November 17, 2017 - Dawn Marks Anniversary of Inhabiting the Main Asteroid Belt
All systems are working well as Dawn continues orbiting Ceres. The adventurer has now been a resident of the main asteroid belt beyond Mars for eight years.
In its elliptical orbit around Ceres, Dawn will descend today from 14,300 miles (23,100 kilometers) to 12,200 miles (19,600 kilometers). It takes the spacecraft a month to complete one orbital revolution. At 12:01 AM PST tomorrow, the ship will glide silently over the terminator, the boundary between night and day on the dwarf planet. (You can visualize that boundary in more familiar terms if you are accustomed to being on a planet. If you were at that location on the terminator on Ceres, or the equivalent point on Earth or any other planet, it would be sunrise, where night turns to day as the planet rotates.)
November 9, 2017 - Dawn Begins Another Slow Descent
Dawn is following its 30-day high-altitude elliptical orbit around Ceres as the flight team investigates flying down much lower in 2018, as described in the October Dawn Journal. The orbit changes slightly each month, so on Nov. 6, when Dawn reached the crest at 23,890 miles (38,450 kilometers), it was higher than it had been since June 14. Now the spacecraft is descending from that orbital peak. Today it will fall from 23,310 miles (37,510 kilometers) to 22,820 miles (36720 kilometers).
November 3, 2017 - Dawn Healthy as Team Investigates New Orbits Around Ceres
Dawn is operating smoothly as it continues orbiting Ceres once per month. During the day today, it will coast from 23,150 miles (37,250 kilometers) up to 23,540 miles (37,890 kilometers) above the exotic terrain. The spacecraft will reach its peak altitude this month on Nov. 6, when it will be 23,890 miles (38,450 kilometers) high. It will then begin its gradual fall down to below 3,100 miles (5,000 kilometers).
NASA determined that Dawn should conduct a second extended mission at Ceres. As the October Dawn Journal describes, this means the exploration of the dwarf planet will continue. The flight team is studying ways to take Dawn down to lower altitudes than ever before in 2018, which would allow the sophisticated probe to conduct valuable, exciting new observations.
September 27, 2017 - Dawn Celebrates 10 Years of Spaceflight
Dawn left its planet of origin 10 years ago this morning to undertake a daring interplanetary journey of discovery. Since then, it soared past Mars and explored what had been the two largest uncharted worlds in the inner solar system, Vesta and Ceres. Thanks to its uniquely capable ion propulsion system, it is the only spacecraft ever to orbit two extraterrestrial destinations. Today's Dawn Journal tracks the spaceship's progress through an extraordinary decade of travels in deep space.
Meanwhile, Dawn is healthy and operating smoothly in its elliptical orbit around Ceres. Over the course of the day today, it will ascend from 16,300 miles (26,200 kilometers) to 17,900 miles (28,700 kilometers) above the dwarf planet.
Dawn is too far from Earth to return even for a special event, but the team members at JPL mission control will celebrate the anniversary this afternoon with cake displaying the mission's interplanetary trajectory (shown in a less comestible form in the Dawn Journal).
September 7, 2017 - Sites on Ceres Receive New Names
The International Astronomical Union approved names for 25 more sites on Ceres discovered by Dawn. You can see a map of the dwarf planet with all the named features here. (We explained the system for naming Cerean features shortly before Dawn began its exploration of the alien world.)
Yesterday Dawn reached the peak of its elliptical orbit, cresting at an altitude of 23,790 miles (38,280 kilometers). Now the spacecraft is beginning a slow fall. Today it will descend from 23,760 miles (38,240 kilometers) to 23,600 miles (37,980 kilometers).
August 31, 2017 - Dawn's Long Residence at Ceres
Dawn entered orbit around dwarf planet Ceres in March 2015. The adventurer has now been at its solar system home for more than 2,400 Cerean days, or a little more than half a Cerean year.
Today's Dawn's elliptical orbit will take it from an altitude of 20,700 miles (33,400 kilometers) to 21,600 miles (34,800 kilometers).
August 23, 2017 - Dawn Dips Down and Flies Up Again
All of Dawn's systems are operating well, and the spacecraft is continuing to be operate smoothly in its elliptical orbit around dwarf planet Ceres.
