NIMS GUIDE TO THE IDA ENCOUNTER Original: August 1993 Revised: May 1995 Table of Contents 1.0 Introduction ................................. 1-01 2.0 Encounter Overview ........................... 2-01 3.0 Encounter Geometries ......................... 3-01 4.0 NIMS Sequence Summary ........................ 4.01 5.0 NIMS Detailed Observation Designs ............ 5-01 6.0 Data Return .................................. 6-01 Page 1-01 Chapter 1 - Introduction Contents Sub-Section Page 1.0 Contents ...................................... 1 1.1 Introduction to the Revised Edition ........... 2 1.2 Original Introduction ......................... 3 1.3 Ida General Information ....................... 3-4 1.4 Ida Ground-based Near-Infrared Spectrum ....... 5 1.5 Asteroid Family Plot .......................... 6 1.6 NIMS Sequence and Science Priorities .......... 7-9 Page 1-02 Introduction to the Revised Edition This document was originally published by the NIMS team in August 1993 as a guide to the Galileo Encounter with the asteroid Ida. It has been revised and corrected for inclusion on the 4th CD-ROM of NIMS Experimental Data Records (EDRs). Some material in the original document has been omitted, and a chapter added describing the Ida data actually returned to the ground. The aim of the revised guide is to provide detailed information on the various NIMS observations and calibrations. Also included is background information on the encounter. An overview of the guide is given below. Please refer to the beginning of each chapter for a detailed list of contents. Chapter 1 gives an introduction to the Ida encounter as well as a discussion of various issues that went into the design of the Ida encounter sequence. Chapter 2 gives an overview of the entire Ida encounter using various timelines. Chapter 3 contains diagrams of various aspects of geometry for the Ida encounter. Chapter 4 summarizes the planned NIMS Ida observations by means of a comprehensize sequence summary, PA summary and Observation Table (OBSTAB). Chapter 5 is a collection of the Detailed Observation Designs made up of OAPEL forms and POINTER plots. Chapter 6 is a summary of the NIMS data return for the Ida Encounter. For information on the NIMS instrument, please see the preprint of the NIMS instrument paper provided elsewhere on the CD-ROM, or refer to the published version: R.W. Carlson, P.R. Weissman, W.D. Smythe, J.C. Mahoney and the NIMS Science and Engineering Teams, "Near-infrared Mapping Spectrometer Experiment on Galileo", Space Science Reviews 60: 457-502, 1992. ACKNOWLEDGEMENTS The NIMS Ida observations in this guide were designed by Marcia Segura and Paul Weissman with the help of Bill Smythe and Bob Carlson. The calibrations were designed by Marcia Segura with help from Bill Smythe. John Hui prepared the original printed guide. Frank Leader subsequently retrieved most of the original material for the CD-ROM, edited the original Postscript files for consistency and clarity, recovered missing material by scanning parts of the original printed document and prepared the last chapter describing the data return. Some figures from the Galileo Ida Encounter Notebook prepared by the Galileo Mission Design Team were incorporated into this guide. Al Stevenson generated the sequence summary. Bob Mehlman oversaw production of this guide. Page 1-03 Introduction On August 28, 1993, Galileo will attempt to record the best spatial and spectral information available on an asteroid. 243 Ida will be the target and will provide the second opportunity for an asteroid flyby by the Galileo spacecraft. This packet is provided to the NIMS team as a guide to the Galileo Ida Encounter. Within these pages, you will find information about the asteroid itself, the plans for obtaining the data, and the plans for the data return. 243 Ida - The Asteroid Ida was discovered by Johann Palisa in Vienna on September 29, 1884. The asteroid was named for the nymph of Crete who nursed young Zeus. It is a faint object as viewed from Earth-based telescopes and little observing was done prior to Galileo's desire to 'fly by' a second asteroid. Ida is an S-type asteroid and a member of the Koronis family which is in the outer belt between 2.8 and 2.9 AU. Ida itself is located at a semi-major axis of 2.86 AU. It is expected to be composed of olivine and pyroxene silicates and have a reddish color. Large light curve variations imply a very elongated shape with an approximate mean diameter of 28 km. Ida's pre-encounter characteristics are summarized below. Gaspra's characteristics are also listed for comparison. o Ida is almost twice as large in diameter and eight times as large in volume as Gaspra (Ida's triaxial ellispoid model is 53 x 23 x 18 km whereas Gaspra's is 19 x 12 x 11 km.) o Ida is in the middle of the asteroid belt. (Gaspra is located in the inner edge.) o Ida has a more rapid spin rate. (Ida's spin period = 4.63 hours; Gaspra's period = 7.04 hours.) o Ida is thought to have a more irregular shape. o Ida is a member of the Koronis family of asteroids. (Gaspra is in the Flora family.) o Ida may be much younger that Gaspra. (10s of millions of years vs. 200 million years for Gaspra.) o Ida is possibly an ordinary chondrite (most common meteorite) parent body. (Gaspra is posibly a stony-iron meteorite parent body.) On the following three pages are: 1) a list of Ida's physical constants that was provided by the Galileo Mission Design Team, 2) a plot of a ground-based near-infrared spectrum of Ida that was presented by David Tholen at the Munich DPS of 1992 and 3) a plot in semi-major axis vs inclination of the known asteroids showing Ida and Gaspra and the asteroid families that they belong to. Page 1-04 GLL-MDT-92-193.IOM/Rev. B Asteroid 243 Ida - Physical Constants Class S, Family 3 - Koronis Family Diameter: 28 +/- 3 km Shape: assume tri-axial ellipsoidal with axis ratios a:b:c = 2.3 : 1.0 : 0.8 +/- 0.4 0.2 coupled with the assumed mean diameter yields: a:b:c = 53 km : 23 km : 18 km (28 km = cube root of (a*b*c)) Synodic Period: 0.1930680 +/- 0.0000005 day Sense of Rotation: unknown, assume