DAWN mission to orbit 1 Ceres & 4 Vesta.

h2ouniverse · Nov 6, 2007

Hi MW and Jon, It is established that it is in hydrostatic equilibrium. The issue is whether there has been differentiation. I.e. whether the interior has been hot enough to melt water and enable the rocky material to coalesce by sinking. The radiogenic heating of the core requires that the rocky material is gathered enough to accumulate the heat energy. You might have a mixture of rock and ice and a round shape, as for most of Callisto. I hope Ceres is differentiated (for that would mean prospects for liquid water, on Ceres as for many worlds similar in size). But it seems there is no guarantee up to now. I wonder how Dawn will give evidence in one way or the other. Regards.

3488 · Nov 6, 2007

Hi Joel, Jon & MeteorWayne, This discussion is getting really interesting. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> Interesting that Callisto has cropped up here. Regarding size & differentition. Callisto is almost perfectly spherical (really no oblateness at all) @ 4,800 KM, verses that of reasonably oblate 1 Ceres @ 975 KM (equator) & 909 KM (polar) approx 7.2% difference. I agree with both Jon & MeteorWayne, that 1 Ceres IS differentiated. Callisto appears undifferentiated, based on encounters by the Galileo orbiter, measuring the gravity field. Joel, do you think that 1 Ceres could have been made by Cold Accretion? Callisto is just far too large & massive, to not be spherical, despite its homogenous interior. Callisto could have been made through cold accretion (possibly the largest such object in the solar system), like that suggested by Vogon13, regarding Iapetus. If 1 Ceres is differentiated, it may resemble Saturn's Dione in many ways (which I think is also differentiated), also with giant cliffs & rifts, as the centre of 1 Ceres froze & the already brittle crust cracked. I think DAWN's orbital motion will help in determing the structure of both 1 Ceres & 4 Vesta. Certainly MASCONs like those in the crust of the Moon WILL be apparent. That is very interesting MeteorWayne, that you suggest the 4 Vesta was once the interior of an object similar to 1 Ceres. That is something that I have not even heard or thought off. <img src="/images/icons/laugh.gif" /> This idea bolsters the case of a 2 Pallas encounter also if the situation after the primary mission allows. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

h2ouniverse · Nov 20, 2007

Hi all, We have now passed Ceres opposition. Does anybody have news about the professional observations (VLT, Keck)?

3488 · Nov 20, 2007

Hi Joel, absolutely nothing @ the moment. Guess it is just a matter of time. Opposition was only on Sunday 11th November 2007, so maybe a bit soon, to expect results??? 2 Pallas was on: Thursday 30th August 2007 & 4 Vesta on: Thursday 31st May 2007. Do not appear to be anything new from 2 Pallas either, although we did get new 4 Vesta observations on Monday 14th May 2007 from HST. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

h2ouniverse · Nov 20, 2007

You're right. But I am so impatient to see these pictures. Because that will be the first time it has been observed since it is thought to be in hydrost. equilibrium... One would assume the observers will take care of some details under a new light.

3488 · Nov 20, 2007

I sincerely hope so Joel. like yourself, I really want to see the new images & information too. I also hoped that 2 Pallas would also have been observed. Lets hope the 1 Ceres information is released soon. Also the observations now of 1 Ceres & 4 Vesta, will be valuable in assisting to plan DAWN's orbital mission. Also perhaps moons might have been found, if so, that will be usefull in mass studies, etc. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Dec 5, 2007

DAWN current position. Thursday 6th December 2007. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Dec 18, 2007

Initial post launch checkouts successfully completed. NASA's Dawn Spacecraft Begins Interplanetary Cruise Phase Tuesday, December 18, 2007. NASA's Dawn spacecraft has successfully completed the initial checkout phase of the mission and begun its interplanetary cruise phase, which is highlighted by nearly continuous thrusting of its ion propulsion system. Dawn is on a 8-year, 3-billion mile journey to asteroid Vesta and dwarf planet Ceres. From JPL site. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

MeteorWayne · Dec 18, 2007

Good to hear our little girl is doing well. Go take a nap while the tiny engine that could does it's job. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Dec 25, 2007

It is superb news. We now know 100% sure that the launch caused no problems. I see there's another thread on Ceres, so there is a lot of interest in this, which is absolutely great. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> Happy Christmas everyone. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

alokmohan · Dec 26, 2007

When in 1801 Piazzi discovered small dots he never thought of such things happening.Hats of f to Piazzi.

docm · Dec 27, 2007

There's a long and very detailed post in the Planetary Societies "Dawn Journal" blog by Dr. Marc Rayman, Dawns Project System Engineer, detailing her recent progress. An absolutely GREAT read; http://www.planetary.org/blog/article/00001266/ Part of the included material is this pic of NGC 3532 and NGC 3372 taken by Dawn's framing camera; http://www.planetary.org/image/FC2_calib_color.jpg <div class="Discussion_UserSignature"> </div>

MeteorWayne · Dec 27, 2007

NIce update, Thanx. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Dec 27, 2007

Thank you very, very much docm. I agree MeteorWayne, that is a fantastic update. <img src="/images/icons/laugh.gif" /> The Framing Camera is working so well, with images so sharp, that it is beyond belief. After being a part of the campaign to save this mission from the axe, this is vindication for everyone who assisted to save DAWN. I will read it properly later as I am on the work computer right now, but this is just GR8. <img src="/images/icons/laugh.gif" /> The Mars encounter in February 2009 as well as 4 Vesta & 1 Ceres will look superb with this camera, no doubting it. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Dec 27, 2007

