PDS_VERSION_ID = "PDS3"
FILE_NAME = "JGE15A01.SHB"
RECORD_TYPE = FIXED_LENGTH
RECORD_BYTES = 512
FILE_RECORDS = 512
^SHBDR_HEADER_TABLE = ("JGE15A01_BIN.SHB",1)
^SHBDR_NAMES_TABLE = ("JGE15A01_BIN.SHB",2)
^SHBDR_COEFFICIENTS_TABLE = ("JGE15A01_BIN.SHB",6)
^SHBDR_COVARIANCE_TABLE = ("JGE15A01_BIN.SHB",10)
SPACECRAFT_NAME = "NEAR EARTH ASTEROID RENDEZVOUS"
TARGET_NAME = "EROS"
INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM"
DATA_SET_ID = "NEAR-A-RSS-5-EROS/GRAVITY-V1.0"
OBSERVATION_TYPE = "GRAVITY FIELD"
PRODUCT_ID = "JGE15A01_BIN.SHB"
PRODUCT_RELEASE_DATE = 2001-05-09
DESCRIPTION = "
This file contains coefficients and related data for the
NEAR15A spherical harmonic gravity model of the asteroid Eros.
NEAR15A is a 15th degree and order model obtained from radiometric
tracking (Doppler and range data) and landmark tracking of the
NEAR spacecraft in orbit about Eros. The gravity model includes
data from the entire mission beginning with orbit insertion on
Feb. 14, 2000 and ending with the first descent maneuver for landing
on Feb. 12, 2001.
Some details describing this model are:
The spherical harmonic coefficients are fully normalized.
The associated GM = 4.46275E-04
The reference radius = 16.0 km
The Eros-fixed reference frame is given by the J2000
pole and prime meridian:
Right ascension = 11.363 degrees
Declination = 17.232 degrees
Prime Meridian = 326.08 degrees
Rotation rate = 1639.389232 degrees/day
Summary of data arcs in NEAR15A solution:
Begin time Length Orbit Period Inclination
(days) (km x km) (days) (asteroid equ.)
------------------------------------------------------------
14-FEB-2000 10 366 x 324 21.8 35
24-FEB-2000 8 365 x 204 16.5 34
03-MAR-2000 29 209 x 200 10.0 38
02-APR-2000 10 210 x 100 6.6 56
11-APR-2000 11 101 x 99 3.4 60
22-APR-2000 8 101 x 50 2.2 65
30-APR-2000 24 52 x 49 1.2 90
24-MAY-2000 21
14-JUN-2000 23
07-JUL-2000 7 51 x 35 1.0 90
14-JUL-2000 10 40 x 35 0.7 90
24-JUL-2000 7 56 x 36 1.0 90
31-JUL-2000 8 52 x 49 1.2 90
08-AUG-2000 18 52 x 49 1.2 105
26-AUG-2000 10 102 x 49 2.3 113
05-SEP-2000 15 103 x 100 3.5 115
20-SEP-2000 10
30-SEP-2000 7
07-OCT-2000 6
13-OCT-2000 7 98 x 50 2.2 131
20-OCT-2000 5 52 x 50 1.2 133
25-OCT-2000 1 64 x 19 0.7 135
26-OCT-2000 8 203 x 64 5.3 144
03-NOV-2000 12 197 x 194 10.0 147
15-NOV-2000 14
29-NOV-2000 8
07-DEC-2000 6 193 x 34 4.2 178
13-DEC-2000 14 38 x 34 0.7 178
27-DEC-2000 13
09-JAN-2001 15
24-JAN-2001 4 36 x 22 0.6 178
28-JAN-2001 1 37 x 20 0.6 179
28-JAN-2001(b) 5 36 x 35 0.7 179
02-FEB-2001 4
06-FEB-2001 6
Observations for the gravity field consist of Doppler and
range measurements from Deep Space Network (DSN) tracking
and landmark observables from the camera images of the
asteroid Eros.
The count time for the Doppler observations is 60 seconds.
The typical accuracy for the Doppler is 0.03 mm/s for the
60 second sample time. The range accuracy is about 3 meters
and is limited by the station calibration accuracy. The actual
rms scatter is less than 0.5 meters in spacecraft position.
The camera images are used to generate landmark observations.
For each landmark we basically have two inertial angle measurements
of a crater center. The two directions on the image are called
line and pixel. Each image may be used to generate anywhere from 1
to 40 landmark observation pairs (line,pixel) with the average
being about 6. The total number of landmarks (or craters) used for
optical navigation is 1554. The measurement noise is about
one pixel in both directions. The smaller landmark positions
on Eros are determined to several meter accuracy.
