obvious that we were pointing right at the warm fracture, just as planned.  We nailed it!  Not that CIRS gets credit for this bit of precision targeting--the camera team was driving and we were along for the ride.  Credit goes once more to Paul Helfenstein and rest of the ISS team, and also the navigation team who put the spacecraft exactly where it was supposed to be.  Now we have to delve deeper to find out what that beautiful observation of Damascus is telling us.

Bonnie J. Buratti  (bio)

Cassini Scientist on the Visual and Infrared Mapping Spectrometer 

Amanda Hendrix (bio)

Cassini scientist on the Ultraviolet Imaging Spectrograph

Well as luck would have it, much of my day yesterday was spent on an airplane flying to Baltimore for a non-Cassini-related meeting Wednesday and Thursday. I knew the data would be coming in while I was in the air and was excited to check it all out once I landed.  For most flybys, I am in front of my computer, watching the data come in real-time.  So I'm on the flight, and I'm working on some UVIS (Ultraviolet Imaging Spectrograph) Enceladus data from a past flyby that I think will be interesting to compare with the data from Monday's flyby, and I'm gearing up for the new UVIS data, listening to my iPod (Sigur Ros, which is always nice n' mellow for a flight) and I hear my name being shouted (above the music) and I look up and it's Bob Pappalardo, who is sitting one row up across the aisle. He's the Cassini Project Scientist for the Extended Mission and has been a colleague and good friend of mine for several years. I take out my ear buds and Bob is shouting at me that, just prior to taking off, he received an email from Carolyn Porco (Imaging Team Lead and fellow blogger) that she'd seen the first of the closest-approach images and her reaction was (an informal version of) “Golly!” That got me all excited and I took my laptop over to his row of seats and we checked out the playback table again to review which images were hitting the ground when. I told Bob, "The second we land you must fire up your remote internet access thing so we can get at those images!!"

Image left: Here's an example of a raw image from Enceladus. Click here for the full image

Went back to my seat, experiencing the first waves of absolute thrill that I always get during these flybys, and happiness because I am so lucky to do this for a living! What fun.  I switched to something more upbeat than Sigur Ros ... I'm thinking old school Oingo Boingo or maybe some MGMT. I'm excited to see these data!

And now it’s Wednesday morning and we’ve all seen the fabulous images. All the excitement was well-founded. Golly, indeed! I’m having fun digging through the UVIS data and we’ll see what they reveal about the south polar region. What an interesting, fascinating little world. What a surprising bit of insight into solar system processes! Thanks to Paul Helfenstein and the Imaging Team for their hard work on the closest-approach “skeet shoot” and mosaic, and to the entire Cassini spacecraft team for their diligence in making this flyby work so incredibly well!

Cheers from Baltimore,

Amanda

Carolyn Porco

Cassini Imaging Team Leader

Click this link to go to raw images from Cassini.

Well, folks, the images are down ... at last!! ...  and I can't print here what I first said upon seeing them.  What a dazzling success!  There doesn't even appear to be any smear.   Paul Helfenstein (imaging team associate who planned the images), you genius ... here's one big hug from me, man!  We here at CICLOPS are all giddy, even moved to tears.

Clearly the skeet shoot maneuver worked (skeet shoot maneuver explained here: http://blogs.nasa.gov/cm/blog/cassini-aug08.blog/posts/post_1218130703424.html).  From our first examination, it appears we so far have the first, third, fourth, and seventh skeet shoot footprints down, and they are upside down from the footprints displayed in our graphic at http://ciclops.org/view/5156/Enceladus_Rev_80_Flyby , so beware of that.

The first two images have captured terrain near (1st skeet shoot) and on (3^rd skeet shoot) Cairo Sulcus, and are clearly littered, completely, with blocks of ice ... not surprising given that we saw such things in our first very high res 4-meter/pixel resolution images taken back in 2005, and not surprising for a very fractured environment.  The next image, our 4th skeet-shoot image (the image on the left here), is also littered with blocks and apparently has caught two unnamed fractures between Cairo and Baghdad. And the last image available at the moment, our 7th skeet-shoot, has caught Damascus Sulcus and looks very much softer than the others, but probably because its resolution is lower.

It seems our pointing has been fabulous, especially for the later images.  Helfenstein
... here's another big hug from me.  You're one cool dude!!

Now we have to figure out if we indeed have captured the sites where the jets are
emerging, so there’s a lot more to do.

But I ask you:  Is there ANYTHING more exciting, more thrilling, more stimulating to the mind, more gratifying to the soul than exploring news worlds?!!!

Carolyn Porco

Cassini Imaging Team Leader

I woke up unusually early this morning, on pins and needles, and looked
out my bedroom window from my house on a narrow ridge in northern
Boulder Colorado, onto the foothills of the Rocky Mountains and the
town below, and wondered how the day would unfold.  I paused to let my
gaze fly, in my mind, beyond the horizon and around and over the Earth,
pulling back in `powers of ten' fashion, imagining our planet suspended
in space.  And I thought about how remarkable the inhabitants of that
small blue world truly are, and how extraordinary their achievements
over these past 4 years have been.

Those years of intensive examination of an alien planetary system have
brought us humans to this juncture, right now, awaiting news from clear
across the solar system of the outcome of our latest bold experiment in
interplanetary maneuvering, focused on one of the most fascinating
places in our solar system... a place we never even knew existed before
we set out on this adventure.

In this painstaking work, we proceed, step by step, to lay bare those
things which hold the greatest promise of comprehension, the greatest
significance for piecing together the story of the origins of the
bodies in our solar system, our Earth, and indeed ourselves.

The images we await now are just a few of those steps.  I wonder: What
will they show?

