December 30 - Dawn Concluding Another Successful Year

Dawn is wrapping up the year in its sixth science orbit since arriving at Ceres in March 2015. Following an elliptical orbit around the dwarf planet, the spacecraft's average altitude today is 5,780 miles (9,310 kilometers).

The December Dawn Journal describes this new orbit more and presents some of Dawn's latest discoveries about the alien world it is exploring.


December 21 - Dawn Measuring Cosmic Rays

In its sixth science orbit around Ceres, Dawn is continuing to measure cosmic rays to improve its low altitude measurements. It takes almost eight days to complete one elliptical orbit. Today, the spacecraft's average altitude is about 5,470 miles (8,810 kilometers).


December 16 - Dawn Team Announces Discoveries about Ice on Ceres

Yesterday the Dawn team presented news about widespread ice just below Ceres' surface, as well as other discoveries about ice on the dwarf planet. You can read about it in this JPL news release.

The discovery of subsurface ice comes from Dawn's measurements of nuclear radiation during the eight months the spacecraft orbited Ceres at 240 miles (385 kilometers). Now the probe is in a high-altitude elliptical orbit, ranging between 4,670 miles (7,520 kilometers) and 5,810 miles (9,350 kilometers) in order to squeeze even more information from those earlier measurements. (See the November Dawn Journal for details.)


December 8 - Dawn Collecting Science Data in New Ceres Science Orbit

Dawn is healthy and making cosmic ray measurements in its new science orbit. (The November Dawn Journal explains the objective of these measurements.)

This sixth Ceres science orbit is elliptical, and navigators' initial measurements show that it ranges in altitude between 4,670 miles (7,520 kilometers) and 5,810 miles (9,350 kilometers).


December 5 - Dawn Reaches Sixth Ceres Science Orbit

This morning Dawn completed a month of ion thrusting to change its orbit around Ceres. It is scheduled to initiate a telecommunications session this afternoon to report on its status. Navigators then will begin making accurate measurements of its orbit, but the spacecraft should be in an elliptical orbit that stays more than 4,500 miles (7,200 kilometers) above Ceres. From this altitude, it will be able to measure the cosmic ray noise in order to improve the data on Ceres' nuclear radiation it accumulated during eight months at an altitude of 240 miles (385 kilometers). (This is explained in the November Dawn Journal).


December 2 - Dawn Closing in on New Orbit

Dawn's ion engine is taking the spacecraft higher and higher above dwarf planet Ceres. Today the spacecraft's average altitude is 4,140 miles (6,660 kilometers). It now takes Dawn more than 5.5 days to complete one orbital revolution.

Ion thrusting is scheduled to conclude on Dec. 5, by which time the probe will be high enough to measure cosmic rays in order to enhance its low altitude measurements of nuclear radiation emitted by Ceres. (This paradox of flying higher to improve data collected at low altitude is explained in the November Dawn Journal).


November 28 - Dawn Making Good Progress to New Orbit

As Dawn continues to raise its orbit, its average altitude today is 3,130 miles (5,040 kilometers).

The November Dawn Journal describes how flying to a higher orbit will help scientists learn more about Ceres. It also explains that with all the ion thrusting Dawn has accomplished since it left Earth in 2007, the spacecraft has now changed its own speed by a remarkable 25,000 mph (40,000 kilometers per hour).


November 23 - Dawn's Ascent Continues Smoothly

Gradually maneuvering to a higher orbit with its ion engine, Dawn's average altitude today is 2,360 miles (3,790 kilometers). Even as mission controllers take time for Thanksgiving, they will check in with Dawn occasionally through NASA's Deep Space Network to verify that the distant spacecraft is operating smoothly.


November 21 - Dawn Climbing Higher

As Dawn spirals higher, its average altitude today is 2,110 miles (3,400 kilometers). It now takes more than two days for the spacecraft to complete one orbital revolution around Ceres.

The spacecraft will continue ion thrusting for two more weeks.


November 18 - Dawn Receives Update from Earth

Dawn stopped ion thrusting on schedule yesterday afternoon and turned to point its main antenna to Earth. Mission controllers at JPL transmitted an updated flight plan to the distant spacecraft. Dawn resumed ion thrusting today shortly after 3:00 a.m. PST to continue its upward spiral.

Dawn's average altitude today is 1,750 miles (2,820 kilometers).


November 15 - Dawn Ascending Above Ceres

Dawn is making good progress maneuvering to its next science orbit. The spacecraft's average altitude today is about 1,560 miles (2,510 kilometers). Over the course of the day, Dawn's ion thrusting will raise the altitude by almost 75 miles (120 kilometers).


November 11 - Dawn On Course and On Schedule

Dawn's graceful spiral ascent to its sixth science orbit around Ceres is going very well. The spacecraft's average altitude today is about 1,270 miles (2,040 kilometers). It now takes the ship more than 27 hours to complete each orbital revolution. (During the eight months Dawn operated at 240 miles, or 385 kilometers, in altitude, it circled Ceres every 5.4 hours.)

Ion thrusting is scheduled to conclude in early December when Dawn is more than 4,500 miles (7,200 kilometers) above the dwarf planet.


November 8 - Dawn Climbing to Higher Altitude Orbit

Dawn began ion thrusting on schedule on Nov. 4. The spacecraft is now spiraling upward to its sixth science orbit around Ceres. Today Dawn's average altitude is 1,100 miles (1,770 kilometers), or nearly 200 miles (300 kilometers) above its fifth science orbit.

Ceres and its permanent companion are now 2.867 AU (266.5 million miles, or 428.9 million kilometers) from the sun, closer than any time since Dawn entered orbit around the dwarf planet in March 2015.


