NASA's Dawn Journal

Dear Dawnright Spectacular Readers

30 Apr 2012 22:04:53 GMT

Dawn is wrapping up a spectacularly rewarding phase of its mission of exploration. Since descending to its low-altitude mapping orbit (LAMO) in December, the stalwart probe has circled Vesta about 800 times and collected a truly outstanding trove of precious observations of the protoplanet. Having far exceeded the plans, expectations, and even hopes for what it would accomplish when LAMO began, the ambitious explorer is now ready to begin its ascent. On May 1, atop its familiar blue-green pillar of xenon ions, the craft will embark upon the six-week spiral to its second high-altitude mapping orbit.

Dear Dawnscoverers

29 Mar 2012 17:04:50 GMT

Vesta is spending the 205th anniversary of its discovery by treating Dawn to more spectacular vistas. When Heinrich Wilhelm Matth�us Olbers first spotted Vesta, he could hardly have imagined that the power of the noble human spirit for adventure and the insatiable hunger for knowledge would propel a ship from Earth to that mysterious point of light among the stars. And yet today our spacecraft is conducting a detailed and richly rewarding exploration of the world that Olbers found.

Dear Ups and Dawns

1 Mar 2012 17:27:07 GMT

Dawn is continuing its exploits at Vesta, performing detailed studies of the colossal asteroid from its low altitude mapping orbit (LAMO). The robotic ambassador is operating extremely well on behalf of the creatures it represents on a distant planet. On this second intercalary day of its ambitious adventure, the spacecraft is doing exactly what it was designed to do: exploring a previously uncharted alien world.

Dear Asdawnished Readers

27 Jan 2012 16:49:10 GMT

Dawn is scrutinizing Vesta from its low-altitude mapping orbit (LAMO), circling the rocky world five and a half times a day. The spacecraft is healthy and continuing its intensive campaign to reveal the astonishing nature of this body in the mysterious depths of the main asteroid belt.

Since the last log, the robotic explorer has devoted most of its time to its two primary scientific objectives in this phase of the mission. With its gamma ray and neutron detector (GRaND), it has been patiently measuring Vesta's very faint nuclear emanations.

Dear Indawnstructibles

30 Dec 2011 21:15:42 GMT

Dawn concludes 2011 more than 40 thousand times nearer to Vesta than it began the year. Now at its lowest altitude of the mission, the bold adventurer is conducting its most detailed exploration of this alien world and continuing to make thrilling new discoveries.

Circling the protoplanet 210 kilometers (130 miles) beneath it every 4 hours, 21 minutes on average, Dawn is closer to the surface than the vast majority of Earth-orbiting satellites are to that planet. There are two primary scientific objectives of this low altitude mapping orbit (LAMO). With its gamma ray and neutron detector (GRaND), the probe is measuring the faint emanations of these subatomic particles from Vesta. Some are the by-products of the bombardment by cosmic rays, radiation that pervades space, and others are emitted through the decay of radioactive elements.

Dear Dawnward Spirals

29 Nov 2011 18:18:10 GMT

Continuing its ambitious campaign of exploration deep in the asteroid belt, Dawn has spent most of the past month spiraling ever closer to Vesta. Fresh from the phenomenal success of mapping the alien world in detail in October, the spacecraft and its human team members are engaged in one of the most complicated parts of the mission. The reward will be the capability to scrutinize this fascinating protoplanet further.

Dear Dawnderfuls

31 Oct 2011 16:57:28 GMT

Dawn has completed another wonderfully successful phase of its exploration of Vesta, studying it in unprecedented detail during the past month. From the time of its discovery more than two centuries ago until just a few months ago, this protoplanet appeared as hardly more than a fuzzy blob, an indistinct fleck in the sky. Now Dawn has mapped it with exquisite clarity, revealing a fascinatingly complex alien world.