retrograde (sigma result) North Pole Position: (IAU convention - equally likely, adopy #1) Solution 1: 260 deg ecliptic longitude, +50 deg ecliptic latitude ( 263 RA, +27 Dec) Solution 2: 82 deg ecliptic longitude, +50 deg ecliptic latitude ( 72 RA, +73 Dec) (uncertainites are +/- 15 deg in each direction) Epoch: (Direction of longest axis) 1993 Aug 29.000 (JD 2449228.500) Solution 1: 120 deg ecl. long., +33 deg ecl. lat. Solution 2: 120 deg ecl. long., -34 deg ecl. lat. 1993 Aug 30.000 (JD 2449229.500) Solution 1: 41 deg ecl. long., +33 deg ecl. lat. Solution 2: 41 deg ecl. long., -32 deg ecl. lat. Albedo: 0.24 +/- 0.03 (IRAS) Magnitudes: H = 10.02 G = 0.203 U-B = 0.44 B-V = 0.81 Lightcurve Amplitude: 0.45 - 0.95 Orbital Elements: (Epoch 1993 nov 9.0 = 2449300.5) a = 2.862 AU (semi-major axis) Q = 2.7388094 AU (perihelion distance) e = 0.0434032 (eccentricity) sin i = 0.0197 (inclination, i=1.13126 deg) W = 113.21057 deg (argument of perihelion) node = 323.66333 deg (longitude of asc. node, from B1950.0) Wbar rate = 64.6 (sec/yr) node rate = -65.6 (sec/yr) Pages 1-05 to 1-06 Page figures are found in nimsgdi.pdf Page 1-07 History of the Ida Sequence The planning for Ida Encounter began in the early fall of 1992 with a series of aim point selection meetings. A dark side, 75 deg south ecliptic latitude, 2400 km range flyby was chosen. This aim point provided for the most illuminated surface area to be visible at closest approach and was a compromise of both NIMS and SSI observation requirements. The aim point itself impacted the sequence. It required that the spacecraft attitude be changed (18 degrees off-sun and 29 degrees off-earth) to insure the observations would not be in the cone pole region and to delay the time of boom obscuration. Downlink capability, due to both the spacecraft attitude and the HGA deployment failure, mandated that all science observations be stored on the tape recorder rather than be returned immediately. This requirement grew to include all engineering data taken during the telemetry gap caused by the turn to the off-Earth attitude, which amounted to approximately one half track of the DMS. The data return strategy overshadowed every other aspect of the sequence development. During the observation design phase, much thought was given to the return of Ida data. Observations that may have been collaborative efforts in previous encounters became standalone activities to reduce tape usage. Series of observations were repeated to accommodate easier tape positioning for return. NIMS fixed map observations were added after every absolute slew in the rotation study portion of the sequence to provide more exact Ida location for the return of subsequent NIMS/SSI data. This effort will reduce the amount of dark sky data return for pointing uncertainties and conserve both downlink capability and DMS start/stop cycles for actual asteroid data. Spacecraft Orientation and Trajectory Galileo off-sun angle: ~ 18 degrees Radial distance: darkside, 2400 km @ closest approach Closest approach point: 75 degrees, south ecliptic latitude Encounter time: August 28, 1993; DOY 93-240/16:52:04 UTC NIMS Science Priorities Using the Asteroid Working Group's science objectives, Ida's physical characteristics, spacecraft range, and experience gained during Galileo's flyby of Gaspra, the NIMS Ida observations were sequenced accordingly ("Start" and "End" times are in rims prior to Ida closest approach.). Priority Start End Observation 1 -5 -1 Fixed Map, 0.8 mrad/sec, collaborative NIMS/SSI mosaic, 95% coverage of error ellipse. 2 -11 -5 Short Map, 0.11 mrad/sec, 2 swaths, full coverage of error ellipse 3 -22 -18 Long Map, 0.03 mrad/sec, 1 swath, full coverage of error ellipse 4 -322 -28 Fixed Map, 0.75 mrad/sec every 90 deg of rotation Full Map, 0.06 mrad/sec every 90 deg of rotation Short Map, 0.11 mrad/sec every 30 degrees between 90 degree samples Short Map, 0.11 mrad/sec every 15 degrees between 30 degree samples throughout 1 full Ida rotation. 5 After closest PCT and RCT calibrations with durations approach of 6 rims each. Page 1-08 The NIMS Sequence The NIMS Ida sequence uses four NIMS instrument modes for science observations: Long Map (LM), Full Map (FM), Short Map (SM) and Fixed Map (XM). The gain states chosen were 4 and 3; 4 being used during the distant observations when Ida is still sub-nimsel in size and 3 being used during the closest observations. The grating offset is the default: 4. The following grating offsets were used to allow sampling of the 1.05 micron absorption band. The 1.05 micron samples maximize the scene contrast and should provide the best information on the olivine/pyroxene band. These are the same grating offsets used in the Gaspra Encounter. Mode Grating Start Position LM 0 FM 0 SM 2 XM 6 Observations: The NIMS science observations are logically divided into two portions; the rotation observations and the "close-in" observations. The rotation portion covers approximate 390 degrees of Ida rotation starting at -322 rims from closest approach. NIMS acquires samples every 90 degrees (XM and FM), 30 degrees (SM), and 15 degrees (SM) of rotation. Note: The XM samples were included to aid in the reduction of pointing uncertainty and thus facilitate asteroid data return. The "close-in" portion covers from -28 rims prior to closest approach (the end of the rotation observations) to 1 rim after closest approach. At -28 rims and -22 rims, NIMS acquires two Long Map (LM) samples. These observations are at the best spectral resolution possible. At -11 rims before closest approach, NIMS observes Ida in Short Map (SM) mode to determine asteroid composition. This observation is done in the best spectral/spatial combination possible. From -5 rims to 1 rim, collaborative NIMS/SSI observations are taken; NIMS acquires data in Fixed Map (XM) mode at the highest spatial resolution possible for the Ida Encounter. NIMS rides along in Fixed Map on an additional SSI observation from -1 to +1 Rim to obtain the highest possible spatial resolution data on the asteroid. Calibrations: Bore-sight - NIMS, UVS, and PPR