On Aug. 22, Dawn dipped down to 3,230 miles (5,200 kilometers). The last time the probe was that close to the alien world of rock, ice and salt was Nov. 29, 2016. Now its orbital momentum is taking it to greater heights again. Over the course of the day today, the spacecraft will climb from 4,900 miles (7,900 kilometers) to 8,000 miles (12,900 kilometers).
August 16, 2017 - Dawn Passes Milestone in Distance
Dawn is monitoring cosmic rays as it follows an elliptical orbit around Ceres, completing one revolution every 30 days. Over the course of the day today, the spacecraft's altitude will decrease from 17,400 miles (28,000 kilometers) to 15,800 miles (25,400 kilometers). As Ceres tugs harder on Dawn, the orbiter's velocity will increase today from 89 mph (143 kph) to 101 mph (162 kph).
Dawn is held by Ceres' firm gravitational grip. As the spacecraft has been in orbit around Ceres since March 2015, Ceres has carried it along on the dwarf planet's orbit around the sun. Meanwhile, Earth follows its own independent heliocentric orbit. This week, Earth and its ambassador to Ceres are π hundred million miles apart. (That translates to the less numerically appealing 505.59 million kilometers.)
August 9, 2017 - Dawn Arcs over in Space and Passes Milestone in Time
Dawn crested an orbital hill on Aug. 7. As it reached an altitude of 23,740 miles (38,200 kilometers), the spacecraft gradually slowed to 46 mph (73 kph). Now its elliptical orbit is slowly taking it lower, and the craft will descend today from 23,450 miles (37,730 kilometers) to 23,080 miles (37,140 kilometers).
Dawn's deep space adventure passes a milestone of interest to terrestrial numerologists, as it marks π2 (pi squared) years of spaceflight this week.
August 2, 2017 - Dawn Operations Continuing
As Dawn measures cosmic rays, it is ascending in its elliptical orbit. Its average altitude today is 22,300 miles (35,800 kilometers). For comparison, that is the altitude of geosynchronous orbit at Earth. In geosynchronous orbit, satellites circle Earth once per day, the same rate at which Earth turns on its axis. Because Ceres' mass (and hence the strength of its gravitational pull) and the length of its day are different from Earth's, synchronous orbital altitude around the dwarf planet is different. With the Cerean day of a little more than nine hours, synchronous orbit is 450 miles (720 kilometers). Dawn descended through that altitude in November 2015 and ascended past it in September 2016.
July 28, 2017 - Dawn Sailing Upward
In its elliptical orbit around Ceres, Dawn dipped down to 3,280 miles (5,270 kilometers) on July 22. That is the closest it has come to its gravitational master since Nov. 29, 2016. The spacecraft spent more than eight months much lower than that, orbiting only 240 miles (385 kilometers) above the alien landscapes of rock, ice and salt. The flight team flew the probe higher to pursue ambitious new science objectives in three different sets of orbits (as described in October and November 2016 and May 2017).
Now Dawn's momentum is carrying it higher again. During the day today, the spacecraft will sail from 15,800 miles (25,500 kilometers) to 17,500 miles (28,100 kilometers).
July 19, 2017 - Dawn's Cosmic Ray Measurements Continue
As Dawn orbits Ceres, it is continuing to monitor cosmic rays in order to refine measurements of the atomic species down to about a yard (meter) beneath the surface of the dwarf planet. Today the spacecraft's altitude will decrease from 13,000 miles (20,900 kilometers) to 10,600 miles (17,100 kilometers). For comparison, GPS satellites orbit about 12,600 miles (20,200 kilometers) above Earth.
July 10, 2017 - Dawn at High Altitude
Dawn reached the peak of its elliptical orbit on July 7. After cresting at almost 23,700 miles (38,100 kilometers) above Ceres, the spacecraft began its slow fall back to lower altitudes. Today Dawn will descend from 23,240 miles (37,410 kilometers) to 22,820 miles (36,730 kilometers). It will reach its minimum altitude on July 22.
