Galileo Near Infrared Mapping Spectrometer Encounter Guides Ashley Gerard Davies, Frank Leader and James M. ("Myche") McAuley Table of Contents 1. Introduction to the NIMS Encounter Guides 2. Rationale behind the NIMS Encounter Guides 3. Creating PDFs of the Guides 3.1 Encounter Guides Naming Convention 4. The "Missing" Guides 4.1 The J0 - Jupiter Orbit Insertion Original Encounter Guide 4.2 The A34 Amalthea Encounter Guide 5. Types of NIMS products 6. Naming NIMS observations and products 7. References 1. Introduction to the NIMS Encounter Guides Through most of the Galileo mission (1989-2003), the Galileo Near Infrared Mapping Spectrometer (NIMS) (Carlson et al., 1992) observed Venus, Earth, the Moon, the asteroids Ida and Gaspra, the impact of fragments of comet Shoemaker-Levy 9 into Jupiter, and Jupiter and its satellites. Each planetary body encounter up to Galileo Jupiter Orbit Insertion in December 1995 and each subsequent orbit of Jupiter generated a NIMS Encounter Guide. Until recently, 37 NIMS Encounter Guides were accessible from Nodes within NASA's Planetary Data System (PDS). An additional, partial Guide for Orbit A34 was not previously delivered to the PDS as observational planning was terminated before completion and, subsequently, no NIMS data were obtained during orbit A34. Additionally, the original observation plan for Jupiter Orbital Insertion (go_0000- j0nimsgd.pdf, see Section 4.1 below) was replaced by the In-Flight Load (go_1104-j0nimsgd.pdf, see Section 4.2 below) and was similarly not available on the PDS. Both the A34 and JOI Encounter Guides have been included in this Collection and are described below. 2. Rationale behind the NIMS Encounter Guides The original aim of these Encounter Guides was to provide detailed information on the wide variety of NIMS observations and their calibrations. Typically, each Guide contains a contents list; an introduction to the orbit and an orbit overview; a summary of the NIMS science objectives, using tables, spreadsheets and timelines; and the observations collected. Later chapters include a comprehensive sequence summary and observation table; detailed observation plots; and the NIMS wavelength edit tables used during the orbit or encounter. These volumes represent the sum of the meticulous, detailed planning that went into observations that revolutionized our understanding of the Jovian system. As such, these Guides are of great historical interest and value. The Encounter Guides also detail observations planned but not executed or returned. Additional value is provided by enabling an independent check on NIMS products currently on the PDS, allowing verification of the naming of NIMS product masks and labels on the PDS, allowing identification and resolution of discrepancies. Table 1 below shows the names of the guide files, the relevant orbit or encounter (the exception is the guide to the In Flight Load), and the targets imaged during that encounter. Table 1 NIMS Encounter Guide Orbit Targets go_0000-j0nimsgd.pdf J0 Europa*, Io*, Jupiter* go_1101-nimsgd.pdf Venus go_1102-nimsgd.pdf Earth, Moon, Venus go_1103-nimsgd.pdf Earth, Moon go_1104-g1nimsgd.pdf G1 Callisto, Europa, Io, Ganymede, Jupiter go_1104-ganimsgd.pdf Gaspra go_1104-idnimsgd.pdf Ida, Dactyl go_1104-j0nimsgd.pdf [In-Flight Load] go_1104-slnimsgd.pdf Jupiter go_1105-g2nimsgd.pdf G2 Callisto, Europa, Ganymede, Io, Jupiter go_1106-c3nimsgd.pdf C3 Callisto, Europa, Io, Jupiter, Rings go_1107-e4nimsgd.pdf E4 Callisto, Europa, Ganymede, Io, Jupiter, Rings go_1108-e6nimsgd.pdf E6 Callisto, Europa, Ganymede, Io, Jupiter go_1109-g7nimsgd.pdf G7 Callisto, Europa, Ganymede, Io, Jupiter go_1110-g8nimsgd.pdf G8 Callisto, Europa, Ganymede, Io, Jupiter go_1111-c9nimsgd.pdf C9 Callisto, Europa, Ganymede, Io, Jupiter, Rings go_1112-c9nimsgd.pdf C9 Callisto, Europa, Ganymede, Io, Jupiter, Rings go_1113-10nimsgd.pdf C10 Adrastea, Amalthea, Callisto, Europa, Io, Jupiter, Metis go_1114-11nimsgd.pdf E11 Europa, Io, Jupiter go_1115-12nimsgd.pdf E12 Europa, Io, Jupiter go_1115-14nimsgd.pdf E14 Callisto, Europa, Io, Jupiter go_1116-15nimsgd.pdf E15 Europa, Io, Jupiter go_1116-16nimsgd.pdf E16 Europa***, Ganymede***, Io, Jupiter** go_1117-17nimsgd.pdf E17 Europa, Jupiter go_1117-18nimsgd.pdf E18 Europa***, Io***, Jupiter** go_1117-19nimsgd.pdf