Dear Dawnniversaries

28 Oct 2011 20:52:19 GMT

Dawn’s fourth anniversary of being in space is very different from its previous ones. Indeed, those days all were devoted to reaching the distant destination the ship is now exploring. Celebrating its anniversary of leaving Earth, Dawn is in orbit around a kindred terrestrial-type world, the ancient protoplanet Vesta.

Dear Magdawnificents

1 Sep 2011 17:48:23 GMT

Dawn has completed the first phase of its exploration of Vesta with tremendous success, and the peripatetic adventurer is now in powered flight again, on its way to a new location from which to scrutinize its subject. Meanwhile, scientists are deeply engaged in analyzing the magnificent views the stalwart surveyor has transmitted to Earth.

Dear Dawncredibles

11 Aug 2011 22:25:57 GMT

Dawn is now beginning intensive observations of the alien world it orbits. The approach phase, which began on May 3, is complete. Today Dawn is in its survey orbit around Vesta.

Dear Residawnts of Vesta

18 Jul 2011 22:08:36 GMT

Dawn has arrived!

After covering 2.8 billion kilometers (1.7 billion miles) on its own, after traveling for nearly four years through the lonely emptiness of interplanetary space, after being bound by the gravity only of the sun, Dawn is finally in orbit around Vesta. To get here, it gently propelled itself with its ion propulsion system for 70% of its journey, or more than 2.6 years. Deep in the asteroid belt, far from its planet of origin, well beyond Mars (which it visited ever so briefly more than two years ago), where no spacecraft has ever been before, Dawn now resides with a giant.

Dear Dawnstinations

23 Jun 2011 19:02:49 GMT

Vesta beckons, and Dawn responds. Now more than halfway through its approach to Vesta, Dawn continues creeping up on the destination it has been pursuing since it began its interplanetary travels. The separation between them gradually shrinks as the probe�s ion thrusting brings its orbit around the sun into a closer and closer match with Vesta�s. At the same time, the giant protoplanet�s gravity tugs gently on the approaching ship, luring it into orbit.

Starting at the beginning of the approach phase on May 3, Dawn interrupted thrusting once a week to photograph Vesta against the background stars. These images help navigators establish exactly where the probe is relative to its target. This technique does not replace other means of navigation but rather supplements them. One of the principal methods of establishing the spacecraft�s trajectory relies on accurately timing radio signals, traveling, as all readers know, at the universal limit of the speed of light, to make the round trip between Earth and Dawn.

Dear Dependawnble Readers

27 May 2011 20:01:44 GMT

Dawn remains healthy and on course as it continues to approach Vesta. Thrusting with its ion propulsion system, as it has for most of its interplanetary journey so far, the spacecraft is gradually matching its solar orbit to that of the protoplanet just ahead.

As these two residents of the asteroid belt, one very new and one quite ancient, travel around the sun, they draw ever closer. Vesta follows its own familiar path, repeating it over and over, just as Earth and many other solar system bodies do. Dawn has been taking a spiral route, climbing away from the sun atop a blue-green pillar of xenon ions.

Dear Dawntalizingly Close Readers

3 May 2011 20:51:25 GMT

Dawn is on the threshold of a new world. After more than three and a half years of interplanetary travel covering in excess of 2.6 billion kilometers (1.6 billion miles), we are closing in on our first destination. Dawn is starting its approach to Vesta.

The interplanetary cruise phase of the mission ends today and the 15-month Vesta phase begins. The first three months are the "approach phase," during which the spacecraft maneuvers to its first science orbit. Many of the activities during approach were discussed in detail in March and April last year, and now we are about to see those plans put into action.

Dear Conndawnsseurs

31 Mar 2011 20:35:56 GMT

Deep in the asteroid belt, Dawn continues thrusting with its ion propulsion system. The spacecraft is making excellent progress in reshaping its orbit around the sun to match that of its destination, the unexplored world Vesta, with arrival now less than five months away
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Spacecraft that use conventional propulsion coast through space most of the time, just as the moon coasts around Earth, and the planets and asteroids coast around the sun. In contrast, Dawn is in powered flight most of the time, using its ion propulsion system to change its orbit. The flight plan requires pointing the ion thruster in just the right direction to deliver the adventurer to its destination. The spacecraft orientation needed to aim the thruster ends up pointing the main antenna in an arbitrary direction. We have seen before that the robotic craft interrupts thrusting for about eight hours each week to direct the antenna toward Earth for communications.