collaborative StarCal, at +30 rims PCT Cal - NIMS Photometric Calibration at +661 rims RCT Cal - NIMS Radiometric Calibration at +2984 rims Page 1-09 Activities Prior to Ida Encounter Certain activities necessary to set the stage for Ida Encounter could not be placed in the EJ3-Ida sequence load due to time/load constraints. These tasks were placed in the EJ2 sequence prior to EJ3. Items of importance to NIMS are the OPNAV frames, instrument turn-on and heater configuration. Although all of the OPNAV images are important to the success of the Ida encounter, #4 and #5 provided NIMS with the opportunity to do two calibrations: Opcal and Ecal. Listed below are the activities of interest to NIMS: Time Activity DOY 93-227/19:38:04 NIMS Shield Heater OFF DOY 93-229/00:56:44 NIMS Replacement Heaters OFF DOY 93-229/00:57:12 NIMS Power ON DOY 93-229/20:25:05 PCT Heater 1 OFF DOY 93-229/20:41:27 OPNAV 4/NIMS OPCAL recorded DOY 93-230/04:25:10 OPNAV 4/NIMS OPCAL playback begins DOY 93-232/06:06:23 OPNAV 4/NIMS OPCAL playback ends DOY 93-233/14:52:55 OPNAV 5/NIMS ECAL recorded DOY 93-233/15:05:10 OPNAV 5/NIMS ECAL playback begins DOY 93-235/05:58:23 OPNAV 5/NIMS ECAL playback ends DOY 93-237/23:05:10 PCT Heater 1 ON Timeline Summary The list below provides an overview of the Encounter events. Time (UTC) Event 08/17/93 (Tue., Day 229) 00:57:11 NIMS Turn On in EJ2 Sequence 08/17/93 (Tue., Day 229) 20:39:21 NIMS OPCAL in EJ2 Sequence 08/21/93 (Sat., Day 233) 14:50:50 NIMS ECAL in EJ2 Sequence 08/27/93 (Fri., Day 239) 11:00:00 Ida Sequence EJ3 Begins 08/28/93 (Sat., Day 240) 11:24:28 NIMS First Observation, Ida Rotation 1 08/28/93 (Sat., Day 240) 16:52:04 Ida Closest Approach 08/30/93 (Mon., Day 242) 19:19:03 NIMS Last Observation, PCT Calibration 08/30/93 (Mon., Day 242) 20:35:00 NIMS TURN Off 09/27/93 (Mon., Day 270) 16:00:00 Ida Sequence EJ3 Ends ---------------------------------------------------------------------------- Month of September, 1993 First Ida Data Return Playback Months of March through June, 1994 Remainder of Ida Data Return Playback ---------------------------------------------------------------------------- Meetings: Tuesdays Regular SROP meeting @ 9:00 a.m. in 264-784 NIMS Science Coordinators meeting @11:00 a.m. in 264-784 Wednesdays Regular S&MD meeting @9:30 a.m. in 264-784 Thursdays NIMS Team Meeting @ 12:00 p.m. in 183-343 Page 2-01 Chapter 2 - Encounter Overview Contents Sub-Section Page 2.0 Contents ..................................... 1 2.1 Introduction to Chapter 2 .................... 2 2.2 Ida Encounter, -12 Hours to +6 Hours ......... 3 2.3 Ida Encounter Summary, -12 to +6 Hours ....... 4 2.4 Galileo Ida Key Events Timeline .............. 5 2.5 NIMS Ida Encounter Overview .................. 6 2.6 NIMS Ida Instrument States ................... 7 Page 2-02 Introduction to Chapter 2 This chapter gives an overview of the entire Ida Encounter. The two figures on pages 3 and 4 show the Ida Encounter Timeline from -12 to +6 hours relative to Ida Closest Approach. The timelines block out the major Remote Sensing Observations for the Ida Encounter. The timeline on page 5, the Galileo Ida Key Events Timeline, shows the science activities occuring during the Ida Encounter, with graphical representations of the major Ida mosaics. The table on page 6 is an overview of the NIMS observations in the Ida Encounter. It lists various geometric quantities and a brief statement of objective for each group of observations. The table on page 7 is a summary of the NIMS instrument states for the NIMS observations in the Ida Encounter. Page 2-03 to 2-07 Page 2-03 to 2-07 figures are contained in file nimsgdi.pdf. Page 3-01 Chapter 3 - Encounter Geometries Contents Sub-Section Page 3.0 Contents ........................................ 1 3.1 Introduction to Chapter 3 ....................... 2 3.2 Galileo VEEGA Trajectory ........................ 3 3.3 Navigating to Ida ............................... 4 3.4 Trajectory Pole View ............................ 5 3.5 Tri-Axial Ellipsoid Model of Ida at C/A ......... 6 3.6 Spacecraft Range from Ida ....................... 7 3.7 Ida Semi-Diameter ............................... 8 3.8 Ida Phase Angle ................................. 9 3.9 Ida Cone Angle ................................. 10 3.10 Latitude of Spacecraft (Sub-Spacecraft Point).. 11 3.11 Longitude of Spacecraft (Sub-Spacecraft Point). 12 Page 3-02 Introduction to Chapter 3 This chapter contains diagrams of various aspects of geometry for the Ida Encounter. The geometry is computed relative to a tri-axial ellipsoid model of Ida. The figure on page 3 shows the entire Galileo VEEGA Trajectory from launch through Jupiter arrival with various 'milestones' labeled along the trajectory. The figure on page 4 shows the geometry of the 4 OPNAV images taken on approach to Ida. The figure on page 5 is a Pole View of the Trajectory of Galileo past Ida during the Ida Flyby, -10 to +10 minutes of closest approach. The figure on page 6 is a plot of the tri-axial ellipsoid model of Ida at closest approach with the NIMS and SSI footprints. The figure on page 7 is a plot of spacecraft range from Ida as a function of time. The figure on page 8 is a plot of Ida's tri-axial ellipsoid semimajor axis as a function of time. The figure on page 9 is a plot of Ida's phase angle as a function of time. The figure on page 10 is a plot of Ida's cone angle as a function of time. The figure on page 11 is a plot of the latitude of the spacecraft with respect to Ida (sub-spacecraft point) as a function of time. The figure on page 12 is a plot of the west longitude of the spacecraft with respect to Ida (sub-spacecraft point) as a function of time. Pages 3-03 to 3-12 Figures for pages 3-03 to 3-12 are in file nimsgdi.pdf. Page 4-01 Chapter 4 - NIMS Observation Summaries Contents Sub-Section Page 4.0 Contents ..................................... 1 4.1 Introduction to Chapter 4 .................... 2 4.2 NIMS Sequence Summary ........................ 3-35 4.3 NIMS PA Summary .............................. 36-40 4.4 NIMS OBSTAB .................................. 