E19 Europa, Jupiter go_1118-20nimsgd.pdf C20 Callisto, Europa, Io, Jupiter go_1118-21nimsgd.pdf C21 Io, Jupiter go_1118-22nimsgd.pdf C22 Europa***, Io, Jupiter go_1118-24nimsgd.pdf I24 Io go_1118-25nimsgd.pdf I25 Europa, Io** go_1119-26nimsgd.pdf E26 Io go_1119-27nimsgd.pdf I27 Io go_1119-28nimsgd.pdf G28 Europa, Ganymede, Jupiter go_1119-29nimsgd.pdf G29 Callisto, Europa, Io, Ganymede, Jupiter go_1120-30nimsgd.pdf C30 Callisto**, Europa***, Io, Jupiter** go_1120-31nimsgd.pdf I31 Io, Jupiter go_1120-32nimsgd.pdf I32 Io, Jupiter go_1120-33nimsgd.pdf I33 Io***, Jupiter go_9999-34nimsgd.pdf A34 Amalthea*, Io* Notes: * planning purposes only ** some observations not returned *** no observations returned The C9 guide appears on two PDS volumes, hence the two copies. 3. Creating PDFs of the Guides Until now, the 37 NIMS Encounter Guides existed on the PDS only in postscript format, with each Guide chapter in an individual postscript file. For each of these Guides, the postscript files have now been concatenated into a single file which has then been converted into PDF/A format to afford easier access and use. In PDF/A format, most Guides are fully searchable with the caveat that some early Guides incorporated scanned images and pages. For two guides, go_1105_g2nimsgd.pdf and go_1120-31nimsgd.pdf, single line stokes were removed from two pages (page 254 in go_1105_g2nimsgd.pdf and page 155 in go_1120-31nimsgd.pdf) to make each file pdf-A compliant. The removal of these strokes is not discernable in the final products. Further, in producing PDF/A compliant files, three additional guides contain pages that are not searchable. These are: go_1104-ganimsgd.pdf (pages 71, 85, 91, 95, 107, 113 and 115); go_1118-24nimsgd.pdf (pages 146 and 147); and go_1118-25nimsgd.pdf (page 155). The partial Encounter Guide for orbit A34 is not searchable as it was not available in electronic format but was created from scans of a paper copy of the Guide. Finally, the inclusion of the Encounter Guide for Jupiter Orbit Insertion, previously not available on the PDS, brings the number of Encounter Guides in the Collection to 39. This set of Guides includes two version of the C9 Guide. 3.1 Encounter Guides Naming Convention The Encounter Guides, having all been derived from the originally archived PostScript files, are named as follows: go_XXXX-YYnimsgd.pdf where: - go represents the Galileo Orbiter - XXXX is the (anachronistic) archive volume identifier containing the original PostScript documents. This identifier was used as a unique differentiator as some of the original PostScript documents had equivalent names on different volumes. We use this volume identifier in the PDF filenames to preserve linkage to the original Guide postscript files, with the following two exceptions: - 0000 is used as the volume identifier for the previously- unavailable Jupiter Orbit Insertion (JOI) Guide (see 4.1 below) - 9999 is used as the volume identifier for the previously- unavailable, partial A34 orbit Encounter Guide (see 4.2 below) - YY, where present, is the two-character designator of the particular target/orbit/encounter. See Section 6 below for more details. This designator is not used for Guides go_1101- nimsgd.pdf, go_1102-nimsgd.pdf and go_1103-nimsgd.pdf. 4. The "Missing" Guides Two Encounter Guides in this Collection are for planned observations that were never obtained, but which are included for completeness. Neither have been available on the PDS before now. The first of these two Guides contains observations originally planned during Galileo Jupiter orbit insertion in December 1995. The second contains preliminary plans for the A34 orbit in November 2002. 