June 30, 2017 - Dawn Operating Smoothly
After adjusting its orbit, Dawn now revolves around Ceres once every 30 days. The spacecraft's altitude will increase from 19,200 miles (31,000 kilometers) to 20,400 miles (32,800 kilometers) over the course of the day today. In this high segment of its elliptical orbit, Dawn's average orbital velocity is 72 mph (116 kilometers per hour).
June 22, 2017 - Dawn Adjusting Orbit
Dawn is firing its ion engine to make a small adjustment to its elliptical orbit around Ceres. Today the orbit brings it down to the low point of 3,400 miles (5,400 kilometers). The spacecraft's momentum then will carry it back to the peak of its orbital altitude in July.
June 15, 2017 - Dawn Healthy after Solar Conjunction
Following conjunction, when Dawn and Ceres moved far enough from the sun that reliable communications could be established this week, the spacecraft transmitted details of its condition and its activities during the period it was out of contact with Earth. The flight team verified that Dawn is healthy and has continued to execute its assignments at Ceres. The probe's primary responsibility now is still measuring cosmic rays so scientists can refine their measurements of the atomic constituents of the dwarf planet down to about a yard (meter) underground.
Traveling in its elliptical orbit, Dawn will descend today from an altitude of 23,300 miles (37,500 kilometers) to 21,600 miles (34,700 kilometers).
June 6, 2017 - Dawn and Ceres Appear Close to the Sun
Mission controllers cannot communicate with Dawn now, as it is much too close to the Sun. The spacecraft is actually 3.7 times as far as the Sun, but from our terrestrial perspective, they are at practically the same place in the sky. Dawn is less than one solar diameter from the brilliant star. The May Dawn Journal describes this alignment, known as conjunction, and suggests how you can use the sun to direct your mind's eye at Earth's distant ambassador to the cosmos.
Despite the radio silence, engineers are confident that the spacecraft remains in its elliptical orbit. Succumbing to Ceres' gravitational pull, Dawn is slowly falling from its peak altitude. Today it will descend from 31,730 miles (51,070 kilometers) to 31,340 miles (50,430 kilometers).
May 31, 2017 - Dawn and Ceres Appear Close to the Sun
As Ceres (with its companion Dawn) and Earth move in their separate orbits around the sun, they are now on nearly opposite sides of our solar system's star, an alignment known as conjunction. From today until June 12, radio signals between Dawn and Earth may be distorted by passing close to the sun on their way back and forth. Therefore, communications are not reliable. The May Dawn Journal describes conjunction in more detail.
The spacecraft is continuing in its elliptical orbit around the dwarf planet. Today the ship reached its greatest altitude, 32,810 miles (52,800 kilometers). At this height, Dawn's orbital velocity is 49 mph (79 kilometers per hour). The February Dawn Journal explains how Dawn maneuvered to this orbit.
May 24, 2017 - Dawn's Mission Proceeding Well
Despite losing a reaction wheel last month, Dawn is performing flawlessly in orbit around Ceres. The May Dawn Journal summarizes the probe's use of reaction wheels and how the flight team has recovered from the three loses over the past seven years.
Dawn's altitude today will increase from 31,290 miles (50,360 kilometers) to 31,690 miles (51,010 kilometers). (Near the peak of its elliptical orbit, the daily change in altitude is less than it has been recently. Therefore, as during part of April, we are rounding off the altitudes to the nearest 10 rather than the nearest 100.)
The mission control team is preparing for Dawn to be nearly aligned with the sun, which will make radio communications unreliable. The May Dawn Journal also provides a way for you to find the distant ship using the sun as a celestial landmark.
May 18, 2017 - Dawn Gets a Navigational Fix
On May 16, Dawn photographed Ceres to help navigators improve their measurements of its elliptical orbit. The spacecraft is in such a high orbit that it takes almost two months for one revolution. Dawn's altitude will increase today from 27,500 miles (44,300 kilometers) to 28,300 miles (45,500 kilometers).
May 11, 2017 - Dawn is Healthy in Orbit High Above Ceres
Dawn is healthy and continuing to follow the elliptical orbit that it flew to in order to observe Ceres' opposition surge on April 29. Over the course of the day today, the spacecraft will ascend from an altitude of 19,700 miles (31,700 kilometers) to 21,100 miles (33,900 kilometers). This high above the dwarf planet, Dawn's orbital velocity is 100 mph (160 kilometers per hour).
