Talk:Cassini–Huygens/Archive 1

=Mission, Technology, Content etc=

Contradiction : records of size etc

 * The Cassini spacecraft, including the orbiter and the Huygens probe, is the largest, heaviest, and most complex interplanetary spacecraft built to date ... Only the two Phobos spacecraft sent to Mars by the Soviet Union were heavier.

Both can't be right.


 * Maybe it should say: most complex interplanetary spacecraft built by NASA to date? Awolf002 17:58, 18 July 2005 (UTC)


 * The Phobos craft may have been heavier, but easily arguable as being much less complex. The sentence is a mangled concept and need to be split up. Matt Whyndham 12:29, 30 August 2007 (UTC)

Trajectory
Hey! What's the "Trajectory" section about?? Is it still being worked on? I can not see what it tries to explain, only that it adds a large graph with no apparent added "value"... Awolf002 14:10, 13 Mar 2004 (UTC)


 * Yes, the section is still being worked on. You can study the speed differences at planets swingby and manuevers and during the whole mission from the chart, so it's great. Yaohua2000 15:21, 13 Mar 2004 (UTC)

I see. So I suppose you plane to make an extra section with more text? I also would like to know, if you think it might be better related to the Wiki entry Gravitational_slingshot as a great example, since there the focus is actually on the features of the trajectory of space probes. What do you think?

Detailed Timeline
Another related question to Yaohua2000: Why do we need the entries in the timeline that gives distances? Is there something significant, there?

I think we can drop the "detailed timeline" entries that are only significant because of a "magic number" in the distance, once they have passed. There is no scientific or other value to them after each date. Anyone opposed? I will clean them up starting April, if nobody objects. Awolf002 15:49, 29 Mar 2004 (UTC)

First orbit
Anyone know how long the first and then subsequent orbits are going to take? There's a wonderful map of the orbit system, but some numbers would be neat. Stargoat 14:56, 1 Jul 2004 (UTC)


 * I've added the projected schedule of satellite encounters to the timeline page. Also see http://saturn.jpl.nasa.gov/operations/saturn-tour.cfm, though it's not dated orbit by orbit. According to Cassini-Huygens Saturn Arrival June 2004 (pdf), the first three apapsides are around 1 Sept., 2004, 1 Dec., 2004, and 1 Jan., 2005.
 * --wwoods 02:24, 2 Jul 2004 (UTC)


 * See my chart "Cassini's speed related to the Sun", which would answer your question.


 * It's a little hard to get numbers from the graph, though I count three periasides in 2004 and 18 in 2005.
 * --wwoods 22:51, 2 Jul 2004 (UTC)

Encounters with Venus
Cassini flew past Venus twice - shouldn't there be a section on that here? Did Cassini make any observations or photos? There's practically no mention of it here... User:Tom walker 11:39 GMT 21 October 2006


 * probably no observations (no instruments designed for it). This during the gravitational assist part of the trajectory.  The main idea is to pick up velocity from the encounters, prior to going outward to the main target. Matt Whyndham 11:44, 30 August 2007 (UTC)

Titan's Ocean (Dec 20)
I can not find any JPL announcement related to proof that there is a liquid ocean on Titan! I suspect this new section added today is bogus. Please provide a reference, or I will remove it. Awolf002 18:29, 20 Dec 2004 (UTC)
 * You mean what? where? in the article? &mdash; Yaohua2000 18:54, 2004 Dec 20 (UTC)
 * oic... &mdash; Yaohua2000 18:57, 2004 Dec 20 (UTC)

Sorry, will be more precise in the future... It still looks bogus to me. Awolf002 19:55, 20 Dec 2004 (UTC)

Still no answer, and no sign of this being correct... I'll remove that section, now! Awolf002 14:06, 21 Dec 2004 (UTC)

Is the probe designed to sink or float when/if it encounters a body of water?--Confuzion 13:53, 1 Jan 2005 (UTC)


 * The probe is optimally designed for the descent through Titan's atmosphere, but has a good chance to survive a landing or splashdown. I think if this happens, it can float in a "hydrocarbon ocean" for a while until it sinks due to wave action or small leaks. Note: Nobody expects liquid water on Titan. Awolf002 14:22, 1 Jan 2005 (UTC)


 * I hardly believe it could sink due to wave action, waves (if any) will tend to be much more gentle there than here on Earth, because of the low gravity. As for small leaks, I don't know, probably there could be some, though if I were building the thing, I'd make it as airtight as possible (except instrumental openings, of course). In any case, battery power and freezing cold will be a much more serious issue once the probe reaches all the way down. --Ugo 22:48, 6 Jan 2005 (UTC)


 * Well, I heard that Titan has very strong winds, so the "seas" could be pretty rough. And, yes it is the openings for measuring the composition of the atmosphere that might doom the probe in the end. However, I put my money of a "squelch down" and the batteries running out. Awolf002 20:29, 9 Jan 2005 (UTC)
 * So, I won my own bet. The data received from Huygens is really amazing! It looks to me like it landed on top of a Methane glacier. Awolf002 11:58, 16 Jan 2005 (UTC)

Instrumentation of Cassini
It would be nice if the instrumentation of Cassini were formatted like that of Huygens. Most instruments on Cassini are more self-explanatory, but if somebody wants to take the time it would be most useful. (unsigned)

100 times better?
We are told the "quality of the images was up to 100 times better than anything seen before." What does this mean? Resolution? Colour depth? Rated at 100 times better because of how interesting they are? Can we specify? Thanks! Intrigue 17:05, 27 Oct 2004 (UTC)


 * When they refer to how much better a picture is than another one, as far as I know it always means resolution. bob rulz 00:24, Oct 28, 2004 (UTC)


 * (Doradus) "They"? I know the Pulitzer prize, for example, doesn't rate quality by resolution alone