41-43 Page 4-02 Introduction to Chapter 4 This chapter summarizes the NIMS IDA observations in terms of a comprehensive sequence summary, PA summary and Observation Table (OBSTAB). The NIMS Sequence Summary is a time-ordered listing of all spacecraft activity pertinent to NIMS operations for the EJ2 and EJ3 Sequences. The information in this summary is derived from the EJ2 and EJ3 SEFs (Spacecraft Event File) with inputs from the NIMS Science Coordinators regarding the start time and duration of the NIMS observations. There are ten columns of information in this table: 1) YR - Year 2) DOY - Day of Year. 3) Time - SCET Time (UTC). 4) PSID - Parameter Set ID of the SEF line. 5) Command - Command name from the SEF. 6) Parameters - Parameters from the above Command Line. 7) Description - Description of the above Command for NIMS. 8) GCM - NIMS Gain, Chopper mode, Instrument Mode. Gain = 1,2,3 or 4. Chopper Mode = R (Reference) or 6 (63Hz). Instrement Mode = 0-15 9) O S - Grating Offset. 10) RIM - SCLK of the Command Line (RIM:MF:RTI) Also, an additional line is inserted into this table at the start and stop times of each NIMS Observation (Oapel) to bracket the commands which affect each NIMS Observation. The NIMS PA Summary is a time-ordered listing of all PAs (Profile Activities) listed in the EJ2 and EJ3 SEFs which affect NIMS observations. The NIMS Observation Table (OBSTAB) is a time-ordered listing of the NIMS obsrvation parameters for use by downlink data processing. It is also derived from the EJ2 and EJ3 SEFs. Page 4-03 to 4-35 Pages contains table found in file nimsgdi.pdf. Page 4-36 PA Summary Table This summary is a listing of the PAs (Profile Activities) used by NIMS just prior to the IDA Encounter in EJ2. INPUT FILE: EJ2_930812.SEF OAPEL PA PSID SCLK1 SCLK2 SCET1 TARGET -------------------------------------------------------------------------- ALSPINSP 192GD 02009875:00 02009878:00 93-229/15:24:59 IDNSOPNAV_04 TARGET 165GD 02010178:89 02010187:00 93-229/20:32:20 CAL IDNSOPNAV_04 SCITLM 176GD 02010184:00 02010184:13 93-229/20:37:25 CAL IDNSOPNAV_04 INITRS 128GD 02010184:89 02010186:06 93-229/20:38:24 CAL IDNNOPCAL_01 CMDRS 157JA 02010185:00 02010195:00 93-229/20:38:26 CAL IDNSOPNAV_04 SSI 147GD 02010186:76 02010188:44 93-229/20:40:17 CAL IDNSOPNAV_04 SMOS 118GD 02010187:06 02010187:86 93-229/20:40:31 CAL IDNSOPNAV_04 SCIREC 175GD 02010187:90 02010188:48 93-229/20:41:27 CAL ALSPINSP 192GE 02015527:00 02015530:00 93-233/14:39:47 IDNSOPNAV_05 TARGET 165GE 02015530:89 02015539:00 93-233/14:43:48 CAL IDNSOPNAV_05 SCITLM 176GE 02015536:00 02015536:13 93-233/14:48:53 CAL IDNSOPNAV_05 INITRS 128GE 02015536:89 02015538:05 93-233/14:49:52 CAL IDNNECAL__01 CMDRS 157JB 02015537:00 02015547:00 93-233/14:49:53 CAL IDNSOPNAV_05 SSI 147GE 02015538:76 02015540:44 93-233/14:51:45 CAL IDNSOPNAV_05 SMOS 118GE 02015539:05 02015539:86 93-233/14:51:58 CAL IDNSOPNAV_05 SCIREC 175GE 02015539:90 02015540:48 93-233/14:52:55 CAL -------------------------------------------------------------------------- Page 4-37 PA Summary Table This summary is a listing of the PAs (Profile Activities) used by NIMS during the IDA Encounter in EJ3. INPUT FILE: EJ3_930727.SEF OAPEL PA PSID SCLK1 SCLK2 SCET1 TARGET -------------------------------------------------------------------------- IDUSROTATI01 TARGET 165IA 02025300:89 02025395:45 93-240/11:22:21 IDA IDUSROTATI01 INITRS 128IA 02025303:84 02025305:06 93-240/11:25:20 IDA IDUSROTATI01 CSMOS 117JA 02025304:77 02025305:14 93-240/11:26:16 IDA IDUSROTATI01 SCIREC 175JA 02025304:85 02025305:32 93-240/11:26:21 IDA IDUSROTATI01 SCITLM 176JA 02025305:00 02025305:13 93-240/11:26:25 IDA IDUSROTATI01 SSI 147IA 02025306:76 02025307:44 93-240/11:28:17 IDA IDUSROTATI01 SCIREC 175IA 02025306:90 02025307:48 93-240/11:28:26 IDA IDUSROTATI01 SCITLM 176IA 02025307:00 02025307:13 93-240/11:28:27 IDA IDUSROTATI01 CMDRS 157KC 02025329:00 02025334:05 93-240/11:50:41 IDA IDUSROTATI01 SSI 147IB 02025329:76 02025332:89 93-240/11:51:32 IDA IDUSROTATI01 SCIREC 175IB 02025329:90 02025333:02 93-240/11:51:41 IDA IDUSROTATI01 SCITLM 176IB 02025330:00 02025330:13 93-240/11:51:42 IDA IDUSROTATI01 INITRS 128JD 02025332:84 02025334:06 93-240/11:54:39 IDA IDUSROTATI01 CSMOS 117JB 02025333:77 02025335:58 93-240/11:55:35 IDA IDUSROTATI01 SCITLM 176JB 02025334:00 02025334:13 93-240/11:55:45 IDA IDUSROTATI01 SCIREC 175JB 02025334:09 02025335:72 93-240/11:55:51 IDA IDUSROTATI01 INITRS 128JE 02025343:84 02025345:06 93-240/12:05:47 IDA IDUSROTATI01 CSMOS 117JC 02025345:06 02025346:76 93-240/12:06:56 IDA IDUSROTATI01 SCIREC 175JC 02025345:59 02025346:77 93-240/12:07:31 IDA IDUSROTATI01 SSI 147IC 02025352:76 02025353:44 93-240/12:14:47 IDA IDUSROTATI01 SCIREC 175IC 02025352:90 02025353:48 93-240/12:14:57 IDA IDUSROTATI01 SCITLM 176IC 02025353:00 02025353:13 93-240/12:14:57 IDA IDUSROTATI01 CSMOS 117JD 02025356:77 02025358:23 93-240/12:18:51 IDA IDUSROTATI01 SCITLM 176JD 02025357:00 02025357:13 93-240/12:19:00 IDA IDUSROTATI01 SCIREC 175JD 02025357:14 02025358:32 93-240/12:19:09 IDA IDUSROTATI01 CSMOS 117JE 02025368:06 02025369:68 93-240/12:30:11 IDA IDUSROTATI01 SCIREC 175JE 02025368:59 02025369:77 93-240/12:30:47 IDA IDUSROTATI01 SSI 147ID 02025375:76 02025376:44 93-240/12:38:03 IDA IDUSROTATI01 SCIREC 175ID 02025375:90 02025376:48 93-240/12:38:12 IDA IDUSROTATI01 SCITLM 176ID 02025376:00 02025376:13 93-240/12:38:13 IDA IDUSROTATI01 CSMOS 117JF 02025379:77 02025381:23 93-240/12:42:06 IDA IDUSROTATI01 SCITLM 176JF 02025380:00 02025380:13 93-240/12:42:15 IDA IDUSROTATI01 SCIREC 175JF 02025380:14 02025381:32 93-240/12:42:25 IDA IDUSROTATI01 CSMOS 117JG 02025391:06 02025392:68 93-240/12:53:27 IDA IDUSROTATI01 SCIREC 175JG 02025391:59 02025392:77 93-240/12:54:02 IDA IDUSROTATI02 INITRS 128JF 02025395:84 02025397:06 93-240/12:58:21 IDA IDUSROTATI02 TARGET 165IB 02025396:44 02025464:00 93-240/12:58:55 IDA IDUSROTATI02 CSMOS 117JH 02025396:77 02025397:14 93-240/12:59:17 IDA IDUSROTATI02 SCIREC 175JH 02025396:85 02025397:32 93-240/12:59:23 IDA IDUSROTATI02 SCITLM 176JH 02025397:00 02025397:13 93-240/12:59:27 IDA IDUSROTATI02 CMDRS 157KD 02025398:00 02025404:00 