Dusk for Dawn: Mission of Many Firsts to Gather More Data in Home Stretch
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.
Pasadena Conference to
Include New Insight into Dwarf Planet CeresAs 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."Dawn's unique
mission to orbit and explore two strange new worlds would have been impossible
without ion propulsion," said Marc Rayman of NASA's Jet Propulsion
Laboratory, Pasadena, California, who has served as Dawn's mission director,
chief engineer and project manager. "Dawn is truly an interplanetary
spaceship, and it has been outstandingly productive as it introduced these
fascinating and mysterious worlds to Earth."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 (35 kilometers)
above the dwarf planet -- about three times the altitude of a passenger jet.But
Wait, There's More: New Science to ComeAlthough 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 new images of
Occator Crater and the surrounding areas have exceeded expectations, revealing
beautiful, alien landscapes," said Carol Raymond of JPL, principal investigator
of the Dawn mission. "Ceres' unique surface appears
to be shaped by impacts into its volatile-rich crust, resulting in intriguing,
complex geology, as we can see in the new high-resolution mosaics of Cerealia
Facula and Vinalia Faculae."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. Raymond and JPL
scientist Jennifer Scully will offer new information on the relationships
between bright and dark materials on the floor of Occator Crater, which show
impact processes, landslides and cryovolcanism.Dawn scientists are using
new high-resolution data from Dawn to test and refine hypotheses about Occator
crater's formation and evolution."Observations,
modeling and laboratory studies helped us conclude that the bright spots are
either formed by impacts interacting with the crust, or that a reservoir of
briny melt contributed to their formation," said Scully.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.Also at COSPAR, Dawn
flight team member Dan Grebow of JPL will describe Dawn's final orbit, designed
to abide by NASA's planetary protection protocols.Low-altitude images
collected by Dawn are posted regularly to the mission's web pagehere.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.For
a complete list of mission participants, visit:https://dawn.jpl.nasa.gov/missionMore
information about Dawn is available at the following sites:https://www.nasa.gov/dawnhttps://dawn.jpl.nasa.gov