November 4 - Dawn Ready to Begin a New Maneuver Spiral

Dawn completed all of its planned activities at an orbital altitude of 920 miles (1,480 kilometers). This week, after the spacecraft transmitted the last of its Ceres science data to Earth, engineers swapped from the primary hydrazine-fueled reaction control system thrusters to the backup thrusters to avoid overusing them. The team also performed a routine verification of the health of the backup camera. (See the October Dawn Journal for more on these activities.)

Dawn is now ready to undertake more than a month of maneuvering to a new orbit. Ion thrusting with engine #2 is scheduled to begin shortly before 5:00 p.m. PDT today.


October 31 - Dawn Completes Another Observation Campaign

Dawn successfully concluded its fifth program of observations in Ceres orbit by transmitting the last of its scientific measurements to Earth on Oct. 29. This month's Dawn Journal describes some of the spacecraft's work in this phase of its exploration of the dwarf planet.

The flight team is now preparing to undertake a new set of maneuvers with the ion propulsion system. Dawn's next spiral to a higher altitude orbit is scheduled to begin on Nov. 4.


October 27 - Dawn's Investigations Going Smoothly

Dawn is healthy and conducting all the commanded measurements of Ceres with its camera and spectrometers. With an orbit period of 18.9 hours, the spacecraft has flown over the illuminated hemisphere 14 times since observations began on Oct. 16, acquiring the planned data each time.


October 20 - Dawn Conducting New Measurements of Ceres

Dawn began its new observations of Ceres on schedule on Oct. 16 at an altitude of 920 miles (1,480 kilometers). Circling the dwarf planet every 18.9 hours, the spacecraft acquires spectra and photographs as it flies over the sunlit surface. Sometimes it rotates to point its main antenna to Earth as it flies over the side in darkness and transmits its measurements to NASA's Deep Space Network. (On other orbits, the spacecraft waits, preserving hydrazine rather than executing additional turns.)

As Earth and Dawn (in orbit around Ceres) follow their separate orbits around the sun, this weekend they will be closer than usual. On Oct. 22, they will be 1.90 AU (177 million miles, or 284 million kilometers) apart, the smallest distance from June 2014 to December 2017.


October 12 - Dawn Team Preparing for New Ceres Observations

Orbiting Ceres at an altitude of about 920 miles (1,480 kilometers), Dawn is traveling over the alien landscapes at about 400 mph (645 kilometers per hour). After ion thrusting concluded last week, navigators measured the parameters of the orbit very accurately. The actual orbit is so close to the planned orbit that the expected refinements in the timing of observations are unnecessary. To optimize the quality of the data to be collected, engineers are making small adjustments to the direction the spacecraft will point its sensors for some of the measurements. Science observations will begin on Oct. 16.


October 6 - Dawn Completes Ascent Spiral

Dawn concluded its ascent on schedule last night by stopping its ion engine at 11:02:48 p.m. PDT. When it began the spiral climb on Sept. 2, the spacecraft was in a 5.4-hour orbit at an altitude of 240 miles (385 kilometers). Now it is in an 18.9-hour orbit about 920 miles (1,480 kilometers) above Ceres. Navigators will measure its orbital parameters carefully to pin down the details. Mission controllers will use the results to refine the timing of Dawn's new observations of the dwarf planet, which are scheduled to begin on Oct. 16.

Nine years ago today, Dawn thrust with its remarkable ion propulsion in space for the first time. As explained in the latest Dawn Journal, the explorer has used its ion engines extensively in the intervening nine years to accomplish extraordinary feats in its interplanetary expedition.


October 3 - Dawn Thrusting to Higher Altitude

Dawn is healthy and continuing to use its ion engine to spiral higher above Ceres. Today the spacecraft's average altitude is 830 miles (1,335 kilometers). Dawn's orbit period is more than 16 hours.


September 30 - Dawn Begins Final Segment of Ascent

During the weekly telecommunications session last night, mission controllers transmitted to Dawn the instructions for the final segment of ion thrusting in its ascent spiral. Shortly before 6:00 a.m. PDT today, the spacecraft resumed powered flight. It is scheduled to stop thrusting at 11:03 p.m. on Oct. 5.

Dawn's average altitude today is 730 miles (1,175 kilometers), three times higher than the mapping orbit it was in from December 2015 until the beginning of this month.


September 27 - Dawn Performing Well on its Ninth Anniversary

Dawn is operating perfectly and making excellent progress as it climbs above Ceres. Its average height today is 660 miles (1060 kilometers). At this altitude, it takes Dawn 13 hours to complete one revolution around the dwarf planet.

Today is Dawn's ninth anniversary of being in space. This month's Dawn Journal reviews the explorer's progress since embarking on its ambitious interplanetary adventure.


September 23 - Dawn's Spiral Ascent Proceeding Well

Dawn is continuing its orbital ascent. Today its average altitude is about 560 miles (900 kilometers). As the spacecraft climbs higher, its orbital velocity naturally decreases. Ceres' gravitational pull is weaker, so Dawn can move more slowly to counter it. In its lowest altitude orbit at 240 miles (385 kilometers), Dawn circled at about 610 mph (980 kilometers per hour). At its current altitude, orbital velocity is 480 mph (775 kilometers per hour).

Dawn has now completed more than 1,500 revolutions around Ceres since its arrival on March 6, 2015. By coincidence, during the same time, Ceres has turned on its axis about 1,500 times.