The explorer's primary responsibility is monitoring the noise from cosmic rays so scientists can remove that unwanted component from the measurements of nuclear radiation it made at low altitude in 2015-2016.
May 5, 2017 - Dawn Continuing to Operate Smoothly in Elliptical Orbit
On May 1, Dawn sent to Earth the last of its data from opposition, when it observed a fully illuminated Ceres as it flew across the line from the sun to the dwarf planet. The team has confirmed that the spacecraft acquired all the planned pictures and spectra, as described in the April Dawn Journal
Dawn is continuing to measure cosmic rays in order to improve its low-altitude measurements of Ceres' nuclear radiation, providing further insights into the atomic constituents down to about a yard (meter) underground.
The spaceship maneuvered extensively with its ion engine over a period of two months to reach its current orbit so it could see Ceres at opposition on April 29. (The complex flight plan is described in the February Dawn Journal.) Today this elliptical orbit carries Dawn from an altitude of 10,400 miles (16,800 kilometers) to 11,900 miles (19,200 kilometers).
May 1, 2017 - Dawn Observes Ceres at Opposition
Dawn performed the planned observations of Ceres at opposition. As explained in the April Dawn Journal, the spacecraft took pictures as well as infrared and visible spectra when it was close to the line from the sun to the bright center of Occator Crater on April 29. Later on April 29 and April 30, Dawn transmitted some of its data to NASA's Deep Space Network, and it will finish today.
As Dawn approaches the lowest point in its orbit, its altitude today will decrease from 9,700 miles (15,500 kilometers) to 8,800 miles (14,100 kilometers). On May 2, the spacecraft will come within 8,600 miles (13,830 kilometers) of the dwarf planet before its elliptical orbit takes it to higher altitudes again. The orbit is described in the February Dawn Journal, and illustrated in this diagram.
The ship is healthy and operating well, using hydrazine to control its orientation following the April 23 failure of a third reaction wheel.
April 25, 2017 - Dawn Observing Ceres; 3rd Reaction Wheel Malfunctions
NASA's Dawn spacecraft is preparing to observe Ceres on April 29 from an "opposition" position, directly between the dwarf planet’s mysterious Occator Crater and the sun. This unique geometry may yield new insights about the bright material in the center of the crater. The April Dawn Journal describes the plan.
While preparing for this observation, one of Dawn's two remaining reaction wheels stopped functioning on April 23. By electrically changing the speed at which these gyroscope-like devices spin, Dawn controls its orientation in the zero-gravity, frictionless conditions of space.
The team discovered the situation during a scheduled communications session on April 24, diagnosed the problem, and returned the spacecraft to its standard flight configuration, still with hydrazine control, on April 25. The failure occurred after Dawn completed its five-hour segment of ion thrusting on April 22 to adjust its orbit, but before the shorter maneuver scheduled for April 23-24. The orbit will still allow Dawn to perform its opposition measurements. The reaction wheel's malfunctioning will not significantly impact the rest of the extended mission at Ceres.
Dawn completed its prime mission in June 2016, and is now in an extended mission. It has been studying Ceres for more than two years, and before that, the spacecraft orbited protoplanet Vesta, sending back valuable data and images. Dawn launched in 2007.
The Dawn operations team has been well prepared to deal with the loss of the reaction wheel. The spacecraft is outfitted with four reaction wheels. It experienced failures of one of the wheels in 2010, a year before it entered orbit around Vesta, and another in 2012, as it was completing its exploration of that fascinating world. (See issues with these devices). When a third reaction wheel stopped working this week, the spacecraft correctly responded by entering one of its safe modes and assigning control of its orientation to its hydrazine thrusters.
Today, Dawn's elliptical orbit will bring it from an altitude of 17,300 miles (27,900 kilometers) to above Ceres to 15,800 miles (25,400 kilometers).
April 21, 2017 - Dawn to Adjust Orbit
To complete its delicate orbital maneuvering, Dawn will adjust its trajectory. Based on the latest navigational data, the flight team has developed a plan to thrust with the ion engine for about five hours on April 22 and a little more than four hours on April 23-24. These trajectory correction maneuvers will bring the spacecraft's orbit closer to the line from the sun to Occator Crater on April 29, as described in the February Dawn Journal. When Dawn crosses that line, it will photograph the bright central region of the crater, and scientists will use the pictures to investigate detailed properties of the material on the ground. (See the March Dawn Journal for an explanation of the science behind this.)
