November 30, 2012 - Dawn's Operating Profile Modified to Conserve Hydrazine Propellant
Dawn's powered flight to Ceres is continuing smoothly. Mission controllers have changed its routine to conserve the hydrazine propellant it will use in its exploration of that dwarf planet. The spacecraft interrupts ion thrusting to turn to point its main antenna less frequently now. In addition, when it does turn, it moves more slowly. The most recent Dawn Journal describes these changes and the motivation for them.
November 2, 2012 - Dawn Continues Thrusting as it Begins Approaching the Sun
Dawn spent most of the past month continuing to reshape its orbit with its ion propulsion system. Although it is making good progress toward Ceres, which is farther from the sun, its course is now bringing it temporarily closer to the sun. It will not be this far from the sun again until May 2014. The latest Dawn Journal explains this enigmatic behavior.
Although most spacecraft coast most of the time, Dawn has now accumulated three years of ion thrust, and much more powered flight is ahead.
September 27, 2012 - Dawn Completes Fifth Year of Flight
Dawn celebrated its fifth anniversary of spaceflight by continuing to thrust with its ion propulsion system on the long journey from Vesta to Ceres, just as it has most of the time since leaving the protoplanet earlier this month.
The probe has thrust for 1,060 days so far in the mission, or 58 percent of the time since launch. Its effective change in speed is more than 7.1 kilometers per second (16,000 miles per hour), well in excess of what any other spacecraft has achieved under its own power. Thanks to the efficiency of the ion propulsion system, all this thrusting has consumed only 267 kilograms (587 pounds) of xenon propellant.
To see more about the spacecraft's progress in five years of interplanetary flight, see the latest Dawn Journal.
September 5, 2012 - Dawn Leaves Vesta Orbit
As Dawn thrust gently with its ion propulsion system, it escaped from orbit around Vesta last night, taking with it the stunning successes of its exploration of that alien world. Leaving orbit was as smooth and gradual as all other maneuvers in the mission, thank to the ion propulsion system. Dawn is now back in orbit around the sun and headed for dwarf planet Ceres. The latest Dawn Journal has details about Dawn's departure.
Dawn is about 19,000 kilometers (11,800 miles) from Vesta today, and the distance is constantly increasing.
August 28, 2012 - Dawn Takes a Parting Shot as it Ascends
Dawn's departure spiral has continued smoothly.
On August 25 - 26, at an altitude of 6,000 kilometers (3,700 miles), Dawn pointed its instruments at Vesta one last time for some final bonus observations. It took pictures and made other measurements of the northern hemisphere to see a little more terrain that has become illuminated since Dawn's previous observations in July. As Vesta's seasons progress, the equinox was on August 20, so the sun is now north of Vesta's equator for the first time since Dawn has been at Vesta.
August 20, 2012 - Dawn Continues Ascent
Dawn is continuing its gradual departure from Vesta. Today its average altitude is nearly 3000 kilometers (about 1850 miles). The last time it was this far from Vesta was August 1, 2011, near the beginning of its exploration of Vesta.
The September issue of Discover Magazine has an extensive article about Dawn's amazing mission at Vesta.
August 17, 2012 - Dawn Resumes Departure Spiral
Mission controllers returned Dawn to a standard operating configuration earlier this week after the reaction wheel developed increased friction. The spacecraft is now using its small hydrazine thrusters to control its orientation instead of the reaction wheels, just as it did from August 2010 to May 2011.
Ion thrusting to follow the departure spiral will resume later today. Because of the hiatus in thrusting, escape will occur on September 5.
August 10, 2012 - Departure Delayed By Balky Reaction Wheel
Dawn interrupted its spiral ascent on August 8 when one of its reaction wheels, used for precise pointing, experienced increased friction. Another reaction wheel exhibited the same behavior in June 2010. As before, protective software turned the wheel off and used the small hydrazine jets to control the pointing. The spacecraft's orbital altitude is more than 2100 kilometers (1300 miles).
Controllers discovered the condition during a routine communications session on August 9. They are now replanning the departure and expect to resume ion thrusting at the end of next week. Escape from Vesta will be delayed by about 10 days, and then the spacecraft will be on its way to Ceres. (The flight from Vesta to Ceres was already planned to be performed with all the reaction wheels turned off.) To make up some of the time, most of the bonus departing observations will not be conducted.