Dear Pleasant Dawnversions

28 Jan 2011 01:17:59 GMT

Deep in the asteroid belt, Dawn continues thrusting with its ion propulsion system. The spacecraft is making excellent progress in reshaping its orbit around the sun to match that of its destination, the unexplored world Vesta, with arrival now less than five months away
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We have considered before the extraordinary differences between Dawn�s method of entering orbit and that of planetary missions employing conventional propulsion. This explorer will creep up on Vesta, gradually spiraling closer and closer. Because the probe and its target already are following such similar routes around the sun, Dawn is now approaching Vesta relatively slowly compared to most solar system velocities. The benefit of the more than two years of gentle ion thrusting the spacecraft has completed so far is that now it is closing in at only 0.7 kilometers per second (1600 mph). Each day of powered flight causes that speed to decrease by about 7 meters per second (16 mph) as their orbital paths become still more similar. Of course, both are hurtling around the sun much faster, traveling at more than 21 kilometers per second (47,000 mph), but for Dawn to achieve orbit around Vesta, what matters is their relative velocity.

Dear Providawntial Readers

30 Jan 2011 19:00:18 GMT

Dawn continues its flight through the asteroid belt, steadily heading toward its July rendezvous with Vesta, where it will take up residence for a year. The spacecraft has devoted most of the time since the previous log to its familiar routine of thrusting patiently with its ion propulsion. But both the distant craft and the operations team each took a little time away from this month, spending it instead in the future. Although the project has not yet perfected time travel, it has achieved enough capability to conduct two successful ventures into the near future.
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On Jan. 10, Dawn performed some of the activities that it will execute in its low altitude mapping orbit (LAMO) at Vesta. From the probe�s vantage point in LAMO, much of the sky will be filled by the ancient protoplanet, only about 180 kilometers (110 miles) away. Vesta will appear as large as a soccer ball from a mere 18 centimeters (7 inches). Completing one revolution every four hours in LAMO, the spacecraft will devote most of its time to training its scientific instruments on the rocky world beneath it, teasing out the secrets Vesta holds about the dawn of the solar system. Other times, the robotic explorer will loop around the body while aiming its main antenna at distant Earth, transmitting its findings and receiving new instructions.

Dear Dawnscriminating Readers

31 Dec 2010 04:30:00 GMT

Dawn finishes 2010 much as it began the year, thrusting with its ion propulsion system in steady pursuit of a distant world. During the next year, the probe will arrive there and begin its scrutiny. In the meantime, it continues thrusting patiently, but now with a difference.
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Dawn is outfitted with three ion thrusters, although it is designed to use only one at a time. (The locations and whimsical names of the thrusters were divulged once the spacecraft was too far from Earth for anyone to see it.) Thruster #3 was the first to see action in the mission, and it propelled the spacecraft until June 16, 2008, after which thruster #1 took over. On Jan. 4, 2010, the ship switched to thruster #2. Prior to this year, #2 had accumulated little more than a day of operation for some tests. But in 2010, it operated flawlessly for 304 days, and Dawn accomplished nearly all of its thrusting this year with only that thruster. While #2 is ready for much more, on Dec. 6 mission controllers assigned thrusting to #3 as part of the strategy of balancing the work for this long journey among the three units.

Dear Dawnoweens

31 Oct 2010 20:51:04 GMT

Continuing its journey to collect treats in the main asteroid belt, Dawn is making excellent progress toward its July 2011 rendezvous with protoplanet Vesta. The gentle thrust of its ion propulsion system is gradually changing its trajectory around the sun, smoothly helping the spacecraft move onto a path that will perfectly match Vesta�s own motion. This pas de deux is just one part of the grand solar system dance, and the choreography is about to provide a particularly pleasing tableau.