Following its elliptical orbit, Dawn will descend today from 24,000 miles (38,600 kilometers) above the dwarf planet to 22,800 miles (36,700 kilometers).
April 17, 2017 - Navigators Verifying Dawn's New Orbit
The Dawn navigation team is studying the spacecraft's new orbit to determine whether a trajectory correction maneuver is needed. As always, they will use the probe's radio signal, from which they can determine Dawn's distance and its velocity toward or away from Earth (but not across the line of sight), as well as the ship's detailed records of its recent ion thrusting and every time it fired a hydrazine jet to control its orientation. (The hydrazine is never used to modify the orbit, because it is far less efficient than the ion engine, but it does alter the orbit a little.) Navigators also will use Dawn's photos of Ceres, taken on April 15 and very early today, which will help pin down its location in orbit.
Because of where Ceres and Earth are in their independent orbits around the sun, it takes a radio signal one hour today to make the round trip from Earth to Dawn and back. (The navigational analysis depends on the exact time, measured to an accuracy of better than 10 billionths of a second.) The time is increasing about five seconds per day.
Dawn's altitude today will decrease from 27,910 miles (44,920 kilometers) to 27,040 miles (43,520 kilometers). The target for this orbit is to be at an altitude of about 12,400 miles (20,000 kilometers) when Dawn flies between the sun and Occator Crater on April 29. The most recent Dawn Journal describes how photographs from that special position may reveal properties of the reflective material at the center of the crater.
April 13, 2017 - Dawn Completes Third Ion Thrust Segment
Last night Dawn completed the third and longest period of ion thrusting to change its orbit. The sophisticated probe will take pictures on April 15 and 17 to help navigators determine its current orbit more accurately. In case the orbit needs any adjustment, the flight team has scheduled a window for further ion thrusting on April 22-24. (See the February Dawn Journal for an explanation of Dawn's orbital maneuvering and the navigation pictures.)
Dawn is slowly descending in its elliptical orbit. Over the course of today, its altitude will decrease from 30,740 miles (49,470 kilometers) to 30,130 miles (48,500 kilometers).
The reason for changing Dawn's orbit around Ceres is to position the spacecraft between the sun and the bright material at the center of Occator Crater later this month. This will allow the spacecraft to make measurements that scientists can use to discover more about the nature of those reflective materials. (The March Dawn Journal explains how high altitude pictures can reveal microscopic properties of the ground.)
April 10, 2017 - Dawn on Course and on Schedule
Dawn is continuing to use its ion engine to rotate its orbital plane around Ceres. This maneuvering is designed to allow the spacecraft to fly directly between the highly reflective center of Occator Crater and the sun. Pictures from that position may help scientists learn more about the properties of the material on the ground there. (See the March Dawn Journal for an explanation of the science behind this "opposition surge.")
As Dawn maneuvers, it is descending. During the day today, its altitude will decrease from 32,200 miles (51,820 kilometers) to 31,780 miles (51,150 kilometers). This third (of four) ion-thrust periods is scheduled to end on April 12. (The February Dawn Journal describes Dawn's complicated route to its next orbit.)
April 7, 2017 - Dawn Turning Its Orbital Plane
High above Ceres, Dawn is making good progress thrusting with its ion engine to swivel the plane of its orbit around the dwarf planet. Having reached the peak of its elliptical orbit this week, the spacecraft is starting to fall to lower altitude as Ceres exerts its relentless gravitational pull. Over the course of the day today, Dawn will descend from 32,930 miles (52,990 kilometers) to 32,780 miles (52,750 kilometers). The objective of the complex maneuvers (which are explained in detail in the February Dawn Journal) is to modify the ship's orbit so that it will pass through the line from the sun to the bright center of Occator Crater on April 29 at an altitude of 12,400 miles (20,000 kilometers). The March Dawn Journal explains how photographs from that special position may provide insight into the nature of the reflective material covering the ground.
