A mission back in time is nearing the launch pad minute by minute. The Dawn spacecraft, NASA’s mission into the heart of the asteroid belt, arrived at Astrotech Space Operations in Titusville, Florida, today for final processing and launch operations.
Dawn will next move 15 miles to the launch pad in early June, with the first launch opportunity in the early evening of June 30. The Dawn spacecraft will employ ion propulsion to explore two of the asteroid belt’s most intriguing and dissimilar occupants--asteroid Vesta and the dwarf planet Ceres. The spacecraft, carrying among its instruments a Los Alamos National Laboratory device called GRaND, is set for an 8-year, 3.2-billion-mile odyssey into the heart of the asteroid belt.
“I am looking forward to launching the fantastic science that GRaND will deliver as Dawn journeys back in time to the beginning of the solar system,” said Tom Prettyman, lead scientist for the Los Alamos instrument and Dawn coinvestigator.
GRaND Adventures
The Los Alamos Gamma Ray and Neutron Detector instrument, GRaND, is one of three science payload instruments on Dawn, which also includes a visual and infrared spectrometer and a framing camera, the mission’s scientific imaging system. GRaND will measure the elemental composition of the asteroids’ surfaces. Radiation detected by GRaND is made by radioactive decay and cosmic ray interactions with the surfaces.
The gamma-ray spectrum provides a fingerprint of the elements within the surface that can be analyzed to determine their abundance. The neutrons provide information about light elements, such as hydrogen and carbon, which are the constituents of ices, as well as strong thermal neutron absorbers, such as iron, titanium, chlorine, gadolinium, and samarium. GRaND can measure many rock-forming elements on Vesta and Ceres.
GRaND’s measurements of hydrogen are needed to determine the distribution of water, which may be present on Ceres as ice or hydrated minerals. From a circular, polar mapping orbit, GRaND will map the abundance of these elements over the entire surface of Vesta and Ceres.
What Will GRaND Tell Us?
GRaND will help answer a number of questions about how the asteroids formed and evolved by showing us maps of where key elements are found and in what abundance. For example, the ratio of potassium to thorium will provide information about the material that grew to form the asteroids and may be useful in determining how the composition of the solar nebula changed with heliocentric distance. The abundance of rock-forming elements, such as iron and titanium, provides information about how igneous rock forms from magma on Vesta. The large impact basin at the south pole of Vesta provides an opportunity to determine the composition of the interior of this planet, providing additional constraints on structure and thermal evolution. The elemental abundance data will also help verify that Vesta is the source of a certain type of meteorites.
Measurements of the abundance of hydrogen and carbon will enable scientists to understand aqueous processes that probably shaped Ceres. Data from all three payload instruments will be combined to provide a complete picture of surface composition, mineralogy, and structure that can be used to answer many questions about the conditions under which planets formed.
The Dawn mission to asteroid Vesta and dwarf planet Ceres is managed by the California Institute of Technology’s Jet Propulsion Laboratory in Pasadena, for NASA’s Science Mission Directorate, Washington, D.C. The University of California at Los Angeles is responsible for overall Dawn mission science. Other scientific partners include: Los Alamos National Laboratory, New Mexico; German Aerospace Center, Berlin; Max Planck Institute for Solar System Research, Katlenburg, Germany; and Italian National Institute of Astrophysics, Palermo. Orbital Sciences Corporation of Dulles, Virginia, designed and built the Dawn spacecraft.
Additional information about Dawn is online at http://dawn.jpl.nasa.gov.
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and Washington Group International for the Department of Energy's National Nuclear Security Administration.
Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.