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risky path for cassini probe?



 
 
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  #1  
Old June 27th 04, 08:32 AM
simon.coombs3
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Default risky path for cassini probe?

the cassini probe is going to pass between the F and G rings,
this will no doubt bring some fantastic imaging opportunities but
isnt it a little risky? whats the chances of an impact? im sure Nasa have
done their home work but even so some risk must be there.

I believe the voyager was to pass through the rings but they decided aganst
it for the same reason im not sure where abouts though.

Simon


  #2  
Old June 27th 04, 11:17 AM
Ed
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"simon.coombs3" wrote:

sc the cassini probe is going to pass between the F and G rings,
sc this will no doubt bring some fantastic imaging opportunities but
sc isnt it a little risky? whats the chances of an impact? im sure Nasa
sc have done their home work but even so some risk must be there.

Yes, there is some risk, which is why Cassini's high gain antenna will
be pointed in the ram (forward) direction during both crossings of the
ring plane in order to provide some degree of shielding from ring particles.

sc I believe the voyager was to pass through the rings but
sc they decided aganst it for the same reason im not sure
sc where abouts though.

Pioneer 11 and Voyager 2 passed through the rings successfully.



  #3  
Old June 27th 04, 11:41 AM
Jonathan Silverlight
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In message , Ed
writes
"simon.coombs3" wrote:

sc the cassini probe is going to pass between the F and G rings,
sc this will no doubt bring some fantastic imaging opportunities but
sc isnt it a little risky? whats the chances of an impact? im sure Nasa
sc have done their home work but even so some risk must be there.

Yes, there is some risk, which is why Cassini's high gain antenna will
be pointed in the ram (forward) direction during both crossings of the
ring plane in order to provide some degree of shielding from ring particles.

sc I believe the voyager was to pass through the rings but
sc they decided aganst it for the same reason im not sure
sc where abouts though.

Pioneer 11 and Voyager 2 passed through the rings successfully.


No and no. (but the information produced by those craft presumably gives
them the confidence to aim Cassini through the gap)
I can document the date when Pioneer 11 was aimed outside (May 1978,
according to "Solar System Log") but not Voyager 2.
--
What have they got to hide? Release the full Beagle 2 report.
Remove spam and invalid from address to reply.
  #4  
Old June 28th 04, 01:43 AM
Ed
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"Jonathan Silverlight" wrote:

E Pioneer 11 and Voyager 2 passed through the rings
E successfully.

JS No and no. (but the information produced by those craft presumably
JS gives them the confidence to aim Cassini through the gap)
JS I can document the date when Pioneer 11 was aimed outside (May
JS 1978, according to "Solar System Log") but not Voyager 2.

Well, my source (David Harland's book, "Mission to Saturn") states:
"...as Voyager 2 crossed the ring plane, it was surrounded by a cloud of
plasma, and had to correct its orientation, due to thousands of micron-
sized grains in the G-ring hitting the spacecraft."

Here's another reference, an on-line article from SSI which also confirms
Voyager 2's flight through the G-ring:

http://tinyurl.com/3gdcb (PDF from Spacescience.org)




  #5  
Old June 28th 04, 08:08 AM
Jonathan Silverlight
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Default

In message , Ed
writes
"Jonathan Silverlight" wrote:

E Pioneer 11 and Voyager 2 passed through the rings
E successfully.

JS No and no. (but the information produced by those craft presumably
JS gives them the confidence to aim Cassini through the gap)
JS I can document the date when Pioneer 11 was aimed outside (May
JS 1978, according to "Solar System Log") but not Voyager 2.

Well, my source (David Harland's book, "Mission to Saturn") states:
"...as Voyager 2 crossed the ring plane, it was surrounded by a cloud of
plasma, and had to correct its orientation, due to thousands of micron-
sized grains in the G-ring hitting the spacecraft."

Here's another reference, an on-line article from SSI which also confirms
Voyager 2's flight through the G-ring:

http://tinyurl.com/3gdcb (PDF from Spacescience.org)


Woops! Thanks for the correction. Looking at "The Far Planets" (the
first book that came to hand) I read that Voyager 2 had "a series of
unexpected thruster firings" implying some force hitting the spacecraft.
  #6  
Old July 4th 04, 09:15 AM
Abdul Ahad
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"simon.coombs3" wrote in message ...
the cassini probe is going to pass between the F and G rings,
this will no doubt bring some fantastic imaging opportunities but
isnt it a little risky? whats the chances of an impact? im sure Nasa have
done their home work but even so some risk must be there.


The initial capture orbit around Saturn seems to have been achieved
with success (sigh of relief...).

I don't know the full shape, size and orientation of Cassini's orbital
ellipse post SOI, but surely similar risks will apply each and every
time the probe passes through periapsis (closest point to Saturn and
the rings in its orbit) throughout its mission from here on?

Presumably NASA will be firing successive burns to fine-tune the orbit
going forward, but anyone know where I can get a diagram / some facts
and figs on the basic current/intended orbit?
Thanks.

Abdul Ahad
http://uk.geocities.com/aa_spaceagent/astronomy.html


I believe the voyager was to pass through the rings but they decided aganst
it for the same reason im not sure where abouts though.

Simon

  #7  
Old July 4th 04, 09:50 AM
Mike Collins
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Default

Abdul Ahad wrote:
"simon.coombs3" wrote in message
...
the cassini probe is going to pass between the F and G rings,
this will no doubt bring some fantastic imaging opportunities but
isnt it a little risky? whats the chances of an impact? im sure Nasa
have done their home work but even so some risk must be there.


The initial capture orbit around Saturn seems to have been achieved
with success (sigh of relief...).

I don't know the full shape, size and orientation of Cassini's orbital
ellipse post SOI, but surely similar risks will apply each and every
time the probe passes through periapsis (closest point to Saturn and
the rings in its orbit) throughout its mission from here on?

Presumably NASA will be firing successive burns to fine-tune the orbit
going forward, but anyone know where I can get a diagram / some facts
and figs on the basic current/intended orbit?
Thanks.

Abdul Ahad
http://uk.geocities.com/aa_spaceagent/astronomy.html


I believe the voyager was to pass through the rings but they decided
aganst it for the same reason im not sure where abouts though.

Simon

http://saturn.jpl.nasa.gov/operation...aturn-tour.cfm
--
Mike Collins
UK
Mike&heather-at-oakwellmount-dot-freeserve-dot-co-dot-uk


  #8  
Old July 4th 04, 10:16 AM
Mike Collins
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Default

Sorry pasted the link twice

http://saturn.jpl.nasa.gov/operations/saturn-tour.cfm
--
Mike Collins
UK
Mike&heather-at-oakwellmount-dot-freeserve-dot-co-dot-uk


  #9  
Old July 4th 04, 12:03 PM
Jo
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Default

In om,
Abdul Ahad typed:

Presumably NASA will be firing successive burns to fine-tune the orbit
going forward, but anyone know where I can get a diagram / some facts
and figs on the basic current/intended orbit?
Thanks.


Abdul,

http://www.esa.int/SPECIALS/Cassini-...6E2VQUD_0.html

For a fascinating animated diagram.

Jo



  #10  
Old July 4th 04, 12:26 PM
simon.coombs3
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Default

well, as per nasa news letter 680 impacts per second recorded during the
pass through..........all very small particles and no damage.


"Mike Collins" wrote in
message ...
Sorry pasted the link twice

http://saturn.jpl.nasa.gov/operations/saturn-tour.cfm
--
Mike Collins
UK
Mike&heather-at-oakwellmount-dot-freeserve-dot-co-dot-uk




 




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