Huygens' landing site
Would someone like to check my math on the calculation of the angular resolution required to determine Huygens' landing site? Supposedly (we'll see on the 14th of '05) using the VLBA they will be able to determine the landing site to within 1 (ONE!) kilometre on Titan's surface when it is at a distance of 1,200 million km!! I've calculated this to be a resolution of about 17 nanoarcseconds. So far as I know this is the highest resolution astronomical observation ever achieved in any part of the electromagnetic spectrum except for an indirect method done once in 1997 which used a shell of gas around the Vela pulsar as a lens to image down to 10 nanoarcseconds.--Deglr6328 10:21, 26 Dec 2004 (UTC)


 * You screwed up by a factor of 10,000. One km at 120 Gm is roughly 170 µarcsec. I fixed the article.
 * One over 120E6 gives the angle in radians (8,3E-10 rad), divide by 2 pi, multiply by 360 times 60 times 60 gives arcseconds (an arcsec is about 4,85 µrad).
 * Urhixidur 16:51, 2004 Dec 26 (UTC)


 * That sounds more realistic.--Deglr6328 19:46, 26 Dec 2004 (UTC)

Huygens data volume
I think someone somewhere didn't do the math properly on this one. I've read in certain places, like here that Huygens will return 400 Mb of data for a full mission (how JPL gets 500MB from 400Mb is beyond me). But I've also read that Huygens will only transmit at ~8000 bits/sec. Now assuming a nominal mission of 2 hours plus .5 hrs on the ground this looks like about 72 megabits or 9 megabytes to me. Where is the mistake here? Is Huygens actually going to transmit faster than this rate?

Iapetus
The page could do with a mention of the discoveries Cassini-Huygens has made at Iapetus. (unsigned)


 * details of all the science outputs are probably beyond the scope of WP. Matt Whyndham 12:29, 30 August 2007 (UTC)

Test of Einstein's theory of general relativity
from reading this section, I don't have a clear picture of what aspect of general relativity is being tested; what do shifts in radio waves nearing the sun have to do with gr? what methods were used in past tests? i.e. why was taking the effort to send cassini on that mission important? --Confuzion 05:38, 12 Jun 2004 (UTC)


 * Here is the text from the JPL news release:


 * "According to the theory of general relativity, a massive object like the Sun causes space-time to curve, and a beam of radio waves (or light) that passes by the Sun has to travel further because of the curvature. The extra distance that the radio waves travel from Cassini past the Sun to the Earth delays their arrival; the amount of the delay provides a sensitive test of the predictions of Einstein's theory. Although deviations from general relativity are expected in some cosmological models, none were found in this experiment."


 * This experiment was piggy-backed onto Cassini, because it provided a very good opportunity. It was a repeat of other space based radio tests, but this one was better designed to evaluate errors due to the interference by the Sun. The primary mission of the spacecraft, however, is still Saturn. Awolf002 12:59, 12 Jun 2004 (UTC)


 * Since that's a government press release and therefore public domain, I've spliced that paragraph into the relevant section of the article. :) Bryan 19:52, 12 Jun 2004 (UTC)

It may or may not be appropriate to delete this section: A paper detailing the Cassini GR experiment was submitted to GR archives at about this same time (Oct 2003), then withdrawn by John Anderson. http://arxiv.org/abs/gr-qc/0308010 "Improved Test of General Relativity with Radio Doppler Data from the Cassini Spacecraft" Since the paper has been withdrawn, unless there is a peer reviewed paper supporting this story, it should probably be deleted.


 * I would agree, we might want to at least reword it. Currently, "gr-qc" has no follow up article on this, so we have no idea what the result of the experiment is. Awolf002 00:35, 25 April 2006 (UTC)

Misc
I removed the "former" from in front of "Soviet Union" in reference to the Phobos probes. Those probes were launched by the Soviet Union, which still existed at the time. Nitpicky, yes...but true. Jumbo 13:29, 1 Jul 2004 (UTC)

=Article, Meta, Wikipedia etc=

References for Featured Article status
If this had inline references, this could easily became a FA. Anybody would be willing to fix this?--Piotr Konieczny aka Prokonsul Piotrus Talk 22:34, 29 January 2006 (UTC)
 * If you feel that information that should be referenced is not, either flag the article as needing more references (I can't remember the template name), or just write here which stuff should have references. The latter would be better I think. There are about 8 inline references for the instrumentation, which is pretty good. JamesHoadley 08:24, 30 January 2006 (UTC)
 * Oh, I didn't notice them. Well, if they are converted to proper Footnotes, we can go for FAC.--Piotr Konieczny aka Prokonsul Piotrus Talk 01:12, 31 January 2006 (UTC)

GA Re-Review and In-line citations
Note: This article has a small number of in-line citations for an article of its size and currently would not pass criteria 2b. Members of the WikiProject Good articles are in the process of doing a re-review of current Good Article listings to ensure compliance with the standards of the Good Article Criteria. (Discussion of the changes and re-review can be found here). A significant change to the GA criteria is the mandatory use of some sort of in-line citation (In accordance to WP:CITE) to be used in order for an article to pass the verification and reference criteria. It is recommended that the article's editors take a look at the inclusion of in-line citations as well as how the article stacks up against the rest of the Good Article criteria. GA reviewers will give you at least a week's time from the date of this notice to work on the in-line citations before doing a full re-review and deciding if the article still merits being considered a Good Article or would need to be de-listed. If you have any questions, please don't hesitate to contact us on the Good Article project talk page or you may contact me personally. On behalf of the Good Articles Project, I want to thank you for all the time and effort that you have put into working on this article and improving the overall quality of the Wikipedia project. Agne 01:09, 26 September 2006 (UTC)

Talk refactored
I moved the sections of this talk page around, and created two main categories. Some minor (e.g. spelling) changes to talk to improve clarity. Matt Whyndham 12:29, 30 August 2007 (UTC)

