The Planetary Data System (PDS) is a distributed data system that NASA uses to archive data collected by Solar System robotic missions and ground-based support data associated with those missions. The PDS is managed by NASA Headquarters' Planetary Sciences Division. The PDS is an active archive that makes available well documented, peer reviewed data to the research community. The archive and data within are held to high quality standards established by the PDS. The PDS is divided into a number of science discipline "nodes" which are individually curated by planetary scientists. The Solar System Exploration Data Services Office at the Goddard Space Flight Center handles PDS Project Management.
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PDS archiving philosophy
The main objective of the PDS is to maintain a planetary data archive that will withstand the test of time such that future generations of scientists can access, understand and use preexisting planetary data. The PDS tries to ensure compatibility of the archive by adhering to strict standards of storage media, archiving formats, and required documentation.
Storage media
One critical component of the PDS archive is the storage media. The data must be stored effectively and efficiently with no degradation of the data over the archive's lifespan. Therefore, the physical media must have large capacity and must remain readable over many years. PDS is migrating toward electronic storage as its "standard" media.
Archiving formats
The format of the data is also important. In general, transparent, non-proprietary formats are best. When a proprietary format is submitted to the archive (such as a Microsoft Word document) an accompanying plain text file is also required. It is assumed that the scientists of the future will at least be able to make sense of regular ASCII bytes even if the proprietary software and support ceases to exist. PDS allows figures and illustrations to be included in the archive as individual images. PDS adheres to many other standards including, but not limited to, special directory and file naming conventions and label requirements. Each file in the PDS archive is accompanied by a searchable label (attached or detached) that describes the file content.
Archiving documents
The archive must be complete and be able to stand alone. There is no guarantee that the people who originally worked with and submitted the data to the archive will be available in the future to field questions regarding the data, its calibration or the mission. Therefore, the archive must include good descriptive documentation of how the spacecraft and its instruments worked, how the data were collected and calibrated, and what the data mean. The quality of the documentation is examined during a mission independent PDS peer review.
Nodes
The PDS is composed of 8 nodes, 6 science discipline nodes and 2 support nodes. In addition, there are several subnodes and data nodes whose exact status tends to change over time.