One year ago today, the ship was in its third Ceres mapping orbit, scrutinizing the exotic landscapes 915 miles (1,470 kilometers) beneath it. Less than four weeks later, it started powering its way down through the uncharted depths of Ceres gravitational field to undertake the final planned observations of its long mission.

When ion thrusting concluded on Dec. 13, 2015, Dawn was orbiting closer to Ceres than the International Space Station is to Earth. From its vantage point only 240 miles (385 kilometers) high, the probe used its suite of sophisticated sensors to develop a richly detailed portrait of the only dwarf planet in the inner solar system. Dawn’s reason for venturing to its fourth mapping orbit was to collect about 35 days of neutron spectra, 35 days of gamma-ray spectra and 20 days of gravity measurements. Given the complexity of operating in the low, tight orbit, mission planners expected it could take about three months to acquire these precious data and transmit them to Earth. Operations turned out to be essentially flawless, and by the time Dawn left that orbit on Sept. 2, it had accumulated 183 days of neutron spectra, 183 days of gamma-ray spectra and 165 days of gravity measurements. In addition, the spacecraft amassed a sensational bonus of 38,000 high resolution photos (including stereo and color) as well as more than 11 million infrared spectra and 12 million spectra in visible wavelengths. The original plan was not to take any pictures or visible or infrared spectra at the lowest altitude.

For such an overachiever, it’s fitting that now, on its ninth anniversary, the spacecraft is engaged in activities entirely unimagined on its eighth. With the critical loss of two of the four reaction wheels used to orient and stabilize the ship in space, the flight team (and your correspondent) considered it unlikely Dawn would survive long enough to celebrate a ninth anniversary. And everyone was confident that whether it was operating or not, it would still be in the fourth mapping orbit. There was a clear intent never to go anywhere else. But as we explained last month, with the extraordinary wealth of information Dawn gleaned, the team has been developing plans for new and previously unforeseen work at higher altitudes. Next month, we will detail the first set of new observations from an orbital perch of about 920 miles (1,480 kilometers).

For now, Dawn is using its ion engine #2 to gradually raise its orbit. We have seen how the spacecraft’s uniquely capable propulsion system leads to intriguing spiral trajectories. Right now, on the ninth anniversary of the last moment Dawn’s rocket stood motionless at Cape Canaveral’s Space Launch Complex 17B, Dawn is 660 miles (1,060 kilometers) above Ceres. With its signature combination of exceptional gentleness and exceptional efficiency, the ion engine will propel Dawn to an altitude 20 miles (35 kilometers) higher by the end of the day today. (In contrast, by the end of the day it launched nine years ago, Dawn had gained about 175,000 miles, or 280,000 kilometers, in altitude. The Delta rocket provided a much stronger thrust at much lower efficiency. We will discuss this further below.)