Old talk
Well, shoot! I seem to have screwed something up here and lost the article entirely. Yaohua2000 used copy and paste rather than the "move page" function to move Cassini-Huygens Mission here, which left the article's history behind, and I was trying to rectify that. Bryan 01:25, 12 Mar 2004 (UTC)


 * Uh-oh, alright. I don't know what to say except good luck. Please note, Yonghua moved the "Cassini probe" page to "The Cassini-Huygens Mission" earlier today. I subsequently moved it to "Cassini-Huygens Mission" as the the "The" was plainly superfluous and then tried to go through various other entries to make sure the wikilinks were up-to-date, esp. those with double redirects. Some time later Yonghua moved the page to just "Cassini-Huygens". Okay, I suppose, but so much for the wikilinks I was trying to update. Why he then altered the Cassini disambig page to point to "The Cassini-Huygens Mission" is beyond me. At this point, I have no further intention to waste any time on this and will get back to work at the office, working on software related to, ahem, the Cassini-Huygens Mission. - Rbs 01:30, 2004 Mar 12 (UTC)


 * I've posted on the Village Pump, and I think I'm going to go on IRC now to see if there are any developers I can ask about this. Drat, drat, drat. Bryan 01:32, 12 Mar 2004 (UTC)


 * Okay, I'm suitably embarassed. It seems that it was simply my browser cache preventing me from seeing the history, nothing actually went wrong. Embarassed, and also relieved. Whew! :) Bryan 01:38, 12 Mar 2004 (UTC)


 * No. It looks like Eloquence fixed it, I assume using an admin tool. - Rbs 01:54, 2004 Mar 12 (UTC)


 * Actually, I think he was just reverting the article; I didn't do that before I moved it, so there would have just been a #REDIRECT there if everything went correctly. Bryan 02:05, 12 Mar 2004 (UTC)

Article picture
I don't understand why the picture for this article is so teeny. I made it a bit bigger to fill the large blank void next to the index but someone changed it back. Are people really viewing this page at like 640X480 or something?


 * I guess that was me (your sig with date is missing, so I'm unsure). If you want to see the full sized picture, you can click on it. So, the size of the picture in the text should be set to fit the "flow" of the text. In my oppinion it was too large and "squeezed" the TOC. Anybody else have an oppinion? Awolf002 15:46, 9 Nov 2004 (UTC)

pictures
This spacecraft has taken the most extraordinary pictures of the Saturnian system, shouldn't we have an article about the Cassini pictures? I never saw pictures like the ones of this spacecraft. most seem pure imagination, but are real. -Pedro 15:10, 25 October 2005 (UTC)
 * I think that the commons page for Cassini-Huygens is the closest thing. I've been wondering lately if WP should have some articles based solely around the images, but that's more magazine style, not Encyclopedia style. (I just added a link to the commons page in the article.) JamesHoadley 08:24, 30 January 2006 (UTC)

Huygens descending--artwork
Came across a new piece of artwork on NASA's site. I don't know enough to know if it's better than the one we have here, although its skies appear even less dark and smoggy. &mdash; Knowledge Seeker &#2470; (talk) 11:07, 10 Jan 2005 (UTC)


 * Most of the artworks are not accuracy enough to the fact. Actually, Saturn will never rise up the horizons at the landing site. But almost all artists make Saturn visible in their work. &mdash; Yaohua2000 16:15, 2005 Jan 10 (UTC)

Thanks for letting me know, Yaohua. That's too bad&mdash;I would have thought they would have made a better effort to be accurate. &mdash; Knowledge Seeker &#2470; (talk) 17:28, 10 Jan 2005 (UTC)

Huygens
Does anyone else think maybe we should move the section on the Huygens probe off to its own article? There's going to be a huge amount of information added in the next couple weeks and the article is already nearly 50Kb long....--Deglr6328 08:01, 9 Jan 2005 (UTC)


 * I agree with Deglr6328. Also, how about merge the timeline with the separated main articles? &mdash; User:Yaohua2000 13:39, 2005 Jan 9 (UTC)


 * Unless, of course, Huygens pulls a Beagle or Genesis and is swallowed by Titan without a trace of information coming back. :) Even so, splitting off the existing Huygens material from this article would significantly reduce its bulk; I'd support such a move. Bryan 18:01, 9 Jan 2005 (UTC)


 * A Genesis? Most of the information in Genesis is coming back. The difference with Huygens if that happens is that no information will be coming back. bob rulz 19:16, Jan 9, 2005 (UTC)


 * I was originally just going to say "pulls a Beagle", but I didn't want to seem like I was picking on Europe. Genesis was a similar enough recent crash to serve as a NASA analogue so I threw it in too. :) Bryan 00:07, 10 Jan 2005 (UTC)


 * However, as Bob points out, we got information back from Genesis - many of the aerogel particle traps were intact post landing and not thought to have been damaged or contaminated during the crash. It wasn't a total wash.  Not that this takes anything away from ESA for Beagle2, either; BBC reports that some of our Mars Global Surveyor imaging may show Beagle2 landed close to the planned site on the Martian surface - http://news.bbc.co.uk/1/hi/sci/tech/4542174.stm Vfrickey 06:54, 4 Jun 2008 (UTC)


 * Sounds good to me too. I support. &mdash; Knowledge Seeker &#2470; (talk) 02:48, 10 Jan 2005 (UTC)

Since nobody has given any cries of outrage at this idea, I'm going ahead and splitting the article. Huygens probe was a redirect to this article, so I'm using that as the main article for Huygens. Bryan 06:00, 13 Jan 2005 (UTC)

The End of Cassini
What is to become of Cassini at the end of the mission in 2008? After it performs its final task (what is that, by the way?), is it going to remain in orbit of Saturn forever? Or will it fly off into deep space? Or will it crash into Saturn or Titan? (unsigned)


