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Dawn Cruise
SkyeLab
post Sep 27 2007, 12:31 PM
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Pushing out of Earth orbit now...........

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elakdawalla
post Sep 27 2007, 02:39 PM
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loon reports from the Cape that AOS happened about 2 hours after launch, at 9:44 EDT. Yay!

Emily


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ustrax
post Sep 27 2007, 02:55 PM
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Horst Uwe Keller, Dawn's FC Team Leader reported to spacEurope an hour ago:

"Now we have telemetry! Everything looks OK.
Looks good. Cameras are responding (heaters)."

He added:

"We just talked about it. We (MPS) are now in charge of 6 cameras operating currently in space!
2 on Rosetta, 2 on DAWN, 1 on VEX, 1 on Phoenix and in addition the detector for the microscope on Phoenix.
Looks like a record to me."

He's happy... smile.gif


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climber
post Sep 27 2007, 04:10 PM
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May be little OT...and that's the reason of this post actualy !
We have 8-11 spacecrafts that can be considered in "Cruise phase" at this time (including 2 bound for Mars : Phoenix and Dawn)
Do I miss any?

New Horrizons
Phoenix
Dawn
Roseta
Messenger
Hayabusa
Deep Impact
Stardust
and may be as well :
Voyager 1
Voyager 2
Ulyses

That's quite an achievment. smile.gif I'm wondering if we ever had as many at the same time.
I'm also wondering if, instead of keeping them in their proper section (Mercury,Mars, Pluto, etc…), it'll not be worth to have a section in the Forum that'll show "Cruise phase Spacecrafts".

Advantage will be that we could go there and check down all status instead of having to remember which Spacecraft is where.
Just a thought.

BTW : Go Dawn, Go mars.gif


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punkboi
post Sep 27 2007, 04:18 PM
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Godspeed, Dawn!


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dvandorn
post Sep 27 2007, 05:18 PM
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Well -- I missed the launch (6:34 am is a little early for me these days, and that's when she lofted by my clock), but I just saw a quick replay of the launch at the beginning of the post-launch news conference, and I have to say, that thing heeled over to the left (from the camera angle I saw) pretty good before straightening out and angling to the right onto its correct trajectory. Took off like a bat out of hell, though...

Four issues were just mentioned -- the RCS switched itself from the primary to the secondary system, for reasons yet unknown; the RCS thrusters are running colder than anticipated, which is making the software controls lock them out, but reversion to hardware controls is keeping them running -- the fix is a minor re-set of the software's criteria values; the RCS brackets are running a little warmer than normal, but are cooling down; and there is a slight difference in electricity being generated between the two solar panels.

Those are the only issues that have been discussed.

-the other Doug


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stevesliva
post Sep 27 2007, 05:39 PM
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Amazing! Given the incredible complexity of the post-launch deployments and sequencing in the Planetary Society Blog post by Marc Rayman, I'm amazed that so much goes on without human intervention...
http://planetary.org/blog/article/00001153/

That post has got to be one of the more informative discussions of autonomous operation that I've read. (Other than perhaps the explanations of the incidents when they have gone wrong)
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Rakhir
post Sep 27 2007, 08:49 PM
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QUOTE (climber @ Sep 27 2007, 04:10 PM) *
We have 8-11 spacecrafts that can be considered in "Cruise phase" at this time (including 2 bound for Mars : Phoenix and Dawn)
Do I miss any?

Already forget Kaguya ? wink.gif
She is still in cruise phase.
(As well as VRAD and Relay sat. unless you count them as part of Kaguya until they are released)
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Toma B
post Sep 28 2007, 07:33 AM
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Just as I thought...nobody in the press conference asked question that I am most interested in... blink.gif
Dawn is going to visit two biggest asteroids Ceres and Vesta. It is going to enter orbit around these two but there was some words before that it can do few close flybys of some small asteroids as well.
I guess that planed flybys are all canceled because slips in launch but there should be new ones.
Does anybody know if there are any candidates?


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ugordan
post Sep 28 2007, 07:36 AM
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QUOTE (Toma B @ Sep 28 2007, 09:33 AM) *
I guess that planed flybys are all canceled because slips in launch but there should be new ones.

IIRC, there never were any planned flybys. It will be determined in flight (based on current trajectory, fuel and ion engine performance) what is feasibly reachable and if it's worth the trouble. One of TPS blog entries mentions something about it as I recall.


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elakdawalla
post Sep 28 2007, 04:35 PM
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QUOTE (Toma B @ Sep 28 2007, 12:33 AM) *
I guess that planed flybys are all canceled because slips in launch but there should be new ones.

Gordan's right, there were no flybys planned in advance, not only because of the uncertainty in launch date but because of uncertainty in performance of the ion engines. And there may well not be any flybys of any real quality unless they get very lucky. Unlike a flyby mission, Dawn can directly translate fuel reserves into a much longer mission at its primary targets. Which is a better use of the xenon, a relatively distant view of a small asteroid or another week spent in orbit at Ceres, or a closer orbit, or a different orbit, etc. etc.? It sounds to me like unless the orbital mechanics gods smile upon them with a really great opportunity that lies fortuitously close to the trajectory, the economics won't work out for any other flybys.

(The answer to this question was on a Planetary Radio show.)

--Emily


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stevesliva
post Sep 28 2007, 04:57 PM
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QUOTE (ugordan @ Sep 28 2007, 03:36 AM) *
IIRC, there never were any planned flybys. It will be determined in flight (based on current trajectory, fuel and ion engine performance) what is feasibly reachable and if it's worth the trouble. One of TPS blog entries mentions something about it as I recall.
I recall that as well, nothing was planned or expected until launch. Similar to the New Horizons Jupiter flyby... they didn't plan the launch to coincide with anything but the primary targets.But I am definitely curious to see what they will pass by, and whether the instruments can do useful science on more distant fly-bys.
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jabe
post Sep 29 2007, 02:10 AM
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QUOTE (abalone @ Jul 21 2007, 03:00 PM) *
If specific impulse reigns supreme then why do they use Xenon instead of hydrogen

I believe it is the ionization energy as well as storage issues..An ion engine needs ions..Xenon ionization energy is lower than hydrogen so if you can use a little energy to ionize it the rest of the available energy can be used to "spit" the ions out...(As well hydrogen is a diatomic gas so electrons are used in the bonds..no free ones available to excite if my chemistry is right smile.gif ) Helium would be next best but still ionization energy is high)
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Greg Hullender
post Sep 29 2007, 05:46 AM
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jabe: No, that's not it, but this has already been discussed at length here, and the actual answer is well worth reading.

http://www.unmannedspaceflight.com/index.p...3274&st=300

--Greg
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jabe
post Sep 29 2007, 11:56 AM
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QUOTE (Greg Hullender @ Sep 29 2007, 05:46 AM) *
jabe: No, that's not it, but this has already been discussed at length here, and the actual answer is well worth reading.

http://www.unmannedspaceflight.com/index.p...3274&st=300

--Greg

Thanks for the link..always wondered why they didn't use helium smile.gif
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