93-240/13:00:27 IDA IDUSROTATI02 SSI 147IE 02025398:76 02025401:89 93-240/13:01:18 IDA IDUSROTATI02 SCIREC 175IE 02025398:90 02025402:02 93-240/13:01:27 IDA IDUSROTATI02 SCITLM 176IE 02025399:00 02025399:13 93-240/13:01:28 IDA IDUSROTATI02 INITRS 128JG 02025401:84 02025403:06 93-240/13:04:25 IDA IDUSROTATI02 CSMOS 117JI 02025402:77 02025404:58 93-240/13:05:21 IDA IDUSROTATI02 SCITLM 176JI 02025403:00 02025403:13 93-240/13:05:31 IDA -------------------------------------------------------------------------- Page 4-38 OAPEL PA PSID SCLK1 SCLK2 SCET1 TARGET -------------------------------------------------------------------------- IDUSROTATI02 SCIREC 175JI 02025403:09 02025404:72 93-240/13:05:37 IDA IDUSROTATI02 INITRS 128JH 02025412:84 02025414:06 93-240/13:15:33 IDA IDUSROTATI02 CSMOS 117JJ 02025414:06 02025415:68 93-240/13:16:42 IDA IDUSROTATI02 SCIREC 175JJ 02025414:59 02025415:77 93-240/13:17:17 IDA IDUSROTATI02 SSI 147IF 02025421:76 02025422:44 93-240/13:24:33 IDA IDUSROTATI02 SCIREC 175IF 02025421:90 02025422:48 93-240/13:24:43 IDA IDUSROTATI02 SCITLM 176IF 02025422:00 02025422:13 93-240/13:24:43 IDA IDUSROTATI02 CSMOS 117JK 02025425:77 02025427:23 93-240/13:28:37 IDA IDUSROTATI02 SCITLM 176JK 02025426:00 02025426:13 93-240/13:28:46 IDA IDUSROTATI02 SCIREC 175JK 02025426:14 02025427:32 93-240/13:28:55 IDA IDUSROTATI02 CSMOS 117JL 02025437:06 02025438:68 93-240/13:39:57 IDA IDUSROTATI02 SCIREC 175JL 02025437:59 02025438:77 93-240/13:40:33 IDA IDUSROTATI02 SSI 147IG 02025444:76 02025445:44 93-240/13:47:48 IDA IDUSROTATI02 SCIREC 175IG 02025444:90 02025445:48 93-240/13:47:58 IDA IDUSROTATI02 SCITLM 176IG 02025445:00 02025445:13 93-240/13:47:58 IDA IDUSROTATI02 CSMOS 117JM 02025448:77 02025450:23 93-240/13:51:52 IDA IDUSROTATI02 SCITLM 176JM 02025449:00 02025449:13 93-240/13:52:01 IDA IDUSROTATI02 SCIREC 175JM 02025449:14 02025450:32 93-240/13:52:10 IDA IDUSROTATI02 CSMOS 117JN 02025460:06 02025461:68 93-240/14:03:12 IDA IDUSROTATI02 SCIREC 175JN 02025460:59 02025461:77 93-240/14:03:48 IDA IDUNROTATI03 INITRS 128JI 02025463:84 02025465:06 93-240/14:07:06 IDA IDUNROTATI03 TARGET 165JA 02025464:44 02025534:00 93-240/14:07:40 IDA IDUNROTATI03 CSMOS 117JO 02025464:77 02025465:14 93-240/14:08:02 IDA IDUNROTATI03 SCIREC 175JO 02025464:85 02025465:32 93-240/14:08:08 IDA IDUNROTATI03 SCITLM 176JO 02025465:00 02025465:13 93-240/14:08:12 IDA IDUNROTATI03 CMDRS 157KE 02025467:00 02025472:00 93-240/14:10:13 IDA IDUNROTATI03 SSI 147IH 02025467:76 02025470:89 93-240/14:11:04 IDA IDUSROTATI03 SCIREC 175IH 02025467:90 02025471:02 93-240/14:11:13 IDA IDUSROTATI03 SCITLM 176IH 02025468:00 02025468:13 93-240/14:11:14 IDA IDUNROTATI03 INITRS 128JJ 02025470:84 02025472:06 93-240/14:14:11 IDA IDUNROTATI03 CSMOS 117JP 02025471:77 02025473:78 93-240/14:15:07 IDA IDUNROTATI03 SCITLM 176JP 02025472:00 02025472:13 93-240/14:15:16 IDA IDUNROTATI03 SCIREC 175JP 02025472:09 02025474:06 93-240/14:15:22 IDA IDUNROTATI03 INITRS 128JK 02025481:84 02025483:06 93-240/14:25:18 IDA IDUNROTATI03 CSMOS 117JQ 02025483:06 02025484:88 93-240/14:26:28 IDA IDUNROTATI03 SCIREC 175JQ 02025483:59 02025485:06 93-240/14:27:03 IDA IDUNROTATI03 SSI 147II 02025490:76 02025493:44 93-240/14:34:19 IDA IDUSROTATI03 SCIREC 175II 02025490:90 02025493:48 93-240/14:34:28 IDA IDUSROTATI03 SCITLM 176II 02025491:00 02025491:13 93-240/14:34:29 IDA IDUNROTATI03 CSMOS 117JR 02025494:77 02025496:23 93-240/14:38:22 IDA IDUNROTATI03 SCITLM 176JR 02025495:00 02025495:13 93-240/14:38:32 IDA IDUNROTATI03 SCIREC 175JR 02025495:14 02025496:32 93-240/14:38:41 IDA IDUNROTATI03 CSMOS 117JS 02025506:06 02025507:68 93-240/14:49:43 IDA IDUNROTATI03 SCIREC 175JS 02025506:59 02025507:77 93-240/14:50:18 IDA IDUNROTATI03 SSI 147IJ 02025513:76 02025516:44 93-240/14:57:34 IDA IDUSROTATI03 SCIREC 175IJ 02025513:90 02025516:48 93-240/14:57:44 IDA IDUSROTATI03 SCITLM 176IJ 02025514:00 02025514:13 93-240/14:57:44 IDA IDUNROTATI03 CSMOS 117JT 02025517:77 02025519:23 93-240/15:01:38 IDA IDUNROTATI03 SCITLM 176JT 02025518:00 02025518:13 93-240/15:01:47 IDA IDUNROTATI03 SCIREC 175JT 02025518:14 02025519:32 93-240/15:01:56 IDA IDUNROTATI03 CSMOS 117JU 02025529:06 02025530:68 93-240/15:12:58 IDA IDUNROTATI03 SCIREC 175JU 02025529:59 02025530:77 93-240/15:13:34 IDA IDUNROTATI04 INITRS 128JL 02025533:84 02025535:06 93-240/15:17:53 IDA -------------------------------------------------------------------------- Page 4-39 OAPEL PA PSID SCLK1 SCLK2 SCET1 TARGET -------------------------------------------------------------------------- IDUNROTATI04 TARGET 165JB 02025534:44 02025600:51 93-240/15:18:27 IDA IDUNROTATI04 CSMOS 117JV 02025534:77 02025535:18 93-240/15:18:49 IDA IDUNROTATI04 SCIREC 175JV 02025534:85 02025535:32 93-240/15:18:54 IDA IDUNROTATI04 SCITLM 176JV 02025535:00 02025535:13 93-240/15:18:58 IDA IDUNROTATI04 SSI 147IK 02025536:76 02025539:89 93-240/15:20:50 IDA IDUSROTATI04 SCIREC 175IK 02025536:90 02025540:02 93-240/15:20:59 IDA IDUSROTATI04 SCITLM 176IK 02025537:00 02025537:13 93-240/15:21:00 IDA IDUNROTATI04 INITRS 128JM 02025539:84 02025541:06 93-240/15:23:57 IDA IDUNROTATI04 CSMOS 117JW 02025540:77 02025543:18 93-240/15:24:53 IDA IDUNROTATI04 SCITLM 176JX 02025541:00 02025541:13 93-240/15:25:02 IDA IDUNROTATI04 SCIREC 175JX 02025541:09 02025543:32 93-240/15:25:08 IDA IDUNROTATI04 SSI 147IL 02025547:76 02025550:89 93-240/15:31:57 IDA IDUSROTATI04 SCIREC 175IL 02025547:90 02025551:02 93-240/15:32:06 IDA IDUSROTATI04 SCITLM 176IL 02025548:00 02025548:13 93-240/15:32:07 IDA IDUNROTATI04 INITRS 128JN 02025550:84 02025552:06 93-240/15:35:04 IDA IDUNROTATI04 CMDRS 157JK 02025551:00 02025567:00 93-240/15:35:09 IDA IDUNROTATI04 SCITLM 176JY 02025552:00 02025552:13 93-240/15:36:10 IDA IDUNROTATI04 CSMOS 117JX 02025552:06 02025554:07 93-240/15:36:14 IDA IDUNROTATI04 SCIREC 175JY 02025552:59 02025554:16 93-240/15:36:49 IDA IDUNROTATI04 SSI 147IM 02025559:76 02025562:89 93-240/15:44:05 IDA IDUSROTATI04 SCIREC 175IM 02025559:90 02025563:02 93-240/15:44:14 IDA IDUSROTATI04 SCITLM 176IM 02025560:00 02025560:13 93-240/15:44:15 IDA IDUNROTATI04 CSMOS 117JY 02025563:77 02025565:33 93-240/15:48:08 IDA IDUNROTATI04 SCITLM 176JZ 