 * It would probably be crashed into Saturn, assuming that they don't approve an extended mission. I wouldn't be surprised if they performed an extended mission (many of these interplanetary probes have been getting extended missions lately; the rovers on Mars, Mars Global Surveyor, Galileo, etc). bob rulz 21:09, 23 September 2006 (UTC)


 * There is probably good cause to put in a new article or subsection for the Cassini ultra-extended mission. There is talk about doing a gravity-assist maneuver and flinging it back toward Jupiter (or, at least, Sun-bound) to keep it from crashing into Titan or Enceledus. Here's a summary of the various options being looked at: http://www.sstd.rl.ac.uk/news/cassini/mission/ext.html 147.145.40.43 18:27, 30 November 2006 (UTC)


 * That's a good summary, and pretty close to the horse's mouth. The decision will be based on the science return for the expended resource (i.e. keeping the mission ops team together for the extra year or whatever).  It isn't really about whether other missions have been extended in the past.  Matt Whyndham 11:54, 30 August 2007 (UTC)


 * Not too far outside saturn's gravity well are the Saturn Trojans possibly remnants of the early solar system and objects like Charon that put out cometary discharges. and a good place to die in the end for a plutonium laden spacecraft. could we touch Cassini down on a smaller trojan? we did it with NEAR.--Infocat13 02:23, 25 January 2007 (UTC)  (spelling cleaned by Matt Whyndham 11:55, 30 August 2007 (UTC))


 * Crashing/landing on a moon is unlikely to be favoured because of the risk of biological contamination. Matt Whyndham 11:51, 30 August 2007 (UTC)

a mission to crash the megabomb that is the Cassini probe (it carries almost 3000x the amount of plutonium of the largest nuke ever detonated on earth) into the hexagonal opening at Saturn's pole in an attempt to create a 'second sun' and make it possible to terraform Saturn's moon Titan, maybe? 86.135.164.200 13:01, 5 August 2007 (UTC)


 * A 'formula quantity' of plutonium-239 is about 6.7 kg or 14 lb. That's what's in your "average" fission weapon or primary for a thermonuclear weapon (well, maybe not that much, with good tampers, etc).  The Cassini probe has 72 lb. of plutonium in it, or about five average-sized nuclear weapons' worth - not 3,000.  Efficiency limitations prevent significant increases in nuclear yield past four formula quantities of Pu-239 - 25 kg or 55 lb. for a yield in the neighborhood of 100-200 kt.  The French MR31 missile warhead, probably the largest pure plutonium nuclear weapon built, may have had close to this much Pu-239, and had a yield of 120 kt.  Moot point though, as Matt points out below. vfrickey 17:05, 2 July 2008 (UTC)  —Preceding unsigned comment added by Vfrickey (talk • contribs)


 * That's just comic-book garbage. The RTG's on Cassini are not explosive.  A very specific configuration of material needs to happen for fissile material to be made into a "megabomb".  See Nuclear weapon design. Randomly throwing it at a planet isn't among the options.  Matt Whyndham 11:51, 30 August 2007 (UTC)


 * Where has all this "Lucifer Project", "2nd Sun" stuff regarding Cassini come from? Why is there concern around the amount of plutonium on this probe in relation to previous missions? Thanks —Preceding unsigned comment added by 194.221.40.3 (talk) 12:44, 23 May 2008 (UTC)


 * There was a grassroots protest movement aimed at scrubbing the launch of Cassini unless (as Michio Kaku suggested) the RTGs onboard could be replaced with solar arrays, fuel cells, or a combination thereof. This despite the fact that the fuel in the RTGs (plutonium-239 oxide) was fabricated as refractory ceramic fuel elements with elaborate graphite "aeroshells" surrounding them, so that (a) exposure of the plutonium fuel during a re-entry (itself incredibly unlikely) would be highly unlikely to occur, and (b) if it did occur, the plutonium fuel would be in a form that would break up (IF it broke up) into small clumps, not finely distributed powder of the sort required to cause a toxicity problem.  This whole "megabomb" trope comes from the fact that 72 pounds of plutonium is distributed among the three RTGs in Cassini.  Read Carey Sublette's High Energy Weapons Archive, 4.2 "Fission Weapon Designs," however, for a good feel of the effort required to create a nuclear detonation with plutonium.  You just can't get a nuclear detonation by randomly crushing plutonium - there would have to be explosives to compress the fissile plutonium past its critical mass/density. vfrickey 16:23, 2 July 2008 (UTC)

Good News! It's an extended tour! Horray!!! --122.105.115.72 (talk) 02:59, 15 November 2008 (UTC)

RTG
Has a decision been made to crash Cassini into Saturn yet? I didn't think so. Also, if this is done the reasoning is about biological contamination, not radiological. (re main article on 17 Sept 06) 80.177.152.35 23:33, 16 September 2006 (UTC)
 * It seems to be the most plausible outcome now according to the possible Solstice Extended Mission from 2010 to 2017--pending its approval from NASA. Refer here: Cassini Extended Missions PDF --Marsbound2024 (talk) 01:06, 18 August 2008 (UTC)

Explanation of style change
I placed the possessive form back in roman text (Cassini's → Cassini's). The Chicago Manual of Style (15th edition) recommends: "As with plurals, when an italicized term appears in roman text, the possessive s should be set in roman." They give the following examples: "the Atlantic Monthly ' s editor" and "Gone with the Wind ' s admirers." This is reasonable since the ' s is not actually part of the title and can help avoid ambiguity. I welcome discussion if anyone is opposed to this. &mdash; Knowledge Seeker &#2470; (talk) 19:23, 15 Jan 2005 (UTC)
 * IMHO it should be itallicised "s", like Atlantic Monthly's, simply because it's more readable on the web. I'm not sure if there is an overriding style guide on this (like an official Wikipedia policy or Web Style guide), but failing that any Manual of Style will do. JamesHoadley 08:24, 30 January 2006 (UTC)