While Dawn and Vesta move ever closer into synchronized orbits in the depths of space, nearer the sun and hence in a more forceful gravitational grip, Earth is traveling more quickly in its own orbit. We have seen before that tighter orbits require greater velocity in order to counterbalance the stronger pull of gravity. Mercury and Venus orbit the sun faster than Earth. Mars moves around the sun more slowly than Earth, and all residents of the more distant asteroid belt (including Dawn) revolve at an even more leisurely pace. Last month, Earth completed its third lap around the sun since Dawn was launched, but the craft is still only about two-thirds of the way through its second loop...

Dear Dawnniversaries

27 Oct 2010 17:04:52 GMT

On the third anniversary of traveling through the solar system on its own since dispatching Dawn on a separate journey, Earth continues to orbit the sun in much the same way it has been. Meanwhile, the spacecraft is thrusting with its ion propulsion system, making steady progress in reshaping its orbit to rendezvous with Vesta in July 2011.
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In its three years of interplanetary travels, the spacecraft has thrust for a total of about 715 days, or 65% of the time (and about 0.000000014% of the time since the Big Bang). While for most spacecraft, firing a thruster to change course is a special event, it is Dawn�s wont. All this thrusting has cost the craft only 189 kilograms (417 pounds) of its supply of xenon propellant, which was 425 kilograms (937 pounds) on September 27, 2007...

Dear Papardawnzzi

31 Aug 2010 02:25:42 GMT

Dawn's journey ever-deeper into the asteroid belt continues to go well, as the spacecraft carries out its familiar routine of thrusting gently with its ion propulsion system. But the interplanetary traveler has changed some of its habits, performing certain activities a little differently now from what its many followers have been accustomed to.
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Dawn is now so far from the sun, that even with its tremendous solar arrays, the most powerful ever used on an interplanetary mission, it does not receive enough sunlight to generate sufficient electrical power to operate all systems and still achieve maximum thrust...

Dear Dawn Days of Summers

26 Jul 2010 22:26:09 GMT

Dawn is flying smoothly through the asteroid belt, now less than a year from entering orbit around Vesta, the first of its two cosmic destinations.

Earlier in July, while the spacecraft was devoting its time to gentle thrusting with its ion propulsion system, members of the mission control team spent some of their time in August 2011. Impressively capable as NASA is, time travel is not within its powers. Instead, the team simulated being in the future, when Dawn will be finishing its approach to survey orbit around Vesta, where it will begin its intensive scrutiny of the alien world. That will be a very busy period not only for the spacecraft but also for the human members of the team...

Dear Daw9.0s

27 Jun 2010 22:22:17 GMT

A new version of the Dawn spacecraft is continuing the ambitious journey through the asteroid belt to uncharted distant worlds. Now holding a new solar system record, the probe is thrusting with its ion propulsion system, patiently and gently changing its orbit around the sun to match that of the immense protoplanet Vesta (and subsequently dwarf planet Ceres).

Even as Dawn continues pushing deeper into space, another spacecraft that used ion propulsion to conduct an exciting mission at a near-Earth asteroid has concluded. After traveling to and studying the diminutive Itokawa, Japan�s Hayabusa spacecraft returned to Earth on June 13. This was long one of your correspondent�s favorite missions, and he has joined many, many other enthusiasts in congratulating the team responsible for this impressive achievement...

Dear Multitudawnous Readers

27 May 2010 16:58:29 GMT

After more than 2.5 years of spaceflight, and more than 6 months in the asteroid belt, Dawn�s interplanetary journey continues smoothly. The mission remains on course and schedule for this expedition to the dawn of the solar system.