I have linked directly to the images in docm's post. Arcturus / Alpha Bootis from DAWN Spacecraft. An ageing Red Giant star approx 40 times the Sun's diameter & 130 times brighter, some 36 light years away. The fourth brightest star visible in our night skies Starfield in Cepheus from DAWN Spacecraft. Diagram of Cepheus starfield. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Feb 3, 2008

My own research suggests that DAWN may pass Comet 79P/du Toit-Hartley Approx: Monday 17th March 2008 @ approx 11 million KM. Wonder if the Framing Camera can capture images?? DAWN safing event on Monday 14th January 2008, was corrected shortly afterwards. The DAWN spacecraft is in excellent health. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

bobblebob · Feb 3, 2008

Didnt someone post in another thread that Dawn went into safe mode abit ago, or am i mistaken?

3488 · Feb 3, 2008

Yes Bradford Ellis (brellis) did on the Mercury MESSENGER thread. DAWN was one of the reasons for the short delay in downloading MESSENGER science data, along with Ulysses. Also the ESA Mars Express went into safing the same day talk about a triple whammy. All three incidents were unrelated, just bad timing. DAWN is absolutely fine I am pleased to report. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

bobblebob · Feb 3, 2008

Good <img src="/images/icons/smile.gif" /> Do they know the reason it went into safing?

MeteorWayne · Feb 14, 2008

Now in interplanetary cruise, the Dawn spacecraft is following a much more leisurely pace than the one it maintained during the initial checkout phase of the mission. While its daily schedule is not demanding, as it follows (and changes) its orbit around the Sun, it is separating from Earth at nearly 4 light seconds per day (more than 1.1 million kilometers, or 720 thousand miles, per day). Every 8 hours, the probe recedes from Earth by a distance equal to that between Earth and the moon. On January 14 shortly before 10:00 pm PST, a high energy subatomic particle, a "cosmic ray," traveled through one of the main panels of the spacecraft and then penetrated one of the electronics units. The energy it carried had been imparted to it through an unidentified cosmic process, and after the particle had traveled across vast distances, that energy was transferred to a small integrated circuit. Such an event is not all that uncommon on spacecraft, and Dawn is designed so that most space radiation does not interfere with its operation. The deposition of energy in this particular component however triggered the electronics to inform the software of a problem. To rectify the situation, other software correctly responded by resetting the computer in that unit. In the last log, we saw that two master computers work together to oversee and control activities on the spacecraft. The computer that was reset in this case was neither of those; it was one of many auxiliary computers with more limited responsibilities. In addition to resetting the computer, software running in the main computer correctly reconfigured systems onboard to "safe mode." The spacecraft then awaited instructions from engineers on Earth (or, more accurately, in Dawn mission control on the top floor of JPL's whimsically named building 264). A few hours later, when it was time for the weekly communications session, the Deep Space Network and mission controllers promptly recognized that t <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Feb 14, 2008

Thank you very much MeteorWayne, A great article, the first detailed explanation I've seen for the reasoning behind the 'safing event'. I was aware that it was no more serious than an errant Cosmic Ray. DAWN was in safe mode for such a short period of time, that the short hiatus in Ion thrusting was not sufficient in causing a problem with trajectory. It appears that DAWN has had a few safing events since launch & the previous one was in November 2007. I think this one would have been a non event, other than the fact that it occured on the same day as MESSENGER's Mercury encounter. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

MeteorWayne · Feb 14, 2008

Yes Andrew, I'm sure the plan allows for many such interruptions in the ion thrusting. Out in space, Cosmic Rays happen, and the craft is designed to survive them with minimal long term effect. If you are going to be cruising in space for years, you'd better have taken that into account! <img src="/images/icons/smile.gif" /> Something to think about during future manned missions out there. Cells are not IC's, but cosmic rays still cause damage. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

rybanis · Feb 14, 2008

Must have been a stressful day around JPL, having all these safing events happen on one day. <div class="Discussion_UserSignature"> </div>

3488 · Feb 14, 2008

Of course, they are so highly energetic, that organic material will suffer damage. I am sure & hope that Cosmic Rays are taken into account in the design of deep space manned craft. DAWN appears to bounce back without incident after each occurance. It appears as though the timing of these events are deliberately inconvenient. DAWN helped delay the download of Mercury science from MESSENGER & Cassini had a Cosmic Ray event shortly after the Iapetus encounter, also delaying science downloading. <img src="/images/icons/crazy.gif" /> I cosmic plot I tell ya <img src="/images/icons/laugh.gif" /> Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Feb 14, 2008

It would be Rybanis. So many of us both inside & outside of JPL want these missions to succeed. These missions are part of a long term investment in human knowledge & survival (yes these missions are THAT important). Ulysses failed to go to its primary frequencies post observations, DAWN going into safing & the ESA Mars Express orbiter also going into safing, ALL at the SAME TIME. <img src="/images/icons/crazy.gif" /> Fortunately ALL incidents were resolved quickly, with no damage caused. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

DAWN mission to orbit 1 Ceres & 4 Vesta.

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