Data Set Information
DATA_SET_NAME NEAR EROS RADIO SCIENCE DATA SET - EROS/FLYBY V1.0
DATA_SET_ID NEAR-A-RSS-1/5-EROS/FLYBY-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : The Near Earth Asteroid Rendevous (NEAR) Eros Radio Science (RS) Data Set is a time-ordered collection of raw and partially processed data collected during the NEAR flyby of minor planet 433 Eros. For more information on the investigation conducted, including mass determinations results, see [YEOMANSETAL1999]. Only data collected in the span after the engine abort anomaly, (with resumption of two-way lock-up Dec 21, 1998) and prior to DSM-2 burn January 3, 1999 was used for the mass estimation. The radio data also supported NEAR Navigation. The data set includes: Directory Description --------- ----------- ODF Orbit Data Files containing closed-loop (two-way) Doppler and sequential range measurements. EOP Earth-Orientation Parameter file ION Ionosphere calibration file TRO Troposphere calibration file TXT Text files describing physical model inputs and estimated solution parameters Typical users of these data might analyze range and Doppler measurements in the ODF to derive the NEAR trajectory during the flyby. Parameters : The ODF contains the most important information (range and Doppler) needed by spacecraft navigators and those interested in determining gravitational parameters of Eros. Each ODF is accompanied by a full PDS label which describes both the content and format of the associated file. ODF data types can include those listed below. Only those marked below with an asterisk are present in this data set ODF. Narrowband spacecraft VLBI, Doppler mode (cycles) Narrowband spacecraft VLBI, phase mode (cycles) Narrowband quasar VLBI, Doppler mode (cycles) Narrowband quasar VLBI, phase mode (cycles) Wideband spacecraft VLBI (nanoseconds) Wideband quasar VLBI (nanoseconds) * One-way Doppler (Hertz) * Two-way Doppler (Hertz) * Three-way Doppler (Hertz) One-way total count phase (cycles) Two-way total count phase (cycles) Three-way total count phase (cycles) PRA planetary operational discrete spectrum range (range units) * SRA planetary operational discrete spectrum range (range units) RE[GSTDN] range (nanoseconds) Azimuth angle (degrees) Elevation angle (degrees) Hour angle (degrees) Declination angle (degrees) X angle (where +X is east) (degrees) Y angle (where +X is east) (degrees) X angle (where +X is south) (degrees) Y angle (where +X is south) (degrees) Processing : ODF's are screened for 'bad' data points, which are removed prior to analysis by the navigation or radio science teams. Data : ODFs were issued approximately daily prior to the NEAR Eros flyby, more often after the engine abort recovery. These ODFs are stored in the ODF directory. File name is of the form ydddeeeC.ODF where y is the one-digit year (1990s implicit) of the first data, ddd is the three-digit day-of-year of the first data, eee is the three-digit day-of-year of the last data. Symbol C denotes an alphabetic character distinguishing separate files issued during the same day. Ancillary Data : Ancillary files are needed for proper analysis and interpretation of the radio data (file type ODF). These are organized in parallel directories and stored approximately chronologically. Earth Orientation Parameter Files (EOP Directory) --------------------------------------------------- Earth Orientation Parameter files are produced by the Time and Earth Motion Precision Observation (TEMPO) Group at JPL. These are ASCII files of variable length records. Each record is delimited by an ASCII line-feed (ASCII 10). File names have the form ydddzeee.EOP where y is the one-digit year of the first data in the file, ddd is the day-of-year of the first data in the file, z is the one-digit year of the last data, and eee is the day-of-year of the last data in the file. The file covers the most recent nine months of past motion and a prediction for three months into the future; these files are typically 30 KB. Each EOP file is accompanied by a PDS minimal label with file name ydddzeee.LBL. Ionosphere Calibration Files (ION Directory) --------------------------------------------------- Ionosphere Calibration files are produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. These are ASCII files of variable length records. Each record is delimited by an ASCII line-feed (ASCII 10). File names have the form ydddeeeC.ION where y is the one-digit year of the first data in the file, ddd is the day-of-year of the first data in the file, eee is the day-of-year of the last data in the file, and C is a character denoting sequence when more than one file with the same ydddeee is handled. C starts from 'A' and progresses to 'B', 'C', etc. with increasing