August 8, 2012 - Dawn Continues Raising Orbital Altitude
Dawn is devoting most of its time to using its ion propulsion system to spiral away from Vesta after its extraordinarily productive exploration of the giant protoplanet. Today the spacecraft's average altitude is 1900 kilometers (1200 miles).
As explained in the most recent Dawn Journal, the probe is scheduled to observe Vesta several times during its departure..
July 25, 2012 - Dawn Completes Mapping Vesta and Begins its Departure
Dawn successfully completed its mapping of Vesta. The probe collected a rich set of pictures and other scientific data from this intensive phase of its exploration.
Now the spacecraft is using its ion propulsion system to gradually raise its orbit so it can escape from Vesta in late August and head for its appointment with dwarf planet Ceres in 2015. It will pause four more times to observe Vesta as it departs.
A summary of Dawn's accomplishments in this mapping orbit and plans for its final views of Vesta are in the July Dawn Journal.
July 19, 2012 - Dawn Concludes Topographical Mapping
Dawn completed the fifth cycle of mapping Vesta today. This was the last cycle to gather stereo images for the development of a topographical map of the newly illuminated regions of the northern hemisphere. The final cycle, like the first, will observe the terrain directly underneath the spacecraft. The visible and infrared mapping spectrometer continues to collect data in the same direction the camera is pointed.
July 14, 2012 - Dawn Acquires More Stereo Images
Dawn concluded the fourth of its six cycles of mapping Vesta. The spacecraft starts its fifth mapping cycle today, pointing the camera ahead and to the right of the point directly beneath it. It is continuing to gather visible and infrared spectra, as well.
July 9, 2012 - Dawn Continues Topographical Mapping
Dawn completed its third cycle of mapping Vesta while simultaneously collecting visible and infrared spectra. In the fourth mapping cycle, which begins today, the spacecraft will aim the sensors at the surface behind and to the right as it orbits. As described in the June Dawn Journal, the images will provide another new view for scientists to use in developing a topographical map of some regions of the previously unseen northern hemisphere.
July 4, 2012 - Dawn Completes First Stereo Mapping Cycle
Dawn has collected another complete set of images of the illuminated surface of Vesta. In this second of six planned mapping cycles, the spacecraft pointed the camera at an angle instead of straight down in order to acquire images for a topographical map. Today the probe began the third mapping cycle, now with the camera pointed both behind and a little to the left of the point directly beneath it. Dawn is continuing to acquire visible and infrared spectra as well. The strategy for mapping Vesta with new illumination is explained in the June Dawn Journal.
June 29, 2012 - Dawn Begins Stereo Imaging
Dawn successfully completed its first mapping cycle, and its second begins today. Instead of pointing the camera directly at the surface beneath it, the spacecraft is aiming it a little ahead and to the left. These images will provide a stereo view so scientists can develop a topographical map. In addition to the pictures, Dawn is using its visible and infrared mapping spectrometer to measure the nature of the minerals.
June 24, 2012 - Dawn Begins Photographing Vesta Again
Dawn has resumed taking pictures of Vesta. As in the mapping performed in October 2011, the first five-day cycle of mapping will be conducted looking straight down. In addition, the spacecraft is continuing to scrutinize Vesta with its visible and infrared mapping spectrometer. In each orbit, lasting just over 12 hours, Dawn aims its instruments at the surface when it is over the day side of Vesta, and it points its main antenna to Earth to transmit the data when it is over the night side.
June 15, 2012 - Dawn Begins New Observation Campaign
In its new orbit, known as the second high-altitude mapping orbit (HAMO2), Dawn began using its visible and infrared mapping spectrometer today to observe Vesta. The spacecraft is at an altitude of about 680 kilometers (420 miles), circling Vesta every 12 hours.
The operations team determined that spiral flight from the low-altitude mapping orbit to HAMO2 was executed so accurately that the fine tuning described in the June 5 mission status was not necessary.