Our Dawn is not the first spacecraft to use this name, although it is traveling farther from home than any other Dawn. This month 2 more craft traveled into space carrying that appellation, at least when translated into English. The Japanese Aerospace Exploration Agency sent Akatsuki to Earth�s neighbor Venus, and Russia�s Rassvet module was attached to the International Space Station in Earth orbit. The solar system is vast, however, and there is plenty of room for all such spacecraft. We send our best wishes for success to these other Dawns as they embark on their missions..

Dear Adawnherents

28 Apr 2010 23:47:49 GMT

Dawn remains on course and on schedule for its appointments with Vesta and Ceres, colossal protoplanets in the main asteroid belt. Under the gentle and continuous thrust of its ion propulsion system, its journey through the solar system brings it ever closer to its first target.

Last month�s log included an overview of many of the spacecraft�s activities during the final 3 months before its August 2011 arrival in the first science orbit at Vesta. In this “approach phase,� the probe will observe Vesta with its camera and one of its spectrometers to gain a better fix on its trajectory and to perform some preliminary characterizations of the alien world prior to initiating its in-depth studies...

Dear Dawnizens of the Solar System

30 Mar 2010 20:51:28 GMT

Dawn is maintaining its smooth and steady course through the solar system as it gradually closes in on Vesta. With the utmost patience and persistence, it continues thrusting with its ion propulsion system, heading toward its July rendezvous with the second most massive member of the main asteroid belt. Even as the spacecraft climbs farther from the sun, Earth's orbit is beginning to bring the planet closer to the probe.

Having thrust for two-thirds of its time in space, Dawn has now achieved the velocity equivalent of about 5.5 kilometers per second (more than 12,000 miles per hour). We have seen before that this does not represent the actual change in speed, but it is still a very useful measure of the effect of the thrusting. Although it has long since surpassed the record for propulsive change in velocity, Dawn is only now at the halfway point in the planned profile of thrusting for its ambitious eight-year expedition. By the time it completes its mission at dwarf planet Ceres (the asteroid belt's most massive resident) in 2015, it will have accomplished twice the effective velocity change it has achieved so far.

At the beginning of this month, mission controllers installed new parameters in the software used to control the spacecraft�s orientation (which engineers refer to as “attitude�) in the zero-gravity conditions of...

Dear Dawnthorities

28 Mar 2010 18:28:40 GMT

Dawn continues patiently forging through the asteroid belt, its permanent residence, as it climbs away from Earth and the Sun. Having thrust with its ion propulsion system for more than 1.5 years, the spacecraft remains healthy and on target for its rendezvous with alien worlds.

Our interplanetary adventurer still has a great deal of ion thrusting to complete before it can begin its orbital exploration of Vesta next year. Although it will suspend thrusting for a few weeks this summer to conduct some special activities (to follow along, be sure to renew your subscription to these logs the first time our helpfully persistent telemarketers call), it will devote most of the time until early August 2011 in powered flight, continuously reshaping its orbit around the Sun...

Dear Dawnthropoids

24 Jan 2010 20:58:38 GMT

Pushing ever farther into space, deeper into the asteroid belt, Dawn is continuing to progress smoothly on its solar system journey.

The spacecraft spends most days climbing away from the Sun atop its pillar of blue-green xenon ions. A day�s thrusting is enough to change the spacecraft�s speed by a very modest 7.3 meters/second (16.3 miles/hour). While such an effect would be entirely inadequate for an interplanetary mission as ambitious as Dawn�s, the extraordinary efficiency of ion propulsion allows the probe to thrust for much more than a day. Although almost all spacecraft coast most of the time, as do planets, moons, and asteroids, this explorer usually maintains a gentle pressure on its orbit, constantly changing it so that it can rendezvous with Vesta next year, leave in 2012, and then rendezvous with Ceres in 2015. Dawn has spent 60% of its time since launch patiently accelerating with the ion propulsion system. It has already managed to change its speed by more than 3.6 kilometers/second (8100 miles/hour), far exceeding the capability of most spacecraft, yet it has a great deal more thrusting ahead. (For a comparison with probes that enter orbit around Mars, visit a previous log.)

