Enceladus Flyby July 14, 2005

[nazcalito]

Here's some missing data for you to ponder. On July 14, 2005, Cassini was supposed to make its closest approach to Enceladus of the Saturn tour at 175 kilometers. It is now July 21, 2005. Where are the images from 175 kilometers away? Even looking at the raw images, all I can find is a handful of images, some totally black, and some of stars as if the camera was pointed the wrong way. There were only two pictures that showed any detail at all, both taken from about 500 kilometers away. The rest (those with any meaningful image) are from considerably further away (like 10,000 km)<br /><br />175 kilometers is close. NASA should have gotten detailed images. What happened? Did (as the starfield shots suggest) the camera get pointed in the wrong direction?<br /><br />

 

[vogon13]

Cassini was only within a 1000 miles of Enceladus for barely a couple of minutes. Camera takes 1 picture per minute. Other instruments were also in use to investigate atmosphere findings of previous fly by.<br /><br />High flyby speeds for all satellites interior of Titan's orbit. Look forward to slow flyby of Iapetus in 2007, lots of close-in pictures then.<br /><br />Sorry, nothing mysterious, no conspiracy here. Move along.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[tony873004]

The best thing about close flybs insn't the moment of closest approach, but the amount of time spent in the 10,000 +/- range.

 

[centsworth_II]

<font color="yellow">"Other instruments were also in use..."</font><br /><br />And due to budget restrictions, there is no dedicated instrument platform that can be used to aim multiple instuments at the target at the same time. The whole craft has to be moved to aim individual instruments, at which time the others are aimed away from the target.<br /><br />That's the real comspiracy, starving the science budget. <div class="Discussion_UserSignature"> </div>

 

[maxtheknife]

Hey Naz,<br /><br />Stop noticing NASA's incompetence, will ya?! <br /><br />Sheesh! How are they supposed to maintain the charade w/ folks like you paying attention? <img src="/images/icons/rolleyes.gif" />

 

[vogon13]

Relative motion and duration of flyby wouild have taxed a scan platforms' capabilities.<br /><br />View of Enceladus would have shifted nearly 180 degrees in just minutes. Camera exposure time is longish due to dim sunlight at Saturn's distance from sun further complicating picture taking sequence.<br /><br />And then some pinhead will ask why they didn't take a flash attachment. <img src="/images/icons/tongue.gif" /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[thechemist]

It seems you missed this thread : Enceladus, the Europa of Saturn<br /><br />The 2m/pixel resolution image of the surface is right there at the end of the thread, and it is amazing !<br /><br />They did a star occultation experiment during the flyby, that is why there are images of stars uploaded. <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[volcanopele2]

The highest resolution images were a ride-along with a UVIS occultation sequence. In this case, all optical instruments, like ISS, UVIS, and VIMS, were pointed at gamma Orionis. During this sequence, ISS snapped a picture every minute or so, knowing that only only one or two images would actually "land" on Enceladus, the others would just show gamma Orionis. Luckily we had two land on Enceladus, one in daylight, the other at night.

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>And due to budget restrictions, there is no dedicated instrument platform that can be used to aim multiple instuments at the target at the same time. The whole craft has to be moved to aim individual instruments, at which time the others are aimed away from the target.<br /><br />That's the real comspiracy, starving the science budget.<p><hr /></p></p></blockquote><br /><br />Actually, Cassini is one of the best-funded of NASA's recent missions. Some have referred to it as the last of the "Cadillac Probes" (those like the Voyagers and Galileo which were bristling with whatever instrumentation they could ask for), and of those probes, it is the most expensive yet, with a budget of over a billion dollars.<br /><br />The real reason wasn't money so much as engineering. After the problems with Galileo's very complicated system, and Voyager 2's jammed up scan platform, the engineers elected to observe the KISS principle, which every engineer knows means "Keep It Simple, Stupid". The KISS principle basically says that if you can do something simpler, do it, because it'll be less likely to get screwed up or break. Galileo was fabulously complex, and most of its brilliantly clever designs worked beautifully. One didn't, though, and the rest all suffered because of it: the collapsable high-gain antenna dish froze up and couldn't fully deploy. Cassini has a classic rigid dish, and all of its instruments are mounted directly on the spacecraft's long cylindrical bus. It need not worry about servomotors failing or joints locking up as lubricant freezes. Also, unlike its outer solar system predecessors, it does not need to fire engines to orient itself. It uses gyroscopes, just like the Hubble, Swift, Chandra, and dozens of other satellites in Earth orbit. This has an added bonus: Cassini can slew itself and all its instruments with remarkable precision. I don't think Voyager could have taken the amazing pictures of Iapetus' le <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[centsworth_II]

I base my comment about the scan platform on a webcast talk I saw by one of the cassini scientists. He was asked if there was anything the scientists wanted on Cassini but didn't get. He said they had all the science instruments they wanted. Then said, regretfully, I thought, that they really would have liked to have a scan platform. <br /><br />There may have been engineering problems. Money would be needed to solve them. But I'll follow the lead of the Cassini scientist and be gratefull that they got all the instruments they wanted, even if they can't be directed at a target at the same time. <br /><br />In any case, my intention was to confront the ridiculous "NASA is hiding something" conspiracy theory that pops up when a particular instument on Cassini is not used on the right target at the right time according to the conspiracy theorist. <div class="Discussion_UserSignature"> </div>