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Cassini's Extended-Extended Mission, July 2010-June 2017
Phil Stooke
post Feb 5 2010, 07:28 PM
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"one of the driving considerations behind the end-of-mission scenarios is to avoid even the small
probability of hitting Europa "

That would need one heck of a gravity assist to hit Europa!

Phil


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Hungry4info
post Feb 5 2010, 10:51 PM
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QUOTE
Dumping your RTG-powered spacecraft in a giant planet avoids lawsuits, terrorist threats, and planetary protection issues.

I recall accusations that the devious, dastardly NASA was trying to "destroy Jupiter" or turn it into a sun by dropping a "nuke" into it with the Galileo plunge.


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nprev
post Feb 5 2010, 11:04 PM
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One thing to keep foremost in mind is that the PPPs & similar protocols are designed with full knowledge of the abundance of ignorance that we currently possess with regard to the tolerances/constraints required to not irrevocably screw up pristine extraterrestrial environments.

In that sense, they represent considerable foresight & forebearance. Minimizing changes to systems with complex (and not even close to being fully understood) interdependent attributes seems exceptionally wise.


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belleraphon1
post Feb 5 2010, 11:13 PM
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I think the science we will get during the close Saturn passes will be magnificent. And those close passes I assume are risky. Not sure if CASSINI could be pulled out of that orbital configuration once she takes those dives.

Nothing lasts forever. I would rather a last grand dive into Saturn than a lonely and useless orbit of the Sun. Even if that were possible in the end.

Craig
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Tom Tamlyn
post Feb 5 2010, 11:17 PM
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QUOTE (Hungry4info @ Feb 5 2010, 05:51 PM) *
I recall accusations that the devious, dastardly NASA was trying to "destroy Jupiter" or turn it into a sun by dropping a "nuke" into it with the Galileo plunge.


Similar comments about the Cassini plunge are easy to find. I'll post no links, because I assume the subject is out of bounds for umsf.com.

TTT
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belleraphon1
post Feb 5 2010, 11:20 PM
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QUOTE (Hungry4info @ Feb 5 2010, 05:51 PM) *
I recall accusations that the devious, dastardly NASA was trying to "destroy Jupiter" or turn it into a sun by dropping a "nuke" into it with the Galileo plunge.


There were indeed. Even suggestions that the rtg's caused a nuclear explosion inside Jupiter's atmosphere.

Curious whether the same claims will be repeated in 2017.

Craig
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nprev
post Feb 5 2010, 11:35 PM
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Well...let's just say that it's a statistical certainty that incredulous claims will be made by those who lack credibility, and eagerly accepted by those who lack critical thinking skills.

(That reminds me: Time for my annual re-reading of Sagan's The Demon-Haunted World: Science As A Candle In The Dark. It's the only book I ever bought for each of my children.)

Onward, anyhow. The XXM promises to provide something hitherto unprecedented for the outer planets: long-term observation of seasonal effects on not just one but at least three active worlds! That is what they call bang for the buck.


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AndyG
post Feb 6 2010, 12:40 AM
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QUOTE (nprev @ Feb 5 2010, 11:35 PM) *
Time for my annual re-reading of Sagan's The Demon-Haunted World: Science As A Candle In The Dark. It's the only book I ever bought for each of my children.


And one that's definitely worth reading annually.

Andy
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Den
post Feb 12 2010, 06:19 PM
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QUOTE (Hungry4info @ Feb 5 2010, 11:51 PM) *
I recall accusations that the devious, dastardly NASA was trying to "destroy Jupiter" or turn it into a sun by dropping a "nuke" into it with the Galileo plunge.


Yeah, our friend Hoaxland at his best laugh.gif Of course the fact that Pu-238 is not even a fissile isotope didn't stop his hyperactive imagination...
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dmuller
post Feb 13 2010, 04:38 AM
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Just noticed it's gonna be a "crashy" 2017 ... one month after Cassini enters Saturn's atmosphere (15 Sep 2017), it is Juno's time to disintegrate in Jupiter's atmosphere (16 Oct 2017)


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elakdawalla
post Feb 13 2010, 05:30 AM
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Yeah, it's pretty awesome that Cassini will be in a Juno-like orbit at the same time Juno is in a Juno-like orbit; it will be fascinating to compare the behavior of the two giant planets' magnetic fields and plasma environments under identical solar conditions. Fascinating, that is, if you're a plasma physicist. Not my cup of tea. But I'm excited on their behalf smile.gif


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Juramike
post Feb 13 2010, 05:42 AM
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So assuming all the orbiting missions get extended, by then we could have 6 planetary bodies being orbited by spacecraft. Awesome!


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stevesliva
post Nov 4 2010, 11:12 PM
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QUOTE (john_s @ Feb 4 2010, 08:14 PM) *
That's a purely gravitational nudge from Titan- no propellant required. That final "close" approach to Titan will be at a range of 86,000 km.

However, it looks like they're perhaps going to try and measure exactly what their margin was!

QUOTE
Tuesday, Nov. 2 (DOY 306)

The results of a study of maneuvers near end of mission were presented at the Mission Planning Forum this week. The topics were the delta-v impact of accidental burn-to-depletions and a possible planned burn-to-depletion near the end of mission. An accidental burn-to-depletion occurs when either insufficient fuel or oxidizer remains to produce the thrust level required during a main engine maneuver. The study looked at the delta-v impact of completing the interrupted maneuver at a later time using hydrazine and the RCS thrusters. A planned burn-to-depletion concept was also discussed in the event that bipropellant remains at the very end of the mission. This burn, if performed, would be done during the last proximal orbit to determine how much usable propellant remained in the tank. The study identified times during the last orbit where the burn could be performed and impact into Saturn's atmosphere would still be assured. There are many issues to consider for both of these concepts and the topic will be studied in more detail when the project looks to plan the later segments of the mission.
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