 * Cassini shouldn't be italicized in the first place. NASA doesn't do so on its website for Cassini. Nor does the ESA. It's also not done consistently in the article. Starfire209 (talk) 13:12, 13 March 2008 (UTC)
 * Nevermind. Although the space agencies don't italicize spacecraft names, it appears that style manuals do. Starfire209 (talk) 14:02, 13 March 2008 (UTC)

Deletion of Cassini–Huygens abbreviations
For those who may be interested, there is a discussion currently over here at AfD about whether the Cassini–Huygens abbreviations article should be deleted. -R. S. Shaw (talk) 02:18, 14 April 2008 (UTC)


 * That article has been merged into this one. Protonk (talk) 18:01, 24 April 2008 (UTC)

Professor Kaku wildly guessed? (Unencyclopedic)
I manually undid the revision at 04:31, 3 February 2008 by user at IP 124.187.218.119. I suspect that while it's appropriate for the article to say that a point of view derided another point of view, it is not appropriate for the article itself to deride a point of view. --James-Chin (talk) 19:32, 25 June 2008 (UTC)

Saturn Solstice Extended-Extended Mission
No, not the car, but the fact that Cassini scientists have proposed a seven year, second extension for the Cassini probe. Although this is of course up to funding and thus up to NASA for approval, this extension would put the decommissioning date at around May 23, 2017 or so instead of 2012. 2012 seems to be a bit of an older date and thus I think 2017 should be used instead. Of course, who knows what NASA intends to do as far as decommissioning Cassini, but the project scientists want to see it out until the Saturn solstice (May 23, 2017). Cassini Extended Missions PDF —Preceding unsigned comment added by Marsbound2024 (talk • contribs) 01:02, 18 August 2008 (UTC)

Signature disc
Worth mentioning the disc containing signatures on the probe? Google-cached ref- 69.145.66.213 (talk) 15:24, 31 October 2008 (UTC)


 * I will look at adding a section mentioning the disc in the near future. The volunteer effort to collect and scan signatures from around the world was sort of a big deal back then. It never got as much attention in the press as the protests against the plutonium RTGs, but for many it was a grand thing worth doing. I think it's definitely noteworthy enough to include in the article. [[Current URL with the relevant source material at JPL.]] JeffTracy (talk) 06:58, 25 April 2011 (UTC)

The Tense of Statements
There are still sentences in this article that are in the future tense about things that "will happen" or "will probably happen" - whereas in reality, they have already happened, and in fact, tasks have been successfully completed. Clearly, that kind of expressions in the future tense are erroneous - and I doubt whether they should have been written in the future tense to begin with. It gives something that requires future effort. Anyway, reading such future-tense sentences is like reading, "If all goes well, man will set foot on the Moon by the end of the decade," which can surely be found in old books and magazines.98.67.164.50 (talk) 16:51, 21 November 2009 (UTC)

An excellent source: describing the complex orbital dynamics--"an astonishingly complex exercise in Keplerian physics and geometry"
This article, A Saturn Spectacular, With Gravity’s Help, which was published in the New York Times on 19 April 2010, is an excellent discussion (in intelligent layman's language) of the Cassini's three major missions [ 1) 2004-2008, high-priority targets in 75 orbits; 2) 2008-2010: 64 similarly-sized orbits with differing orientations; and 3) another 22 orbits using Titan's gravity to flip itself from one side of Saturn to the other]. It is a particularly useful source for explaining, and graphically illustrating, the complex orbital dynamics that it terms: "an astonishingly complex exercise in Keplerian physics and geometry."  Very interesting.  N2e (talk) 21:41, 21 April 2010 (UTC)

Cassini–Huygens Swan Song
I was curious about NASA's plans for the Cassini–Huygens spacecraft final exit, I realize those plans are flexible and determined by critical issues like low fuel and funding however it wasn't so long ago that NASA engineers were toying with the idea of letting Cassini break Saturn orbit and drift away to explore and eliminate the possibility of contaminating Saturn's moons. Exploring a similar idea could they still break orbit and aim Cassini back towards Jupiter which after some extra scientific exploration slingshot the spacecraft on a suicide plunge towards the Sun, I realize this is a lot to ask with current fuel levels -however if future spacecraft survival depends on limiting travel time via gravitational slingshots & fast speeds courtesy of our Sun lets see how fast (think speed record)and how long (as in not designed for) the Cassini–Huygens can survive its fiery plunge. Jalanp2 (talk) 21:02, 14 July 2010 (UTC)


 * The problem Cassini has is propellent. This is a shame, because with its 3 RTGs, it could function until about 2050.  Basically, Cassini encounters moons often.  These moons change its orbit.  This is generally a good thing, because Cassini makes slight adjustments which the flybys amplify, so Cassini can go all over the Saturnian System at little expense of fuel.  The trouble is that when the propellent runs out, Cassini will be thrown around until it crashes into something such as Saturn, 1 of its moons, or a ring, or it will be ejected from the Saturnian System.


 * Leaving Saturn with enough velocity to make it to Jupiter so it can end up in the Sun would be extremely difficult to accomplish. Considering that the RTGS have decades of life in them, it might be better to maneuver Cassini so that a flyby of a moon such as Titan ejects it from the Saturnian System and throws it into the L2 point of Saturn where it can observe the Saturnian System for decades.  Another Possibility is to park Cassini in the L4 or L5 point of Titan.  Because of the gravitational perturbations of the other moons, this would be stable for less than a decade, but it would still allows observations from within the Saturnian system into the 2020s.


 * 64.175.35.23 (talk) 07:52, 1 February 2011 (UTC)

Questions about validity of Titan Surface photos
Please either remove the information about the successful relay of the pictures (politically correct solution), or else include referenced information about questions about the validity of that claim.

