August 30, 2018 — Dawn Continues Exploring Ceres Even as Mission End Approaches
Dawn is operating flawlessly at Ceres as it continues to acquire high-resolution data. In its final orbit of the mission, the spacecraft performs its measurements as it streaks only about 22 miles (35 kilometers) above the ground, then soars up to 2,500 miles (4,000 kilometers) and plunges back down again. Each loop takes 27 hours.
Dawn relies on hydrazine propellant to control its orientation in the zero-gravity of spaceflight. The explorer will continue operating until the last of the hydrazine is spent, most likely in September or October. It will struggle briefly, but the long and successful mission will be at its end. A pair of Dawn Journals in August describe what will happen to the spacecraft, both right away and for decades to come, as well as the feelings that one member of the team (yours truly) may experience when this extraordinary extraterrestrial expedition concludes.
August 9, 2018 — Dawn Scrutinizing Ceres from Low Altitude
Dawn is continuing its work in the final orbit of its mission. Once every 27 hours, the spacecraft swoops down to about 22 miles (35 kilometers) above Ceres and collects valuable scientific data with a suite of sensors. You can see some of the fabulous views here.
As illustrated in the March Dawn Journal, the low point of Dawn's elliptical orbit gradually shifts south, allowing the spacecraft to investigate different areas as its mission progresses.
July 13, 2018 — Dawn Operating Smoothly in Ceres Orbit
Dawn is performing all of its assignments in its elliptical orbit, dipping down to about 22 miles (35 kilometers) above the ground every 27 hours. Here are some of the high-resolution pictures Dawn has taken.
In June, the spacecraft turned frequently between pointing its scientific instruments at the dwarf planet and pointing its main antenna to Earth. As explained in the most recent Dawn Journal, now Dawn observes Ceres at low altitude for five orbits in a row. It transmits its findings to Earth on the sixth.
June 28, 2018 — Dawn Continuing to Scrutinize Ceres After Last Ion Thrusting of the Mission
Dawn fired its ion engine twice last week to shift the longitude slightly of its south-to-north low altitude flight over dwarf planet Ceres. The pair of maneuvers allowed the spacecraft's sensors to view different areas within Occator Crater. (Recent Dawn Journals describe the nature of this highly elongated elliptical orbit and Dawn's photography and other measurements.)
Now that Dawn is in its final orbit around Ceres, there are no further plans to use the ion engines. For more on this, see this status report. (The next Dawn Journal will have further details.)
The probe flies as low as 22 miles (35 kilometers). Prior to this month, Dawn's lowest altitude was 240 miles (385 kilometers). You can see exquisite pictures here, revealing amazing new details of the alien landscapes.
June 21, 2018 — Dawn Adjusting its Orbit
Dawn is continuing to operate flawlessly in its final orbit of the mission, dipping down to about 22 miles (35 kilometers) above dwarf planet Ceres every 27 hours. Recent Dawn Journals explain more about this elliptical orbit and how the spacecraft operates in it.
Dawn is firing its ion engine twice this week to make a small adjustment in the orbit to optimize its scientific measurements.
June 13, 2018 — Dawn Returning Pictures and Other Data in Lowest Orbit
Dawn completed ion thrusting on schedule on June 6, reaching its final orbit. The spacecraft's elliptical path now takes it around Ceres once every 27 hours, ranging in altitude from about 22 miles (35 kilometers) to 2,500 miles (4,000 kilometers). The explorer's lowest altitude before last week was 240 miles (385 kilometers).
Dawn began observing Ceres on schedule on June 9. Exquisite pictures showing greater detail than ever before are posted in the image gallery. (If you don't look, you'll miss out on stunning new views of Ceres.) The March and April Dawn Journals describe some of the challenges of photographing the dwarf planet when traveling at low altitude and high speed.
The May Dawn Journal summarizes some of the accomplishments last month and begins looking ahead to the end of this extraordinary mission.
June 5, 2018 — Dawn Making Good Progress to New Orbit
Dawn is continuing to use its ion engine to gradually shrink its elliptical orbit around Ceres. Ion thrusting started on May 31 and is scheduled to end on June 6. The targeted final orbit will range in altitude from about 22 miles (35 kilometers) to 2,500 miles (4,000 kilometers).