Summary of the number of observations for each arc:
Begin time Doppler Range Landmark pairs
------------------------------------------------------------
14-FEB-2000 7975 2126 4506
24-FEB-2000 6877 1456 2987
03-MAR-2000 19843 7578 9972
02-APR-2000 7385 1819 8303
11-APR-2000 7688 2450 2913
22-APR-2000 6852 1731 1497
30-APR-2000 21976 5410 3539
24-MAY-2000 20326 5514 4854
14-JUN-2000 22902 4414 8645
07-JUL-2000 6640 380 1666
14-JUL-2000 12757 1490 1371
24-JUL-2000 7906 600 2255
31-JUL-2000 9671 1757 2812
08-AUG-2000 19051 2934 4995
26-AUG-2000 10772 2172 5589
05-SEP-2000 12157 3288 7393
20-SEP-2000 6529 2007 5754
30-SEP-2000 4557 1588 6372
07-OCT-2000 4329 693 4716
13-OCT-2000 8156 1572 4901
20-OCT-2000 5355 1001 1037
25-OCT-2000 541 164 270
26-OCT-2000 6699 2164 3553
03-NOV-2000 12032 3128 4759
15-NOV-2000 10497 3249 4782
29-NOV-2000 6745 1670 2585
07-DEC-2000 5660 1008 2645
13-DEC-2000 8460 2584 3024
27-DEC-2000 9321 3422 2911
09-JAN-2001 10090 2892 3517
24-JAN-2001 3187 349 904
28-JAN-2001 552 0 177
28-JAN-2001(b) 3691 478 771
02-FEB-2001 4000 195 618
06-FEB-2001 6438 897 1000
Each Landmark pair consists of one line and one pixel measurement.
Total Doppler observations = 317,617
Total Range observations = 74,180
Total Landmark pixel observations = 127,593
Total Landmark line observations = 127,593
This product is a set of four tables: a header table (binary),
a names table (ascii), a coefficients table (binary), and a covariance
table (binary). Definitions of the tables follow.
The NEAR15A gravity model is delivered as a Spherical Harmonics
Gravity ASCII Data Record (SHGADR) and is produced at JPL by
Alex Konopliv of the NEAR Radio Science Team."
START_ORBIT_NUMBER = 1
STOP_ORBIT_NUMBER = NULL
START_TIME = 2000-02-14T16:00:00Z
STOP_TIME = 2001-02-12T15:15:00Z
PRODUCT_CREATION_TIME = 2001-05-09T00:00:00Z
PRODUCER_FULL_NAME = "ALEX S. KONOPLIV"
PRODUCER_INSTITUTION_NAME = "JET PROPULSION LABORATORY"
PRODUCT_VERSION_TYPE = "PRELIMINARY"
PRODUCER_ID = "NEAR RADIO SCIENCE"
SOFTWARE_NAME = "SHBGRV;V1.0"
/* Structure Objects */
OBJECT = SHBDR_HEADER_TABLE
ROWS = 1
COLUMNS = 9
ROW_BYTES = 56
INTERCHANGE_FORMAT = BINARY
DESCRIPTION = "The SHBDR Header includes
descriptive information about the spherical harmonic
coefficients which follow in SHBDR_COEFFICIENTS_TABLE.
The header consists of a single record of nine data
columns requiring 56 bytes. The Header is followed by
a pad of binary integer zeroes to ensure alignment
with RECORD_BYTES."
OBJECT = COLUMN
NAME = "REFERENCE RADIUS"
DATA_TYPE = IEEE_REAL
START_BYTE = 1
BYTES = 8
UNIT = "KILOMETER"
DESCRIPTION = "The assumed reference
radius of the spherical planet."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "CONSTANT"
DATA_TYPE = IEEE_REAL
START_BYTE = 9
BYTES = 8
UNIT = "N/A"
DESCRIPTION = "For a gravity field model
the gravitational constant GM in kilometers cubed per seconds
squared for the planet. For a topography model, set to 1"
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "UNCERTAINTY IN CONSTANT"
DATA_TYPE = IEEE_REAL
START_BYTE = 17
BYTES = 8
UNIT = "N/A"
DESCRIPTION = "For a gravity field model
the uncertainty in the gravitational constant GM in kilometers
cubed per seconds squared for the planet. For a topography
model, set to 0."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "DEGREE OF FIELD"
DATA_TYPE = MSB_INTEGER
START_BYTE = 25
BYTES = 4
UNIT = "N/A"
DESCRIPTION = "Degree of the model field."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "ORDER OF FIELD"
DATA_TYPE = MSB_INTEGER
START_BYTE = 29
BYTES = 4
UNIT = "N/A"
DESCRIPTION = "Order of the model field."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "NORMALIZATION STATE"
DATA_TYPE = MSB_INTEGER
START_BYTE = 33
BYTES = 4
UNIT = "N/A"
DESCRIPTION = "The normalization indicator.