Under "Huygens lands on Titan", it is stated without proper support that "Cassini successfully relayed 350 of the pictures that it received from Huygens of its descent and landing site". This conclusion has been contested, published at the Virginia Academy of Sciences.

The Titan surface photos that were published show a smoke plume that blows in the wind, an unlikely phenomenon. The photos are rather identified as photos from a specific location on Earth. It is an open question why they were published as being successfully transmitted.

12.160.67.170 (talk) 13:46, 8 December 2011 (UTC)mjr


 * Uh, that page is very obviously a joke. - Parejkoj (talk) 15:08, 8 December 2011 (UTC)


 * No, the Virginia Acadamy of Sciences is a valid reference, not a joke site. Generally, in science, claims are allowed to be contested.  This is especially true of claims by governmental agencies and NGOs. 12.160.67.170 (talk) 15:23, 8 December 2011 (UTC)MJR 8 Dec 2008

Redirect of Narrow Angle Camera
Anyone know why Narrow Angle Camera redirects here? Doesn't really seem appropriate given that multiple interplanetary spacecraft Have NACsGeorgeryall (talk) 21:08, 14 March 2012 (UTC)

The storm is 8,000 kilometers across?
The article says:
 * The storm is 8,000 kilometers (5,000 mi) across

Titan is only 2500 km in radius. That would cover the entire southern hemisphere.

Just granpa (talk) 23:26, 9 August 2012 (UTC)


 * Hello. It is in reference to a storm in Saturn, not Titan. Cheers, BatteryIncluded (talk) 00:47, 10 August 2012 (UTC)

Tests of the General Relativity - Contradiction
The section seems to have a contradiction:

"This is currently the best measurement of post-Newtonian parameter γ; the result γ = 1 + (2.1 ± 2.3) × 10−5 agrees with the predictions of standard General Relativity."

"Although some measurable deviations from the values that are calculated using the General Theory of Relativity are predicted by some unusual cosmological models, no deviations were found by this experiment."

Please correct or clarify. Thanks, BatteryIncluded (talk) 15:34, 11 March 2013 (UTC)


 * It seems consistent to me... although perhaps could be better worded. (2.1 ± 2.3) is consistent with zero (the value predicted by GR).  Some cosmological models predict greater deviations than 2.3x10^-5, ergo they would be detectable.  However, the measured value is still consistent with zero (i.e. less than one sigma from zero).  Am I missing something? Sailsbystars (talk) 15:42, 11 March 2013 (UTC)


 * Not argueing the math; It is the technical/statistical languange (deviation) that makes it confusing. I am suggesting to state in no uncertain terms whether the experiment agrees or not with the theory. On one side the article states that the radio signals travelled trough bent space-time, and then it states there were no deviations detected. Clarity to non-physicists readers should be the goal.  Thanks, BatteryIncluded (talk) 16:57, 11 March 2013 (UTC)


 * The "no deviations were found" refers to the deviations predicted by the alternative cosmological models, not the GToR. I went and changed it to "..no deviations of this type were found by this experiment." Remove the warning if you are satisfied. (not logged in) 16:10, 19 May 2013 (CET)

"Gestation"
Sorry, this made me laugh. I have changed the word "gestation" in the first paragraph to "development". — Preceding unsigned comment added by 68.40.190.237 (talk) 22:30, 21 July 2013 (UTC)

Success or Failure
I am not an expert on this but I am watching a documentary on the probe. It is not clear whether or not the mission was a general failue or success. Could someone put in it a simple paragraph confirming whether or not the mission was deemed a success or failure. — Preceding unsigned comment added by 92.28.250.78 (talk) 20:53, 7 June 2012 (UTC)

Cassini's mission is to deliver lots of data on the Saturnian system, with the data being studied back here on Earth. That mission has been accomplished. It has been successful. It'd only be a failure if it returned no data. — Preceding unsigned comment added by 24.223.130.60 (talk) 00:32, 10 January 2014 (UTC)

Errors regarding RTG and Earth flyby
The article references for those two numbers some russian news website (http://en.ria.ru/analysis/20091111/156797969.html). This website got both values wrong.

1) The earth flyby was 1.171 km (727 mi):
 * http://saturn.jpl.nasa.gov/mission/quickfacts/
 * http://scholar.lib.vt.edu/theses/available/etd-120899-134345/unrestricted/06chapter_3.PDF
 * http://sci.esa.int/cassini-huygens/31240-getting-to-saturn/

2) The mass of the plutonium on the spacecraft was not 33kg Pu-238 as stated. Each RTG has 10.9kg Plutoniumdioxide:
 * http://sci.esa.int/cassini-huygens/35026-engineering/?fobjectid=35026&fbodylongid=1629
 * "The power is derived from three Radioisotope Thermoelectric Generators (RTGs), each of which use heat from the radioactive decay of 10.9 kg of plutonium dioxide..."


 * http://sci.esa.int/cassini-huygens/1975-vorbemerkung-dieser-text-ist-die-bersetzung-eines-vom-jpl/
 * "Ein RTG ist mit etwa 10,9 kg Plutoniumdioxid ..."


 * http://saturn.jpl.nasa.gov/spacecraft/safety/eisss1.pdf
 * "Each of these RTGs contains approximately 10.8 kg (24 lb) of plutonium dioxide..."

PuO2 is made of Pu with an atomic weight of 244 and 2xO with an atomic weight of 2x16. This gives, that Pu makes 86,89% of the mass, resulting in only ~9,47kg of Plutonium (all isotopes). For the concentration of only Pu-238 you have to know the isotope concentrations (pure Pu-238 (which it is not) would result in 9,43kg Pu-238). There are also a few hundred grams of Pu for the heating unit.

