DAWN mission to orbit 1 Ceres & 4 Vesta.

brellis · Sep 29, 2007

not Pallastine? <img src="/images/icons/tongue.gif" /> Ceresly, folks. Humor mars the discussion. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> I'm a recovering optimist - things could be better. </div>

MeteorWayne · Sep 29, 2007

I just won't inVesta much time in this punfest.... <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 · Sep 29, 2007

Hi FranOntanaya, I see your point, but if we have the chance for 2 Pallas, I think it would be very sad to not take it. H2Ouniverse & myself have discussed the possibity of a 1 Ceres lander, perhaps even a sample return. Obviously we will need the DAWN orbital data, particularly from the lower altitude orbits, before we present the case to NASA & / or ESA. 1 Ceres is not so difficult to reach, 2 Pallas is a real horror, with the 35 degree inclination. However celestial mechanics with DAWN has given us an option (provided all other objectives are met) to visit this giant asteroid & I am of the opinion, to not look a gift horse in the mouth. 2 Pallas will cross the descending node in December 2018, so DAWN will not even have to leave the plane of the orbit of 1 Ceres. The max temperature of 1 Ceres is a 'warm' -38 C as you mentioned, so perhaps there is a frozen gas cycle. However observations have not shown variations on the surface, but there is maybe a tenuous 'atmosphere' & frost deposits. We'll see when DAWN arrives. 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 · Sep 29, 2007

Hi brellis, I had not thought of that, Astronomy from 1 Ceres, but what a thought. DAWN might be able to view the inner solar system with the Sun hidden by the bulk of 1 Ceres, but it would be risky, not to point the camera at the Sun, even from that distance. We do not want a repeat of Apollo 12, when the TV camera was knackered by sunlight. I wonder if there really is that much water ice there. I could only think of it surviving under a layer of insulating regolith, as it would be too warm for it not to sublime in the sunlight, particularly in the 'tropics'. Hi MeteorWayne, yes it would be good to view the parent body of the Pallesite Meteorites. Of course, 4 Vesta & 1 Ceres come first in this mission, but if the option is there, than really 2 Pallas must be attempted also. A giant asteroid, difficult to reach for much of the time, but looks as if it is reachable with DAWN. 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>

franontanaya · Sep 29, 2007

Well, it seems the plan is to leave it there: http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=DAWN "The end of the primary mission takes place in July of 2015. After the end of the mission Dawn will remain in orbit around Ceres." I guess they would need not only enough Xenon left, but also enough hydrazine for the orbit insertion, and healthy enough panels. The article states that the ion engines work at full with 2.6 kW, but at the end of the mission the solar panels will produce only 1.3 kW, to be substracted the 200 W for heating, plus systems and communications. That horse has no teeth to look at, I fear... <img src="/images/icons/frown.gif" /> <div class="Discussion_UserSignature"> </div>

brellis · Sep 29, 2007

$446 Million - what a deal. Leaving it in orbit around Ceres is just great. Odds are they'll find something wonderful happening there! <div class="Discussion_UserSignature"> I'm a recovering optimist - things could be better. </div>

PistolPete · Sep 29, 2007

Well, that's about 8 years away. A lot can happen in eight years. I wouldn't give up hope quite yet. <div class="Discussion_UserSignature"> So, again we are defeated. This victory belongs to the farmers, not us.-Kambei Shimada from the movie Seven Samurai </div>

MeteorWayne · Sep 29, 2007

Well, we really have at least 7 years to even worry about planning such a mission. Lets not get cart in front of horse. When we get to Vesta, then we can even begin to think about "beyornd Ceres." <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>

franontanaya · Sep 29, 2007

Yet, maybe it would be more worthwhile to find a "typical asteroid belt" body close to Ceres and study it with detail, if we didn't have a chance for good flybys on the way. Should we expect an high chance of Ceres having several tiny moons? What's the minimum distance DAWN's cameras can focus at? Their specs are "an f/7.9 refractive optical system with a focal length of 150mm". <div class="Discussion_UserSignature"> </div>

alokmohan · Sep 29, 2007

Iagree.At this point we should not speculate beyond ceres.Let time be mature.

chyten · Oct 4, 2007

Isn't Dawn supposed to image several asteroids "along the way", like Galileo did?

MeteorWayne · Oct 4, 2007

AFAIK (and I looked around a bit) no other asteroids come particularly close to the path. I'm sure if one comes close enough for an image they will snap a shot as long as it does not compromise in any way the Primary Mission objectives, Vesta and Ceres. <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 · Oct 4, 2007