September 19 - Dawn on Course as it Spirals Up

Dawn is on course and on schedule as it uses ion engine #2 to spiral upward. The spacecraft's average altitude today is about 485 miles (780 kilometers). In a higher orbit, Dawn travels more slowly and each revolution takes longer. Yesterday the ship passed above the altitude at which it takes as long to circle Ceres as Ceres takes to rotate on its axis. One Cerean day is nine hours and four minutes. Now even higher, Dawn's orbit period has increased to more than nine-and-a-half hours.


September 15 - Dawn to Receive Updated Flight Plan Today

Dawn is steadily raising its orbit, and all systems are functioning well. Shortly after 4:30 p.m. PDT today, the spacecraft will pause ion thrusting and rotate to point its main antenna to Earth for a telecommunications session with NASA's Deep Space Network. Mission controllers at JPL will transmit an updated flight plan to guide Dawn through the next week of maneuvering. Thrusting will resume about 4:00 a.m. tomorrow. This pattern is followed each week as the distant probe flies to its next science orbit. (We explained the reason for these regular updates here.)

Dawn's average altitude today is about 415 miles (670 kilometers).


September 12 - Dawn Spiraling Higher

Dawn is continuing to thrust with ion engine #2, spiraling to higher orbits above Ceres. Dawn's average altitude is more than 365 miles (590 kilometers) today. At this height, it takes the spacecraft 7.5 hours to complete one orbital revolution.


September 9 - Dawn's Ascent Continues Smoothly

As planned, Dawn paused its ion thrusting yesterday in order to aim its main antenna at Earth. It reported back on its health and the progress of maneuvering to raise its orbit. Mission controllers transmitted the instructions for the next week of ion thrusting, and then the spacecraft resumed its ascent spiral.

Dawn's average orbital altitude today is almost 325 miles (520 kilometers).


September 6 - Dawn Climbing to Higher Altitude

On schedule on Sept. 2, Dawn began firing its ion engine to raise its orbital altitude. Its average height above the alien world today is 290 miles (465 kilometers). As the spacecraft moves higher, it orbits more slowly because Ceres' gravitational hold weakens. In Dawn's low orbit at 240 miles (385 kilometers), each revolution took less than 5.5 hours. Today, Dawn takes more than six hours to circle the dwarf planet.


September 2 - Dawn Begins Maneuvering to Higher Altitude

Dawn radioed the last of its low altitude data to JPL this morning, marking the conclusion of an outstandingly productive phase of its exploration at Ceres from 240 miles (385 kilometers) above the alien world. Then the spacecraft turned its main antenna away from Earth on schedule to begin five weeks of maneuvering to a higher orbit. (For details, see the August Dawn Journal.)

Dawn's ultraefficient ion engine will consume very little xenon propellant during the upward spiral. The thrust is very gentle so progress will be gradual. By the end of the day today, the probe will have moved to an orbit about 6 miles (10 kilometers) higher.

Fascinating new findings from Dawn's scientific investigations of Ceres are highlighted in a Sept. 1 news release.


August 31 - Dawn Completing Low Altitude Phase of Ceres Mission

After more than eight months scrutinizing Ceres from an altitude of 240 miles (385 kilometers), Dawn is preparing to move to a new orbit. The spacecraft has collected an extraordinary wealth of information on the dwarf planet and will transmit its final findings to NASA's Deep Space Network from today through Sept. 2.

Dawn is scheduled to begin ion thrusting on Sept. 2 shortly before 9:00 a.m. It will spend most of the subsequent five weeks spiraling to a higher altitude.

This month's Dawn Journal describes some of the measurements Dawn has made at this altitude and looks ahead to raising the orbit.


August 24 - Dawn Very Productive in Extended Mission

As Dawn continues its extended mission, it is using all of its scientific instruments to study Ceres. The probe is scheduled to radio its most recent pictures and other data to Earth from about 11:00 p.m. PDT on Aug. 26 until shortly after 5:00 a.m. PDT on Aug. 28. It will then turn its sights back to Ceres.

The spacecraft has been carrying out all of its activities perfectly. Scientists have received an extraordinary wealth of information about the dwarf planet, far exceeding what they anticipated when Dawn descended to this fourth science orbit more than eight months ago.


August 17 - Dawn Healthy and Performing Well

Dawn is collecting new Ceres data as it orbits the dwarf planet every 5.4 hours at an altitude of 240 miles (385 kilometers).

On Aug. 13-14, the spacecraft sent a large volume of findings to Dawn mission control at JPL. Later today it will again turn to point its main antenna at Earth to begin another communications session that will last for more than 30 hours. On Aug. 19, it will resume its measurements.


August 10 - Dawn Completes Mapping at Another Stereo Angle

Dawn has completed another phase of its stereo imaging of Ceres, providing more pictures to use in making a high resolution topographical map. The spacecraft transmitted its latest pictures and other data to NASA's Deep Space Network on Aug. 8-10.

For the rest of this month, the explorer will point its camera at a different angle as it photographs the dwarf planet and uses its other sensors to measure gamma ray, visible, infrared and neutron spectra.


August 3 - Dawn Conducting a Very Smooth Extended Mission

Dawn is operating flawlessly as it continues its observations of Ceres. The spacecraft is acquiring more stereo photos to improve the topographical maps and more spectra to provide insights into the dwarf planet's composition.

On July 30-31, Dawn aimed its five-foot (1.5-meter) main antenna at Earth and sent its pictures and other data. The next telecommunications session will begin shortly after 2:00 AM PDT on Aug. 4 and conclude more than 30 hours later.


