PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM ^TEXT = "AAREADME.TXT" OBJECT = TEXT PUBLICATION_DATE = 2019-01-31 NOTE = "AAREADME.TXT describes this volume." END_OBJECT = TEXT END Volume DWNCLGRD_1B Dawn GRaND Raw Level-1B Ceres Archive ============================================================================== Brief Volume Description ============================================================================== This volume contains data from the Dawn GRaND calibrated level-1B (RDR) Ceres data set covering the entire Ceres mission to date (2015-03-13 to 2018-10-26), including all prime mission, Ceres extended mission 1 orbits XMO1 through XMO4, and Ceres extended mission 2 orbits XMO5 to XMO7. Other data through the Ceres extended mission orbit 2(XMO2) were previously archived by the PDS on volume DWNCAGRD_1B version 1. Version 2 of this volume included data through the end of the first extended mission. Those volumes are superseded by this one and all of the data previously provided are unchanged here. A description of how the GRaND data are organized can be found in the Software Interface Specification (SIS) and Data Processing document (in the DOCUMENT directory) and in Prettyman et al. (2011) Space Science Reviews, Vol. 163(1-4), pp. 371-459, http://dx.doi.org/10.1007/s11214-011-9862-0 NOTE: Reading the Science Plan (DOCUMENT/SCIENCE_PLAN/DAWN_SCIPLAN_V5_4.PDF) is critical to the understanding of Dawn observations and science objectives. Other critical documentation in the DOCUMENT directory include the volume SIS, the data processing description, and the pointing geometry discussion. The RDR includes calibrated, time-series spectra and counting rates along with information needed for analysis and mapping. Improved reduction and analyses of gamma ray spectra has enabled the identification of additional elements [Yamashita et al., 2014, 45th Lunar and Planetary Science conference, Abstract 2674] and quantification of global concentrations of K and Th ; Prettyman et al., 2014, 45th Lunar and Planetary Science conference, Abstract 2565]. Energy-calibrated and corrected gamma ray spectra included on this volume support studies to bound and quantify the major elemental constituents of silicate minerals. The RDR data set includes position, pointing, and measurement geometry data that can be used with both the RDR and Experimental Data Records (EDRs) for studies with neutron and gamma ray data. All data are stored in the 'DATA' branch of the directory tree. In addition to the data files, ancillary information is stored in a separate PDS label (.LBL) file. Information about data gaps and other issues affecting the quality of the data can be found in the Confidence Level Note in the data set catalog (grand_l1b_ceres_ds.cat) Users of these data are encouraged to acknowledge both the PDS and the principal investigators of the instruments whose data are used in analysis in all publications. ============================================================================== Volume Set Information ============================================================================== This volume is part of the GRaND Calibrated level-1B RDR data volume set. This volume set includes the following volumes: Volume ID Description --------------------------------------------------------- DWNXGRD_1B Dawn GRaND L1-B RDR cruise data DWNMGRD_1B Dawn GRaND L1-B RDR Mars flyby images DWNVGRD_1B Dawn GRaND L1-B RDR Vesta Encounter Archive DWNCGRD_1B Dawn GRaND L1-B RDR Ceres Approach through extended mission ============================================================================== Mission Facts ============================================================================== The "Dawn Ceres Science Orbits and Phases" table below provides a list Dawn Ceres Encounter mission phase start dates. ------------------------------------------------------------------------------ Dawn Ceres Science Orbits and Phases ------------------------------------------------------------------------------ start date (DOY) Orbit Phase Name (ID) Orbit Radius ------------------------------------------------------------------------------ 2014-12-26 (360) Approach CERES SCIENCE APPROACH (CSA) 2015-04-24 (114) RC3 CERES SCIENCE RC3 (CSR) ~14,000 km 2015-05-09 (129) Transfer CERES TRANSFER TO SURVEY (CTS) 2015-06-04 (155) Survey CERES SCIENCE SURVEY (CSS) ~4870 km 2015-07-01 (182) Transfer