Cassini Probe Does Titan Flyby

EccentricAnomaly writes "Today, Cassini had its first close encounter with Titan around 8:30AM PDT. Data from the flyby will start coming down around 6:30PM PDT, and you can watch the pictures live on NASA TV. If you want higher resolution or just to stare at one picture for a while, the raw images will be put on the web right away, with pretty press images to follow the next day. And if you want to know about the observations planned for the flyby, you can read this PDF or watch this animation."

Links to the actual Quicktime and GIF files

[waynegoode]

The links on the webpage open pop-up windows to show the video. You can't right click and save the files. I did a little right-clicking and source viewing and found the URLs of the actual files.

• Large Quicktime [arizona.edu]
• Large GIF Small [arizona.edu]
• Small Quicktime [arizona.edu]
• Small GIF Small [arizona.edu]

The animation link web page, I meant to say

[waynegoode]

I am refering to the last link, the one about animations, http://ciclops.lpl.arizona.edu/view.php?id=500

Sorry I left that out.

Re:welll

[pedroloco]

If you're counting moons outwards from Saturn (or, more precisely, in order of increasing orbital semi-major axis length), Titan is more like the 19th moon [wikipedia.org] (or 15th if 4 recently discovered moons are excluded).

sci.space.news

[noselasd]

Subject: Cassini Image: Eyes on Xanadu
From: [e-mail] (Ron)
Newsgroups: sci.space.news
Followup-To: sci.space.policy
Date: 26 Oct 2004 09:25:07 -0700

http://www.nasa.gov/mission_pages/cassini/multim ed ia/pia06107.html

Eyes on Xanadu
October 25, 2004

Cassini image of Titan, revealing the bright continent-sized terrain
known as Xanadu

This image taken on Oct. 24, 2004, reveals Titan's bright
"continent-sized" terrain known as Xanadu. It was acquired with the
narrow angle camera on Cassini's imaging science subsystem through a
spectral filter centered at 938 nanometers, a wavelength region at which
Titan's surface can be most easily detected. The surface is seen at a
higher contrast than in previously released imaging science subsystem
images due to a lower phase angle (Sun-Titan-Cassini angle), which
minimizes scattering by the haze.

The image shows details about 10 times smaller than those seen from
Earth. Surface materials with different brightness properties (or
albedos) rather than topographic shading are highlighted. The image has
been calibrated and slightly enhanced for contrast. It will be further
processed to reduce atmospheric blurring and to optimize mapping of
surface features. The origin and geography of Xanadu remain mysteries at
this range. Bright features near the south pole (bottom) are clouds. On
Oct. 26, Cassini will acquire images of features in the central-left
portion of this image from a position about 100 times closer.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. The Jet Propulsion
Laboratory, a division of the California Institute of Technology in
Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission
Directorate, Washington, D.C. The Cassini orbiter and its two onboard
cameras were designed, developed and assembled at JPL. The imaging team
is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission, visit
http://saturn.jpl.nasa.gov and the
Cassini imaging team home page, http://ciclops.org

Credit: NASA/JPL/Space Science Institute

And

Cassini-Huygens makes first close approach to Titan

Today the NASA/ESA/ASI Cassini-Huygens spacecraft makes a fly-by of Saturn's
largest moon Titan - the closest ever performed.

Read more:
http://www.esa.int/SPECIALS/Cassini-Huygens /SEMB2E 0A90E_0.html

Re:4Gbit Solid State Recorders

[badfrog]

Interference has always been a huge factor, the Space Shuttle still used iron-core memory in its systems in the late 80s, because it wasn't affected by radiation. Can't just pop in some SDRAM and expect it to work out there.

Re:good flavor

[red floyd]

n the moon with the completely water frozen surface, orbiting jupiter (or maybe it was saturn)

Europa, the second Galilean moon (Io, Europa, Ganymede, Callisto).

Re:4Gbit Solid State Recorders

[HunahpuMonkey]

> From NASA's faq - "Cassini stores the gathered information on two Solid State Recorders (SSR)
> with a combined capacity of 4 gigabits, about the volume of a compact disk (500MB)."
>
> It seems scientists are pretty confident that they can unload much data during Cassini's 9 hours
> downlink session.
>
> Imagine if there were some downtimes when earth communication cannot be established
> for a couple of days...

According to CNN [cnn.com] that very problem exists. The buffers in those recorders are in danger of writing over the data before it can sucessfully be sent to Earth.

"The flyby of Titan was expected to go smoothly in space, but bad weather on Earth could affect Cassini's transmissions to the Deep Space Network, scientists said.

Cassini has only one chance to send data back to Earth before it is overwritten with data from its next set of observations, scientists said."

Also sampling Titan's atmosphere...

[jangobongo]

Not only will the Cassini be taking pictures, but its ion and neutral mass spectrometer will "scoop up" and sample Titan's atmosphere as it passes at a distance of 1,200 kilometers (745 miles).