July 29 - Ops Team Confirms Dawn in Good Orbit

The operations team conducted the regular assessment of Dawn's orbit and determined that it is so good, no orbit maintenance maneuvers (OMMs) are necessary. The last time an OMM was performed was June 17. Instead of ion thrusting during the OMM windows on July 31-August 1 and August 8, Dawn will continue acquiring data on Ceres.

The spacecraft began collecting data with all its sensors at this low altitude of 240 miles (385 kilometers) on Dec. 16, 2015. Tomorrow Dawn will complete its one thousandth revolution around the dwarf planet since then.


July 27 - Dawn Continues Productively in Extended Mission

Dawn is healthy and continuing to observe Ceres. The spacecraft transmitted a large volume of pictures and other scientific data to NASA's Deep Space Network on July 25-26. Dawn has sent almost 45,000 photos of the dwarf planet to Earth, and you can see a new one every weekday here.

The July Dawn Journal explains NASA's decision to extend Dawn's mission to explore Ceres.


July 20 - Dawn Performing More Investigations of Ceres

Since completing its last transmission of data on July 18, Dawn has been collecting more data with all of its scientific instruments as it circles dwarf planet Ceres every 5.4 hours. It will send more data to Earth on July 21 and 22.

Dawn has been in orbit around Ceres for more than 500 days. During that time, it has revealed complex and fascinating landscapes and provided scientists with a wealth of information on the alien world.


July 13 - Extended Mission Proceeding Flawlessly

Dawn is being very productive in its extended mission. It has been taking more stereo photographs (including some in color) as well as measuring spectra of Ceres in visible, infrared, gamma rays and neutrons. The spacecraft is healthy and continuing in its orbit 240 miles (385 kilometers) above the alien surface.

For readers who follow the Dawn Journal, there has been a delay for personal reasons, but don't worry: the Dawn Journals will resume soon and will continue as long as Dawn continues its ambitious and exciting mission of exploration. There is much more to look forward to!


July 6 - Dawn Exploring Ceres in Extended Mission

NASA Headquarters approved an extension of Dawn's mission at Ceres, taking advantage of the probe's capabilities to continue making discoveries about the nature of this fascinating dwarf planet.

Dawn has been acquiring more stereo images and gathering additional information with all of its spectrometers. The spacecraft began sending its latest data to Earth early this morning, and it will continue until tomorrow afternoon when it resumes its observations.


June 30 - Dawn Completes Prime Mission and Continues Observing Ceres

Today marks the official conclusion of Dawn's prime mission, which began when the spacecraft left Earth on September 27, 2007. The mission has far surpassed all of its objectives for exploring protoplanet Vesta and dwarf planet Ceres. Some interesting statistics and other information on the prime mission are here.

Dawn transmitted a large volume of scientific data to Earth on June 27-28, and it is continuing to observe Ceres even as the prime mission concludes. On July 1-2, it will transmit more pictures and spectra from its final mapping orbit at an altitude of 240 miles (385 kilometers).


June 24 - Dawn Making More Ceres Measurements

The spacecraft transmitted a large volume of Ceres measurements on June 22-23 and now is collecting even more stereo photos and spectra of the dwarf planet.

Dawn and Ceres orbit the sun together, independently of Earth. Shortly before 4:00 AM PDT today, the spacecraft was pi astronomical units from Earth, or about 292 million miles (470 million kilometers). One astronomical unit is the average distance between Earth and the sun.


June 17 - Dawn To Complete Orbit Adjustment

Dawn has had another very productive week of operations, but it has still more to do. Occasionally Dawn executes small maneuvers with its ion engine to keep the orbit synchronized with the observation plans. These orbit maintenance maneuvers (OMMs) are always performed in two windows separated by eight or nine days. The first part of the latest OMM was on June 9. Today the spacecraft will complete the OMM, this time with two thrust segments. Starting about 4:00 PM, it will use its ion engine for a little over an hour, and then it will thrust once more for 44 minutes starting shortly after 1:00 AM tomorrow. The combined effect of all three thrust segments is to change Dawn's velocity by about 0.8 mph (1.3 kilometers per hour).

Following the OMM, the spacecraft will point its main antenna at Earth to transmit more pictures and spectra. On June 19, it will resume observing Ceres.


June 14 - Dawn Stereo Mapping Proceeding Well

Yesterday and today the spacecraft transmitted its latest Ceres data to Earth. Now it is taking more stereo photos to reveal the three dimensional character of the alien landscapes. It is also continuing to acquire neutron, gamma ray, visible and infrared spectra of Ceres.


June 9 - Dawn to Adjust Orbit

Dawn started beaming more photographs and spectra to JPL yesterday, and it is continuing today.

Every three weeks, the flight team evaluates Dawn's orbit to determine whether an adjustment is needed. These "orbit maintenance maneuvers" (OMMs) were described in the February Dawn Journal. Most of the OMMs have not been necessary and so were canceled. Now a small refinement is needed, and the first part will be executed this afternoon starting shortly after 4:00 PM. Dawn will thrust with its ion engine for about an hour. The spacecraft will perform more small maneuvers on June 17 and 18.


June 6 - Dawn Operations Remain Smooth

After sending its most recent findings to Earth on June 4-5, Dawn is observing Ceres again, acquiring new photographs and spectra. The mission has already surpassed all of its original objectives for exploring the dwarf planet, and it is continuing to collect bonus data.


May 31 - Dawn Continuing to Study Ceres

Dawn is transmitting its latest pictures and spectra of Ceres to NASA's Deep Space Network.The spacecraft is healthy and all systems are working well. Early tomorrow morning it will resume observing the dwarf planet.

