Full Version: Cassini's Extended-Extended Mission
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I know it makes scense to plunge into Saturn, my original comments were more a knee jerk reaction on hearing they were going for the plunge.
I think it's a sad thing to crash a spacecraft like Cassini into Saturn.
I remember that when Cassini was developed many options were mentioned, like orbiting Titan or swing te spacecraft out of the Saturn system in an orbit around the sun.
I remember that when Cassini was developed many options were mentioned, like orbiting Titan or swing te spacecraft out of the Saturn system in an orbit around the sun.
By making the most of what Cassini was designed to do ( orbit Saturn and observe it's system ) I assume they've traded any possible outside-of-the-box fates for Cassini for just more Saturn observations, assuming the XXM will use up the vast majority of remaining fuel.
Yes, sure, CAP-Team, but the science is inferior. Here we will get the mass of the rings, chemistry of the upper atmosphere of Saturn, the manetic field at very low altitudes, plus great ring/inner moon imaging opportunities. Escaping Saturn gives us nothing, and I think it was already found to be too difficult to get into Titan orbit, plus inferior science (a bit on Titan but nothing on the rest of the system.
Phil
Phil
QUOTE (CAP-Team @ Feb 5 2010, 02:01 PM) 
I think it's a sad thing to crash a spacecraft like Cassini into Saturn.
I remember that when Cassini was developed many options were mentioned, like orbiting Titan or swing te spacecraft out of the Saturn system in an orbit around the sun.
I remember that when Cassini was developed many options were mentioned, like orbiting Titan or swing te spacecraft out of the Saturn system in an orbit around the sun.
Well, a lot has happened since Cassini was developed.... in fact, one of the driving
considerations behind the end-of-mission scenarios is to avoid even the small
probability of hitting Europa (qv Galileo). Dumping your RTG-powered spacecraft in
a giant planet avoids lawsuits, terrorist threats, and planetary protection issues.
"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
probability of hitting Europa "
That would need one heck of a gravity assist to hit Europa!
Phil
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.
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.
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.
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
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
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
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
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.
(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.
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
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
Of course the fact that Pu-238 is not even a fissile isotope didn't stop his hyperactive imagination...
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)
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 
So assuming all the orbiting missions get extended, by then we could have 6 planetary bodies being orbited by spacecraft. Awesome!
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.
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.
The recent NASA-JPL webcast presentation about the Cassini mission's "Grand Finale" featured, among many other interesting things, a slide with a diagram of the 2017 "proximal orbits".
I thought that diagram was really interesting, so I saved a couple of screen grabs.
Does anyone here know if the diagram is available in hi-rez form somewhere?
Also, does the size of the blue dots represent navigation error probable size?
Thanks very much.
Click to view attachment Click to view attachment
I thought that diagram was really interesting, so I saved a couple of screen grabs.
Does anyone here know if the diagram is available in hi-rez form somewhere?
Also, does the size of the blue dots represent navigation error probable size?
Thanks very much.
Click to view attachment Click to view attachment
From the DPSEPSC conference;
https://twitter.com/LeighFletcher/status/789569457425227776
QUOTE
Spilker: Last Cassini images on plunge will be ~10hrs before, followed by downlink, then desperate in situ samples before *the end*
https://twitter.com/LeighFletcher/status/789569457425227776
Thursday press conference coming, with INMS team involved:
https://www.jpl.nasa.gov/news/news.php?feature=6809
It must involve Enceladus in some way, right?
EDIT: Yep! Looks like the October 28th, 2015 flyby found a large amount of hydrogen in the plume: http://astrobiology.com/2017/04/hydrotherm...able-zones.html
https://www.jpl.nasa.gov/news/news.php?feature=6809
QUOTE
These new discoveries will help inform future ocean world exploration -- including NASA's upcoming Europa Clipper mission planned for launch in the 2020s -- and the broader search for life beyond Earth.
It must involve Enceladus in some way, right?
EDIT: Yep! Looks like the October 28th, 2015 flyby found a large amount of hydrogen in the plume: http://astrobiology.com/2017/04/hydrotherm...able-zones.html
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