numbers of similar coverage files. Frequently, ION files are released at one week intervals to cover a single month; ydddeeeA.ION would be the file released during the first week, ydddeeeB.ION would be the file released during the second week, etc. The files archived here are monthly files that contain actuals for the previous month. Each ION file is accompanied by a PDS minimal label with file name ydddeeeC.LBL. Typical file sizes are less than 50 kB. Troposphere Calibration Files (TRO Directory) --------------------------------------------------- Troposphere Calibration files are produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. These are ASCII files of variable length records. Each record is delimited by an ASCII line-feed (ASCII 10). File names have the form ydddeeeC.TRO where y is the one-digit year of the first data in the file, ddd is the day-of-year of the first data in the file, eee is the day-of-year of the last data in the file, and C is a character denoting sequence when more than one file with the same ydddeee is handled. C starts from 'A' and progresses to 'B', 'C', etc. with increasing numbers of similar coverage files. TRO files are typically released at the beginning of a month and cover the previous. Each TRO file is accompanied by a PDS minimal label with file name ydddeeeC.LBL. Typical file sizes are less than 50 kB. Text Files (TXT Directory) -------------------------- Two file types are included in the TXT directory. The first type is NMLMODL.TXT and is accompanied by a minimal PDS label NMLMODL.LBL. It is the nominal set of namelist parameters used to define physical characteristics of the spacecraft's motion and tracking observables used by the JPL orbit determination software suite. The second file is PARAMSUM.TXT, accompanied by minimal PDS label PARAMSUM.LBL, which is a summary of the estimated (solved-for) parameter set. GM9 is the solved-for Eros GM in units of km^3/s^2. Coordinate System : Analysis was conducted in the frame of the DE-403 solar system model, aligned with the 1993 ICRF/J2000 reference frame. Software : Software for parsing, reducing, and analyzing data such as these has been developed at several institutions and elsewhere. Because such software must usually operate at the bit-level and is written for a narrow range of platforms, it is not suitable for general distribution. No software is included with this archival data set.
DATA_SET_RELEASE_DATE 1999-11-30T00:00:00.000Z
START_TIME 1998-12-04T12:00:00.000Z
STOP_TIME 1999-01-03T12:00:00.000Z
MISSION_NAME NEAR EARTH ASTEROID RENDEZVOUS
MISSION_START_DATE 1996-02-17T12:00:00.000Z
MISSION_STOP_DATE 2001-02-28T12:00:00.000Z
TARGET_NAME EROS
TARGET_TYPE ASTEROID
INSTRUMENT_HOST_ID NEAR
INSTRUMENT_NAME RADIO SCIENCE SUBSYSTEM
INSTRUMENT_ID RSS
INSTRUMENT_TYPE RADIO SCIENCE
NODE_NAME Small Bodies
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Overview : Data in this archival data set have been processed as part of the activities of the NEAR Radio Science Team. In general, this is a weak to fair data set. The principal limitation is the small amount of data prior to the flyby and immediately after a large, unknown delta-v thrust anomaly. Review : This archival data set was reviewed by the NEAR Radio Science Team prior to submission to the Planetary Data System (PDS). Prior to creation of the final version of the archival data set, key elements of the archive were distributed for preliminary review. These included electronic versions of example PDS labels, CATALOG files, and Software Interface Specifications. These materials were distributed to PDS personnel, the experiment investigator, and others, as appropriate. Data Coverage and Quality : Significant events for Radio Science during Eros Flyby are as follows: START STOP YY/DDD UTC Time YY/DDD UTC Time Comments ------ -------- ------ -------- ---------------- 98/354 22:00:00 98/354 22:03:20 Rendevous-1 settling burn 98/354 22:03:20 98/355 06:40:00 Anomaly; unknown thrust vector(s) 98/356 08:06:00 Resume two-way Doppler (ERT) 98/357 19:43:00 Eros close-approach 98/359 02:54:00 Resumption of SRA data (ERT) 99/003 17:00:00 DSM-2 maneuver Limitations : The limitations in this data set derive from tracking geometry and measurement data types. There are no known defects in the data.
CITATION_DESCRIPTION Yeomans D.K., Giorgini J.D., A. Konopliv, and E. Grayzeck, NEAR EROS RADIO SCIENCE DATA SET - EROS/FLYBY V1.0, NEAR-A-RSS-1/5-EROS/FLYBY-V1.0, NASA Planetary Data System, 1999.
ABSTRACT_TEXT The NEAR Eros Radio Science Data Set is a time-ordered collection of raw and partially processed data collected during the NEAR flyby of minor planet 433 Eros.
PRODUCER_FULL_NAME JON D. GIORGINI
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