Dear Plausible Dawniabilities

30 Jan 2010 18:11:19 GMT

Patiently and reliably continuing with its interplanetary voyage, Dawn is now flying in a new configuration and, from the perspective of those readers who may be on Earth, in a new direction.

The spacecraft still spends most of its time gradually changing its orbit around the Sun by thrusting with its ion propulsion system. The probe is outfitted with 3 ion thrusters, assigned the heartwarming names thruster #1, thruster #2, and thruster #3... (The nomenclature and locations of the units were divulged in a log shortly after launch, before such information could be distorted and used unethically by others.)

Dear Dawnters and Sons

30 Dec 2009 18:00:08 GMT

The Dawn mission continues to go smoothly, as Earth�s distant envoy carries out its interplanetary journey. Although the craft still devotes most of its time to the slow but efficient reshaping of its orbit around the Sun to match Vesta�s, controllers gave it some extra assignments since the last log to ensure its systems remain healthy and to prepare for its studies of Vesta.
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Dawn usually interrupts ion thrusting once a week for about 8 hours to point its main antenna to Earth. On November 30, however, instead of resuming thrusting, it dutifully followed different instructions that were stored onboard...

Dear Dawnticlimaxes

27 Nov 2009 21:03:38 GMT

Dawn continues to make steady progress through the solar system as it maintains a gentle pressure on its orbit around the Sun. It has spent 95% of the time since the last log thrusting with its ion propulsion system, stopping only briefly each week to communicate with the mission control team on distant Earth.

The probe is on an exciting journey to unlock secrets from the dawn of the solar system ensconced in the mysterious worlds Vesta and Ceres. And yet there is one aspect of this expedition that likely is much less exciting than some readers may expect...

Dear Dawn-o�-lanterns

31 Oct 2009 14:58:13 GMT

Dawn continues to make steady progress on its journey through the solar system. The spacecraft has devoted another month to thrusting with its ion propulsion system, ever with its sights set on its rendezvous with Vesta in July 2011. While it will have other assignments along the way, propelling itself to the giant protoplanet deep in the main asteroid belt remains its principal responsibility...

Dear Dawnniversaries

28 Sep 2009 04:38:29 GMT

Dawn is celebrating the second anniversary of leaving its home planet by engaging in the same function it has performed most of its time in space: with the utmost patience, it is using its ion propulsion system to gradually modify its orbit around the Sun.

In its interplanetary travels, the spacecraft has thrust for a total of about 389 days, or 53% of the time (and about 0.000000008% of the time since the Big Bang). While for most spacecraft, firing a thruster to change course is a special event, it is Dawn’s wont. All this thrusting has cost the craft only 103 kilograms (228 pounds) of its supply of xenon propellant, which was 425 kilograms (937 pounds) on September 27, 2007...

Dear Indawnmitables

30 Aug 2009 16:03:24 GMT

The Dawn mission remains on course as the spacecraft continues to thrust with its ion propulsion system, patiently, persistently, and gently changing its orbit to keep its appointment with protoplanet Vesta in two years. Meanwhile, closer to mission control and in stark contrast, brave firefighters work hard to protect JPL and the nearby homes of many of its employees and others in the community.

The probe has continued in “quiet cruise” since the last log. During this month, engineers did give the robot a few extra tasks to ensure it remains healthy, but these were routine. When each such assignment was conducted the first time or two that Dawn was in space, they were treated as special activities, with even greater diligence than is normally applied to the unforgiving and complex undertaking of flying a spacecraft far from Earth. Now however, the commands for these activities are stored onboard well ahead of time along with the routine commands for thrusting, communicating with Earth, and carrying out all the other functions the spacecraft normally conducts without the mission control team devoting extra attention...