The May Dawn Journal explains how scientists use Dawn's photographs of craters to measure the age of geological features. It also presents some surprising information about samples on Earth from Vesta, which Dawn explored in 2011-2012.


May 26 - Dawn Completes Another Mapping Campaign

Dawn has completed the photography of the Ceres landscapes it began on April 11, pointing its camera slightly ahead and to the left. Combining pictures from that perspective with the earlier pictures looking straight down makes stereo views.

The spacecraft is now transmitting its last set of pictures and other data to Earth. After it finishes tomorrow, it will begin a new photography campaign, this time taking pictures with the camera looking slightly ahead and to the right. These pictures will form new stereo views, allowing further refinements in topographical maps of the alien terrain.

Since arriving in orbit on March 6, 2015, Dawn has now completed more than 1,000 revolutions around the dwarf planet.


May 19 - Dawn Executing All Planned Observations

Dawn is hard at work observing Ceres and storing the data in computer memory. The spacecraft is programmed to pause its measurements early on May 21, when it will turn to point its main antenna to Earth and radio the data to JPL.

Dawn is continuing to operate in "hybrid control," using its two operable reaction wheels in combination with hydrazine to control its orientation. Mission controllers activated the two reaction wheels in December when the probe reached this low altitude orbit. As long as they operate, the two wheels allow the dwindling supply of hydrazine to be used very efficiently.


May 16 - Dawn Operating Smoothly

Dawn is devoting most of today and tomorrow to sending more Ceres data to Earth.

Every three weeks, the flight team evaluates Dawn's orbit to determine whether a small adjustment maneuver with the ion engine is needed. (These "orbit maintenance maneuvers" were described in the February Dawn Journal.) Today the team concluded that the orbit is so good that no maneuver is necessary.


May 13 - Another Lucky Day for Dawn

On this Friday the 13th, Dawn is maintaining its long streak of good luck (supplemented with some skill) in exploring Ceres. The spacecraft began transmitting its most recent pictures and spectra to Earth yesterday and will finish late this morning. It will resume observing the dwarf planet around noon.


May 9 - Dawn's Fourth Mapping Orbit Continues

After beaming its latest Ceres measurements to NASA's Deep Space Network on May 7-8, Dawn is now making still more.

One year ago today, Dawn completed its first mapping orbit around Ceres at an altitude of 8,400 miles (13,600 kilometers) and began spiraling lower. A single revolution at that altitude required 15 days. Now in its fourth mapping orbit, Dawn's altitude is 240 miles (385 kilometers), and its pictures are 35 times sharper. Held tighter in Ceres' gravitational grip, Dawn travels four times faster at this lower altitude, and a single orbital loop now takes less than 5.5 hours.


May 6 - Dawn Performing Well

Dawn is completing another productive week of Ceres observations, taking pictures for topography and collecting spectra for the atomic and mineralogical composition. It will send more data to Earth on May 7-8. While pointing its camera and spectrometers at Earth, the spacecraft broadcasts a radio signal through an auxiliary antenna. That signal is used for precise tracking of Dawn's orbital motion to map the variations in Ceres' gravitational field, which provides insight into the interior structure of the dwarf planet. (All these methods of learning about Ceres have been described in recent Dawn Journals.)


May 3 - Dawn Passes Milestones at Ceres

Dawn is healthy as it continues its mission at Ceres. The spacecraft is transmitting its latest data to Earth today and tomorrow.

Dawn's orbital residence at Ceres now exceeds its time in orbit around Vesta in 2011-2012. And today Dawn's interplanetary journey has been in progress for pi thousand days. For details on these and other milestones, see the April Dawn Journal.

Five years ago today, Dawn began its approach phase to Vesta, including its first photographs of the protoplanet.


April 29 - Dawn Continues Overachieving

Dawn's exploration of Ceres is proceeding flawlessly. The spacecraft has acquired more pictures for mapping Ceres' topography as well as new infrared and nuclear spectra. It sent this large volume of data to Earth on April 28-29 and is now observing Ceres again.

The April Dawn Journal summarizes how many more measurements Dawn has accomplished at Ceres than originally planned.


April 22 - Dawn Mapping Ceres' Topography

Dawn is continuing to take pictures with its camera pointed ahead and to the left as it orbits Ceres, providing stereo views of the dwarf planet's terrain. The spacecraft will transmit its latest pictures and spectra to the Deep Space Network on April 23-24.

The operations team conducted its regular assessment of Dawn's orbit this week. They concluded the orbit was so good that an orbit maintenance maneuver was not needed.


April 18 - Dawn Gathering More Ceres Data

Dawn remains healthy in its lowest orbit around Ceres, 240 miles (385 kilometers) above the alien surface. It is taking new pictures and gathering other data as it circles Ceres every 5.4 hours. Tomorrow morning the spacecraft will begin sending all these measurements to Earth, and the next day it will start collecting even more data.


April 15 - Mapping Progressing Well

After filling its memory with more observations of Ceres, Dawn began transmitting its results to Earth yesterday afternoon. Tonight it will resume studying the dwarf planet.


April 11 - Dawn Beginning New Ceres Mapping

Dawn is taking pictures and collecting spectra of Ceres. It is now pointing its camera and other instruments slightly ahead and to the left as it circles the dwarf planet. With pictures taken at an angle, scientists will have stereo views so they can construct a more detailed topographical map than they developed in the third mapping orbit. (The March Dawn Journal and the links there explain the stereo imaging in more detail.)

On April 9-10, Dawn maneuvered with its ion engine to synchronize its orbit with the plan for observing Ceres. (These orbit maintenance maneuvers are described in the February Dawn Journal.) Then on April 10-11, it pointed its main antenna to Earth to radio its latest observations to the planet where its journey began.