CERES TRANSFER TO HAMO (CTH) 2015-08-17 (229) HAMO CERES SCIENCE HAMO (CSH) ~1950 km 2015-10-23 (296) Transfer CERES TRANSFER TO LAMO (CTL) 2015-12-16 (350) LAMO CERES SCIENCE LAMO (CSL) ~850 km 2016-06-19 (171) XMO1 CERES EXTENDED LAMO (CXL) ~850 km 2016-09-02 (246) Transfer CERES EXTENDED TRANSFER TO JULING (CTJ) 2016-10-10 (284) XMO2 CERES EXTENDED JULING (CXJ) ~1950 km 2016-11-03 (308) Transfer CERES EXTENDED TRANSFER TO GRAND (CTG) 2016-12-13 (348) XMO3 CERES EXTENDED GRAND (CXG) 8.0-9.5e3 km 2017-02-23 (054) Transfer CERES EXTENDED TRANSFER TO OPPOSITION (CTO) 2017-04-28 (118) XMO4 CERES EXTENDED OPPOSITION (CXO) 1.4-5.5e4 km 2017-07-01 (182) XMO5 CERES EXTENDED 2 HOLDING (CX2) 1.0-2.5e4 km 2018-05-15 (135) XMO6 CERES EXTENDED 2 INTERMEDIATE (C2I) 0.9-4.5e3 km 2018-06-09 (160) XMO7 CERES EXTENDED 2 ELLIPTICAL (C2E) 0.5-4.3e3 km ------------------------------------------------------------------------------ GRaND, as a time-series instrument, does not easily conform to arbitrary mission phase boundaries. Raw telemetry data are queried from the telemetry database weekly and delivered to the GRaND team. In general, there is a one-to-one correspondence between the time intervals contained in the raw data queries and those in the 1A EDR data files. The 1A data files are loosely grouped into mission phases and the 1B processing produces a single file per "phase". The Ceres extended mission was proposed with several new "orbits" at various radii that were designed to achieve various objectives (Level-1 requirements). The orbits were creatively named Extended Mission Orbit X or XMO1, XMO2, ... XMO1 remained at the LAMO altitude and is also called extended LAMO or CXL. XMO2 was near the HAMO altitude but slightly elliptical with the primary objective of observing Juling crater at different local times and illumination conditions. This orbit is also referred to as the Juling orbit or CXJ. XMO3 was even more elliptical with a minimum altitude of ~7500 km where the GRaND instrument no longer detects the presence of Ceres. The purpose of this orbit was to collect GRaND background data at an altitude where the surface of Ceres could still be monitored with the other instruments. This orbit is also called the GRaND orbit or CXG. Lastly, the orbit altitude was raised high enough for the orbit plane to be changed (XMO4) so that the Ceres "opposition surge" could be observed at zero phase. This orbit is also called "Opposition" or CXO. The Ceres extended mission 2 originally proposed to leave Ceres to make a flyby of the asteroid Adeona. However, that proposal was not accepted by NASA. Following the XMO4 orbit, a small maneuver was performed to adjust the orbit to facilitate the expected Ceres departure for Adeona. When NASA asked the Dawn project to plan to stay at Ceres and make low altitude, high resolution observations, the Dawn spacecraft was left in this holding orbit while the details of how to get the spacecraft safely to a lower orbit, and how to make the observations once there were worked out. This mission design and planning effort took roughly six months once the project was informed that it would not be leaving Ceres. The extended mission plan was to transfer the spacecraft into an elliptical orbit with a periapsis altitude below 50m with an apoapsis above the HAMO altitude. During the transfer down to this low orbit, the transfer was paused at an intermediate altitude so that additional VIR deep southern hemispheric observations could be made now that the illumination conditions at these latitudes was acceptable. The second extended mission thus ended up with three new orbits XMO5 (Holding), XMO6 (Intermediate), and XMO7 (Elliptical) and the associated transfers. ============================================================================== File Formats ============================================================================== The data files on this volume are all simple ASCII tables. Each data file has an detached ASCII header (PDS label). The PDS label contains information describing spacecraft, target, and data record format. A data set description, instrument description, and other PDS documents are in .CAT files in the /CATALOG directory. Additional documentation is generally located in the DOCUMENT directory. Note for Windows users: In more recent versions of the Microsoft Windows operating system the .CAT by default is reserved as 