As Dawn thrust yesterday, its smooth orbital path took it briefly down to an altitude of about 75 miles (125 kilometers), the closest it has yet been to Ceres. Also, as the spacecraft maneuvers lower, it takes less time to complete each orbit. In the science orbit it left last week, one revolution required 37 hours. Today it takes about 28 hours for each loop around the dwarf planet. After thrusting concludes in the new orbit, it will take Dawn just over 27 hours for each revolution, as we explained in the April Dawn Journal.
May 31, 2018 — Dawn Completes Observations and Begins Ion Thrusting
Dawn successfully completed all of its planned observations of Ceres in its latest orbital phase. (See the March Dawn Journal for an overview.)
After transmitting its data to distant Earth, the spacecraft began using ion engine #2 to lower its orbit again. Since arriving in its most recent orbit on May 14, Dawn's altitude has varied smoothly from 280 miles (450 kilometers) up to 2,900 miles (4,700 kilometers). When ion thrusting concludes next week, the orbital altitude will range from about 22 miles (35 kilometers) to 2,500 miles (4,000 kilometers). (See the March Dawn Journal for an illustration of the orbits.)
May 23, 2018 — Dawn Spacecraft Performing Flawlessly in New Orbit
Dawn is carrying out its latest campaign of Ceres observations flawlessly. The March Dawn Journal described the plans for this new phase of the mission.
The explorer has completed five of the ten planned revolutions of photography and spectroscopy. Each elliptical orbit around the dwarf planet takes one and a half days as the altitude ranges from about 280 miles (450 kilometers) up to 2,900 miles (4,700 kilometers). (The small difference between this minimum altitude and the one in the previous mission status report is a result of a refinement in how we present the orbital information in a nontechnical way. The orbit is exactly what mission controllers designed.)
May 15, 2018 — Dawn Ready for New Ceres Observations
Yesterday Dawn completed one month of maneuvering with its ion engine to a new orbit around dwarf planet Ceres. Now in extended mission orbit 6 (XMO6), Dawn will take pictures as well as infrared and visible spectra starting today. The March Dawn Journal described the plans for this new phase of the mission.
Dawn was aiming for an elliptical orbit that ranged in altitude from 270 miles (440 kilometers) to 2,900 miles (4,700 kilometers), and measurements of the orbit parameters by Dawn's navigation team after thrusting completed confirmed that the spaceship is right on target.
May 10, 2018 — Dawn Flying Closer to Ceres
Dawn is continuing to fire its ion engine to reduce its altitude above Ceres. The spacecraft has now decreased the size of its elliptical orbit so much that on May 8, it dipped down to less than 560 miles (900 kilometers) above the dwarf planet. The last time it was that close to the ground was in September 2016.
Dawn started today at an altitude of nearly 3,500 miles (5,600 kilometers). Tonight it will reach down to 450 miles (720 kilometers) before it begins sailing up again. It now takes the ship less than two days to complete one revolution around the dwarf planet. The April Dawn Journal shows Dawn's spiral descent.
May 4, 2018 — Dawn Pauses Thrusting for an Update
Dawn's spiral descent to a new orbit is going smoothly. (The April Dawn Journal includes an illustration of Dawn's descent profile.) Today the spacecraft is scheduled to pause ion thrusting and point its main antenna to Earth. Controllers will radio the spacecraft a routine update to its flight plan, which will cover the next week of ion thrusting.
Today Dawn's shrinking elliptical orbit carries it from 2,000 miles (3,200 kilometers) up to 4,300 miles (6,900 kilometers). Whereas the peak altitude presented in the April 26 mission status update was 7,300 miles (11,800 kilometers), the next orbital crest, which occurs early tomorrow morning, will be 4,300 miles (7,000 kilometers). It now takes the probe only three days to complete one revolution around Ceres, or one-tenth of what it was before ion thrusting began on April 16.
April 26, 2018 — Ion Thrusting Contracts Dawn's Orbit
Dawn is continuing to thrust with its ion propulsion system to lower its orbit around Ceres in preparation for taking new pictures and conducting other scientific observations next month. (The March Dawn Journal has an overview of the plan.) As explained in the April 17 mission status, this maneuvering makes each peak in the spacecraft's elliptical orbit lower than the one before. And in the April 5 mission status, we saw that the elliptical orbit reached 24,300 miles (31,900 kilometers) before ion thrusting began. Today Dawn will sail up to a peak again, but now it will be only 7,300 miles (11,800 kilometers).
As Dawn's orbit shrinks, it takes less time to complete each revolution. Prior to thrusting, Dawn looped around the dwarf planet once every 30 days. Now it takes less than a week, and as thrusting continues, the orbit period will get even shorter.