Dawn's main computer is using software controllers installed five years ago this week, shortly before the spacecraft arrived at Vesta. And exactly two years earlier, they also loaded new software. (Follow the link to find out how you can get a copy of the software for your own use, or simply put your computer or smartphone in the main asteroid belt, send us the coordinates, and we'll install it for you.)


April 8 - Dawn to Execute Small Maneuver This Weekend

Dawn is continuing to observe Ceres. Tomorrow it will begin the second half of the orbit maintenance maneuver it performed on April 1 and 2. It will thrust with ion engine #2 for almost two hours starting about 3:30 PM and then again for almost 2.5 hours beginning shortly before 11:00 PM.

After it completes the maneuvering on April 10, the spacecraft will use its main antenna to establish contact with the Deep Space Network and transmit all the data it collected since the last communications session on April 6.


April 5 - Dawn Healthy and Operating Well

Since thrusting with its ion engine on April 1 and 2 to refine its orbit around Ceres, Dawn has been collecting more data on the dwarf planet. It is taking pictures, measuring the gravity field, and collecting infrared, gamma ray and neutron spectra. Shortly after 9:30 AM PDT today, the spacecraft will turn its sensors away from Ceres to point its 5-foot (1.5-meter) antenna to Earth. It will resume its scientific observations by 1:30 PM tomorrow.


April 1 - Dawn to Adjust Orbit

At the end of another productive week, Dawn is transmitting its most recent scientific data to the Deep Space Network . The March Dawn Journal presents some of the mission's latest findings about Ceres.

The spacecraft will start executing an orbit maintenance maneuver (OMM) shortly after 5:00 PM PDT today. It will thrust with its ion engine for a little more than two hours, and then about 1:00 AM PDT on April 2 will begin thrusting again for the same duration. Following that, Dawn will resume its observations of Ceres. The second half of the OMM will consist of two more thrust segments on April 9-10. (OMMs are explained in more detail in the February Dawn Journal.)


March 29 - Operations Team Verifying Dawn's Orbit

As Dawn continues its exploration of Ceres, the operations team is conducting its regular evaluation of the spacecraft's orbit around the dwarf planet. The probe has been doing an excellent job collecting data, but small deviations from the planned orbit gradually accumulate. Occasionally the ion engine is used to perform an "orbit maintenance maneuver," as explained in the (February Dawn Journal.)The team will decide this week whether to adjust the orbit.

Today is the 209th anniversary of the discovery of Vesta. When Heinrich Wilhelm Matthäus Olbers first spotted it, he could hardly have imagined that a ship from Earth would travel to that mysterious point of light among the stars. And yet Dawn did, and it provided a detailed and richly rewarding exploration of the world that Olbers found.


March 25 - Dawn Making New Observations

Dawn is operating flawlessly as it acquires more photos and spectra of Ceres. The explorer transmitted its findings to Earth on March 23-24, and it will send the data it is collecting now on March 27-28.


March 22 - Dawn Revealing New Sights

Dawn is healthy and continuing its observations of Ceres. After transmitting data to Earth on March 18 and 19, the spacecraft began a new set of measurements. Now, instead of looking straight down, it is pointing its sensors a little bit to the left as it circles Ceres. This provides a slightly different perspective on the alien landscape and may reduce the rate at which the probe consumes its dwindling hydrazine propellant. (Hydrazine is essential for Dawn's operation.)

A new view of the famous bright area in Occator crater, photographed by Dawn from the closest it will ever come to the intriguing geological feature, is now available here.You can see other new Ceres images based on Dawn's measurements at the Ceres image gallery.


March 18 - Dawn Concluding Another Week of Observations

After spending most of the week observing Ceres, Dawn paused this morning to point its main antenna at Earth. It is now radioing its precious data to the Deep Space Network. It will resume its measurements tomorrow around noon.


March 15 -Dawn Maintaining Its Productive Exploration Routine

With its suite of sensors pointed at the alien landforms 240 miles (385 kilometers) beneath it, Dawn is collecting more data as it orbits Ceres. It sent its latest findings to Earth on March 13 and 14.


March 11 -Dawn Continuing to Observe Ceres

Dawn is healthy and all systems are operating well as it takes more pictures and acquires more neutron, gamma ray and infrared spectra of Ceres.

On March 13, it will pause its observations to transmit the most recent data to Earth.

Dawn arrived in orbit on March 6, 2015, a historic culmination of an extraordinary interplanetary journey. The explorer began extensive photography of Ceres and measurements of infrared and visible spectra even before Ceres' gravity took hold. The spacecraft's gamma ray and neutron detector was activated on March 12, 2015, even though scientists understood that its detailed measurements would not begin until reaching this low altitude.


March 9 -Orbit Maintenance Maneuvers Deemed Unnecessary

Dawn is aiming its main antenna at Earth, transmitting its latest photos and other measurements of Ceres. It will resume collecting data this afternoon.

As the flight team was working on the details of the orbit maintenance maneuvers described in the March 7 status report, they determined that the current orbital parameters are satisfactory. Therefore, rather than take the spacecraft's time away from observing Ceres to perform the maneuvers to achieve a small improvement in the orbit, they have decided to let it continue to point its sensors at the dwarf planet without these interruptions.