April 4, 2017 - Dawn Begins Ion Thrusting Again
Earlier today, Dawn began 8.5 days of ion thrusting. This is the third and largest of the four maneuvers the spacecraft is executing to change its orbit around Ceres, as explained in the February Dawn Journal. During this thrust period, Dawn will swivel its orbit by almost 90 degrees. These complicated orbital operations are designed to allow the probe to fly directly between the sun and Occator Crater's famous bright region. Photographs taken from that vantage point may allow scientists to discover properties of the material on the ground, even at the microscopic level. (See the March Dawn Journal for the science behind this remarkable capability.)
Rotating the plane of Dawn's orbit is most efficient when the spacecraft is at high altitude and traveling slowly. That's why the two previous maneuvers propelled the ship to high altitude. (The three diagrams in February may help clarify this.) Over the course of the day today, Dawn ascends from 32,810 miles (52,810 kilometers) to 32,950 miles (53,020 kilometers). As it soars higher and higher, the spacecraft is slowing down under Ceres' relentless gravitational pull. Just as a ball thrown high goes slowest at the peak of its arc, Dawn's average orbital velocity today is only 44 mph (71 kilometers per hour). At this low speed, the daily change in altitude is less than it has been recently. Therefore, we are rounding off the altitudes today to the nearest 10 rather than the nearest 100. On the night of April 5, Dawn will reach the crest of its orbit, 32,990 miles (53,090 kilometers) above the dwarf planet.
March 30, 2017 - Dawn Team Preparing for More Ion Thrusting
Dawn's orbit today carries the spacecraft from an altitude of 31,000 miles (49,900 kilometers) to 31,500 miles (50,700 kilometers). On March 28, the spacecraft took pictures of Ceres to help navigators plot its course in this highly elliptical orbit as accurately as possible. Their results are being incorporated into final preparations for the resumption of ion thrusting on April 4 to swivel Dawn's orbit. As described in the February Dawn Journal, this will be the third of four segments of maneuvering to allow the explorer to take special photos of Ceres at the end of April. Scientists will use the pictures to measure how bright the center of Occator Crater is when viewed along the same direction as the incoming sunlight. The March Dawn Journal explains how this can provide insight into fine details of the material on the ground.
March 27, 2017 - Dawn's Mission Continuing Smoothly
Dawn is healthy and performing all of its duties flawlessly, including measuring cosmic rays high above Ceres. Although slowing as it ascends in orbit because of Ceres’ gravitational pull, today the spacecraft will go from an altitude of 29,100 miles (46,900 kilometers) to 29,800 miles (48,000 kilometers). (For an explanation of Dawn's current orbit, and the changes it will make soon, see the February Dawn Journal.)
March 22, 2017 - Dawn Sailing Upward
With the momentum it gained from ion thrusting earlier this month, Dawn is continuing to ascend in its orbit around Ceres. Today it will climb from 24,300 miles (39,100 kilometers) to 25,500 miles (41,000 kilometers) above the dwarf planet. As it reaches its peak altitude early next month, Dawn will use its ion engine to change the angle of its orbit. (For details of this complex cosmic choreography, see the February Dawn Journal.)
March 17, 2017 - Dawn Coasting to Higher Altitudes
Dawn is continuing to measure cosmic rays, which is its highest priority assignment. Following the orbital path it maneuvered to earlier this week, the spaceship is now coasting to higher and higher altitudes. Today Dawn will glide from 17,000 miles (27,300 kilometers) to 18,700 miles (30,000 kilometers). As described in the most recent Dawn Journal, this temporary orbit will position the spacecraft so it can use its ion engine early next month to swivel its orbit around Ceres.
For those of you who missed Pi Day on March 14, don't despair. You can celebrate it tomorrow when Dawn is pi hundred million miles from Earth.
March 13, 2017 - Dawn Completes Second Thrust Segment
Last night, orbiting more than 8,900 miles (more than 13,400 kilometers) above Ceres, Dawn completed the second of four periods of ion thrusting. As explained and illustrated in the February Dawn Journal, after powering its way in orbit, the spacecraft now has so much momentum that it will coast upward for nearly a month. Over the course of the day today, the ship will sail from 9,100 miles (14,600 kilometers) to 11,100 miles (17,900 kilometers).