June 5, 2012 - Dawn Nearly in Targeted Orbit
Dawn's complex spiral course from its low-altitude mapping orbit to its second high-altitude mapping orbit has been extremely smooth. It is now at the planned altitude of about 680 kilometers (420 miles). As described in the latest Dawn Journal, the spacecraft also needed to change the angle of its orbit plane from the sun, and that has been accomplished as well. Navigators now will make accurate measurements of the new orbit and then controllers will use the ion propulsion system to fine tune it to match exactly the conditions needed for the next intensive observation campaign, scheduled to begin on June 15.
May 29, 2012 - Dawn Progressing to Next Mapping Orbit
Dawn is making good progress to its next mapping orbit, thrusting with its ion propulsion system and sometimes using Vesta's gravity for a free ride. Today the craft's average altitude is about 590 kilometers (365 miles).
May 22, 2012 - Dawn's Climb to New Orbit Proceeding Well
Dawn continues to use its ion propulsion system to change its orbit around Vesta so it can conduct new observations. Today the spacecraft's average altitude is about 450 kilometers (280 miles).
May 15, 2012 - Dawn Continuing to Spiral Higher
Dawn's ascent to its next mapping orbit at an altitude of about 680 kilometers (420 miles) is progressing smoothly. As it uses its ion propulsion system to follow the complicated orbital route to the new target, today the probe's average altitude is about 355 kilometers (220 miles).
May 8, 2012 - Dawn Raising Orbital Altitude
The spacecraft is gradually raising its orbital altitude with its ion propulsion system, spiraling upward in a reverse of the method it used in November and December to reach the low altitude orbit. Dawn's altitude is constantly changing, but today the ship's average altitude is about 275 kilometers (170 miles).
May 1, 2012 - Dawn Concludes Outstandingly Successful Low Altitude Phase
Investigating Vesta since December 12 from an average altitude of 210 kilometers (130 miles), Dawn accumulated an extraordinary amount of information about this unique world. Now having exceeded all expectations for this phase of the mission, it began its six-week ascent to a higher orbit on May 1.
Dawn's orbital stay at Vesta is being extended by 40 days, and that allowed it to remain at low altitude for an extra month, performing even more observations. Additional time will be spent in higher orbits as well before it departs on August 26, 2012 for the long journey to Ceres.
March 29, 2012 - Dawn's Investigations of Vesta Continue
Dawn has had another very productive month of using all sensors to investigate Vesta. The spacecraft is operating very smoothly in its low-altitude mapping orbit.
Meanwhile, as Earth and Dawn follow their separate orbits around the sun, the probe is now on the opposite side of the sun from Earth. As explained in the most recent Dawn Journal, you can find the ship's approximate location by using the sun as a reference. Only a few probes have ever operated so far from home.
Go here to see new and intriguing views of the alien world Dawn is revealing.
February 29, 2012 - Dawn Continuing to Scrutinize Vesta from Low Altitude
Dawn has maintained its intensive pace of collecting data on Vesta. While priority remains on measuring the composition of the surface and mapping the gravity field, all scientific instruments are being used to study the protoplanet from an average distance of 210 kilometers (130 miles). The latest Dawn Journal describes the variations in altitude as Dawn loops around Vesta.
The plan for Dawn's year at Vesta had the spacecraft spending 70 days in the low altitude mapping orbit. As explained in the January and February Dawn Journals, operations at Vesta have gone so well that the 40 days held as margin to resolve problems are still available. Therefore, they are being applied to extend this phase of the exploration of Vesta. Dawn's measurements are now going beyond what had been anticipated.
On February 21, the spacecraft's main computer was temporarily overloaded with tasks, so it rebooted and the spacecraft entered safe mode. Operators responded quickly and had Dawn back to its normal operational configuration in less than three days.
A new image of Vesta is posted every weekday here.
January 27, 2012 - Low Altitude Mapping of Vesta Proceeding Well
Dawn is in good health and using all of its sensors to make detailed measurements of Vesta, following the pattern it has used from the beginning of the low altitude mapping campaign.
On January 13, a software bug caused the main computer to reboot and Dawn entered safe mode. The operations team soon detected the spacecraft's condition. They subsequently returned the probe to the correct configuration and resumed normal operations. Engineers understand how to avoid triggering this bug again.