Enceladus 50 KM Cassini brush pass.

3488 · #1 (**permalink**) 07-March-2008, 12:34 AM

Cassini Spacecraft to pass Enceladus at an altitude of only 50 KM / 31 miles on: Wednesday 12th March 2008.

Enceladus 50 KM Cassini brush pass.

Very interesting.

Andrew Brown.

ToSeek · #2 (**permalink**) 07-March-2008, 04:19 AM

Email from Carolyn Porco:

Quote:

March 6, 2008

Dear Friends and Colleagues,

As you may already know, Cassini is set to begin a series of scraping Enceladus flybys that will take place in 2008. The first one occurs next week on March 12, and will take us flying within a mere 50 km (~ 30 miles) over the equatorial region of the moon, approaching from the north and then departing towards the south, with passage through the edges of the moon's famous south polar plume. This very low altitude is about one seventh (1/7) the distance that the International Space Station flies above the Earth and is the closest we've flown yet to any object in the Saturn system.

We should come away from this flyby with a better idea of the composition of the plume, in particular, a better measure than we've had up until now of the abundances of ammonia and some simple organic compounds, both of which are important to ascertaining the astrobiological potential of the source environment of the jets.

Today, CICLOPS is releasing a detailed description of the sequence of observations that will take place during this event, and a map previewing the imaging coverage that is planned.

Go to ...

http://ciclops.org

... to find out more.

Also, owing to email distribution problems we recently had here at CICLOPS, it seems that the vast majority of you never received the Star Trek announcement that we sent out ... twice ... about a month ago. If this is true for you, the announcement can be found at

http://diamondskyproductions.com/news/2-11-2008.php

In the meantime, stay tuned for Enceladus!

Enjoy,

Carolyn Porco
Cassini Imaging Team Leader
Director/CICLOPS
Space Science Institute
Boulder, CO

3488 · #3 (**permalink**) 07-March-2008, 07:50 PM

Hi ToSeek,

I take it that you too are part of the CICLOPS Alliance?

I got that same e-mail.

Only a few days now till that fascinating Enceladus encounter. I can't wait.

Andrew Brown.

RGClark · #4 (**permalink**) 08-March-2008, 03:31 PM

Cool. Looking forward to that.

Bob Clark

01101001 · #5 (**permalink**) 11-March-2008, 03:59 AM

Universe Today: Passing Through the Plumes; Enceladus Flyby on Wednesday

NASA News Release: Cassini Spacecraft to Dive Into Water Plume of Saturn Moon

Quote:

NASA's Cassini spacecraft will make an unprecedented "in your face" flyby of Saturn's moon Enceladus on Wed., March 12.

The spacecraft, orchestrating its closest approach to date, will skirt along the edges of huge Old-Faithful-like geysers erupting from giant fractures on the south pole of Enceladus. Cassini will sample scientifically valuable water-ice, dust and gas in the plume.

The source of the geysers is of great interest to scientists who think liquid water, perhaps even an ocean, may exist in the area. While flying through the edge of the plumes, Cassini will be approximately 200 kilometers (120 miles) from the surface. At closest approach to Enceladus, Cassini will be only 50 kilometers (30 miles) from the moon.

NASA Blog: Enceladus-flyby-Mar2008

Quote:

Enceladus Approach Maneuver Cancelled -- We're Good to Go!

Monday greetings from the engineering side of the Cassini flight team! I'm very happy to report via this blog that we just decided to cancel the final Enceladus approach Orbit Trim Maneuver (OTM), OTM-148, and its back-up maneuver labeled JTM-148. Since these burns were scheduled after midnight local time in California last night and tonight, respectively, I don't think many of us will mourn their cancellation. These final targeting maneuvers for Wednesday's thrilling close flyby of Saturn's icy companion were deemed unnecessary, largely due to excellent performance at OTM-147 four days ago. In fact, we were able to save a little bit of propellant for the mission overall by canceling these maneuvers!

NASA sort of looks like they're getting into blogging: NASA Blogs (The fancier NASA Blog index doesn't yet list everything.)

In the last few weeks have appeared a NASA EDGE blog, Shana's blog (Deputy Administrator Shana Dale), and now the Enceladus Flyby blog.

Edit: Dang. I missed the existing thread here in Exploration because I used "flyby" as a search term. See topic Enceladus 50 KM Cassini brush pass..

ToSeek · #6 (**permalink**) 11-March-2008, 04:48 PM

Quote:

Originally Posted by 01101001

Edit: Dang. I missed the existing thread here in Exploration because I used "flyby" as a search term.