02025564:00 02025564:13 93-240/15:48:18 IDA IDUNROTATI04 SCIREC 175JZ 02025564:14 02025565:42 93-240/15:48:27 IDA IDUNROTATI04 SSI 147IN 02025570:76 02025573:89 93-240/15:55:12 IDA IDUSROTATI04 SCIREC 175IN 02025570:90 02025574:02 93-240/15:55:22 IDA IDUSROTATI04 SCITLM 176IN 02025571:00 02025571:13 93-240/15:55:22 IDA IDUNROTATI04 CMDRS 157LC 02025574:00 02025592:00 93-240/15:58:24 IDA IDUNROTATI04 SCITLM 176EA 02025575:00 02025575:13 93-240/15:59:25 IDA IDUNROTATI04 CSMOS 117JZ 02025575:06 02025576:78 93-240/15:59:29 IDA IDUNROTATI04 SCIREC 175EA 02025575:59 02025576:87 93-240/16:00:04 IDA IDUNROTATI04 SSI 147IO 02025582:76 02025585:89 93-240/16:07:20 IDA IDUSROTATI04 SCIREC 175IO 02025582:90 02025586:02 93-240/16:07:30 IDA IDUSROTATI04 SCITLM 176IO 02025583:00 02025583:13 93-240/16:07:30 IDA IDUNROTATI04 CSMOS 117EA 02025586:77 02025588:43 93-240/16:11:24 IDA IDUNROTATI04 SCITLM 176EB 02025587:00 02025587:13 93-240/16:11:33 IDA IDUNROTATI04 SCIREC 175EB 02025587:14 02025588:52 93-240/16:11:42 IDA IDUNROTATI04 SSI 147IP 02025593:76 02025596:89 93-240/16:18:28 IDA IDUSROTATI04 SCIREC 175IP 02025593:90 02025597:02 93-240/16:18:37 IDA IDUSROTATI04 SCITLM 176IP 02025594:00 02025594:13 93-240/16:18:38 IDA IDUNROTATI04 SCITLM 176EC 02025598:00 02025598:13 93-240/16:22:40 IDA IDUNROTATI04 CSMOS 117EB 02025598:06 02025599:79 93-240/16:22:44 IDA IDUNROTATI04 SCIREC 175EC 02025598:59 02025600:01 93-240/16:23:20 IDA IDUNIDAGLM01 INITRS 128JA 02025598:84 02025600:06 93-240/16:23:36 IDA IDUNIDAGLM01 CMDRS 157KF 02025600:00 02025606:00 93-240/16:24:42 IDA IDUNIDAGLM01 TARGET 165JC 02025600:51 02025612:65 93-240/16:25:16 IDA IDUNIDAGLM01 CSMOS 117EC 02025600:82 02025604:71 93-240/16:25:36 IDA IDUNIDAGLM01 SCIREC 175ED 02025600:90 02025604:82 93-240/16:25:42 IDA IDUNIDAGLM01 SCITLM 176ED 02025601:00 02025601:13 93-240/16:25:42 IDA IDUSFINROT01 SSI 147IQ 02025604:76 02025607:89 93-240/16:29:35 IDA IDUSFINROT01 SCIREC 175IQ 02025604:90 02025608:02 93-240/16:29:44 IDA IDUSFINROT01 SCITLM 176IQ 02025605:00 02025605:13 93-240/16:29:45 IDA -------------------------------------------------------------------------- Page 4-40 OAPEL PA PSID SCLK1 SCLK2 SCET1 TARGET -------------------------------------------------------------------------- IDUNIDAFIN01 CMDRS 157KG 02025607:00 02025614:00 93-240/16:31:46 IDA IDUNIDAFIN01 CSMOS 117ED 02025607:06 02025612:65 93-240/16:31:50 IDA IDUNIDAFIN01 SCITLM 176EF 02025608:00 02025608:13 93-240/16:32:47 IDA IDUNIDAFIN01 SCIREC 175EF 02025608:02 02025612:70 93-240/16:32:48 IDA IDUS6COLOR01 INITRS 128IB 02025610:90 02025612:06 93-240/16:35:48 IDA IDUS6COLOR01 TARGET 165IC 02025612:06 02025615:81 93-240/16:36:54 IDA IDUS6COLOR01 CSMOS 117IA 02025612:06 02025615:81 93-240/16:36:54 IDA IDUS6COLOR01 SSI 147IR 02025612:06 02025615:89 93-240/16:36:54 IDA IDUS6COLOR01 SCIREC 175IR 02025612:75 02025616:04 93-240/16:37:40 IDA IDUS6COLOR01 SCITLM 176IR 02025612:78 02025613:00 93-240/16:37:42 IDA IDUNIDACHM01 CMDRS 157KH 02025615:00 02025622:00 93-240/16:39:52 IDA IDUNIDACHM01 TARGET 165JE 02025615:81 02025621:27 93-240/16:40:46 IDA IDUNIDACHM01 INITRS 128JC 02025615:84 02025616:06 93-240/16:40:48 IDA IDUNIDACHM01 CSMOS 117EE 02025615:86 02025621:26 93-240/16:40:49 IDA IDUNIDACHM01 SCITLM 176EG 02025616:00 02025616:13 93-240/16:40:52 IDA IDUNIDACHM01 SCIREC 175EG 02025616:05 02025621:43 93-240/16:40:56 IDA IDUNIDACHM01 SSI 147IS 02025616:76 02025620:89 93-240/16:41:43 IDA IDUSHIRES_01 INITRS 128IC 02025619:84 02025621:06 93-240/16:44:50 IDA IDUSHIRES_01 TARGET 165ID 02025621:06 02025625:68 93-240/16:46:00 IDA IDUSHIRES_01 CSMOS 117IB 02025621:06 02025625:68 93-240/16:46:00 IDA IDUSHIRES_01 SSI 147IT 02025621:06 02025628:11 93-240/16:46:00 IDA IDUSHIRES_01 SCIREC 175IS 02025621:49 02025625:82 93-240/16:46:28 IDA IDUSHIRES_01 SCITLM 176IS 02025621:52 02025621:65 93-240/16:46:30 IDA IDUSENCNTR01 TARGET 165IE 02025625:68 02025628:13 93-240/16:50:44 IDA IDUSENCNTR01 CSMOS 117IC 02025625:77 02025628:11 93-240/16:50:50 IDA IDUSENCNTR01 SCIREC 175IT 02025625:88 02025628:17 93-240/16:50:57 IDA IDUPRADOBS01 CMDRS 157LA 02025628:00 02025630:00 93-240/16:53:00 IDA IDUMSWWING02 SCITLM 176MA 02025628:13 02025628:26 93-240/16:53:09 IDA IDUPRADOBS01 TARGET 165LA 02025628:13 02025635:60 93-240/16:53:09 IDA IDUMSWWING02 SCIREC 175MA 02025628:18 02025657:08 93-240/16:53:12 IDA IDUPRADOBS01 CSMOS 117LA 02025628:40 02025635:41 93-240/16:53:27 IDA IDUPPOLOBS01 CMDRS 157LB 02025635:00 02025638:18 93-240/17:00:05 IDA IDUPPOLOBS01 TARGET 165LB 02025635:60 02025638:28 93-240/17:00:45 IDA IDUPPOLOBS01 CSMOS 117LB 02025635:87 02025638:01 93-240/17:01:03 IDA IDHUSTRCAL01 TARGET 165KA 02025638:29 02025640:48 93-240/17:03:26 SKY IDHUSTRCAL01 CMDRS 157KA 02025639:00 02025671:00 93-240/17:04:08 SKY IDHUSTRCAL01 CSMOS 117KA 02025640:06 02025651:70 93-240/17:05:12 SKY IDHUBORSIT01 TARGET 165KB 02025653:24 02025657:26 93-240/17:18:33 SKY IDHUBORSIT01 CMDRS 157KB 02025656:00 02025665:00 93-240/17:21:19 SKY IDHUBORSIT01 CSMOS 117KB 02025657:06 02025661:39 93-240/17:22:24 SKY IDHUBORSIT01 SCIREC 175KA 02025657:20 02025662:03 93-240/17:22:33 SKY IDHUBORSIT01 SCITLM 176KA 02025657:26 02025657:39 93-240/17:22:37 SKY ALSPINSP 192EH 02026275:00 02026305:00 93-241/03:47:12 IDUNPCTCAL01 SCIREC 175EH 02026287:85 02026294:02 93-241/04:00:16 IDA IDUNPCTCAL01 CMDRS 157EG 02026288:00 02026309:00 93-241/04:00:20 IDA IDUNPCTCAL01 SCITLM 176EH 02026288:00 02026288:13 93-241/04:00:20 IDA ALSPINSP 192JB 02028599:00 02028629:00 93-242/18:57:01 IDUNRCTCAL01 SCIREC 175EI 02028613:85 02028624:02 93-242/19:12:07 IDA IDUNRCTCAL01 CMDRS 157EH 02028614:00 02028625:00 93-242/19:12:11 IDA IDUNRCTCAL01 SCITLM 176EI 02028614:00 02028614:13 93-242/19:12:11 IDA -------------------------------------------------------------------------- Pages 4-41 to 4-43 Pages contains table found in file nimsgdi.pdf. Page 5-01 Chapter 5 - Detailed Observation Designs Contents Sub-Section Page 5.0 Contents ..................................... 1 5.1 Introduction to Chapter 5 .................... 2 5.2 IDA Far Rotation Observations ................ 4-35 5.3 Ida Near Encounter Observations .............. 