DAWN mission to orbit 1 Ceres & 4 Vesta.

[mithridates]

Here's another plan of the route taken by Dawn with more detail on exactly when it'll be using the motor and when not:<br /><br />http://www.forskning.no/Bilder/1191034484.92/1191034484.92_content.jpg<br /><br />It's from this article in Norwegian:<br />http://www.forskning.no/Artikler/2007/september/1191014734.47 <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[gunsandrockets]

<Here's another plan of the route taken by Dawn with more detail on exactly when it'll be using the motor and when not:><br /><br />Fascinating.<br /><br />If you compare the map you linked to with the map Andrew linked to you can see a very big difference in the course to Mars.<br /><br />The Andrew map, with the earlier planned launch date of June, shows DAWN taking two circuits around the Sun before reaching Mars. The mithridates map, with the actual launch date of September, shows DAWN zipping to Mars in a single circuit around the Sun. In fact it shows DAWN's Apohelion on approach to Mars outside of the orbit of Mars!<br /><br />Now that I think about it, the map with the earlier launch date doesn't make sense to me. The launch date shown is June 2007 and the Mars arrival date is February 2009; that is less than two years total travel time. So how could DAWN circle the sun twice while outside the orbit of Earth in less than two years time? I must be missing something!

 

[3488]

Hi gunsandrockets.<br /><br />Yes that is strange, two orbits around the Sun outside Earth's orbit in less the two years.<br /><br />I do not quite get that myself. It does look on mithridates map that DAWN will approach <br />Mars from the night side of Mars, using Mars to pump the trajectory further outward.<br /><br />I do not understand that either. Surely such a maneuver will acheive the opposite????? <br /><br />I really must be missing something myself here.<br /><br />Thank you mithridates for your links.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[gunsandrockets]

< It does look on mithridates map that DAWN will approach <br />Mars from the night side of Mars, using Mars to pump the trajectory further outward. I do not understand that either. Surely such a maneuver will acheive the opposite? /><br /><br />I am very much a noob when it comes to orbital mechanics, and I am trying to pick up what little I can whenever I can. With that qualifier foremost...<br /><br />... I understood gravity-assist maneuvers depended on whether the spacecraft passed by the leading vs the trailing side of a planet in the planet's solar orbit, not the day vs night side of a planet. And I can't tell from the corseness of the map which side DAWN will pass by Mars anyway!<br /><br /> <br /><br />

 

[MeteorWayne]

It was from the news conference, I couldn't find it in the documents either. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

News today:<br /><br />Dawn Mission Status: Spacecraft Tests Ion Engine<br /><br /> 10.09.07 <br /><br /> <br />NASA's Dawn spacecraft successfully completed the first test of its ion propulsion system over the weekend. The system is vital to the success of Dawn's 8-year, 1.6 billion-kilometer (3-billion-mile) journey to asteroid Vesta and dwarf planet Ceres. <br /><br />"Dawn is our baby and over the weekend it took some of its first steps," said Dawn project manager Keyur Patel of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We have two months more checkout and characterization remaining before Dawn is considered mission operational, but this is a great start." <br /><br /> link <br /><br />Members of the Dawn mission control team have been sending up commands and checking out spacecraft systems ever since its successful launch on Sept. 27. The first test firing of one of Dawn's three ion engines was the culmination of several days of careful preparation. <br /><br />On Saturday, Oct. 6 at 6:07 p.m. Pacific Daylight Time (9:07 p.m. Eastern Daylight Time), the ion propulsion system began thrusting. Over the next 27 hours, spacecraft controllers and navigators at JPL monitored the engine's performance as it was put through its paces. <br /><br />"We evaluated the engine's capabilities at five different throttle levels," said Jon Brophy, the Dawn project's ion propulsion manager at JPL. "From flight idle through full throttle, the engine performed flawlessly." <br /><br />Dawn's ion engines are extremely frugal powerhouses. The 27 hours of thrusting from the ion engine resulted in the consumption of less than .28 kilograms (10 ounces) of the spacecraft's xenon fuel supply -- less than the contents of a can of soda. Dawn's fuel tank carries 425 kilograms (937 pounds) of xenon propellant. Over their lifetime, Dawn's three ion propulsion engines will fire cumulatively for about 50,000 hours <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[halcyondays]

<<<<br /> 1.6 billion-kilometer (3-billion-mile)<br /> />>><br /><br />Well, let's hope NASA have not made another metric/imperial screw-up !