Todd Barber

Cassini Lead Propulsion Engineer (bio)

Hello from the "flip" side of Enceladus!  I'm happy to report via this blog that the Deep Space Network in Canberra, Australia, locked onto Cassini's radio signal around 9:03 p.m. PDT on Monday, Aug. 11. 

We've executed yet another successful flyby of Saturn's ice-geyser moon!  Playback data has just begun streaming to our breathless scientists and engineers at JPL, and it will continue throughout the evening and into tomorrow morning.  With the rest of you, I'm pumped up for the raw (unprocessed) images that will be posted Tuesday morning, Pacific Time.  For the latest raw images, check here:

http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-list1.html

Cassini engineering may pay my bills, but Cassini science sparks my passions.

A few engineers are still here, working away this evening, making sure the spacecraft came through its scientific marathon unscathed.  I can't speak for all these engineers, but I can tell you the propulsion subsystem is healthy and is ready for yet another Reaction Wheel Assembly (RWA) bias after midnight PDT.  Thankfully, this activity is fairly commonplace, so long before then I plan to be celebrating another engineering success with some Olympics viewing, perhaps an appropriate beverage, and an indefatigable smile.  It's been a long day but oh so tremendous!  Now let the flood of Enceladus science data commence! 

Todd

Carolina Martinez 

JPL News Team

This is a video clip of the Cassini mission control area and Grant Eller, on console, confirming with the Deep Space Station in Canberra, Australia, that data has begun transmitting from Cassini to Earth.  Play clip 

Here is a high-resolution, broadcast quality clip of the same event: High-resolution clip

And here's an interview clip with Todd Barber, Cassini lead propulsion engineer:  Play clip

You can get a high-resolution, broadcast quality clip of Todd here: High-resolution clip

Tomorrow we will have more postings from our scientists and engineers and their comments on the images. 

Raw images may begin to appear in the pre-dawn hours (PDT) with some of the best raw views arriving in the late afternoon.  For the latest raw images see:  http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-list1.html

Todd Barber,

Best wishes from Pasadena, California on this fine day!  As I write
the highly anticipated Enceladus flyby is underway.

I was in the office this weekend trying to get caught up a bit (a
weekend tradition), allowing me to hit the ground running on another
busy work week.  This week holds exciting promise and scientific
anticipation, though, in addition to my typical engineering duties.
Over the weekend, we did two Reaction Wheel Assembly (RWA) biases to
optimize the rotational speeds of these objects.  Through angular
momentum changes, these wheels can turn and point the spacecraft,
allowing incredible precision.  One of my tasks is to calculate how
much propellant these biases use, so that's one thing I'm working on
today.

Speaking of propellant usage, there have been some questions about how
much propellant we will use in the maneuvers around Enceladus and for
the flyby itself.  As I mentioned in my prior blog entry, we were
actually able to cancel our approach maneuver, OTM-163.  In addition,
the next propulsive maneuver (OTM-164) is nearly two weeks off,
setting up Cassini for solar conjunction and yet another Enceladus
encounter (E5) in October.  OTM-164 will be rather large, however,
using roughly 10 kg of bipropellant, about 6 kg of nitrogen tetroxide
(oxidizer) and 4 kg of monomethylhydrazine (fuel).  For the E4
encounter itself, I don't have a propellant-usage prediction handy,
but I can tell you it will be at most a few tens of grams of hydrazine
(the monopropellant fuel), for yet another RWA bias.

The bottom line is that we have plenty of propellant for our two-year
extended mission and beyond.  Thanks for that great question, and
we'll see all of you on the other side of Enceladus!

Todd

John Spencer

Cassini Scientist on the Composite Infrared Spectrometer (bio)

Our next Enceladus encounter is very soon, at 21:06 Universal Time or 14:06pm Pacific time. This promises to be a spectacular encounter, giving our first high-resolution sunlit view of the south polar region since the discovery of activity there three years ago (the most recent encounter, in March 2008, observed the south pole only in the darkness of Saturn's shadow). Our instrument, the Composite Infrared Spectrometer (CIRS), will be mapping the heat radiation from the warm tiger stripes as we did in last March's flyby, but on that flyby our best views were from a range of 14,000 km (8,500 miles), allowing us to see details of the heat radiation on scales as small as 4 km (2.5 miles). This time we'll start our observations from a range as close as 900 km (560 miles), showing us Enceladus in fabulous close-up, with CIRS mapping details as small as 270 meters (0.17 miles). As we scan the south pole we're screaming away from Enceladus at nearly 18 kilometers/second (40,000 mph) so we have to work fast to make the most of this high-resolution opportunity.

Image left: Heat radiation from tiger stripes. Full caption

I'm most excited about the observation we'll be attempting at about 21:11 UT, when we will try to put the CIRS short-wavelength detector right along one of the most active tiger stripes, called Damascus Sulcus, from a distance of only 4,500 km (2,800 miles). On our last flyby we saw temperatures as high as at least 180 Kelvin (-135 Fahrenheit) on this part of Damascus, from 15,000 km (9,000 mile) range, and from three times closer we might see even higher temperatures because the warm material, which we think occupies a strip just tens or hundreds of meters wide along the fractures, will fill more of our detector and give us a more accurate reading. However, this is a challenging observation because our detector consists of a linear array of ten pixels, which will be aligned parallel to the fracture. Pointing may not be perfect this close to the moon, so we may get all ten detectors, or none of them, on Damascus. You might ask why we didn't align the detector across the fracture rather than parallel to it, to be sure that at least some of our pixels would fall on the warm material. But we needed to align the spacecraft in the direction that allows it to rotate as fast as possible to keep up with Enceladus as we zoom past, and we didn't have the luxury of also optimizing the orientation of the detector.

The animation to the right depicts Cassini flying close to Enceladus.