April 17, 2018 — Dawn Maneuvering to Lower Orbit
Dawn is flying to a lower altitude over Ceres. Under the gentle thrust of ion engine #2, the spacecraft is gradually reshaping its orbit around the dwarf planet. It will take a month to maneuver to the new orbit, designated extended mission orbit 6 (XMO6). Last month's Dawn Journal gives an overview of the plans.
Today Dawn will descend from 16,900 miles (27,300 kilometers) to 15,200 miles (24,400 kilometers).
Although the new orbit will be lower than the previous orbit, Dawn continues to follow an elliptical path around Ceres. The ion thrusting will gradually shrink that ellipse. As a result, most of the time Dawn will get closer to Ceres but sometimes it will ascend, although to a lower peak altitude each time. This will become more apparent as we track the altitude in upcoming mission status reports.
April 12, 2018 — Dawn About to Fly Lower
Mission controllers are putting the finishing touches on the instructions Dawn will follow to fly to a new orbit. Ion thrusting will begin next week. It will require about a month to descend so the probe can undertake new observations, as described in the most recent Dawn Journal.
As it turns out, Dawn is already descending today, but that is for a different reason. The spacecraft is continuing in its elliptical orbit. It reached the high point on April 7. Over the course of the day today, Dawn's altitude will decrease from 22,700 miles (36,500 kilometers) to 21,900 miles (35,300 kilometers).
Tomorrow, Dawn will celebrate its 3,000th Cerean day in orbit around the dwarf planet. The adventurer arrived in orbit in 2015 (an unprecedented and exciting accomplishment that was described here). Ceres turns on its axis in 9 hours, 4 minutes (one Cerean day), considerably faster than Earth, although not all that different from the giant planet Jupiter, which takes 9 hours, 56 minutes.
April 5, 2018 — Dawn Approaching Orbital Summit
Dawn's 30-day elliptical orbit is carrying it to its highest point above Ceres. Just as a ball thrown upward gradually slows before falling downward, the spacecraft is decelerating under the constant pull of the dwarf planet's gravity. Orbiting at an average altitude today of 24,000 miles (38,700 kilometers), the spacecraft is ascending at only 11 mph (18 kph). On April 7, it will reach the crest of its orbit, 24,300 miles (39,100 kilometers) high.
Meanwhile, the mission control team at JPL is continuing to prepare for piloting Dawn to a new orbit for new observations, as described in the most recent Dawn Journal.
March 29, 2018 — Dawn Sailing Upward on Noteworthy Anniversary
As Dawn follows its elliptical orbit around Ceres, it is sailing higher. Over the course of the day today, it will climb from 11,300 miles (18,200 kilometers) to 12,100 miles (19,600 kilometers). As the latest Dawn Journal explains, the spacecraft will not remain in this orbit for much longer.
Today is the 211th anniversary of the discovery of Vesta, the first stop on Dawn's deep-space mission of exploration. For two centuries, that enigmatic world, the second largest in the main asteroid belt, appeared as little more than one of the myriad glowing jewels in the nighttime sky. In 2011-2012, Dawn transformed it into a complex, fascinating world, finding it to be more closely related to the terrestrial planets than to typical asteroids. Some of the discoveries are summarized here.
March 20, 2018 — Dawn Operating Smoothly as Team Prepares for Ambitious New Observations
Dawn has been in excellent health and continues to operate smoothly in orbit around Ceres. The operations team has made excellent progress in preparing to guide Dawn to lower altitudes and perform important new observations. Maneuvering with the ion propulsion system will begin next month. The latest Dawn Journal presents an overview of the plans for the two new orbits Dawn will occupy.
As the spacecraft continues its current elliptical orbit, it will descend today from 11,800 miles (19,000 kilometers) to 9,100 miles (14,600 kilometers) above the dwarf planet. On March 23, it will dip down to a little under 2,800 miles (4,400 kilometers) before going up again.
January 3, 2018 — Dawn Flight Team Planning for New Activities
The Dawn flight team is hard at work developing methods to fly Dawn much closer to Ceres than it has ever been. The December Dawn Journal describes some of the plans.
Meanwhile, the spacecraft is healthy as it continues in its high-altitude elliptical orbit. Over the course of the day today, the spacecraft will climb from 23,400 miles (37,600 kilometers) to 23,700 miles (38,200 kilometers). It will reach the crest of its orbit at 24,030 miles (38,670 kilometers) on Jan. 6.