Dear Indawnfatigables

3 Aug 2009 15:21:52 GMT

Shhhh! Dawn is in “quiet cruise,� and we do not want to disturb it. The indefatigable spacecraft is devoting most of its time to thrusting with its ion propulsion system, applying a gentle but persistent pressure to its trajectory around the Sun. With patience, it will reshape its orbit to match those of the mysterious and intriguing protoplanets Vesta and Ceres. In order to conduct its detailed explorations of each of these exotic worlds, Dawn will accompany them around the Sun, visiting with Vesta in 2011�2012 and rendezvousing with Ceres in 2015...

Dear Astrodawns

28 May 2009 00:43:14 GMT

Dawn�s mission continues to go very well, as the spacecraft nears the end of the longest coasting period of its astronomical journey. The deep-space member of the team has completed more special activities under the helpful guidance of the terrestrial contingent.
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The previous log described the installation of software in the spacecraft�s main computer. (Known as flight software 8.0, this name was chosen as part of Dawn�s new outreach effort to increase public awareness of the number 8. Please consider yourself aware. The outreach plan for the designation of the subsequent version of the software is expected to be 12.5% better.) The software had been tested extensively in simulators on Earth, but the ultimate test is its performance in keeping the spacecraft running smoothly. Because Dawn devotes more time in space to thrusting with its ion propulsion system than doing anything else (this does not count the time it spends in eager anticipation of the exciting rewards to be garnered at its destinations Vesta and Ceres), it was important to verify that the capability to thrust was not compromised with the new software. Despite the assiduity with which 8.0 was developed, the possibility of a subtle bug being introduced could not be discounted...

Dear Dawnterested Readers

28 Jun 2009 15:33:23 GMT

Having completed the longest planned coasting period of its entire mission, Dawn is now back to its familiar routine. On June 8, the ion propulsion system was called back into action to propel the probe to its rendezvous with asteroid Vesta.

The spacecraft began its 7-month coast period on October 31, 2008. Since then, it had used its ion thrusters for a measurement of the solar array power, a small adjustment in its course to Mars (the gravitational effect of which provided a boost to its distant destination), and tests of the software remotely installed on the main computer in April. The accumulated thrusting during all of those activities added only about 10 hours to the mission�s log of 282 days when coasting commenced...

Dear Dawngrades

8 May 2009 02:34:56 GMT

The upgraded Dawn spacecraft is now traveling in a new direction in its orbit around the Sun. The mission continues to go smoothly during this long coasting period, scheduled to conclude in June, when powered flight with the ion propulsion system will resume. Dawn has many computers in its onboard crew and one that serves as the captain of the ship. This primary computer�s software had been unchanged since February 2008. That last modification involved only a small patch, making version 7.0.3 of the software. That was preceded by a small update in January 2008 and one in December 2007. Prior to this month, Dawn had had only one complete in-flight replacement of its main software, in November 2007...

Dear Charles Dawnwins

14 Mar 2009 02:48:28 GMT

While Dawn and Mars move in their separate orbits around the Sun, they are approaching each other at the stately pace of 2.56 kilometers/second (5720 miles/hour). Gradually, the gravitational pull of the planet will grow as the distance shrinks, and the spacecraft�s path will start to change, beginning the boost we seek. By about noon PST on February 14, the tug from Mars will have grown to be the same as the famously gentle thrust from Dawn�s ion propulsion system. When Dawn is closest to Mars, speeding past it at 5.31 kilometers/second (11,900 miles/hour), the red planet will be exerting 34,000 times greater force than the blue-green xenon beam generates...

Dear Dawntpanics

31 Mar 2009 15:35:15 GMT

Dawn continues to coast quietly and calmly in its orbit around the Sun, keeping its main antenna pointed to faraway Earth. The mission control team has given the spacecraft relatively few assignments in recent weeks, providing time to prepare for a busier future. To ensure the distant craft remains healthy and safe, operators transmitted instructions for conducting routine maintenance, activities that are familiar to the probe now that it has been on its deep-space journey for more than 1.5 years. Perhaps what is most noteworthy and satisfying since the last log is not what Dawn did, but rather what it did not do...