Hi chyten. MeteorWayne is correct. Currently there does not really appear to be much in the way of opportunistic encounters, before 4 Vesta. This may change, as the knowledge gained from the performance of the Ion engine, etc becomes apparent. What ever, fuel margins are very good, largely due to the fact that the launch, was so spectacularly accurate, the Delta 2 did a superb job. This has saved fuel, no question about it. There are less TCM (Trajectory Correct Maneuvers) required. Unless a really large or interesting asteroid can be found, I would rather DAWN, just press ahead to 4 Vesta & 1 Ceres first, then if enough fuel is left, perhaps an extended stay at 1 Ceres, with a stab at a 2 Pallas encounter afterwards in an extended mission, rather than using surpluses, hunting small fry before hand. Also I do not know yet, about possibilities between 4 Vesta & 1 Ceres either (as DAWN will be within the asteroid belt proper during this cruise). IMO 4 Vesta & 1 Ceres are priorities, with 2 Pallas as a high priority for any possible extended mission. I too would love to see some close encounters with other asteroids on route like Galileo (we learned a hell of a lot from the 951 Gaspra & 243 Ida encounters & NASA / JPL did the right thing by still rendezvouing with them despite Galileo's HGA problems). 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 · Oct 4, 2007

That's the way I feel too, Andrew. Finish the investigations of Vesta and Ceres, and see how much fuel is left. Pallas would certainly be a desirable target afterward. However, in 8 years we might have a better target in mind. It's 8 years away; there's plenty of time to consider our options. But first, don't muck about with the Primary Mission. Too much time, effort, and money has been invested in getting the craft underway. The targets are too interesting to risk the mission. At this time, even the performance charachteristics of the ion engines is not known. Besides, any diversions would likely delay arrival at Vesta or Ceres, and that would be a mistake. Just MHO, which is of course right <img src="/images/icons/wink.gif" /> Wayne <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 · Oct 4, 2007

Hi MeteorWayne, Yes thats true. My thoughts precisely. The primary mission is not in question IMO either. Given the excellent start, options do become available. AFAIK, the Ion engine will not be switched on for some time, I think not until near the Mars encounter in March 2009. We'll know much more by then. 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>

JonClarke · Oct 4, 2007

We have seen quite a bit of the small fry already, thanks to Galileo, Hayabusa, Deep Space 1, NEAR, etc. But we have seen nothing of the "dwarfs". Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

3488 · Oct 4, 2007

Hi jon, Yes that's true. I suppose the closest we have seen to a dwarf planet up close is Neptune's Triton with Voyager 2. Of course, Triton is in orbit around Neptune, so does not count & also Triton was certainly heavily modified during the capture. I suppose we could add the Saturn moons Rhea & Iapetus, as well as the Uranus moons Titania & Oberon, as they are quite large objects, dwarf planet sized, but again, do not qualify as they orbit Saturn & Uranus, not the Sun. Really though, I am really looking forward to 4 Vesta & 1 Ceres though, two really very different mini worlds. This is truly a great mission, a very long time in coming & trying to get happen. Hopefully it will be worth the effort, that those of us who campaigned to get this mission up & running. I think it will be. 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>

gunsandrockets · Oct 4, 2007

<AFAIK, the Ion engine will not be switched on for some time, I think not until near the Mars encounter in March 2009. /> That didn't sound right to me, so I did a little googling and came up with this... http://www-ssc.igpp.ucla.edu/dawn/mission.html ... considering the fact that Dawn takes much more than a year to reach Mars, the ion engine must be thrusting way before Mars flyby, probably thrusting for most of Dawn's flight time.

gunsandrockets · Oct 4, 2007

I found this too... http://www-ssc.igpp.ucla.edu/dawn/DawnJournal_30Sept07.html ... sounds like the Ion engine will be switched on in December. "Over the subsequent days, the team gradually reconfigured the spacecraft subsystems to prepare for the extensive testing and checkout scheduled to conclude in mid December. By the time this report was filed, the team had sent 148 sets of commands to Dawn and had scrutinized thousands of measurements of temperatures, pressures, voltages, currents, data buffer volumes, valve and switch positions, and many many other parameters. Now the spacecraft is ready to be put through its paces before it begins its ion propelled voyage past Mars and then on to the uncharted and distant worlds Vesta and Ceres."

MeteorWayne · Oct 4, 2007

IIRC, the ion engines will be switched on in a month or two for a performance test, pointing away from the earth to slow it down. See my comment a few pages ago. <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 · Oct 4, 2007

Sorry gunsandrockets, I was mistaken. There is still a period prior to Ion engine switch on, but it is well before the Mars encounter. Thank you for pulling me up on that one. My mistake, I own up to it. Route plan showing Ion thrusting & coasting. 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>

gunsandrockets · Oct 4, 2007

Thanks for pointing out that map to me. I had glanced at it before, but silly me, I had failed to notice the legend with the thrusting vs non-thrusting indications! That will teach me to pay closer attention. I find the time/place of thrusting shown on that map interesting. During transfer to Vesta and then to Ceres the ion engine is almost constantly thrusting. But during transfer to Mars the engine is thrusting only about half the time (only during the time when it it closer to Perihelion?)

gunsandrockets · Oct 4, 2007

<See my comment a few pages ago.> I went through five pages of comments and can't find it.

3488 · Oct 4, 2007

Hi gunsandrockets. MeteorWayne did post this. it will be an interesting test. Lets hope it goes OK. 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>

gunsandrockets · Oct 4, 2007

Got it. Thanx.

DAWN mission to orbit 1 Ceres & 4 Vesta.

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