Threads merged.

01101001 · #7 (**permalink**) 11-March-2008, 05:08 PM

Quote:

Originally Posted by ToSeek

Threads merged.

Thank you.

Nature News: Probe readies for dip into geyser on Enceladus

Quote:

“Last time, we just skimmed the edge,” says Cassini scientist John Spencer at the Southwest Research Institute in Boulder, Colorado. At its closest point in the fly-by, the probe will come within 200 kilometres of the plume’s source (see graphic).

A key question is, will it find ammonia? The gas is an antifreeze, allowing water to remain liquid at lower temperatures. But during the last fly-by, ammonia was strangely absent. If it remains undetected, this would suggest that the moon’s interior is hot enough to host liquid water.
[...]
Cassini will return to Enceladus in August, for the second of eight further fly-bys in its extended mission. Each time, it will inch closer to the plume’s centre. Scientists want to test the waters slowly — any encounters with particles bigger than one millimetre could damage the spacecraft.

JPL Cassini-Huygens

1 Day 1 Hour 58 Minutes to flyby

Paul Scott Anderson · #8 (**permalink**) 12-March-2008, 01:50 AM

Quote:

Originally Posted by 3488

Hi ToSeek,

I take it that you too are part of the CICLOPS Alliance?
I got that same e-mail.
Only a few days now till that fascinating Enceladus encounter. I can't wait.

Andrew Brown.

I'm part of it too. I can't wait, either.

Paul

01101001 · #9 (**permalink**) 12-March-2008, 04:06 AM

JPL Cassini-Huygens

15 hours to flyby

01101001 · #10 (**permalink**) 12-March-2008, 06:06 PM

JPL Cassini-Huygens

1 hour to flyby

NASA Blog: Enceladus-flyby-Mar2008

Quote:

[Amanda Hendrix]: Well our flyby sequence has officially started!! Last night we began our observations of Enceladus! We are very distant, but getting closer all the time, over the northern hemisphere. The first observation was a long stare at Enceladus, which is still pretty far away and small, but this is a nice opportunity to do compositional measurements. As of 9 a.m. Pacific, radar observation of Enceladus began, which will give us an idea of the roughness of this side of Enceladus, at centimeter scales. The closest approach is around 1 p.m. Pacific today.

The entire flyby sequence is on-board the spacecraft, and there's really no opportunity to change it at this point. We're in it for good. However, the sequence gets thoroughly tested prior to uplink, so we are confident that things will go smoothly. The next time we hear from Cassini will be tonight after the flyby at around 7 p.m. Pacific.

Quote:

[John Spencer:] Today's Enceladus flyby is a bit more adventurous than most satellite flybys by Cassini.
We are dipping into the jet of water vapor and ice spewing from Enceladus' south pole, because by doing so we can take full advantage of the amazing opportunity to study
fresh samples from inside this strange world. The mass spectrometer, dust, and plasma
instruments will be running flat-out, gathering priceless information on the composition
of the gases and the ice particles for the sixty seconds or so that Cassini will be in
the dense part of the plume.

Plume particles are wonderful things to study, but it's possible to have too much of a
good thing - at the speed that Cassini is going, particles as small as a millimeter in
size could cause serious damage to the spacecraft if we ran into one. So the decision to
enter the plume was not taken lightly. [...]

More detail and more entries there.

ToSeek · #11 (**permalink**) 12-March-2008, 07:55 PM

Enceladus Approach Maneuver Cancelled -- We're Good to Go!

Quote:

STATUS REPORT
Date Released: Wednesday, March 12, 2008
Source: Jet Propulsion Laboratory

Mar 12, 2008 01:34:06 PM

Todd Barber, Cassini Lead Propulsion Engineer

Monday greetings from the engineering side of the Cassini flight team! I'm very happy to report via this blog that we just decided to cancel the final Enceladus approach Orbit Trim Maneuver (OTM), OTM-148, and its back-up maneuver labeled JTM-148. Since these burns were scheduled after midnight local time in California last night and tonight, respectively, I don't think many of us will mourn their cancellation. These final targeting maneuvers for Wednesday's thrilling close flyby of Saturn's icy companion were deemed unnecessary, largely due to excellent performance at OTM-147 four days ago. In fact, we were able to save a little bit of propellant for the mission overall by canceling these maneuvers!

