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Feature/Overview
and Objectives
Dawn
Dictionary
Why Ceres and Vesta?
Technology
Orbit Visualization Tools:
Ceres
Vesta
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Credit: NASA/JPL |
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GRaND Functional Testing
Reported by Tom Prettyman
"December 20 , we completed functional testing of GRaND following spacecraft (S/C) vibe and pyroshock. GRaND performed nominally and is ready to proceed to the next phase of environmental testing. The spacecraft will undergo some additional testing this week, and will then be packed up and shipped from OSC to the Naval Research Laboratory (NRL). In January, the S/C will continue environmental testing (thermal-vac) and mission scenario testing in NRL's large thermal vacuum chamber ("big blue"). Once testing at NRL is complete, the S/C will be shipped to the cape for integration with the launch vehicle. We'll keep you posted on progress."
Side note: LANL team members (Tom and Bruce) supported the test remotely and were able to monitor instrument telemetry and state-of-health from Los Alamos. While some of the future tests will require travel, the ability to carry out a portion of these remotely reduces cost and increases participation by the GRaND team. A big "thank you" is owed to the Dawn project, Betina Pavri and Jason Kim, for making this happen.
What is GRaND?
The Gamma Ray and Neutron Detector (GRaND) will measure the elemental composition of the surfaces of Vesta and Ceres. Galactic cosmic rays, consisting primarily of high energy protons, interact with nuclei within the top few meters of the surface, producing showers of secondary particles, including gamma rays and neutrons. Gamma rays and neutrons produced within the top meter can escape into space, and are measured in orbit by GRaND. The gamma ray energy spectrum provides a "fingerprint," which can be analyzed to determine the abundance of major rock forming elements such as Fe and Si. The neutron energy spectrum can be analyzed to determine the abundance of light elements, such as H and C, which are the major constituents of ices. Gamma rays are also emitted by the decay of radioactive isotopes, such as K and Th. Elemental abundances determined by GRaND will provide constraints on the formation and evolution of the asteroids. |
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accountability report