[X] My Assistant

[Decepticon]

I hope this gets approved!

http://www.space.com/missionlaunches/05071...yby_future.html

[Guest_Analyst_*]

Not every mission is useful only because there are no other missions. Why do you need a flyby spacecraft and not only the impactor, if you have the Rosetta orbiter with 11 instruments watching? As for the extended missions: Both spacecraft have degraded cameras and only one or two other instruments. It is a matter of additional costs: 20 or 30 million are probably o.k., more is not.

Analyst

[Bob Shaw]

Why not use the Deep Impact bus as an impactor? Then Rosetta can look at the hole it makes... ...assuming that DI could make it at all to Rosetta's target, that is!

Bob Shaw

[Comga]

Why not use the Deep Impact bus as an impactor? Then Rosetta can look at the hole it makes... ...assuming that DI could make it at all to Rosetta's target, that is!

Bob Shaw

It can't. The orbit is all wrong. Also, I believe the targeting software was in the Impactor, which was designed to point its camera right at the target. Besides, while it is a sturdy and healthy craft, it would have to survive for another eight years for Rosetta to observe the impact.

Besides, a large fraction (50%?) of the science return was said to have come from the pre-impact images. The Flyby spacecraft can do this again, at Comet Boethin, and such an extended mission has been proposed.

I respectfully disagree with Bruce on impacting Comet C-G before Rosetta arrives. If they were really worried about the dust, they could always "hide" behind the nucleus. More likely, they would just sit back a good safe distance and still be able to see. It would be interesting to see an estimation of the dust flux as a function of distance, assuming this nucleus is as dusty as Tempel 1.

[mars loon]

It can't. The orbit is all wrong. Also, I believe the targeting software was in the Impactor, which was designed to point its camera right at the target. Besides, while it is a sturdy and healthy craft, it would have to survive for another eight years for Rosetta to observe the impact.

Besides, a large fraction (50%?) of the science return was said to have come from the pre-impact images. The Flyby spacecraft can do this again, at Comet Boethin, and such an extended mission has been proposed.

I respectfully disagree with Bruce on impacting Comet C-G before Rosetta arrives. If they were really worried about the dust, they could always "hide" behind the nucleus. More likely, they would just sit back a good safe distance and still be able to see. It would be interesting to see an estimation of the dust flux as a function of distance, assuming this nucleus is as dusty as Tempel 1.

Actually the back-up plan for Deep Impact was to use the flyby as an impactor on Comet Temple-1 if the impactor missed. The newly proposed "DIXI" extended mission plan, as i mentioned above, is to fly by Comet Boethin in 2008. A funding decison will be announced around September 2006.

Bob, as comga wrote, this DI cant fly to Comet 67P/Churyumov-Gerasimenko. A DI target burn to enable the Comet Boethin flyby has already been completed last July 2005 shortly after the July 4 impact.

Bruce, thanks for the complement above. I am glad we can agree on this new Discovery DI clone proposal to impact Comet 67P/Churyumov-Gerasimenko. In fact 2 teams have proposed this concept.

Analyst, the Deconvolution has achieved the full image resolution expected with the DI HRI and all the instruments are working perfectly.....

and tedstryks follow-up comments are right on target

[Comga]

Actually the back-up plan for Deep Impact was to use the flyby as an impactor on Comet Temple-1 if the impactor missed.

I believe that may have been a contingency if the Impactor died early in the flight. By the time the Impactor hit or missed, it was well too late to retarget the Fly-by.

"I am glad we can agree on this new Discovery DI clone proposal to impact Comet 67P/Churyumov-Gerasimenko. In fact 2 teams have proposed this concept. "

I must be falling behind. Which two groups proposed this concept?

Impactor-only missons to Churumov-Gerasimenko have been discussed, but I don't know if anyone proposed it or will propose it.

"Analyst, the Deconvolution has achieved the full image resolution expected with the DI HRI and all the instruments are working perfectly..... "

Yes, indeed. There is a heck of a difference between the Stardust Nav-Cam and the Deep Impact High Resolution Instrument, which met its resolution and SNR requirements after deconvolution. Not to mention the IR spectrometer and the filter wheels AND the Medium Resolution Instrument, which alone is more powerful than the Nav Cam.

[Guest_BruceMoomaw_*]

I believe that may have been a contingency if the Impactor died early in the flight. By the time the Impactor hit or missed, it was well too late to retarget the Fly-by.

"I am glad we can agree on this new Discovery DI clone proposal to impact Comet 67P/Churyumov-Gerasimenko. In fact 2 teams have proposed this concept. "

I must be falling behind. Which two groups proposed this concept?

Impactor-only missons to Churumov-Gerasimenko have been discussed, but I don't know if anyone proposed it or will propose it.

"Analyst, the Deconvolution has achieved the full image resolution expected with the DI HRI and all the instruments are working perfectly..... "

Yes, indeed. There is a heck of a difference between the Stardust Nav-Cam and the Deep Impact High Resolution Instrument, which met its resolution and SNR requirements after deconvolution. Not to mention the IR spectrometer and the filter wheels AND the Medium Resolution Instrument, which alone is more powerful than the Nav Cam.

(1) The plan to hit Tempel 1 with the main craft was indeed an emergency expedient to be carried out if the Impactor failed to pass its functioning tests before release.

(2) I'm very far from saying that a repeat of DI should be the next Discovery selection -- I'm just saying that it would be considerably more scientifically useful than I initially thought. If I had to make a guess as to the two front-runners for the next Discovery selection, I should say a CONTOUR repeat (maybe jazzed-up with a different spacecraft), or the U. of Arkansas' "Hera" scheme for a large-scale sample return from 3 different near-Earth asteroids.

(3) Even with deconvolution, the resolution on Deep Impact's HRI was only about half as good as had been planned -- although this still made it far better than the MRI, let alone the Stardust camera (which had some troubles of its own, since they were never able to completely clean all the early contamination off its optics).