 

[MeteorWayne]

<img src="/images/icons/smile.gif" /> Good catch !! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[mithridates]

I was trying to find a "Where is Dawn now" map yesterday both on the site and on the Solar System simulator but nothing for either of them. Anybody know where we can see Dawn's current position? <br /><br />(I followed the one for Cassini about once a week for the whole trip to Saturn; seem to be addicted to those current position maps) <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[3488]

Hi mithridates,<br /><br />You know what??<br /><br />I am damned if I can find it either. I do not think that there is one for DAWN.<br /><br />Hi HalcyonDays.<br /><br />I do not think, that fiasco will ever be allowed to happen again. Some very hard & <br />embarrassing lessons were learned from the failure of the Mars Climate Orbiter.<br /><br />BTW, the DAWN ION engine test was a 100% success. The ION engine worked even better <br />than expected, during the 27 hour test.<br /><br />This mission is going extremely well. <img src="/images/icons/laugh.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[brellis]

<font color="yellow">I followed the one for Cassini about once a week for the whole trip to Saturn</font><br /><br />I loved reading the Cassini status reports during the cruise phase. "The spacecraft is in excellent condition and all monitored systems are functioning nominally" <img src="/images/icons/smile.gif" /><br /><br />Those reports disappeared when they revamped the site upon arrival at Saturn <img src="/images/icons/frown.gif" /> <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>

 

[3488]

Hi brellis,<br /><br />I wonder if that was because, during the cruise to Saturn, there was little to report<br />other than the excellent Jupiter encounter & the fascinating approach to Saturn<br />beginning with the very interesting Phoebe encounter.<br /><br />Thats my thought on as to why the Mission Stauts reports were changed.<br /><br />As to why there is no Where is DAWN now page, I am at a loss. The New Horizons<br />one is very good & even the Mars Phoenix Lander has said page.<br /><br />Most strange.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[MeteorWayne]

I did write to the Dawn crew suggesting a "Where is it now" page.<br /><br />Of all the missions, it's one of the more interesting paths, traversing the asteroid belt <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[3488]

Could not agree with you more mate.<br /><br />It IS a fascinating route, would love to follow it accurately.<br /><br />I will have to write to the DAWN team myself then, to back up your letter / email.<br /><br />It would be a worthy feature on their site.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[mithridates]

Okay, I just sent off an email myself too. I assume that they just haven't gotten around to it yet or simply forgot that people might be interested in tracking it like the other probes. <div class="Discussion_UserSignature"> <p>----- </p><p>http://mithridates.blogspot.com</p> </div>

 

[h2ouniverse]

Y<br />In addition, with the ion propulsion, they will have to do ranging very frequently to check the trajectory. So why not reporting?<br />Unless they do not want spectators to start spreading speculations whenever there is a stop or change in the thrust?

 

[alokmohan]

NASA's Dawn spacecraft successfully completed the first test of its ion propulsion system over the weekend. The system is vital to the success of Dawn's 8-year, 1.6 billion-kilometer (3-billion-mile) journey to asteroid Vesta and dwarf planet Ceres. <br />http://www.spaceref.com/news/viewpr.nl.html?pid=23755<br />

 

[holmec]

Good news! It flies! Fly the coop DAWN. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[3488]

It is extremely good news.<br /><br />This mission is going very well indeed.<br /><br />Looking forward to the first ligh images, what ever they may be, Earth Moon system in high phase,<br />distant mug shot of Jupiter, Pleiades, etc.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[docm]

If I had 4 thumbs they'd all be up <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

The half a decade has nothing to do with going well or not.<br /><br />The long path was chosen to get the most science to the targets, get the most science out of the visit, while making the mission affordable enough that it could actually happen. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[alokmohan]

One thing we should realise.

 

[h2ouniverse]

The cost of operations, and so partially the duration of the mission are more and more important in the global financial budget of a mission.<br />Unfortunately for your point, that is still of second order vs launch costs. So the mass you take on board for your propulsion is still expensive. And you cannot multiply the ion thrusters and the solar panels needed to power-supply them without increasing the cost of the mission.<br />Regards.<br />

 

[h2ouniverse]

Also the Xenon gas is very expensive. (and produced in low quantities by industry)<br />I was surprised to see the huge amount of Xe on board Dawn (490kg?). Surely represents a significant cost.

 

[alokmohan]

If they could make it less costly?