March 7 -Dawn to Adjust Its Orbit

Dawn's exploration of Ceres is continuing to go extremely well. As explained in the February Dawn Journal, the flight team occasionally needs to adjust the spacecraft's orbit to keep it synchronized with the intricate plans for observing the dwarf planet. They have now determined that Dawn should perform a set of "orbit maintenance maneuvers" for this purpose. Mission controllers are now working on the details to send to the spacecraft, and it will use its famously efficient ion engine to thrust for almost 1.5 hours on March 9, then wait for 6.5 hours and then thrust again for shortly over an hour on March 10. It will perform two additional maneuvers on March 17 of just over an hour and just under an hour, with two hours between them.


March 4 -Dawn at Maximum Distance from Earth

As Dawn continues exploring Ceres, today it is at its greatest distance from Earth for the entirety of its extraordinary extraterrestrial expedition. It is more than 3.95 AU (367 million miles, or 591 million kilometers) from its original planetary home. Details and a diagram are in the February Dawn Journal.

Dawn will spend much of today and tomorrow radioing data to mission controllers. It will take the signals almost 33 minutes to travel from the spacecraft to Earth. The probe will resume its scientific observations early tomorrow afternoon.


February 29 -Dawn Surpasses Its Objectives

Dawn is transmitting its latest pictures and spectra to NASA's Deep Space Network today. Shortly before midnight tonight, the spacecraft will turn to point its sensors at Ceres again and resume its observations.

Dawn's long interplanetary adventure to explore two of the last uncharted worlds in the inner solar system has been extremely productive. The probe has successfully completed all of the measurements it was designed to make, fulfilling the objectives set for it many years ago. Nevertheless, it will continue to acquire data as it orbits the distant dwarf planet. For details, see the February Dawn Journal.


February 26 -Dawn Sends Back More Valuable Observations

Dawn is wrapping up another good week in its final mapping orbit at Ceres. On Feb. 24-25, it returned a wealth of data including photos, nuclear spectra from its gamma ray and neutron detector and infrared spectra from its visible and infrared mapping spectrometer. It is collecting still more data now, which it is scheduled to send to Earth on Feb. 28-29.


February 22, 2016 -Dawn's Exploration Continuing Smoothly

Orbiting Ceres at about 610 mph (980 kilometers per hour), Dawn circled the dwarf planet five times on Feb. 19-20 with its main antenna aimed at Earth, sending pictures and spectra to NASA's Deep Space Network. Following that, it returned to pointing its sensors at the ground beneath it and has been acquiring more data since then.


February 19, 2016 -Dawn Maintaining Productive Pace of Operations

Dawn has been collecting more data on Ceres this week with its camera and spectrometers, and all systems are working well. It will begin transmitting the results to Earth shortly before 1:00 PM PST today. The probe will resume observing Ceres a little after 4:00 PM tomorrow.


February 16, 2016 -Dawn Working Well at its Fourth Planetary Body

After spending much of Feb. 14 and 15 beaming data to Earth, Dawn is back to photographing Ceres and making other measurements.

Tomorrow is the seventh anniversary of Dawn flying past Mars, robbing the Red Planet of some its orbital energy around the sun in order to help fling the spacecraft on its way to more distant and exotic destinations. Dawn achieved a cosmic bull's-eye in gaining that gravitational boost. The equivalent change in the spacraft's speed was 5,800 mph (9,400 kilometers per hour). In exchange Mars slowed down by a rate of one inch (2.5 centimeters) per 180 million years to keep the solar system's energy account balanced. Dawn has been to four planetary bodies, starting on Earth in 2007, sailing past Mars in 2009, orbiting protoplanet Vesta in 2011-2012, and residing since last year at dwarf planet Ceres, its final home.


February 12, 2016 -Dawn Observing Ceres from its Planned Orbit

Dawn transmitted another large volume of Ceres measurements to JPL via the Deep Space Network on Feb. 10 and 11. Now it is back to observing the dwarf planet, collecting more data, which it will send to Earth on Feb. 14 and 15. Also on Feb. 14, controllers will send new instructions for continuing the program of exploration. We love Dawn, but that goes without saying, so no Valentine's sentiments will be included in the interplanetary messages.

Approximately every three weeks, the flight team analyzes the spacecraft's orbit to determine whether to adjust it with the ion engine. (We mentioned this in the mission status reports on Jan. 19 and 21, and the February Dawn Journal will include an explanation.) Based on their latest assessment, Dawn's orbit continues to be so good that no minor corrections are warranted. The present orbital parameters match very well with the plans for new pictures and spectra. This is the second time in a row that "orbit maintenance maneuvers" were deemed unnecessary.


February 8, 2016 -Dawn Continuing to Study Ceres

Aiming its suite of sophisticated sensors at the ground below, Dawn is orbiting closer to Ceres than the International Space Station is to Earth. The explorer is healthy and continuing to perform all of its duties.


February 5, 2016 -Dawn Seeing More and More of Ceres

Dawn is gathering more Ceres data, circling the dwarf planet every 5.4 hours with its combined gamma ray and neutron detector, infrared mapping spectrometer and camera pointed at the landscapes beneath it. Meanwhile, it is transmitting a broad radio signal through one of its auxiliary antennas so we can track its orbital motion to improve measurements of Ceres' gravity field. Shortly after 9:00 PM PST today, the spacecraft will begin sending its results through its main antenna to Earth.

Dawn has photographed about 90% of Ceres from this low altitude orbit. Many people who share our fascination with that distant alien world ask about new pictures of the famous bright area (or famously bright area) at the center of Occator crater, but Dawn has not observed it yet. That is just the way the orbit has worked out. Mission planners did not design the orbit or the schedule of observations and telecommunications to view any specific targets. Rather, as mentioned in the January Dawn Journal, the team designed them so that over the course of six weeks, the probe would see most of the surface. As we will see in the February Dawn Journal, the first few weeks of LAMO don't contribute to this pattern, so the beginning of the six week period was January 10. By simple coincidence, Dawn will not have the opportunity to see Occator until the very end of that period. Therefore, we all wait patiently. After Occator is photographed, the standard process for releasing images will be followed. The need for accuracy and scientific review of the data sometimes slows the release of some products, but all of the data are released to the public after the science team has performed the necessary analysis and interpretation for scientific publication. It will be worth the wait!


