Dawn is dead, but Dawn is not gone: Today NASA said that the Dawn spacecraft has fallen out of contact with Earth, presumably because it’s run out of the thruster fuel that was used to keep its antennas oriented toward Earth and its power-generating solar panels oriented toward the sun.
After Dawn missed out on communications sessions on Wednesday and today, NASA declared an end to the mission.
During its 11 years in space, Dawn sent back unprecedented closeups of the asteroid Vesta as well as Ceres, which is the largest known asteroid and the smallest confirmed dwarf planet.
Dawn will continue circling Ceres for decades to come in the main asteroid belt, 257 million miles out from the sun.
The spacecraft’s doom was not at all unexpected. Mission managers knew it was just a matter of time before the hydrazine fuel ran out. Coincidentally, the gas gauge hit empty just after NASA’s planet-hunting Kepler probe met a similar fate.
Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate, paid tribute to a mission that narrowly dodged cancellation during the run-up to its launch in 2007.
“Today, we celebrate the end of our Dawn mission – its incredible technical achievements, the vital science it gave us, and the entire team who enabled the spacecraft to make these discoveries,” Zurbuchen said in a news release. “The astounding images and data that Dawn collected from Vesta and Ceres are critical to understanding the history and evolution of our solar system.”
Among the most astounding images were Dawn’s views of Ceres’ mysterious white spots, which reflected sunlight so brightly they were dubbed “alien headlights.” Detailed readings from Dawn’s suite of four science instruments led scientists to conclude that the spots were deposits of sodium carbonate, pushed up from the dwarf planet’s interior.
Those deposits contributed to evidence that Ceres once harbored liquid water, potentially in the form of oceans, and that frozen water still exists beneath the surface and at the bottom of shadowed craters. There’s even a chance life could have existed on Ceres.
Scientists will continue to follow up on Dawn’s findings.
“In many ways, Dawn’s legacy is just beginning,” said the mission’s principal Investigator, Carol Raymond of NASA’s Jet Propulsion Laboratory. “Dawn’s data sets will be deeply mined by scientists working on how planets grow and differentiate, and when and where life could have formed in our solar system. Ceres and Vesta are important to the study of distant planetary systems, too, as they provide a glimpse of the conditions that may exist around young stars.”
Because of the life-on-Ceres question, NASA decided to keep Dawn spinning in orbit rather than sending the probe down to crash onto the dwarf planet’s pockmarked surface. Dawn’s orbital path is stable enough to remain in orbit for at least 20 years, and engineers have more than 99 percent confidence the orbit will last for at least 50 years.