4.1 The J0 Jupiter Orbit Insertion (JOI) Guide Guide go_0000-j0nimsgd.pdf is the NIMS Guide to the J0 Orbit and described the original observation plan of Jupiter and satellites during Galileo Jupiter orbit insertion (JOI), which took place on 7 December 1995. This observation plan was replaced with the In-Flight Load (IFL) described in Guide go_1104-j0nimsgd.pdf. The J0 Guide includes details of what would have been high spatial resolution observations of active volcanic centers obtained during a close flyby of Io. The pdf was created from postscript files preserved by Frank Leader (JPL) and, with this archive delivery, is made available on the PDS for the first time. 4.2 The A34 Amalthea Encounter Guide Guide go_9999-34nimsgd.pdf contains preliminary planning of operations for the A34 Orbit, named after the Galileo encounter with Amalthea on 5 November 2002. Galileo flew within 250 km of Amalthea. The Guide is incomplete as more detailed observation planning ended when the decision was made not to return any imaging data from the Encounter. This Guide nevertheless serves as a historical record from the final days of the Galileo mission. To our knowledge, no postscript files exist for this document. The Guide was created from the sole remaining paper copy of the A34 Encounter Guide, and, as such, includes pencil and pen annotations on some pages and on some figures. As the pages were scanned, the PDF of the Guide is not searchable. 5. Types of NIMS products It is informative to describe NIMS product types, characteristics, and processing steps. The following description draws heavily on material in Davies (2022). NIMS observations consist of a three-dimensional data cube, with the x and y dimensions representing sample and line, and the z direction representing wavelength. Behind the cube are additional layers (backplanes) of information for each pixel, including latitude, longitude, emission angle, and distance to target. NIMS data were returned from the Galileo spacecraft and consolidated into NIMS Experiment Data Record (EDR) Files containing raw data numbers (DNs). The EDRs comprised the base data set from which spectral image products were created. There were a number of different radiance and reflectance products derived from each NIMS EDR. NIMS radiance data products are in either "tube" or "cube" format. These data are in radiance units of µW cm-2 str-1 µm-1. Tubes and cubes are generated independently from the EDR data. Tube products contain raw radiance values and have a 50% swath overlap in the instrument mirror-sweep direction. A tube may contain multiple observations of the target. NIMS cube products are processed to remove the 50% swath overlap seen in the tube products. Cube products also combine, where present, multiple appearances of a target within a single observation into a single view of the target, and are re-navigated to improve backplane location information. On rare occasions, a pair of EDRs were combined into a single cube product. There are therefore more NIMS cubes than there are tubes. 6. Notes on naming NIMS observations and products NIMS Jovian system observations have both a name and an identifer. The observation name declaims the orbit (e.g., "G2" for orbit 2, with the prime target being Ganymede; after orbit C9 this orbit designation became a two-digit number), target (e.g., "I" for Io), instrument ("N" for NIMS), a six-letter designation broadly reflecting the process to be observed (e.g., "CHEMIS"), and a version number (e.g., "01A"), yielding the observation name "G2INCHEMIS01A." The NIMS product identifier for this observation shows the orbit ("g2"), target ("i"), a three-digit sequence number ("006"), and the level of processing. Regarding the latter, a radiance tube identifier ends with "tr" (g2i006tr). A radiance cube identifier ends with "cr" (g2i006cr). Reflectance product identifiers end with either "ti" if a tube product, or "ci" if a cube product. The PDS Image Atlas Website initially presents NIMS products by observation identifier, whereas the NIMS Encounter Guides refer to observations by their observation name. However, the PDS Image Atlas webpage allows a user to add additional sort fields, allowing products to be sorted by observation name. Additionally, the website allows download of a comma-separated variable file with user-selected observation information and metadata, one way to reconcile observation names and product identifiers. 7. References Carlson R. W., Weissman P. R., Smythe W. D. and Mahoney J. C. (1992) Near-Infrared Mapping Spectrometer Experiment on Galileo, Space Science Reviews, In: Russell C.T. (eds) The Galileo Mission. Springer, Dordrecht. doi.org/10.1007/978-94-011-2512-3_18. Davies, A. G. (2022) Cautionary Analysis of Spectral Radiance from Io's Active Volcanoes Derived from Galileo Near-Infrared Mapping Spectrometer Data, Astronomical Journal, 16, 2, doi.org/10.3847/1538-3881/ac3012.