For gravity field:
0 coefficients are unnormalized
1 coefficients are normalized
2 other."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "NUMBER OF NAMES"
DATA_TYPE = MSB_INTEGER
START_BYTE = 37
BYTES = 4
UNIT = "N/A"
DESCRIPTION = "Number of valid names in
the SHBDR Names Table. Also, the number of valid
coefficients in the SHBDR Coefficients Table."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "REFERENCE LONGITUDE"
POSITIVE_LONGITUDE_DIRECTION = "EAST"
DATA_TYPE = IEEE_REAL
START_BYTE = 41
BYTES = 8
UNIT = "DEGREE"
DESCRIPTION = "The reference longitude for
the spherical harmonic expansion; normally 0."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "REFERENCE LATITUDE"
DATA_TYPE = IEEE_REAL
START_BYTE = 49
BYTES = 8
UNIT = "DEGREE"
DESCRIPTION = "The reference latitude for
the spherical harmonic expansion; normally 0."
END_OBJECT = COLUMN
END_OBJECT = SHBDR_HEADER_TABLE
OBJECT = SHBDR_NAMES_TABLE
ROWS = 253
COLUMNS = 1
ROW_BYTES = 8
INTERCHANGE_FORMAT = BINARY
DESCRIPTION = "The SHBDR Names Table
contains names for the solution parameters (including
gravity field coefficients) which will follow in
SHBDR_COEFFICIENTS_TABLE. The order of the names
in SHBDR_NAMES_TABLE corresponds identically to the
order of the parameters in SHBDR_COEFFICIENTS_TABLE.
Each coefficient name is of the form Cij or Sij
where i is the degree of the coefficient and j is
the order of the coefficient. Both indices are three-
digit zero-filled right-justified ASCII character strings
(for example, C010005 for the 10th degree 5th order C
coefficient, or S002001 for the 2nd degree 1st order
S coefficient). The eighth byte in the table is an
ASCII blank used to ensure that the row length
is equal to RECORD_BYTES. Names of other solution
parameters are limited to 8 ASCII characters; if less
than 8, they will be left-justified and padded with
ASCII blanks. The Names Table itself will be padded
with ASCII blanks, if necessary, so that its length is
an integral multiple of RECORD_BYTES."
OBJECT = COLUMN
NAME = "PARAMETER NAME"
DATA_TYPE = CHARACTER
START_BYTE = 1
BYTES = 8
UNIT = "N/A"
DESCRIPTION = "The name of the
coefficient or other solution parameter, left-
justified and padded with ASCII blanks (if needed)
to 8 characters."
END_OBJECT = COLUMN
END_OBJECT = SHBDR_NAMES_TABLE
OBJECT = SHBDR_COEFFICIENTS_TABLE
ROWS = 253
COLUMNS = 1
ROW_BYTES = 8
INTERCHANGE_FORMAT = BINARY
DESCRIPTION = "The SHBDR Coefficients Table
contains the coefficients and other solution parameters
for the spherical harmonic model. The order of the
coefficients in this table corresponds exactly to the
order of the coefficient and parameter names in
SHBDR_NAMES_TABLE. The SHBDR Coefficients Table will be
padded with double precision DATA_TYPE zeroes so that
its total length is an integral multiple of RECORD_BYTES."
OBJECT = COLUMN
NAME = "COEFFICIENT VALUE"
DATA_TYPE = IEEE_REAL
START_BYTE = 1
BYTES = 8
UNIT = "N/A"
DESCRIPTION = "A coefficient Cij or
Sij or other solution parameter as specified in the
SHBDR Names Table."
END_OBJECT = COLUMN
END_OBJECT = SHBDR_COEFFICIENTS_TABLE
OBJECT = SHBDR_COVARIANCE_TABLE
ROWS = 32131
COLUMNS = 1
ROW_BYTES = 8
INTERCHANGE_FORMAT = BINARY
DESCRIPTION = "The SHBDR Covariance Table
contains the covariances for the spherical harmonic model
coefficients and other solution parameters. The order of
the covariances in this table is defined as columnwise
vector storage of the upper triangular matrix formed by
the product of the SHBDR Names Table with its transpose.
For example, if the Names Table has four entries A, B,
C, and D, then the covariances are given by the column
vectors in the upper triangular matrix of
| A | [ A B C D ] = | AA AB AC AD |
| B | | BA BB BC BD |
| C | | CA CB CC CD |
| D | | DA DB DC DD |
That is, the covariance table will list (in this order)
AA, AB, BB, AC, BC, CC, AD, BD, CD, and DD.
The SHBDR Covariance Table will be padded with double
precision DATA_TYPE zeroes so that its total length is
an integral multiple of RECORD_BYTES."
OBJECT = COLUMN
NAME = "COVARIANCE VALUE"
DATA_TYPE = IEEE_REAL
START_BYTE = 1
BYTES = 8
UNIT = "N/A"
DESCRIPTION = "The covariance value
for the coefficients and other solution parameters
specified by the product of SHBDR_NAMES_TABLE with
its transpose, after omitting redundant terms."
END_OBJECT = COLUMN
END_OBJECT = SHBDR_COVARIANCE_TABLE
END