36-49 5.4 Ida Calibration Observations ................. 50-53 Page 5-02 Introduction to Chapter 5 Detailed Observation Designs Each NIMS Detailed Observation Design consists of an OAPEL form and a Pointer plot. The OAPEL form is a brief description of the design of the observation. The Pointer plot is a plot of the target body with the NIMS footprint incorporated in the mosaic design superimposed on the target body. The size and orientation of the target body is plotted as it appears at the time of the first NIMS footprint plotted. For long observations, the target body may rotate or move relative to the spacecraft during the observation. Some observations, such as calibrations, do not have Pointer plots. The first four OAPEls, IDUSROTATI01, IDUSROTATI02, IDUNROTATI03 and IDUNROTATI04 each cover a complete rotation of Ida. These OAPELs are further sub-divided into multiple OAPELs which cover specific rotational phases of IDA. There is only one Pointer plot for each of these four rotation OAPELs. Page 5-03 This page is intentionally left blank. Page 5-04 to 5-53 Pages contains tables and figures found in file nimsgdi.pdf. Page 6-01 Chapter 6 - Data Return Contents Sub-Section Page 6.0 Contents ..................................... 1 6.1 Introduction to Chapter 6 .................... 2-3 6.2 NIMS Obstab (Data Returned) .................. 4-7 6.3 NIMS Ida Data Table .......................... 8-12 6.4 NIMS Ida Pointing Discussion ................. 13-18 Page 6-02 Introduction to Chapter 6 Data Return The Ida data were recorded on tape during the Ida Encounter and partially played back over a number of months. Due to the low data rates, not all of the NIMS Ida observations were returned. Efforts were made to locate IDA in the NIMS data using jailbar searches and then, using assumptions based on the design of the mosaics, small segments of selected mosaics were returned so as to maximize Ida data return. Unfortunately a problem with the scan platform gyros caused the spacecraft to change from inertial mode to cruise mode, causing the mosaics and scan platform slews to execute in an unpredictable manner such that dark sky data was returned instead of Ida data in many cases. A discussion of the scan platform problems follows later in this chapter. The NIMS data are stored in EDRs (Experiment Data Records) produced by JPL-MIPS (Multi-mission Image Processing System). The NIMS EDR is described in the NIMS Experiment Data Record SIS (Software Interface Specification) Number 232-08. This document is part of the Galileo Project document GLL-625-610. The NIMS EDR file name is determined by the start time (SCLK) of the data. It begins with the letter "N", which is followed by the partition number, RIM and MOD91 counts; the file extension is a number which represents the version number of duplicate files. For example, if the clock is in its second cycle and the first record's SCLK is equal to 12345678.90.7, and this is the first such EDR, then the file will be named: "N21234567890.1". The MIPS-generated EDRs have a Vicar label, followed by a PDS/ISIS label, binary header records and the data records. For archiving on CD-ROM, the Vicar labels are detached (but kept separately on the CD) and the file is renamed so as to conform to the 8.3 DOS file-naming convention as follows: The initial "N" becomes an "E", the partition number is preserved, the RIM count is split between the name and the extension, and a final character (A,B,...) is added to the extension to distinguish any EDRs that start in the same RIM. For example, the MIPS EDR N21234567890.1 becomes E2123456.78A. Along with this NIMS Guide, other files are distributed on the NIMS EDR CD to help describe the NIMS data. Among these files are the OBSCAT, OBSPLN and RIMCAT. The OBSCAT is very similar to the OBSTAB described below in this chapter and as well as in its PDS label on the CD. The OBSPLN, the planned OBSTAB, is a table similar to the planned Obstab found in Chapter 4 of this NIMS Guide. It is also described in its PDS label on the CD. The RIMCAT is a table which describes the NIMS EDR data on a RIM by RIM basis. It contains one entry (row) for each RIM of each NIMS EDR. The RIMCAT may be used to track instrument mode and state changes, etc. It too is described in its PDS label on the CD. The table on the following four pages, the NIMS Obstab (Observation Table), is a time-ordered listing of the NIMS observation parameters for the data returned from the Ida Encounter. It will be used for Page 6-03 systematic processing of the EDR data into cubes and tubes. The NIMS Obstab found in Chapter 4 of this NIMS Guide is the Planned Obstab - the Observation Table for the NIMS data that was sent to the spacecraft's tape recorder. The table on the following five pages gives a brief summary of the NIMS data returned for the Ida Encounter. Since Ida's position and velocity were not well known during the planning stages of the Ida observations, a large amount of empty space was scanned in each mosaic to ensure that Ida would be observed. As stated above, due to limited down-link capabilities and low data rates, not all Ida observations were returned. Only portions of some mosaics were returned. For each NIMS EDR the SCLK range is given along with the OAPEL names of the NIMS observations that take place during that time period. For each observation the time ranges for which data were returned along with the time ranges in which NIMS actually observed Ida are listed, along with additional comments. Dactyl, Ida's moon, was detected in three NIMS observations: IDUNIDAFIN01, IDUNIDACHM01 and IDUSHIRES_01. The time ranges for when NIMS saw Dactyl are also listed in this table. The last three NIMS EDRs in this table contain NIMS boresight, PCT and RCT calibration data. Next in this chapter is a NIMS memo which discusses the scan platform's anomalous behavior during the Ida Fly-by. Towards the beginning of the Ida Encounter the scan platform gyros were turned off due to a perceived overheating of the gyros. The response of the AACS was to switch from inertial mode to cruise mode for the rest of the