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MISSION ACCOMPLISHED

Dawn is coming to an end

La missione dei molti primati continuerà a raccogliere dati anche nelle sue fasi finali.

As NASA’s Dawn spacecraft prepares to wrap up its groundbreaking 11-year mission, which has included two successful extended missions at Ceres, it will continue to explore - collecting images and other data. 

Within a few months, Dawn is expected to run out of a key fuel, hydrazine, which feeds thrusters that control its orientation and keeps it communicating with Earth. When that happens, sometime between August and October, the spacecraft will stop operating, but it will remain in orbit around dwarf planet Ceres. 

Dawn is the only spacecraft to orbit two deep-space destinations. It has given us new, up-close views of Ceres and Vesta, the largest bodies between Mars and Jupiter. During 14 months in orbit from 2011 to 2012, Dawn studied Vesta from its surface to its core. It then pulled off an unprecedented maneuver by leaving orbit and traveling through the main asteroid belt for more than two years to reach and orbit Ceres, which it has been investigating since 2015. 

At Ceres, the spacecraft discovered brilliant, salty deposits decorating the dwarf planet like a smattering of diamonds. The science behind these bright spots is even more compelling: they are mainly sodium carbonate and ammonium chloride that somehow made their way to the surface in a slushy brine from within or below the crust. 

These discoveries were fueled by the tremendous efficiency of ion propulsion. Dawn wasn’t the first spacecraft to use ion propulsion, familiar to science-fiction fans as well as space enthusiasts, but it pushed the limits of this advanced propulsion’s capabilities and stamina.

 

These days, near the end of Dawn’s second extended mission at Ceres, the spacecraft continues to wow us week after week, with very close photos shot from only 22 miles  above the dwarf planet - about three times the altitude of a passenger jet. 

Although the Dawn mission is winding down, the science is not. Besides the high-resolution images, the spacecraft is collecting gamma ray and neutron spectra, infrared and visible spectra, and gravity data. The observations focus on the area around Occator and Urvara craters, with the main goal of understanding the evolution of Ceres, and testing for possible ongoing geology. 

The first results of this mission phase, which started in early June, are being presented this week at the Committee on SPAce Research (COSPAR) meeting in Pasadena. Dawn scientists are using new high-resolution data from Dawn to test and refine hypotheses about Occator crater’s formation and evolution.  

The new images so far support the hypothesis that exposure of subsurface material in that region is ongoing, and that it is geologically active, feeding from a deep reservoir. Eleonora Ammannito of the Italian Space Agency, deputy lead for the Dawn visible and infrared mapping spectrometer, will present updated maps at the conference showing the distribution of briny materials across Ceres’ surface.  

The Dawn mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. JPL is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team.