We took an engineering image of Enceladus yesterday evening, a so-called "optical navigation" or "op-nav" image. Rather than being used for science, we actually used this image to measure the position of Enceladus very accurately with respect to known background stars. This helped us improve our knowledge of Enceladus' location, and the result of this latest op-nav is that Cassini remains on target for its historic rendezvous with Enceladus and its icy south polar plumes in two short days. We in engineering wish our science colleagues on the mission a very fruitful and eye-opening close encounter with one of Saturn's most intriguing moons.

Enceladus Flyby Underway

Quote:

Mar 12, 2008 02:00:48 PM

Amanda Hendrix, Cassini Scientist on the Ultraviolet Imaging Spectrograph (bio)

Well our flyby sequence has officially started!! Last night we began our observations of Enceladus! We are very distant, but getting closer all the time, over the northern hemisphere. The first observation was a long stare at Enceladus, which is still pretty far away and small, but this is a nice opportunity to do compositional measurements. As of 9 a.m. Pacific, radar observation of Enceladus began, which will give us an idea of the roughness of this side of Enceladus, at centimeter scales. The closest approach is around 1 p.m. Pacific today.

The entire flyby sequence is on-board the spacecraft, and there's really no opportunity to change it at this point. We're in it for good. However, the sequence gets thoroughly tested prior to uplink, so we are confident that things will go smoothly. The next time we hear from Cassini will be tonight after the flyby at around 7 p.m. Pacific. We are being fairly cautious, though: even though Cassini will come about 30 miles of the surface, while flying through the plume we will be 120 miles from the surface. So we're "dipping our toes" in the plume a little more than we've done before!

Cheers from Houston,

Amanda

Closest approach is RIGHT NOW!!

Swift · #12 (**permalink**) 12-March-2008, 07:56 PM

The most recent stuff from the blogs:

Quote:

Mar 12, 2008 03:29:19 PM | John Spencer, Cassini Scientist on the Composite Infrared Spectrometer

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.

Swift · #13 (**permalink**) 12-March-2008, 08:00 PM

From ToSeek's second link,

Quote:

The next time we hear from Cassini will be tonight after the flyby at around 7 p.m. Pacific.

That's about 6 hours from now.

3488 · #14 (**permalink**) 12-March-2008, 11:28 PM

Quote:

Originally Posted by Swift

From ToSeek's second link,

That's about 6 hours from now.

Hi everyone, downlink start's in less than one hour.

Lets hope that all went well, no ice / clathrate particle damage to Cassini, or navigational errors that sent Cassini slamming into Enceladus? I know, I'm just being silly, but this really matters, it really does & that's why I'm a little worried.

What an incredible mission this is.

Andrew Brown.

Swift · #15 (**permalink**) 13-March-2008, 03:08 AM

From the blog:

Quote:

Enceladus Data Back on Planet Earth! Mar 12, 2008 11:03:53 PM | Todd Barber, Cassini Lead Propulsion Engineer

Howdy, folks. We've just heard from the Cassini mission control area and
can report that the data downlink has started! The signal was received via
the Goldstone, California, Deep Space Network station at roughly 7:01 pm
PDT. Our engineers are assessing the first post-flyby data as we speak,
but everything looks great at first blush.

The downlink data playback will run through the evening, and we hope to
have raw images hit the Cassini Web site before dawn, about 5 a.m. Pacific,
Thursday, March 13.

01101001 · #16 (**permalink**) 13-March-2008, 06:00 PM

NASA Cassini-Huygens raw images. Probably, select Enceladus from the menu, or Newest Images (Latest? whatever) button may be sufficient.

I can't vouch. The server's really slow. Maybe because the pictures are so awesome.

Ah, finally got the first page of Enceladus images. Eh. Most are wide shots. Maybe the second page will be more awesomer. If I can wait that long.

Wasn't worth the wait. Maybe the third page. But, I don't have the patience. I think I'll go read a book or something more interactive. Posting a request for a page and waiting 3 minutes is tough.

parejkoj · #17 (**permalink**) 13-March-2008, 07:01 PM

Heh... I remember hearing people talk about this when I was working for INMS. The 5-sigma error bars for this pass were something like 100m, maybe less--in 2003!!! People were joking that we should have mounted INMS to the end of the MAG boom, and taken Cassini low enough to scrape the surface of Enceladus. You know, to get a good mass sample....

Zoom!

I'd love to see the results of the particle and fields instruments from this, even if it wasn't quite as close as we'd have liked...

spin0 · #18 (**permalink**) 13-March-2008, 07:24 PM

I made a quick BW composition of Enceladus, distance approx 31000-34000km, 1389x2787 px.

Colour images in progress...