Dear Dawncers

2 Mar 2009 21:55:12 GMT

Dawn continues on course for its pas de deux with Mars on February 17. The planet�s gravity will gracefully assist the spacecraft on its way to rendezvous with its intended celestial partners Vesta and Ceres in the more distant asteroid belt. Even the extraordinary capability of its ion propulsion system would not be sufficient for Dawn to complete its celestial dance without the help of Mars.
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In the last log we saw that the mission operations team was preparing to adjust the probe�s flight path to keep it on target for next month�s flyby. Just getting to the vicinity of Mars is not sufficient, as the passage by the planet is only one short segment of a very long itinerary. Indeed, choreographing Dawn�s trajectory is a complex matter of finding the most efficient route through the solar system to travel from the moving platform on which it started (Earth) to encounter Mars in just the right way to reach Vesta at the proper time to complete its work there before it has to begin the trek to Ceres to meet it on schedule, aided during most of the journey by the ion propulsion system. Dawn must arrive at Mars on time, traveling in the correct direction and at the necessary location, for the gravitational slingshot to yield the desired effect. Flying the spacecraft through that “window� at Mars is like threading a celestial needle...

Dear Dawnlight Saving Times

13 Mar 2009 00:05:11 GMT

Now boosted into a new solar orbit courtesy of Mars, Dawn continues its interplanetary journey. The spacecraft is healthy and coasting, keeping its main antenna pointed to Earth, as it will for most of the next 3 months. After that, it will resume its familiar routine of devoting most of the time to gently thrusting with its ion propulsion system, with only a short period each week for communications.

Following the last log, as the probe succumbed to the gravitational pull of the red planet, its trajectory gradually began to change. Flying true to the plan, Dawn swooped close to Mars and then left it behind on a new course, having taken advantage of Mars's gravity...

Dawn Journal--December 30, 2008

23 Jan 2009 21:29:23 GMT

Dawn continues to close in on Mars, ready for the gravitational slingshot that will help it on its expedition to the asteroid belt and its quest to gain insights into the evolution of the solar system. The ship remains on course, with the latest calculations of its trajectory being very close to those described in the last log. The spacecraft will streak about 549 kilometers (341 miles) above the planet at 4:28 p.m. PST on February 17.
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While Dawn and Mars move in their separate orbits around the Sun, they are approaching each other at the stately pace of 2.56 kilometers/second (5720 miles/hour). Gradually, the gravitational pull of the planet will grow as the distance shrinks, and the spacecraft�s path will start to change, beginning the boost we seek. By about noon PST on February 14, the tug from Mars will have grown to be the same as the famously gentle thrust from Dawn�s ion propulsion system. When Dawn is closest to Mars, speeding past it at 5.31 kilometers/second (11,900 miles/hour), the red planet will be exerting 34,000 times greater force than the blue-green xenon beam generates...

Dawn Journal--November 26, 2008

26 Nov 2008 22:28:11 GMT

November 26, 2008

Dear Indawnviduals,

The Dawn spacecraft is healthy and on course for its flyby of Mars early next year. The planet�s gravity will help boost the probe on its way to rendezvous with Vesta. While the spacecraft has its sights set on the asteroid belt (via Mars), its path is now bringing it closer to Earth. Meanwhile, from Earth�s perspective, Dawn appears to be approaching a blindingly close encounter with the Sun. With so much happening in the solar system, all readers, whether local or not, are invited to turn their attention here.
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In the last log, we saw that Dawn was nearing the end of an extended period of thrusting with is ion propulsion system that began on December 17, 2007. When it left Earth on September 27, 2007, the Delta II rocket deposited the spacecraft into a carefully chosen orbit around the Sun. By October 31, 2008, the spacecraft had completed the thrusting it needed to change that orbit so it would encounter Mars at just the right time, location, and angle to sling it on its way to Vesta. During this interplanetary cruise phase, Dawn thrust for 270 days, or 85% of the time. Expending less than 72 kilograms (158 pounds) of xenon propellant, the spacecraft changed its speed by about 1.81 kilometers per second (4050 miles per hour)...