Nabrufa (talk) 22:05, 1 July 2014 (UTC)

Enceladus x Europa
"" Nearly a decade after entering orbit, on April 3, 2014, NASA reported that evidence for a large underground ocean of liquid water on Enceladus, a moon of Saturn, had been found by Cassini. According to scientists, evidence of an underground ocean suggests that Enceladus is one of the most likely places in the Solar System to "host microbial life". ""

This sentence is generally wrong, because it was Europa where Cassini found the fluid water under thick sheets of ice. Matyáš Cigler 77.186.84.160 (talk) 23:37, 3 November 2014 (UTC)


 * Hello. Both Europa and Enceladus seem to have an ocean under the ice sheet. Please see: Enceladus. Cheers, BatteryIncluded (talk) 23:50, 3 November 2014 (UTC)

Thank you very much for the answer, I realised later how wrong I am, anyway we all are still learning. 77.185.40.59 (talk) 08:37, 6 November 2014 (UTC)

Observations of Europa
Just to say, I think in they Jupiter flyby section, the article should mention that Cassini also observed Europa, from a distance, during its flyby. These observations were re-analysed recently and used to give constraints on water plumes from Europa. See http://www.jpl.nasa.gov/news/news.php?feature=4417 Robert Walker (talk) 10:12, 16 June 2015 (UTC)

External links modified
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Suggestion: Remove the infographs
These two  images should be removed, in my opinion. They are too "loud" and make the article seem less encyclopedic. The first one is placed in a horrible position and that's another reason why it should go. Huritisho 06:56, 6 October 2015 (UTC)
 * Agreed. Removed. In fact, it would be a good idea to go through Wikipedia and remove all "infographics".  — Aldaron • T/C 12:30, 6 October 2015 (UTC)

NASA-TV/ustream (10/26/2015@2:00pm/et/usa) - "Enceladus FlyBy" Teleconference.
NASA-TV/ustream and/or NASA-Audio (Monday, October 26, 2015@2:00pm/et/usa)   - NASA will detail an "Historic FlyBy" through a "plume of icy spray" of Enceladus on 11:22 am/et/usa, Wednesday, October 28, 2015 - Enjoy! :) Drbogdan (talk) 02:14, 23 October 2015 (UTC)
 * BRIEF Followup - REPLAY LINK (Audio; 43:41) => http://www.ustream.tv/recorded/76308203 - Enjoy! :) Drbogdan (talk) 19:39, 28 October 2015 (UTC)

Semi-protected edit request on 26 April 2017
It says ( is a Flagship-class NASA–ESA–ASI robotic spacecraft) It should say It is a Flagship-class NASA–JPLESA–ASI robotic spacecraft as JPL did some of this as well 198.52.13.15 (talk) 10:35, 26 April 2017 (UTC)
 * JPL is a NASA field center, so that statement would be redundant. ChiZeroOne (talk) 00:36, 27 April 2017 (UTC)
 * Pictogram voting comment.svg Note: Marking as answered. Also the article is no longer protected. regards,  DRAGON BOOSTER   ★  07:08, 28 April 2017 (UTC)

Use of future
"On October 28, 2015, Cassini performed a close flyby of Enceladus, coming within 49 km (30 mi) of the surface, and passing through the icy plume above the south pole.[69] Images and other data from the flyby will be received within 48 hours.[69]"

I suppose this was written on October 28, 2015 and that "will be" made sense only then. Sentences in Wikipedia should be written for a longer life span than one day. Or is there another meaning I do not understand? (My own language is French.) --Dominique Meeùs (talk) 09:50, 14 April 2017 (UTC)

You're right. I've removed that sentence. The downlink already happened, and I don't think Wikipedia needs to the planed times for a downlink. (Especially since it happened almost two years ago.)

Fcrary (talk) 00:30, 31 July 2017 (UTC)

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The flyby sections
If I'm not mistaken, Fotaun was the one who added a couple of subheadings about the flybys of the moons on Saturn. That is unnecessary detail. Cassini has made like dozens or even hundreds of flybys and it is not relevant to cite them. We could just say that the probe made several flybys of the moons, but we don't need a subheading for each one of them Huritisho 17:52, 17 October 2015 (UTC)

A separate "list" article with a table of all the flybys might be useful and more appropriate. Fcrary (talk) 20:29, 2 September 2017 (UTC)

Instrument providers in the overview section
I think the description of instrument providers should be abbreviated and/or moved out of the overview section. Currently, it contains a long and detail list of the contributions from ASI (which is also overstated, e.g. they did not provide the entire radar instrument.) Parts of instruments were provided by a very long list of European countries; Germany and the United Kingdom were the principle institutions for two of them. A balanced description of all the instrument providers, at this level of detail, does not belong in the overview section. Fcrary (talk) 20:29, 2 September 2017 (UTC)

Pre-End of Mission Edits on September 15th, 2017
It will be a moot point in a few hours, but I wanted to say that those who edited the article before 11:00 UTC on September 15th, 2017, to discuss the mission in the past tense should double check their clocks. Only when https://saturn.jpl.nasa.gov/mission/grand-finale/cassini-end-of-mission-timeline/ lists the "Final Signal Sent from Saturn" time as 0 should the mission be considered over and the probe gone. — Preceding unsigned comment added by KurisuYamato (talk • contribs) 05:51, 15 September 2017 (UTC)

Time active in space
In the second paragraph, it says "Cassini was active in space for more than 18 years." Should this not say 19 years? Master of Time  ( talk ) 21:08, 15 September 2017 (UTC)

Total mission cost in 2017
JPL has put up a revised mission cost that includes extended missions. Approx. $3.9 Billion

https://saturn.jpl.nasa.gov/mission/grand-finale/cassini-quick-facts/

I leave that for someone to properly insert into the article and cite.