The Dawn Journal also explains that this maneuvering is designed to change Dawn's orbit so it can perform unique measurements of the highly reflective salt deposits in Occator Crater.
March 10, 2017 - Dawn Thrusting to New Orbit
On March 8, Dawn began five days of ion thrusting. This is the second of four thrust periods the spacecraft is executing over two months. The maneuvering will change its orbit around dwarf planet Ceres to let the spacecraft fly through the imaginary line from Occator Crater to the sun at the end of April. Today Dawn reaches down to about 6,300 miles (10,200 kilometers), the lowest altitude of its current orbit, even as it is using its ion engine to fly higher. (For details, including diagrams of the orbit changes, see the February Dawn Journal.)
March 7, 2017 - Dawn Passes Second Anniversary at Ceres
Yesterday Dawn marked the second anniversary of arriving at Ceres, a major milestone in its ambitious and spectacular exploration of a fascinating alien world. The event also marked Dawn becoming the first spacecraft to reach a dwarf planet, the first spacecraft to orbit one, and the first spacecraft to orbit any two extraterrestrial destinations.
Dawn is continuing to measure cosmic rays to improve the accuracy of its measurements of Ceres' atomic composition. Today the ship's orbit takes it from 9,200 miles (14,800 kilometers) above Ceres to 8,400 miles (13,500 kilometers). Tomorrow night Dawn will be at the correct orbital location to begin the second segment of its ion thrusting maneuvers to change its orbit so it can make special measurements of the bright material in Occator Crater at the end of April. (The February Dawn Journal has the full story.)
March 2, 2017 - Dawn Orbiting High Above Ceres
Dawn is healthy and all systems are operating well. As explained in the February Dawn Journal, the explorer has completed the first of four segments of ion thrusting to maneuver to a new orbit where it will make special measurements to gain insight into the nature of the reflective material in Occator Crater. In its current orbit, Dawn will ascend today from an altitude of 9,400 miles (15,100 kilometers) to 9,900 miles (15,900 kilometers).
You can do your own celestial navigation today. The February Dawn Journal explains how to use the moon to locate Dawn and Ceres in the sky before the moon sets this evening.
February 27, 2017 - Dawn on Course for New Orbit
Yesterday Dawn completed the first of four segments of ion thrusting to maneuver to a new orbit around Ceres. The spacecraft raised its orbital altitude with four days of firing its ion. Next week it will begin a five-day thrust period. Over the course of the day today, Dawn's present orbit will carry it from 6,700 miles (10,700 kilometers) to 7,700 miles (12,300 kilometers) above the dwarf planet.
The February Dawn Journal explains the complex and elegant maneuvers Dawn will execute over the next two months to fly to a new orbit so it can perform a unique observation of the bright region in Occator Crater at the end of April.
February 23, 2017 - Dawn Maneuvering to New Orbit Around Ceres
After arriving in its sixth science orbit around Ceres in December, Dawn completed all of its assigned work there. Now the spacecraft is using its ion engine to fly to a new orbit in order to make special measurements in April. (The January Dawn Journal explained the nature of the new observations.) For the first stage of its maneuvering, Dawn began four days of ion thrusting on Feb. 22.
February 15, 2017 - Dawn Captures More Views of Ceres
Dawn trained its camera and mapping spectrometer on Ceres again on Feb. 10-11. The spacecraft has transmitted some of its findings to Earth and will radio the rest tomorrow. The explorer is also continuing to measure cosmic rays to improve the accuracy of its measurements of Ceres' nuclear radiation.
February 8, 2017 - Dawn Healthy and Productive
Dawn is operating very smoothly in its sixth orbital phase at Ceres. It finished radioing its latest pictures to Earth on Feb. 6 and will acquire more pictures and visible spectra on Feb. 10-11. Meanwhile, as the probe continues to revolve around Ceres every eight days, it is monitoring cosmic rays to help remove "noise" from its low altitude measurements of nuclear radiation.
The latest Dawn Journal describes an intriguing new assignment for the spacecraft in its ongoing exploration of the dwarf planet.