February 1, 2016 -Dawn Mapping Proceeds Flawlessly

Dawn continues to operate flawlessly in its final mapping orbit around Ceres. The spacecraft is pointing its main antenna at Earth today, transmitting its latest pictures and other data. It will resume its observations tomorrow shortly before 10:00 AM PST.

The latest Dawn Journal describes some of the measurements Dawn is making to reveal the nature of the first dwarf planet discovered.


January 25, 2016 -Dawn's High Resolution Observations Continue

After concluding its telecommunications session on Jan. 23, Dawn brought Ceres back into its sights. It has been collecting more data since then as it circles the dwarf planet at an average altitude of 240 miles (385 kilometers).

One year ago today, the spacecraft was 147,000 miles (237,000 kilometers) from Ceres, using its ion engine to approach the alien world. Later in the day, it took its second set of pictures to navigate to the uncharted destination. Those were its photos to surpass the resolution provided by the Hubble Space Telescope. Now Dawn's sharp pictures show about 830 times the detail that Hubble's images revealed. The Jan. 29, 2015, Dawn Journal described the navigation pictures and even looked ahead to the improvement we would achieve in the current low altitude orbit. The last year has been a fantastic period of discovery.


January 21, 2016 -Dawn Collecting Data with Good Orbital Accuracy

Dawn remains healthy and productive, taking photos and spectra of Ceres. It will continue doing so until Jan. 22, when it is scheduled to transmit more of its precious data to Earth.

The spacecraft's orbit around the dwarf planet is close enough to what mission planners had specified for this period that it is not necessary to perform the pair of orbit maintenance maneuvers described in the Jan. 19 mission status update. Instead, the spacecraft will continue pointing its sensors at Ceres during the windows that were scheduled for the maneuvers. The next decision on whether to perform orbit maintenance maneuvers will be in three weeks.


January 19, 2016 -Dawn About to Resume Observing Ceres

The spacecraft spent the weekend filling its computer memory with more Ceres data, and it has been sending those findings to NASA's Deep Space Network since yesterday morning. Shortly after noon PST today, it will resume its observations.

Meanwhile, the flight team is using the latest navigational measurements to determine Dawn's orbit very accurately and calculate what it will be for the next few weeks. Based on these and other analyses, the mission director will decide tomorrow whether Dawn should perform an orbit maintenance maneuver. If so, mission planners already have windows in Dawn's intricate schedule on Jan. 23-24 and Jan. 31-Feb. 1. (Orbit maintenance maneuvers in this low altitude orbit are always done in pairs separated by about eight days.)


January 15, 2016 -Dawn Maintaining its Productive Pace

Dawn used its main antenna for about 26 hours on Jan. 13 and 14 to transmit a wealth of data to Earth. Now the spacecraft is taking more photographs and other scientific measurements while orbiting about 240 miles (385 kilometers) above Ceres’ surface.

Dawn is healthy and continuing to operate smoothly. The two reaction wheels that were activated on Dec. 14 have been functioning well, and the consumption of hydrazine propellant (used in combination with the reaction wheels to control the probe's orientation) is very good.


January 11, 2016 -Dawn Hard at Work Observing Ceres

After completing its orbit maintenance maneuver on Jan. 8, Dawn spent much of the weekend with its main antenna aimed at Earth as it revolved around Ceres, beaming its latest data to NASA's Deep Space Network. Then around 9:00 AM PST on Jan. 10, the spacecraft turned to point its science instruments at the ground beneath it and resumed its program of observations of the dwarf planet. It will continue until 7:00 PM PST on Jan. 13, when it is scheduled once again to start transmitting the precious measurements stored in its memory.


January 8, 2016 -Dawn to Perform Small Orbit Maintenance Maneuvers

After devoting much of the week to observing Ceres, Dawn will execute a pair of burns with its ion engine today to modify its orbit. Starting a little after 1:00 PM, the ship will thrust for less than two hours, wait about six hours as it continues to revolve around Ceres and then thrust again for less than two hours, finishing around 11:00 PM. With its uniquely efficient and gentle ion engine, these small orbit maintenance maneuvers will keep the explorers' orbital motion aligned with the plan the flight team has devised for systematically studying the alien world from this low orbital altitude of 240 miles (385 kilometers). Dawn will spend most of the weekend sending its pictures and other data to Earth. When it has finished on the morning of Jan. 10, it will begin collecting still more data.


January 4, 2016 -Dawn Concludes a Productive New Year's Weekend

After using its ion engine for almost 11 hours on Dec. 31 - Jan. 1 to adjust its orbit slightly, keeping it synchronized with the plan for mapping Ceres, the spacecraft resumed its observations. Since then, it has been taking more pictures and measuring spectra of infrared light and two kinds of nuclear radiation. It has also been sending a radio signal that engineers and scientists use to track its orbit in order to map the interior structure of the dwarf planet. (The radiation and orbit measurements are explained in the most recent Dawn Journal.)

This afternoon the spacecraft will turn to point its main antenna to Earth and then spend about a day transmitting its latest results. Tomorrow afternoon it will turn once again to aim its sensors at the rocky, icy ground and collect more data until its next pause on Jan. 8