'Security Catalog.' The .CAT files contained in this volume are ASCII text files, and can be read by any form of text editor. To make Windows open files with this name extension as text files, do the following. In Windows Explorer, open the 'Tools' menu and select 'Folder Options'. Select the 'File Types' tab and select 'CAT' from the list. Press 'Change...' and then choose your preferred text editor or viewer. We do not know of any harmful effects this might have on the operating system or other programs, but do not guarantee it will be entirely safe to make this change. If problems occur, the change can be undone in the same 'File Types' window by changing the default application back to 'crypto shell extension'. ============================================================================== Errata ============================================================================== Every effort has been made to assure that the data and documentation are of the best possible quality. However, mistakes are inevitable. There is a file called ERRATA.TXT found at the root level of this volume which contains a list of known deficiencies or caveats associated with data on this volume at the time this volume was produced. ============================================================================== Volume Contents and Structure ============================================================================== This section describes the volume structure and naming conventions. Below is a tree diagram of the volume, followed by a description of the directory function and key files in each directory. DWNCGRD_1B (root directory) | |- AAREADME.TXT Describes volume contents, and organization (this file) | |- ERRATA.TXT Describes known deficiencies or caveats in the data or | on this volume. | |- VOLDESC.CAT High level description of volume contents. | | |- [CATALOG] PDS catalog files containing information describing the | data, instrument, instrument personnel, relevant references, | the spacecraft, and mission. A more detailed description of | the contents of this directory is provided in the file | /CATALOG/CATINFO.TXT. | |- [DATA] Contains the time series data files. | |- [DOCUMENT] Contains documents describing the instrument, and data | acquisition, processing, and usage. A more detailed | description of the contents of this directory is provided in | the file /DOCUMENT/DOCINFO.TXT. | |- [EXTRAS] Contains files which facilitate the use of the data on the | disk, but which are not actually required for the use or | understanding of those data. A more detailed description of | the contents of this directory is provided in the file | /EXTRAS/EXTRINFO.TXT. | |- [INDEX] Contains a table of contents for all files located on this | volume, and the volume set to date. A more detailed | description of the contents of this directory is provided in | the file /INDEX/INDXINFO.TXT. ============================================================================ Contacts ============================================================================ This volume was produced for the Planetary Data System (PDS) at the Small Bodies node. The data, and associated metadata were supplied by Dr. Thomas H. Prettyman, of the Planetary Science Institute. The volume was assembled at the Dawn Science Center (DSC), by Joseph N. Mafi. For questions or problems regarding the volume, please contact Dr. Carol Neese at the PDS Small Bodies Node: Email neese@psi.edu Telephone 520-622-6300 Mail Carol Neese Planetary Science Institute 1700 E. Ft. Lowell, Ste. 106 Tuscon, AZ 85719-2395 USA For question regarding the data, please contact Dr. Tom Prettyman of PSI: Email prettyman@psi.edu Telephone 520-622-6300 Mail Planetary Science Institute Albuquerque, NM USA For questions regarding PDS Standards or other archives available from the PDS, please contact PDS Operator at the PDS Engineering Node (at JPL): Email pds_operator@jpl.nasa.gov Telephone 818-354-4321 Mail Planetary Data System, PDS Operator Jet Propulsion Laboratory Mail Stop 202-101 4800 Oak Grove Dr. Pasadena, CA 91109-8099 USA The PDS assumes no legal liability for errors on this disk. All users are encouraged to verify the correctness of the data prior to submitting any publications or other work based on these data. Please report errors on this disk to the Small Bodies Node of the PDS through the ERRATA reporting procedures described above.