February 1, 2017 - Dawn Transmitting Latest Pictures to Earth
Dawn smoothly executed its Ceres observations on Jan. 27, including the first photography in three months. The spacecraft transmitted its new spectra and some of the pictures to Earth on Jan. 30. Today it is beaming more of the pictures home. It will send the last of the data next week. Dawn is also continuing to perform its primary assignment of measuring cosmic rays to improve the census of the atomic species it made when it was at a lower altitude.
The explorer has more in store during the remaining five months of its extended mission. To learn about the recent observations plus plans for new orbital maneuvers and new photography, see the January Dawn Journal.
January 27, 2017 - Dawn Observing Ceres from a New Perspective
Dawn is taking pictures and spectra of Ceres today for the first time since arriving in its current orbit early last month. As illustrated here, the spacecraft is seeing Ceres at a new angle. The data will be transmitted to Earth next week.
In addition to these bonus observations, Dawn is continuing its primary activity of measuring cosmic rays to enhance the determination of the atomic constituents of the material down to about a yard (meter) underground.
January 23, 2017 - Dawn Healthy and Operating Normally
In a communications session with the Deep Space Network on Jan. 17, mission controllers observed that Dawn was in safe mode, as explained in the Jan. 19 mission status update. Shortly after that update was posted, the team guided Dawn out of safe mode. Since then, all telemetry confirm that it is healthy. The team radioed additional instructions on Jan. 20 and 21 to return the robotic probe to its standard configuration. Later this week, it will resume measuring cosmic rays to improve the quality of earlier measurements of nuclear radiation from the dwarf planet. Meanwhile, the investigation into the software glitch that triggered safe mode is continuing.
Orbiting Ceres once every eight days, Dawn's average altitude today is 5,740 miles (9,230 kilometers). Yesterday the spacecraft reached its highest point on this orbital loop of 5,800 miles (9,340 kilometers), and now its elliptical path is bringing it closer to the dwarf planet. It will descend to its lowest altitude on Jan. 26, when it will be 4,680 miles (7,530 kilometers) high.
January 19, 2017 - Dawn Team Investigates Software Glitch
Dawn has been orbiting Ceres and measuring cosmic rays to improve the quality of earlier measurements of nuclear radiation from the dwarf planet. Throughout its nine-year interplanetary mission, the spacecraft's main computer has constantly performed calculations about its location in the solar system. On Jan. 14, software detected a discrepancy in those calculations and called for safe mode, a standard configuration used to ensure the spacecraft is safe and stable when it encounters conditions its programming cannot accommodate. During the next communications session with the Deep Space Network on Jan. 17, mission controllers observed that Dawn was in safe mode.
Engineers have since confirmed that all spacecraft systems are healthy, and they are investigating the details of what triggered the anomalous condition in the calculations. The flight team will continue their analyses and determine next week when to resume normal spacecraft operations. Dawn's primary objective now remains the cosmic ray measurements, and there is more than enough time in the extended mission to acquire the desired data.
Now in its sixth science orbit since arriving at Ceres in March 2015, the veteran explorer takes almost eight days to complete each elliptical revolution. During that time, Dawn's altitude ranges from 4,670 miles (7,520 kilometers) to 5,810 miles (9,350 kilometers). Today the ship's average height above the alien world is 4,730 miles (7,620 kilometers).
January 12, 2017 - Dawn Operating Smoothly in Elliptical Orbit
Dawn is making excellent progress in its measurement of cosmic rays to enhance the measurements it made closer to Ceres to determine the dwarf planet's atomic constituents.
The spacecraft takes almost eight days to complete each elliptical orbital revolution, going as low as 4,670 miles (7,520 kilometers) and as high as 5,810 miles (9,350 kilometers). Over the course of the day today, the ship will sail from 4,770 miles (7,670 kilometers) up to 5,180 miles (8,330 kilometers).
January 5, 2017 - Dawn Healthy and Productive as 2017 Begins
Dawn has gotten the new year off to a smooth start. The spacecraft is healthy and operating well in orbit around dwarf planet Ceres. Now halfway through its one-year extended mission, the probe is continuing to measure cosmic rays to improve atomic composition measurements it made at low altitude.
Jan. 1 was the 216th anniversary of Giuseppe Piazzi's discovery of Ceres. See the December Dawn Journal for some of Dawn's latest discoveries about this former planet.