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Unmanned Spaceflight.com > Other Missions > Cometary and Asteroid Missions > Dawn
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SkyeLab
Pushing out of Earth orbit now...........

biggrin.gif
elakdawalla
loon reports from the Cape that AOS happened about 2 hours after launch, at 9:44 EDT. Yay!

Emily
ustrax
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
climber
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
punkboi
Godspeed, Dawn!
dvandorn
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
stevesliva
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)
Rakhir
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)
Toma B
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?
ugordan
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.
elakdawalla
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
stevesliva
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.
jabe
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)
Greg Hullender
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
jabe
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
Del Palmer
Latest Dawn journal:

http://dawn.jpl.nasa.gov/mission/journal_9_30_07.asp
punkboi
Interesting journal. Hopefully, a "Where is Dawn now?" page will be posted on the mission website soon.
Stephen
QUOTE (punkboi @ Oct 3 2007, 03:41 AM) *
Interesting journal. Hopefully, a "Where is Dawn now?" page will be posted on the mission website soon.

Speaking of "Where is Dawn now?", where the "Dawn" subforum on UMSF.com? Or are we going to continue working out of this present thread from now until it reaches the asteroid belt?

=====
Stephen
djellison
It doesn't need a subforum until it starts doing science in a few years. It has ONE thread right now...maybe it'll get another - but a thread on it's own in a subforum would be a tumble-weed like situation. On that basis, the front page of the C & AM subforum would need to be split into 6 subforums which would be a pointless overcomplication.

Doug
volcanopele
I could see the creation of a new thread though wink.gif
ugordan
QUOTE (volcanopele @ Oct 3 2007, 09:09 AM) *
I could see the creation of a new thread though wink.gif

That might be a good idea, seeing as how it's finally happening and on its way. 30 pages to go through just to read the current news is a bit of an overkill smile.gif
Stephen
QUOTE (djellison @ Oct 3 2007, 04:59 PM) *
It doesn't need a subforum until it starts doing science in a few years. It has ONE thread right now...maybe it'll get another - but a thread on it's own in a subforum would be a tumble-weed like situation.

I notice Phoenix isn't "doing science" thus far either yet it has a subforum all its very own.

And then there's MSL, which last I checked hasn't even been built yet, much less launched.

And of course there's New Horizons which will be spending much of the next decade in hiberation before it starts doing science at Pluto, and Messenger which is still heading Mercury-ward. True, both did do a teensie bit of science at Jupiter and Venus, respectively. On the other hand I do seem to recall them getting their own sub-forums (sub-fora?) even before they got that far.

On the other hand I notice Kayuga hasn't got a subforum of its own yet either so I guess that puts Dawn in good company. rolleyes.gif

=====
Stephen
Greg Hullender
I think it's simpler than that; it's because there is no "Where is Dawn" link on the page yet. Until then, they haven't officially lanched, as far as I'm concerned, and they don't deserve a subforum yet.

Perhaps we should start a new thread titled "Where is Dawn?"

--Greg :-)
jamescanvin
QUOTE (Stephen @ Oct 4 2007, 03:03 AM) *
I notice Phoenix... MSL... New Horizons...


Yeah, but look at how many threads are in each of those forums, too many for me to count!

Once the threads start mounting then a case for keeping them all together in a sub-forum can be made, but that time isn't now.

James
CAP-Team
Here's where Dawn is now:

Click to view attachment

Earth as seen from Dawn:

Click to view attachment
djellison
QUOTE (Stephen @ Oct 4 2007, 03:03 AM) *
rolleyes.gif



Yeah - that pretty much sums it up. Subforums get made when they're required - not becaue of some line in the sand or event that takes place. They're made because one topic dominates another forum.

Doug
punkboi
QUOTE (CAP-Team @ Oct 4 2007, 03:00 AM) *
Here's where Dawn is now:

Click to view attachment

Earth as seen from Dawn:

Click to view attachment


Cool- Did you create that yourself? Or which website did you get that from?

