Twelve Instruments, One Goal Archive Usable Science Data

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Twelve Instruments, One GoalArchive Usable
Science Data

• Diane Conner, Jet Propulsion Laboratory,
• California Institute of Technology
• Reta Beebe, New Mexico State University

Cassini Mission to Saturn
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Cassini Tour Highlights
Cassini will spend 4 years orbiting the Saturn
system. During that time, the spacecraft will
make 75 orbits about the planet and 45 flybys of
Titan.
Some of the exciting events early in the Saturn
tour include Phoebe encounter - 11 June 2004
(closest approach is 2,000 km) Saturn Orbit
Insertion - 1 July 2004 Huygens Probe Release -
25 December 2004 Huygens Probe Mission -
14 January 2005 http//saturn.jpl.nasa.gov
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About the PDS

• Cassini is archiving science data with the
  Planetary Data System (PDS)
• http//pds.jpl.nasa.gov
• The PDS is responsible for the preservation and
  distribution of science data from NASAs
  planetary missions.
• Composed of eight specialized teams, called
  "nodes that have expertise in specific science
  disciplines.

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Science Targets
Cassinis 5 groups of science objectives at
Saturn are
Saturn - the planet and its atmosphere
Magnetosphere
Saturns extensive Rings
Icy Satellites
Titan - and its atmosphere
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Saturn System
The order of the rings and moons, starting with
the closest to Saturn, is Saturn Epimetheus
Titan D-Ring Janus Hyperion C-Ring G-Ring
Iapetus B-Ring Mimas Phoebe Cassini
Division E-Ring New Discoveries A-Ring Ence
ladus Encke Division Tethys Pan Telesto Atlas
Calypso Prometheus Dione Pandora Helene F
-Ring Rhea
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Archiving Goals

• Develop a cohesive and useful science data
  archive from Cassinis 12 instruments.
• Sustain a Saturn data analysis program.
• Saturn and Jupiter data comparisons from missions
  such as Voyager, Galileo, and Jupiter Icy Moons
  Orbiter (JIMO)
• Provide a resource for future mission planning.

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Lessons Learned from Galileo

• Lessons learned from the Galileo Mission to
  Jupiter have driven the Cassini archive design
• Plan early in mission.
• Make archive products part of the processing
  pipeline.
• Build a mechanism for tracking archive progress.

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Challenges

• Distributed Operations
• Teams are responsible for instrument operations
  and archiving.
• Collaborative science
• Make datasets compatible
• Large data sets (Over 10 TB for Cassini) .
• Validate data for science content and format.
• Distribute data

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Distributed Environment

• Twelve instruments operated by teams around the
  world.

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Development Timeline
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Archive Design

• Describe each teams archive plan in an interface
  specification.
• Output archive products from data processing
  pipelines.
• Include validation methods for science content
  and format.
• Document calibration methods/algorithms.
• Represent time consistently throughout the
  archive.
• Use consistent coordinate systems in data
  products and documentation.
• Hold peer reviews of plans and sample products.
• Verify data products can be used without
  specialized software.
• Implement a tracking and reporting mechanism.

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Ingredients of a Useable Archive

• Archive Peer Design Reviews identified areas that
  required work.
• DOCUMENTATION of the mission, spacecraft,
  instruments and datasets,
• STANDARDIZATION of data formats - to ensure
  long-term access, data formats should be as
  simple as possible,
• PRESERVATION of navigation and calibration,
• VALIDATION of data products for format and
  content,
• OPTIMIZATION for correlative studies

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Documentation

• Mission Events
• Science objectives
• Capabilities of Spacecraft and Instrument
• Interface and Specifications that describe data
  products

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Standardization

• Data formats
• Simple ASCII time series or tables preferred for
  non-imaging instrument data.
• Consistent time representation
• File and directory names
• Keywords
• Internal to data
• Coordinate systems
• Planetocentric or planetographic - use
  international standard IAU
• East or west longitude - be consistent

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Preservation

• Calibration algorithms as a function of time
• PDS Navigation Ancillary Information Facility
  SPICE formatted data files
• Spacecraft Pointing
• Trajectory of spacecraft, Saturn and satellites
• Instrument boresights and field of view
  descriptions
• Primary target in observation
• Spacecraft and instrument configurations

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Validation

• Design review of data formats and volume contents
• Identify areas that need to most work early.
• Peer review of sample volume
• Put data formats, documentation, and software to
  the test.
• Science analysis
• Archive products are output from processing
  pipeline and sent to science teams.

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Optimization

• Correlative studies within scientific disciplines
• Atmospheres
• Surfaces
• Physics
• Search parameters
• Temporal spatial resolution
• Similar formats content
• Coordinate system
• Time representation
• ASCII tables

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Summary

• Review plans, sample data, and documentation
• Make archiving a high priority - integrate into
  ground system
• Design the archive as a system - it should be
  possible to use products from various instruments
  together
• Pay attention to
• DOCUMENTATION the mission, spacecraft,
  instruments and dataset
• STANDARDIZATION data formats to ensure long-term
  access
• PRESERVATION navigation and calibration
• VALIDATION data products for format and content
• OPTIMIZATION for correlative studies

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Cassini Lessons Learned

• More lessons learned from Cassini
• Work with PDS as early as possible, preferably at
  the proposal stage
• proposers need to know how to make a usable
  archive
• Instruments should be designed to produce data
  that can be used across experiments
• Involve the science community in designing a
  cohesive archive where data products can be used
  together.

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Saturn

• Latest Image of Saturn

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