Introduction to the PSA
The need for ESA to establish a science data archive for planetary exploration
missions stemmed from the approval of Horizon 2000, ESA's first long term
progamme in 1983/84. As the first cornerstone mission approved within Horizon
2000, Rosetta was the starting point for the definition of this archive, with
the view that it should become mandatory for all future ESA planetary missions.
It is the aim of the Agency to provide a single interface that will deliver
reviewed and validated data products from all of ESA's planetary missions to
the scientific community.
It was decided at an early stage that the Planetary Science Archive would use
NASA's Planetary Data System (PDS) standard as a baseline for defining the
structure and format of the data sets. At the time of archive definition, the
PDS was already a well known and understood data standard within the planetary
science community. Use of this standard also ensures cross-compatibility with
all other PDS compliant data.
Learn more about PDS.
Services
PSA support to the Data Producers
The PSA provides expert consultancy to the individual data producers throughout
the archiving process as well as support for many archiving related activities:
- Data Archive Workshops (organised on request)
- These are workshops supported by instrument teams to provide expert advice on the
use of their data. See the
Data Workshops page for further details.
- SPICE Workshops (organised on request)
- Usually one per year, supporting the use of SPICE and ancillary data with archived instrument
data. See the
Ancillary Data page for further details.
- Individual Archive Consultancy
- PDS Standard Support
- Coordination of Mission Data Archive Working Groups (DAWG)
- Coordination and support of mission geometrical parameter information
- Co-ordination and chair for Peer Reviews
- Dataset support tools (see Tools page)
- Dataset validation and ingestion
- The PSA Volume Verification Tool (PVV)
- Can verify the structure of the whole data set
- Can verify the content of the ODL language
- Can verify the references, catalogue structure, etc
- Database construction and maintenance
PSA support to the Data Users
The consumer can query the data products and data sets via the JAVA based user
interface supported on nearly all available computer platforms. Support is provided
to end users to cover all aspects of data retrieval and usage:
- PSA Scientific Advisory Group
- Users are invited to offer advice on ways to improve the services provided by the PSA
- Aim to meet once per year
- Help desk: if you have any queries about the PSA you can contact us directly.
- Data Query and Retrieval
- PDS Standard Support
- Co-ordination and chair for Peer Reviews
- Design, Production and Delivery of ancillary data
- SPICE conversion
- Software consultancy and support
- ESOC data long-term archive preparation
- Science planning information, long-term archive preparation
Summary of the archive process
The PSA provides expert consultancy to all of the data producers throughout
the archiving process. As soon as an instrument is selected, PSA begin working
with the instrument team to define a set of data products and data set structures
that will be suitable for ingestion into the long-term archive.
A Data Archive Working Group (DAWG) is established for each mission and meets regularly to
discuss archiving matters at the top level. In these meetings the data types, data structures
and the data set organisation are discussed and defined for each instrument. Many parameters
used within the archive are applicable to all instruments on a mission, and these 'mission-wide'
issues are agreed upon during the DAWG meetings as well.
All data providers are strongly encouraged to use the same data formats and data sets internally
as those that will be delivered to the PSA. This way, only one data pipeline is required,
converting from raw instrument telemetry through to archivable products. The development of
the data pipeline is closely monitored by the PSA through the DAWG meetings and individual
meetings and teleconferences. An 'Archive Scientist' is appointed for every mission to support
the development of the archives and provide immediate consultancy to all teams, ensuring that
the data sets being constructed are compliant to the PDS Standards required by the PSA, and that
all necessary data/information is provided for an end-user to manipulate the data.
Consultancy is also provided to support the instrument teams with their documentation. All teams
are required to include a number of documents in their data sets. Chief among these is
the Experiment to Archive Interface Control Document (EAICD), which can be found in the DOCUMENT
directory for all ESA planetary mission data sets. The EAICD provides a full description of the
data set(s) being archived by an instrument, including a summary of the data pipeline, the
structure of the data products, data sets and any calibration or geometry information provided.
This document should be the starting point for anybody when trying to understand a data set.
The aim is to have data pipelines and supporting documentation prepared before launch so that
a team can immediately begin delivering data without the need for considerable development
during the active mission phase. During the mission, data are delivered to the PSA at regular
pre-determined intervals. Typically deliveries are made every 3 to 6 months, although this depends
upon how active a mission is in collecting data (e.g. cruise phase deliveries may be more sporadic
if a spacecraft is not actively collecting science data for longer periods).
All data from ESA's planetary missions have a proprietary period, usually between 6 and 12 months.
During this time, the data are only available to instrument team members. At the close of the
proprietary period, the data are released and made available to any user via the PSA.
At the close of a mission's active operations, the archive will undergo a period of maintenance
during which updates from the Principal Investigator teams are accepted and supplementary data
sets can be added to the PSA for long-term archiving. This should be the closing phase of an
archive, preparing the data for long-term storage and ensuring that all data within the archive
will be useful and understandable in years to come without further significant updates.
Each phase of the archive process is controlled by a corresponding peer review, during which
external experts are asked to validate the data and documentation for their suitability for
long-term archiving. Typically, the review process follows the three major steps in archive
development:
- first review phase concentrating on the EAICD and the initial pipeline
- second review phase concentrating on the first data delivery
- third review phase reviewing the full archive at the end of a mission