EDIT: Interesting that Phoenix has been near Earth ever since launch... I think the second TCM later this month should change that
ugordan
QUOTE (punkboi @ Oct 4 2007, 07:27 PM) *
I think the second TCM later this month should change that

No, it won't. TCMs are correction maneuvers, not huge boosts.
CAP-Team
QUOTE (punkboi @ Oct 4 2007, 07:27 PM) *
Cool- Did you create that yourself? Or which website did you get that from?

EDIT: Interesting that Phoenix has been near Earth ever since launch... I think the second TCM later this month should change that


Yes, I created the image with a program called xplanet (by Hari Nair) and you can use spice kernels you can download from the NASA NAIF site.
It's a bit like Celestia but for still images.

Phoenix is still relatively close to Earth because it went inwards first (thus moving faster than Earth) , it's just since last week Phoenix is starting to move out.
Phoenix and Dawn will stay relatively close to each other till Phoenix reaches Mars.
volcanopele
Wow, you're right, Dawn is available on the NAIF site smile.gif Which means I can import it into Celestia, sweetness! Wish New Horizons was available...
Stephen
QUOTE (djellison @ Oct 4 2007, 08:54 PM) *
Yeah - that pretty much sums it up. Subforums get made when they're required - not becaue of some line in the sand or event that takes place. They're made because one topic dominates another forum.

Glad to hear there's a defensible logic behind such things. As opposed to ad hoc rules of a more arbitrary kind. smile.gif

=====
Stephen
belleraphon1
Sweetness and LIGHT.....

First ion thruster test......

http://www.planetary.org/blog/article/00001186/

Craig
Marz
Marc cracks me up!!!

"The drama was captured in the stirring name of the file that was transmitted to the spacecraft: dz002e.scmf"

Truly excellent and enjoyable reading, and great news everything's checking out ship-shape. I hope he can continue keeping me entertained in the 7.4 years to Ceres... are we there yet?
peter59
Science Instruments Checked Out
October 15 - 19
Dawn's science instruments were powered on and given their first health checks this week. The gamma ray and neutron spectrometer, imaging camera, and visible and infrared mapping spectrometer all operated perfectly.
peter59
Second Ion Thruster Checkout Completed Successfully
October 22 - 26
The mission operations team completed the checkout of a second ion thruster this week. In one of the tests, the thruster was operated for 27 hours continuously at 5 different throttle levels, and in two other tests it was operated at maximum power for 4 hours each time. All spacecraft systems performed extremely well.
nprev
Thanks for the update, Peter. Green bird, baby, green bird...GO DAWN!!! smile.gif

Slightly OT here, but has anyone else noticed that, provided that VEX, Chang'e and/or Kaguya survive, we should have active missions happening on or around all the major bodies of the inner Solar System in 2011? If the hangtime for them all extends to Dawn's arrival at Ceres, then that envelope gets pushed out to the Belt. What a heady time for UMSF!

EDIT: Forgot about Juno going to Jupiter...if everything converges right, then we've got it covered all the way out to Saturn at that time!!!
brellis
QUOTE (nprev @ Oct 27 2007, 06:32 AM) *
has anyone else noticed that, provided that VEX, Chang'e and/or Kaguya survive, we should have active missions happening on or around all the major bodies of the inner Solar System in 2011? If the hangtime for them all extends to Dawn's arrival at Ceres, then that envelope gets pushed out to the Belt. What a heady time for UMSF!

EDIT: Forgot about Juno going to Jupiter...if everything converges right, then we've got it covered all the way out to Saturn at that time!!!


