Available in PDS4 Format CERTIFIED










    Gravity








    Gravitational variations exerted on the spacecraft as it orbits the planet modify the orbit. This is reflected in subtle deviations in the Doppler signal relative what would be observed if the spacecraft followed the computed orbit. These deviations are utilized to constrain models of the interior mass distribution and structure. (Note: The intensity of the core implies a less dense and possibly less well-defined core.)
    Introduction

    Instrument Description
    The Juno mission has the overall goal of answering the outstanding questions about Jupiter's origin and structure. This is a radio science experiment that uses the telecommunications system for sending data back to the deep space net. It will utilize X and Ka band transponders on board the spacecraft and low gain antennae (LGAs) to provide Doppler shifts derived from tracking data. Coherent Ka-band uplink/downlink is available when the spacecraft is being tracked by the Deep Space Network's DSS-25 in Goldstone, CA because it is the only station in the network with a Ka-band transmitter.

    Asmar, S.W, et al., (2017) The Juno Gravity Science Instrument, Space Sci Rev (2017) 213:205–218, DOI 10.1007/s11214-017-0428-7

    Measurement Objectives
    The primary objective of the Gravity Science Experiment is to determine the internal structure of Jupiter by mapping its gravity field from polar orbit. To provide the necessary data the Gravity Science Experiment utilizes the X and Ka-band transponders on-board the Juno spacecraft and Doppler tracking equipment at the Deep Space Network.

    Early Results
    By representing the gravity field derived from variations in the Doppler shifts with a series of harmonics, it has been shown that Jupiter’s gravity field is not symmetrical about the equator, reflecting the pattern of cloud top zonal winds. Fitting the non-zero odd gravitational harmonics J3, J5, J7 and J9 reveals that the winds extend to depths of 3,000 km, about a 20th of the planets radius involving about 1% of the total mass. Fitting the even gravitational harmonics J4, J6, J8 and J10 to constrain interior models indicates the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere. This analysis will be refined as Doppler data is accumulated.

    Iess, L., et al., (2018) Measurement of Jupiter’s asymmetric gravity field, Nature, 555:220-222

    Kaspi, Y., et al., (2018) Jupiter’s atmospheric jet streams extend thousands of kilometres deep, Nature, 555:223-226

    Guillot, T. et al., (2018) A suppression of differential rotation in Jupiter’s deep interior, Nature, 555: 227-230.


    Cruise and Earth Flyby Data and PDS3 Jupiter Data through perijove 2 are now available (Note: data were not acquired during Jupiter Insertion on July 5, 2016 (perijove 0).


    Useful Mission Documents

    Jupiter Data

    The Jupiter data consists of 2 main components: primary data files and ancillary files that cover various timespans and utilize different formats. The primary data files are TNF, ODF and RSR. These are supported by cumulative ancillary datasets (AMC, EOP, ION, SFF, TRO, and WEA).

    The primary data files contain:

    • TNF – Tracking and Navigation Files contain the primary output of the closed-loop receiver. It is a time series of properties of the uplinked radio signal which contains everything an antenna did for its ~10 hour track. The Juno information includes a range of operating modes, however non-Juno information may be included. Within the TNF files about 20 record types are defined, each designed for a particular audience, although it is frequently the case that users need more than one record type. The emphasis of the data is on phase of the transmitted and received signals. (See TNF SIS for detailed description of the records and fields).


    • ODF - Orbit Data Files (available through Orbit 14) contain the minimally processed output of the closed-loop receiver. It contains the most important information needed by spacecraft investigators, and investigators interested in determining gravity fields. See https://pds.nasa.gov/ds-view/pds/viewProfile.jsp?dsid=JUNO-J-RSS-1-OCRU-V1.0. The files are a time series of properties of the downlinked radio signal, recorded with standard equipment. The data set includes two types of files: those spanning ~50 day files and those spanning ~ 0.5 days on either side of perijove


    • RSR - Radio Science Receiver Files contain a time series of properties of the downlinked radio signal. During Perijove times, the downlinked radio signal is recorded with specialized equipment such as the Wideband VLBI Science Receiver. Independent data files spanning the same time interval are available for different combinations of frequencies and antennas.


    The time spans of TNF, ODF, RSR do not precisely overlap. The DSN is uplinking and downlinking near-continuously to dozens of missions. It's basically an instrument that is simultaneously flying on every spacecraft NASA has, plus most European ones. Changes in uplink signal happen all the time; thus, breaking an ~10-hour block into a defined series of observations and individual files is not done.

