Cassini-Huygens Reaches Orbit Around Saturn

Mick Ohrberg writes "The probe Cassini-Huygens is now officially in orbit around Saturn. Last nights' retro-burn was completed according to plan, down to the second, which in and of itself is an amazing feat, considering all data received is 1h24m old, as well as 900 million miles away. I must say, it was fairly exciting to watch the webcast, and see the signal fade behind the A-ring, and all but disappear behind the B-ring - all in (somewhat delayed) real-time. The SOI (Saturn Orbit Insertion) also saw Cassini-Huygens whisk by Saturn at around 68,000 mph at an altitude of about 12,000 miles from the cloud tops - the closest to the gas giant the probe will ever be during its planned 4-year mission, for instance the much awaited Huygens mission to Titan."

Comments

typo title

[bluethundr]

The NAME, I say I say the NAME, son is Christiaan Huygens. Associate of the Protestant Defender and natural philosopher.

Pictures of the actual ring pass through?

[Jugalator]

It would be interesting to see how it looked like meanwhile it was in the ring system?

Or when it was nearby enough to see the massive amounts of rocks inside.

Or didn't it pass through the actual rings?

Christiaan Huygens

[rastakid]

Just like Huygens I'm Dutch, and thus I was taught a lot about him in school during the physics hours.
The biggest thing Huygens brought the physica is the 'Huygens source'. A simplified explanation: A Huygens source starts sending out sound (air vibration) because the source itself got vibrated by another source. So, a Huygens source doesn't 'create' sound, but simply relays it.

Of course this is really simplified and in reality it's fairly more complex.

Re:They must have been nervous

[underpar]

The antenna had to be moved into position to be a shield. You never know what lame part may mess up and ruin the whole show. I think what concerned me (as someone who knows nothing) was that it had to do a few things just right in order to make it and it's really hard to account for all of the variables.

Re:delays

[Bob 4knee]

...some sort of technology that allowed some independent operation on the part of the probe might be a valuable investment for the next go-round.

It's in there this time. See:

http://www.cnn.com/2004/TECH/space/07/01/cassini.o rbit/index.html

NASA also designed Cassini to be independent because the time lag of one hour and 24 minutes -- the time for light to travel 930 million miles from Saturn to Earth -- means controllers on Earth cannot immediately react to unexpected problems.

Instead, Cassini operates on its own.

"The spacecraft has been programmed to continue even in the event of an emergency," said Mitchell in a statement. "We don't want Cassini to call home if a problem arises, we want it to keep going."

Receiving data that is over there is very hard...

[techmuse]

considering all data received is 1h24m old, as well as 900 million miles away Recieving old data is easy. Receiving data that is 900 million miles away is very hard. The spacecraft is 900 million miles away. The data must be here, or we could not have received it. ;)

Re:Hey..?

[SB9876]

While the risk of the Pu RTGs breaking open if Cassini had hit the Earth on those slingshot maneuvers was non-zero, the risk to human health was non-existant. The stupid - 'toxic enough to kill every human on Earth' line was complete BS.

For one, it's know that at least 3 RTGs have burned up on reentry, one US and two USSR. We didn't all die.

Second, while Plutonium is toxic, it's not that bad - caffeine has a lower fatal dose than Plutonium.

Re:Amazing.

[mikael]

I found the FAQ interesting too, and am truly amazed by the beauty of the images (I definitely want a 6-foot wall poster of Jupiter and the moons).

Given the problems with bits being cut off from images due to time/memory constraints, I wonder if it would be possible to design camera sensors so that the returned pixels are ordered so that you could get increasing resolutions through time ie. First the (even,even) pixel coordinates first, then (odd,odd), finally followed by (even,odd)/(odd,even) so that you'd always get a full image if at a lower resolution.

Is "Saturnian" the proper adjective?

[peter303]

Most of our planet names come from the Latin form. Sometimes I see the Greek name used as the adjective. In this case it would be "Chronus", even more awkward.

Re:I'm not obsessed by size or anything

[Iron Sun]

Trollish , if partially true. Saturn sans rings is probably, though debatably, marginally less interesting than Jupiter. Stuff like the uncertainty over the length of its day shows that it has some surprises in store, though.

But Titan sure has to be the most interesting object in the Solar System at the moment, if only because it's the biggest bit of unexplored surface left. The good probability of extraterrestrial oceans is also pretty damn cool. Go, Huygens!

Re:I'm not obsessed by size or anything

[amightywind]

Next to the earth, Titan may be the most chemically complex body in the solar system. It remains to be seen if it geologically complex. I have a feeling the real show will start tomorrow with the first Titan flyby. Cassini should be able to see/detect liquid hydrocarbons if they are there with IR imaging, IR spectrascopy and radar. A major world is about to be revealed with some of the best instruments ever flown.

Waves in the Rings?

[S_Dub]

Can anyone explain the seemingly horizontal waves that are running through all of the rings? They seem to be fairly uniform and direction and size. However, the orientation does not seem to be radial from the planet itself or any other object... Any conjecture out there as to what has caused this? They almost seem like an artifact in the images themselves.

Also, is anyone else a little disappointed that these are the best images we're going to get of the rings or are there going to be better pictures in the future? This is the closest the spacecraft is going to get to the rings, yet I really was hoping to see the individual components of the rings themselves. I've seen the intro to Voyager, and I wanted to see tumbling boulders...

cool stuff

[serenarae]

I don't know if this has already been mentioned, but there are 616,800 hand-written signatures from 81 countries on a disc inside Cassini. I remember when I was in 7th grade and my entire class sent in our signatures to NASA. Now it's seven years later and my name is billions of miles away in space. How cool is that?

Re:Amazing.

[bob_jenkins]

There's also the error correction code they're using (Viterbi-encoded convolution codes) which multiplies the amount of data the probe has to send by a factor of 6.

A probe sent today would use Turbo codes or LDPC (Low Density Parity Check) codes, which nearly reach the Shannon limit for channel capacity. The Shannon limit is a theoretical limit -- we could get faster encoders and decoders than LDPC codes (encoders particularly need work), but they're about at the end of the road for channel capacity. (These codes will work on 1s and 0s, but they can also take into account the analog strength of each bit measured to improve their performance. Decoding them involves iteratively forming and testing beliefs about what an encoded codeword should decode to.)

I wasn't able to locate what error rate can be corrected by the Viterbi code they're using now, or how much lower their bitrate could be with the same amount of correction if they were using a code that met the Shannon limit. Help?

Tin Foil Hat

[mosb1000]

I can't believe that the people on that website are real. They claim that NASA use RTG's and RHU's to cover up military plutonium launches. Where do they expect these probes to get power from?

I mean, seriously, I've seen some pretty crazy theories in my time, but this one takes the cake. Why would the military use NASA to cover up it's activities, how would this even work. Wouldn't the military still have to cover up their activities regardless of what NASA does?