New Horizons and the Voyagers will still be humming too smile.gif
punkboi
New journal up:

http://dawn.jpl.nasa.gov/mission/journal_10_24_07.asp
peter59
More Ion Thrusting Tests Completed
November 12 - 16
The week-long systems test of interplanetary cruise thrusting completed successfully on Monday. The third ion thruster was tested this week, and like the other two, it performed perfectly. The thruster operated at 4 throttle levels, including full power. In a separate activity, the mission operations team powered off the reaction wheels to test pointing control with hydrazine thrusters during ion thrusting.
punkboi
A week late, but whatever:

http://dawn.jpl.nasa.gov/mission/journal_11_13_07.asp

Still no "Where is Dawn now?" page on the official website, eh? wink.gif
peter59
Main Antenna Checked Out and New Software Uploaded
November 19-23
This week the spacecraft was commanded to use its main antenna for the first time and measurements showed that it is in fine condition. New software was installed in one of Dawn's computers (and its backup), correcting a minor bug that was discovered shortly after launch.
punkboi
"Where is Dawn now?" page finally up:

http://dawn.jpl.nasa.gov/mission/live_shots.asp
peter59
"Dawn has started IPS cruise thrusting to Vesta. The thrust came on at
4:08 PM pacific. We are on our way."—Project Manager, Keyur Patel 12/17/07
punkboi
http://www.planetary.org/blog/article/00001266/

New Dawn Journal up... Planetary.org posted calibration photos taken by the spacecraft's Framing Camera
IM4
Good news everyone!
Extended version of the Dawn trajectory is now available at HORIZONS (two additional segments till April 2008). I did some simulations and found that Dawn will pass within 0.048 AU from comet 79P/du Toit-Hartley somewhere around March 17, 2008. Exact date and distance depends on actual thrusting, nevertheless, upcoming event will be the closest of this kind till EPOXI encounter with comet Hartley-2.
Comet 79P was rediscovered last November in its 5th apparition and will pass perihelion in May 2008. That's a faint comet, but I hope not a smallest one. Even with coma/tail size of 20-30 thousands km Framing Camera and VIR spectrometer will be able to distinguish some details. I think that's a good opportunity to test and calibrate instruments on the real object, especially for VIR, which is a relative of Rosetta's VIRTIS spectrometer.

PS Attached image features comet orbit, Dawn trajectrory and planets positions on March 17, 2008.
tedstryk
That is still 7 million miles, but it could be done, at least as a test. It also flies by a really big object in February 2009. mars.gif

Ted
elakdawalla
The latest Dawn Journal is now up at JPL and TPS websites. In it, Marc reports that Dawn did go into safe mode on January 14, 2008, the same day as the MESSENGER flyby and when Ulysses went haywire, but Marc told me that the Dawn safing at least had nothing to do with any of the other drama in the solar system; it was a routine, well-understood event, and the spacecraft is fine.

--Emily
JTN
(I'm not normally into fields'n'particles, so forgive my ignorance...)
So, we lost the magnetometer. Is there any way, from science or engineering data, that we'll be able to tell anything at all about the magnetic environment of Ceres/Vesta? Not quantitative, just enough to spot Mercury-level surprises.
I know they don't put those awkward booms on spacecraft for the fun of it... just asking.
Holder of the Two Leashes
In a word, no.

If Vesta appears unusually bright, it could be guessed that deflection of the solar wind by a field might have prevented weathering, at least over a significant portion of past history. If gravity data indicates a very dense core for Vesta, that would also be an indication that a magnetic field is more likely, but won't tell you anything about whether it is really there. Any realistic value for what you could expect at Vesta will not affect high energy cosmics rays very much, those which provide part of the signature for GLAST.

For Ceres, it was speculated that salty underground water reservoirs might have a magnetic signature, like they do on Ganymede. If they are there, and they do, then there is no way now for DAWN to know about it.
ugordan
QUOTE (Holder of the Two Leashes @ Feb 14 2008, 08:28 PM) *
deflection of the solar wind by a field might have prevented weathering

Isn't the majority of space weathering related to micrometeoroid impacts?
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