encounter. The cone actuator has a different response in cruise mode than in inertial mode. All mosaics executed in cruise mode were affected by this response difference. Sometimes the mosaics were executed with slight deviations from the predicted mosaic, sometimes with large offsets in execution and sometimes not at all! Examples of the scan platform behavior are given in this section. This change in the execution of the scan platform behavior had a large effect on the amount of NIMS Ida data returned. Once Ida's position was determined more precisely, the plan was to return only the data in which NIMS would see Ida. This plan was based on the assumption of how the scan platform behaved in inertial mode. Since the scan platform behaved in a manner different from that predicted, NIMS did not see Ida in many of the small segments of mosaics that were returned. This problem was greatest in the first half of the encounter sequence where Ida's size was of the order of a few NIMS pixels and the mosaics were of short duration. The mosaics in the second half of the Ida encounter were longer in duration so that they still completed even though they were executed in cruise mode. The scan platform's behavior, though, was still very erratic in these large mosaics, as illustrated in the attached memo. Even with the constraints of limited data return and the problems with the anomalous scan platform behavior, the NIMS Ida observations which had the highest priority were returned, along with the bonus of finding and observing Dactyl, Ida's moon. Pages 6-04 to 6-12 The tables of pages 6-04 to 6-12 are in file nimsgdi.pdf. Page 6-13 JET PROPULSION LABORATORY IOM NIMS 94-xxx-FL 21-JUL-1994 To: Bill Smythe From: Frank Leader (UCLA) Subject: A Brief Discussion of Scan Platform Anomalous Behavior During the IDA Fly-by. CC: Galileo SDT. Due to the overheating of the scan platform gyroes, AACS switched from Inertial Mode to Cruise Mode near -230 rims before closest approach to IDA near the start of the Rotation_2 segment. In Cruise Mode, the scan platform was not able to perform mosaics as expected in Inertial mode. Sometimes the mosaics were executed with slight deviations from the predicted mosaic, sometimes with large offsets in execution (time lags up to 30 mfs) and sometimes not at all. This erratic behavior made it very difficult for the NIMS team to predict where IDA would be in a particular mosaic, causing the NIMS Team to miss a large number of opportunities to return NIMS observations of IDA due to the limited number of bits-to-ground available for the IDA data return. The following is a sample of some of the scan platform anomalies observed during the IDA Fly-by. The observed scan platform pointing values come from AACS in the NIMS EDR and the predicts come from TISIM files produced by Pointer. These data are also available in the form of C-Kernels available from the Galileo SDT. Figures 1 and 2 illustrate one of the occasions when a mosaic was not executed at all. Both planned (thick line) and measured Scan Platform RA (PRA) are plotted as a function of time for two nearly identical NIMS CSMOS mosaics. Figure 1 illustrates a mosaic executed when the spacecraft was still in Inertial Mode at the start of Rotation_1 and Figure 2 is from a mosaic executed at the start of Rotation_4 when the spacecraft was in Cruise Mode. In each case the scan platform was to slew about 4 mrad at a rate of .75 mrad/sec, completing the slew in 8 mf (5 1/3 seconds). In Figure 1 the slew completed in the alotted time and NIMS 'saw' IDA at mf 8; within the error ellipse of the model. In Figure 2 the scan platform did not complete the slew in the allotted time and NIMS failed to 'see' IDA. Figure 3 illustrates an example of when a mosaic executed in Cruise Mode but was offset in time up to about 30 mfs (20 seconds). The thick line is the planned slew and the thin line is the observed slew. In this mosaic, the scan platform did not slew to the commanded position of -167.7 degrees in PRA prior to the start of the mosaic but remained stationary at the pre-commanded PRA of -167.6 degrees. The scan platform did not move until about 10 mf into the mosaic and then slewed at the commanded slew rate, causing an effective time-offset in the mosaic of about 30 mfs. Fortunately the slew crossed IDA and NIMS was able to return some useful data for this specific observation. Unfortunately, due to 30 mf time-offset in execution, the NIMS Team wasted many DMS-MROs in locating the mfs when NIMS 'saw' IDA. Page 6-14 Figure 4 illustrates the scan platform behavior in a larger mosaic towards the end of the Fly-By (IDUNIDACHM01) where the scan platform deviated from the planned motion but not too greatly. Here the smooth continuous line is the planned mosaic and the wavy dis-continuous line is the observed mosaic. Scan platform RA (PRA) is plotted versus scan platform DEC (PDEC). In the observed mosaic the scan platform seems to have built up an error and then corrected to where it should be in the planned mosaic. The number 1 in the figure shows where the scan platform jumped abruptly in time executing one of these corrections. This jump in scan platform PRA was evident in the NIMS data as NIMS was observing IDA at the time, and made it impossible for the NIMS Team to register the NIMS spectra on IDA. With the spacecraft in Cruise Mode, the scan platform cone controller (SAS) seems to have been slow to respond to cone slew commands typically used in CSMOS mosaics. The deviation of the cone slew from planned is not uniform for all CSMOS mosaics. Sometimes the slew would cross IDA before the end of the slew and NIMS would 'see' IDA, but at a time much later than that predicted. Unfortunately there was little support from the AACS Team in helping to understand the erratic behavior of the scan platform in Cruise Mode in time to come up with a plan to return as much NIMS observations of IDA as possible. The only consolation received was the statement that "Cruise Mode was not meant for taking Science Data." Pages 6-15 to 6-18 The figures of pages 6-15 to 6-18 are in file nimsgdi.pdf.