Help for Data Users
By following the links at
the left you will eventually come to a PDS archive
volume containing your data of interest. All PDS archive
volumes have a similar structure. Understanding this
structure will help you get the most from the data.
What You'll Find on a
PDS Archive Volume:
All files with extensions
.txt, .lbl, .cat, .tab, and
.asc are ASCII text files. Files with other
extensions are binary files that may not be viewable in
contains a file with a name ending in info.txt
that describes the contents of that directory.
aareadme.txt - An
introduction to the data volume. Read this first.
errata.txt - An
optional file containing notes and errata about the
voldesc.cat - A
short text file that serves as a PDS label for the
Don't overlook this
valuable source of information about the data set. These
files are copies of the PDS Catalog descriptions of the
data set, the instrument that collected the data, the
spacecraft, the mission, personnel involved in making
the archive, and a list of references to published
This directory contains
documentation such as the data product Software
Interface Specification that most missions are required
The file index.tab
(or a file with a similar name) lists every data product
on the archive volume, its directory and file name, and
other information that varies depending on the data set.
Its contents are described by the associated PDS label
index.lbl. If the data set is spread over more
than one volume, there will also be a cumulative index
table (cumindex.tab) that lists the data products
on all volumes created to date. See the last volume in
the set for the complete cumulative index.
The data products
themselves are under a directory that may be named
"data" or may have a data-set-specific name. There may
be more than one data directory. For instance, on some
archive volumes the data are organized by year under the
directories 2002, 2003, etc.
Every data product is
described by a PDS label. The label may either be
embedded (attached) at the beginning of the data file,
or in a separate file (detached) with the same name,
extension .lbl. PDS labels are ASCII text in a
keyword = value format that can be read both by humans
and by software. In some cases a data product is stored
in multiple files which are described by a single label.
The thing to remember is when you download a data file,
download the label too.
directories include Software, Calib
(calibration), Extras, Geometry, Browse,
and others. Read the info.txt file in each
directory for more information.
If you have questions about Geosciences
Node data sets:
One place to look for help is the
Frequently Asked Questions page.
If you don't see your question there, check the
to see if it's been discussed there. There are
forums for announcements, data users, data providers,
Analyst's Notebook users, and Orbital Data Explorer
users. You may post your question in one of the forums
(after signing up for a free account), or you may email