Fuel saving (semi)resonant close Titan appproaching orbit

[vogon13]

Not sure of the practicality of this, but with the Cassini extended mission coming up, wanted to throw this idea out.<br /><br /><br />A drawback of a ('regular') resonant orbit is that close approaches to the object you are in resonance with is forbidden, lest the gravitational perturbations knock you out of the resonance.<br /><br />A possible way out of this (in regards to Titan) is to be in a resonant orbit that consists of 2 orbits to complete the resonance.<br /><br />For instance, let's say we are approaching Saturn and pass Titan on the trailing hemisphere. We set the distance and inclination of our path such that we return to Titan (after an appropriate # of Titan orbits about Saturn) and this time, make a complimentary pass over the Titanian leading hemisphere. The distance and angle of this pass being such that it negates the effects of the first pass. Additionally, it is quite possible all the leading (or trailing) hemisphere passes have to be conducted while Cassini is approaching Saturn, and all the complimentary passes will have to be conducted by Cassini out bound from Saturn. The passes would be ~roughly 90 degrees apart relative to Satun, and does not really affect this idea beyond the regions on Titan's surface available for examination are moved a bit. <br /><br />Then we just alternate leading and trailing hemisphere flybys of Titan.<br /><br />Seems like this is a mimimal (relatively speaking) fuel type situation.<br /><br />Now, granted, the flyby geometries of these passes are very similar, so what science can we do in an orbit like this ?<br /><br />It turns out, the radar instrument can view Titan at a slightly different angle every pass. We can build up a series of parallel ground tracks and 'fill in the map' for the radar instrument.<br /><br />Just working this out in my head, in the simplest form of this resonant orbit, we can build up contiguous radar coverage in 4 large areas on the Titan surface.<br /><br />(radar instrument cannot look 'straigh <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>

 

[3488]

I like that Vogon,<br /><br />Also the alternate passes can also be headed slightly north - south so not only<br />would the SAR get to image a slightly different strip in the Titan tropics & mid latitudes,<br />also the entire polar regions would be filled in over time.<br /><br />The Equinox on Titan (northern Spring / Southern Autumn) will be in August 2009 <br />(four months earlier than Saturn itself), so using this very fuel minimal approach to follow <br />on Titan studies, we could also observe volatile migration between Titan's polar regions.<br /><br />Also because the longitudal difference will be fairly minor over alternate passes, mass <br />concentrations within Titan will be measurable.<br /><br />I cannot see why this could not work. There are no other really large moons to upset the<br />resonance over the relatively short term (perhaps only Rhea in the longer term).<br /><br /><img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> Happy Boxing Day everyone. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[vogon13]

Oh, forgot to add this part:<br /><br />If for some wild reason this idea is original with me, and is adopted by the Cassini crew, the cost for using this concept is one more close flyby of Iapetus.<br /><br />Use of this trajectory constitutes legal acceptance of this term and condition.<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>

 

[3488]

Don't also forget, when Cassini looks as though failure is approaching, the impact option <br />on Iapetus is to be kept open. <img src="/images/icons/laugh.gif" /><br /><br /><img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> Happy Boxing Day everyone. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[vogon13]

Don't hold your breath on switching burning up Cassini in the Saturnian atmosphere for zero scientific benefit to a highy interesting and informative study of the mysterious black crud's regeneration rate on Iapetus.<br /><br /><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>

 

[3488]

You think that is more likely. I agree with you 100% on that. <br /><br />Disposal into the Saturn atmosphere is about as useful as a chocolate kettle. <br /><br />I think really Vogon, a push for Titan & Iapetus studies in a vastly extended mission is worthwhile. <br /><br />I like the proposed Enceladus & Dione close encounters, they should still go ahead<br />no matter what, but after, implement your Titan idea with Iapetus encounter & <br />impact at the very end.<br /><br />I do not think the Saturn atmospheric entry will be of any scientific benefit what so ever.<br /><br />With Galileo at Jupiter, it was different as the HGA had failed, but if working an Io impact<br />was in my book of suggestions. An Iapetus impact IMO is a must fror the failing Cassini<br />(hopefully get real time images with the ISS Narrow Angle during approach).<br /><br /><img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> Happy Boxing Day everyone. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[jsmoody]

You should email your ideas to the Cassini team. I had an idea for the end of mission - Bring Cassini into the ring plane to try and get closeups of some of the ring particles. It would probably be the end of the spacecraft but it would be worth it even if they only got one or two good closeups. I emailed the idea to them and they responded that indeed, they were looking at that as a possibility for the end of mission among other options.<br /> <div class="Discussion_UserSignature"> No amount of belief makes something a fact" - James Randi </div>