    The ancillary data files include:

    • EOP – Earth Orientation Parameters files contain the orientation and time transformation for Earth’s orientation in space, a detailed description of time-varying rotation state of Earth (varies seasonally). These are cumulative files where the last 3 last three months in every file is a prediction, so those values will be superseded as soon as measured values become available, thus the last file supersedes the others.


    • AMC – Advanced media calibration files contain calibration data collected from the Advanced Water Vapor Radiometer (AWVR) at Goldstone The Ka-band signal is very sensitive to weather at the ground station. The DSN has a specialized weather station at DSS-25, the only antenna capable of Ka-band uplink. This file contains information about those conditions. For redundancy there are 2 older identical radiometers ( files named *_01_* come from AWVR1. Ones named *_02_* come from AWVR2). See Asmar et al 2017 "Juno Gravity Science Instrument" https://link.springer.com/article/10.1007/s11214-017-0428-7.


    • ION – Information about the Ionospheric conditions at the DSN stations, which affects radio signals. These files contain historical and predicted Earth ionosphere conditions. They are based on an empirical model of Earth ionosphere line-of-sight total electron content for pointing of each DSN antenna. There is generally a new ION file and a new TRO file (see below) every month. As long as these are collected and archived, the coverage will be continuous. Note, however, that a file released in the middle of its own month will have predictions to fill out the month. Generally, you should wait until the middle of a month to collect the ION or TRO files for the previous months, which will be based on measurements.

    • TRO – Information about tropospheric conditions at the DSN stations, which affects radio signals. These files contain historical and predicted Earth troposphere conditions at the DSN stations, which affect radio signals.


    • SFF – Small Forces file contain the maneuver history of the spacecraft. They are cumulative files with newer files replacing the older ones. They are refined with time (see the SFS SIS)

    • WEA – DSN weather files contain the weather conditions at three tracking stations. These are accumulated so that the last file of the year contains all the information.


    • Raw Data- Directory containing the EDR data file
      Archive Structure
      Data Set Description (pdf)
      Documents - Directory containing the Document Collection.
      Data Files
      Ancillary Data
      Index

      Selecting Data



      A typical user will define a start and stop time and retrieve all files of a given type. An exception to this involves the cumulative files (ie. EOP, SFF, WEA). Here the user wants the file with the latest end date of those that satisfy the query. Alternatively, the user may submit a list of URN values derived from the data or ancillary indices to retrieve the desired data.

      The following tables are provided to allow the user to scope out the data:

      Physical Parameters for Juno's Perijove and Near Equator Crossing and Reference to the Red Spot (csv)
      Physical Parameters for Juno's North and South Pole Passages (csv)
      Physical Parameters for Juno's Apojove and Far Equatorial Crossings (csv)



      Geometry Files - Each table contains geometry data for a time interval of +/-5 hours of perijove in 10 minute intervals.

      Jupiter Data This file summarizes the contents of the raw data archive.

      These indices summarize the contents of the raw data and Ancillary archives.

      Selecting Data at the file level

      Cruise and Earth Flyby Data

      Raw Data
      Index
      Introduction
      Data Files
      Ancillary Data
      Software Interface Specification Document (SIS)- Instrument and data structures description index


      Raw Data - Directory containing the EDR data files
      These indices summarize the contents of the raw data and Ancillary archives.
      Data Index (TNF, RSR, ODF) TBD
      Ancillary Index (AMC, EOP, ION, SFF, TRO, WEA) TBD

      Selecting Data at the file level [TBD]

      Citing Data Sets for Publications
      Jupiter Raw Data CITATION DESC = BUCCINO, D.R., Juno Jupiter Gravity Science Raw Data Set V1.0, JUNO-J-RSS-1-JUGR-V1.0, NASA Planetary Data System, 2016.

      Cruise Raw Data CITATION_DESC = BUCCINO, D.R., Juno Gravity Science Outer Cruise Raw Data Set V1.0,JUNO-J-RSS-1-OCRU-V1.0,NASA Planetary Data System, 2016

      Bibliography - A listing of team members to facilitate literature searches


      Spice - Archived Juno SPICE ancillary data providing observation geometry (positions, orientations, instrument pointing, time conversions, etc.) are available from the PDS NAIF Node.