--23.119.204.117 (talk) 15:49, 19 September 2017 (UTC)

Results
The mission was successful beyond belief and grabbed the attention of the public in general, as well as of many editors. But it is too common that when a space mission is finished, editors' interest fades and the trailing scientific papers are hardly looked at by editors. Now that the fireworks are finished, I am requesting that more editors look at the new data, the whole point of this mission. There is a wealth of recent reports in "Google Scholar" (many many more to come) that you can use to enrich wikipedia's articles on Saturn's system. For starters you can mine data from this one: https://arxiv.org/ftp/arxiv/papers/1510/1510.05870.pdf

This is true for every past space mission. There is a lag between end of the mission(s) and publishing of the research, so I encourage everybody to look at the results of past missions and update Wikipedia accordingly. Cheers, BatteryIncluded (talk) 14:19, 24 September 2017 (UTC)

End of mission phrasing
In the introduction, the article says, "...until September 15, 2017, on which date Cassini was de-orbited to burn up in Saturn's upper atmosphere." That's not quite true. The drop into the atmosphere at the end was due to a distant Titan encounter on September 11, and the last spacecraft maneuver to set that up was in July. Is there a better way to phrase the introduction, since "was de-orbited" implies some active event on the 15th. Fcrary (talk) 00:15, 13 October 2017 (UTC)

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misson progress
Can please add somebody the very nice mission progress from the German Wiki with is real nice to follow up. The special dates here mention can also be added, but atm it is a bit 'staccato'. Thanks in advance --  LAZA74 (talk) 11:52, 23 December 2017 (UTC)

Gravity assist details
Gravity assist includes : but that graphic shows Venus gravity assists of nearer 3.0 km/s rather than the 7.0 km/s quoted in the article. - Rod57 (talk) 14:15, 17 January 2018 (UTC)

Why was it launched on Titan IV
Titan IV says "It (C-H) was the only use of a Titan IV for a non-DOD launch." - it would be nice if this article explained why. Perhaps it was the only US launcher that could launch the ~23,000 kg mass of the 3rd stage Centaur to get it out of earth orbit ? - Perhaps it was originally intended to be launched on Shuttle-Centaur until that was canceled ? - Rod57 (talk) 13:58, 17 January 2018 (UTC)


 * The Cassini-Huygens probe was launched by the Titan IV-Centaur (rocket) because it was the world's ONLY unmanned rocket with enough overall energy to send the (heavy) space probe off our planet and into a trajectory that would take it to Saturn. Now the Titan IV is no longer made, and all that we had have already been expended.
 * A little bit of history here: A Saturn V or a Saturn IB-Centaur could have done the job, but the last Saturn V was fired in 1973 to launch the Skylab, and the last Saturn IB was fired in 1975 to carry the Apollo-Soyuz mission. No Saturn IB - Centaur was ever built.
 * After the Space Shuttle Challenger self-destructed in 1986, all considerations of putting a Centaur rocket into a Space Shuttle were discarded. Also, this was after an upgraded version of the Centaur had been planned and designed. The new Centaur was going to carry 75 percent more LOX and liquid hydrogen than the previous version, and over $750 million had been spent on the R&D for this new rocket. The idea at that time had been to have enough energy to send Cassini on a straight shot to Jupiter, and thence a gravitational assist to Saturn - exactly what had been done by Pioneer 11, Voyager 1, and Voyager 2.
 * After all of this, the Titan IV-Centaur did not have enough energy to send Cassini on a straight shot to Jupiter, and thence to Saturn. A lot of careful planning was done, including a lot of computer simulations, and those showed that it was possible to use the rocket to send Cassini inwards towards Venus, fly past Venus once, and then over a year later, past Venus again, and then months later, past the Earth once, gaining enough momentum to reach Jupiter with enough velocity to continue on to Saturn. This basic trajectory to Jupiter is called "V-VEGA" = "Venus-Venus-Earth-Gravity-Assist". [The previous space probe, Galileo, had used "VEEGA" = "Venus-Earth-Earth-Gravity-Assist" to reach Jupiter, but with a lower velocity at Jupiter, so that it could go into orbit there.] 47.215.180.7 (talk) 08:35, 18 January 2018 (UTC)

The firing of the retrorocket to put Cassini into orbit
The firing of the retrorocket to put Cassini-Huygens into orbit around Saturn is not completely described. Nowhere in this article does it say really how long that small rocket was burned. I just remember that it took quite a while, but I cannot remember if it was for 60 minutes, 90 min., 120 min., or whatever. I do know that 460 newtons is not very much thrust. In describing other space missions, thrusts are described in kilonewtons, meganewtons, and giganewtons. One newton is the amount of constant force that will accelerate one kilogram of mass by one meter per second per second. That is tiny. A related tiny unit is the unit of pressure, the pascal, which is one newton per square meter.47.215.180.7 (talk) 08:54, 18 January 2018 (UTC)


 * It was a 96 minute burn. Do we need that level of detail? If so, what else is missing? I'm afraid I'd have to dig for a citable reference; I work on the mission and happened to have the relevant spreadsheet in front of me. I'm sure the timeline is out there in a public and citable form, but I 'd have to look. Relatively speaking, 460 N is quite a bit. You're thinking in terms of the rockets launch vehicles use. For the spacecraft itself, much lower thrust and acceleration is fine (actually, often good; I'd hate to put a deployed magnetometer boom or solar array under 20 m/s^2 of acceleration.) Fcrary (talk) 23:33, 20 January 2018 (UTC)

Weaseling
I would not have expected weasel words in an article about a satellite:


 * "The Flagship-class robotic spacecraft..."

--Mortense (talk) 13:12, 22 February 2019 (UTC)


 * Which of those do you think is the weasel word? - Parejkoj (talk) 18:15, 22 February 2019 (UTC)
 * Indeed, I'm not seeing anything wrong. Are you interpreting "Flagship" as being a weasel word? No, it is a classification, a specific type of NASA mission. — Huntster (t @ c) 23:11, 22 February 2019 (UTC)