"One important goal of this flyby is to confirm scientists' model of Titan's atmosphere to prepare for the Huygens probe descent," according to this article at SpaceDaily.com. [spacedaily.com]

Re:4Gbit Solid State Recorders

[Anonymous Coward]

Yes. It's EZW-encoded based on the time and the shifted return frequency. It's only about 2.4 MB per minute.

http://saturn.jpl.nasa.gov/operations/encoding.c fm

Re:good flavor

[Anonymous Coward]

it seems that everybody is looking at mars and wondering why are space program is not really doing too much

Nobody's doing too much because the rest of the Solar System is a dead wasteland. If Mars had something to offer, then we'd see all the world's powers scrambling to get first dibs. The best use of resources at this point would be to continue improving new launch/reentry technology and perfecting space stations.

raw images

[Anonymous Coward]

The raw images may be higher resolution but guess what....they are also "raw"! That means they haven't been processed yet. The image data isn't very useful unless you have the necessary parameters / algorithms to process the data.

There will be several steps in processing the image data, bad pixel correction (I guess these CCDs should have very few); white/black balance; tonal / grey calibration; others? I'd be surprised if there weren't a few others.

I guess the white/black balance is the most important thing I mentioned ....responsiveness accross the CCD won't be the same and must be compensated for. I don't know if they've got a seperate grey calibration step (you'd need calibration data to reproduce it)....you could fiddle with tone curves yourself to make stuff pleasing to the eye / see different stuff.

Can anyone supply more details on the calibration?

So far as I know it's not worth downloading the raw images unless you want to exercise some bandwidth....I think that Nasa might give out the calibration data to some people (remember British scientists discovering possible new moon?)....Anyone know all the ins and outs?

Re:4Gbit Solid State Recorders

[djvern]

Actually, we have a saying: "The rain in Spain falls mainly on DSS-63" The rain is a very large concern for everyone here tonight. We have already requested a backup downlink session tomorrow in case of problems tonite. Basically, we stole a 70 meter antenna from another project. The critical data will make it down at the end of the Madrid pass, as there is dual coverage with a 34 meter Goldstone, CA station. Best of luck.

Life on Europa?

[CRepetski]

A flyby of the second Galilean moon could prove to be especially beneficial, as it has some of the most favorable conditions for life (or past life) in our solar system.

Re:4Gbit Solid State Recorders

[jnik]

When Cassini isn't doing an encounter, it's sitting around doing pretty much nothing

Hardly true. Now, granted, I don't have the Cassini instrument duty-cycle schedule right here, but I can at least take a quick look at the projected orbit plots. It looks like apicenter is about 60-70 Rs. Frontside magnetopause distance is 20-25 Rs (roughly), the flanks are likely further out, and I'd put money on the tail extending at least 70 Rs. Even on the front side I'm sure there's plenty of science to be done in the sheath, bow shock, and even upstream solar wind.

So the plasma instruments and magnetometer would be busy for probably half the distance of each orbit. I imagine the cosmic dust analyzer is probably useful the whole time, and the UV cameras (I'm too lazy to compare the resolution to Hubble...). That's a lot of data.

And it really does come down pretty slow. At 35 kbit/s, that's roughly a day and a half, best case, to empty the recorders, out of approximately two weeks for an orbit (not always being in "view", either, and the DSN sometimes needed for other things...).

I'm sure somebody would find some use for extra storage if it were there, but the limitation doesn't mean Cassini's spending any great amount of time idle.

Re:raw images

[H01M35]

From the FAQ [nasa.gov]

Why does the contrast look different between images?

The camera measures light from an object at each point in an image and assigns it a number from zero to 4095 depending on its brightness. Sometimes the scientist can't afford to send this amount of data for each pixel because of the amount of storage it takes. The camera has the ability to convert this range of values to those from zero to 255. The camera does this according to a preset table of values designed by the scientists. This table devotes many of the 256 levels for less bright things and less levels for brighter pixels. Part of calibrating an image on the ground is to reverse this table and get back pixels in the range of zero to 4095. Because you're looking at the raw data, images sent back in this mode will have dimmer things look brighter compared to the brighter parts of the image than in images not in this mode.

Why does the image look bizarre/psychedelic?

As in the previous question, the other way the camera can send back less data (by sending pixels with values from zero to 255 instead of zero to 4095) is to send back only the lower binary digits of the number. This is like having a list of amounts of money and only recording the amount of cents for each one and assigning the brightness in an image to the amount of leftover cents. Pixels with brightness values just under 255, like amounts just under a dollar, will appear almost white, while pixel values just over 255, like amounts just over a dollar with not many cents, will appear dark. The ideal use of this mode is for image scenes that are dark with almost all of the pixel values less than 255. If the scene is simple with gradual increases in brightness, then even if the original values get over 255 and go dark again, the scientists can figure out what the real value was. If the scene is very complicated or the original values are much brighter than 255, the image can have many bright and dark transitions with strange contours. In this case, the image will look very bizarre but not have much scientific value.

Seems like they want more detail in the dimmer areas. There's also an interesting look at the filter combinations that they can use.

Re:Really Glad NASA didn't screw up this one!!!!

[Silverlancer]

Not exactly. Cassini isn't the first mission to use a nuclear power system first of all, and second of all if it did explode there would be no explosion and the radioactivity would be spread so much that it would be lost among Earth's background radiation. Read up before you comment.

Re:4Gbit Solid State Recorders

[Anonymous Coward]

You clearly don't know anything about electronics/systems that operate in space. IPods would quickly broke because:

1. Temperatures ranging from -200 C to 300 C (at least)
2. Sound pressure and shaking during a launch
3. Malfunctioning of electronics caused by cosmic rays and solar wind

Additionally, every gram which NASA sends to the orbit costs a LOT of cash. Materials/design of IPod would weight too much and take too much space.