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NASA Space

Cassini's Elaborate Orbital Mechanics 116

Posted by kdawson
from the tour-engine dept.
jamie found an article at the NY Times about the extreme orbital mechanics gyrations required to extend the Cassini mission at Saturn by seven more years. Here's a graphic of the mission extension, which NASA took two years to arrive at. "The plans are for Cassini to keep working for seven more years, but it currently has only 22 percent of the maneuvering propellant it had when it started. Figuring out how to more than double the duration of the mission with less than a quarter of the fuel is hard. Cassini's orbital mechanics present an astonishingly complex exercise in Keplerian physics and geometry. The enormous array of science objectives and targets — moons, rings, Saturn itself — makes it one of the most complex missions ever flown. ... 'Without Titan,' Mr. Seal [Cassini's mission planning supervisor] said, 'we would go into one orbit around Saturn and be stuck there.' Thus Titan, in the argot of orbital mechanics, is Cassini's 'tour engine.' [T]he final 'reference trajectory' ... now includes 56 passes over Titan, 155 orbits of Saturn in different inclinations, 12 flybys of Enceladus, 5 flybys of other large moons — and final destruction."
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Cassini's Elaborate Orbital Mechanics

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  • by ItsJustAPseudonym (1259172) on Tuesday April 20, 2010 @02:15PM (#31913552)
    ...to see the software and user interface that NASA uses to plan the orbits? I wonder how much of it is automated and how much is interactive. We could envision a totally automated system in which they input a desired list of waypoints, some of which might have required time-windows, and the software cranks out the flight plan.

    Does anybody here have experience with this?
  • by sznupi (719324) on Tuesday April 20, 2010 @02:16PM (#31913558) Homepage

    Cassini spent a lot of time in the vicinity of Enceladus and its water geysers; another place where there could be life, with some traces of it hatched for the ride on our spaceship.

    Alas, there's way too litle fuel even for routes with lowest energy requirements [wikipedia.org] :(

  • The real news alert (Score:1, Interesting)

    by MyLongNickName (822545) on Tuesday April 20, 2010 @02:25PM (#31913666) Journal

    kdawson actually posted a story worthy of the front page of Slashdot. I acutally did a doubletake.

  • Re:I call bullshit (Score:3, Interesting)

    by geekoid (135745) <dadinportland.yahoo@com> on Tuesday April 20, 2010 @02:44PM (#31913904) Homepage Journal

    It's very simple:

    You have no fucking clue how this kind of science works, and you don't seem to remember the 'failures'

    But hey, you let your experience with fictional TV show dictate how you think of the world, because I don't think you could really do any better then that.

  • by dotancohen (1015143) on Tuesday April 20, 2010 @02:58PM (#31914044) Homepage

    Not for Cassini, but Linux Journal did a report on the UI that the Mars rover drivers use:
    http://www.linuxjournal.com/article/7570 [linuxjournal.com]

  • by Facegarden (967477) on Tuesday April 20, 2010 @03:00PM (#31914062)

    ...to see the software and user interface that NASA uses to plan the orbits? I wonder how much of it is automated and how much is interactive. We could envision a totally automated system in which they input a desired list of waypoints, some of which might have required time-windows, and the software cranks out the flight plan.

    Does anybody here have experience with this?

    As awesome as something like that sounds like it could be, we probably don't have much automation for that yet - it's probably just a bunch of physicists doing math on a computer.

    But if we do have or ever make something like that, it would probably be pretty awesome. I'm imagining a big 3d solar system view with all kinds of neat loopy lines for trajectories and such.

    The math is so complex though - you have to take relativity into account because time literally slows down the closer to a massive body you get. I've been reading a Brief History of Time lately and this shit is insane.

    Also... Rachel?
    -Taylor

  • by Coren22 (1625475) on Tuesday April 20, 2010 @03:22PM (#31914332) Journal

    My thought as well. How long after it enters the atmosphere, but before it breaks up will there be. Is it possible that it could end up "floating" on the atmosphere and not actually break up, that would be some great pictures. Though I am sure that is very unlikely. The most likely occurrence I see is that as the craft enters enough of the atmosphere to be called an atmosphere all the sensors would be ripped off from the deceleration and we would cease to receive signal from it.

  • by professorguy (1108737) on Tuesday April 20, 2010 @04:30PM (#31915146)
    Am I the only one who remembers the protesters around Cape Canaveral when Cassini launched? That's because its initial trajectory was unbelievably convoluted: the ship actually traveled to Venus first, got a gravity boost then traveled back out and used the Earth for its next boost.

    The protesters feared that a miscalculation could cause Cassini to re-enter Earth's atmosphere on this near-miss flyby and disgorge its thermopile of plutonium into the stratosphere.

    So it was a crazy flight from the very first day.

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