NSSDC Archives SAMPEX Data

Volume 10, Numbers 3 & 4, December 1994
by Sardi Parthasarathy

The Solar Anomalous Magnetospheric Particles Explorer (SAMPEX) is the first of the Small Explorers (SMEX) spacecraft series. In July 1992, it was launched into a near-polar orbit with four instruments - a low energy ion composition analyzer (LEICA), a heavy ion large telescope (HILT), a mass spectrometer telescope (MAST), and a proton/electron telescope (PET) - that together provide overlapping fluxes of cosmic rays in the energy range of about 1-400 MeV/nucleon for all elements between hydrogen and iron, with good isotopic resolution.

SAMPEX investigators have been able to determine the atomic charge composition of a number of elements through rigidity cut-off calculations involving model magnetic fields. (Cosmic rays are known to contain an "anomalous" excess in C-N-O-Ne fluxes in a mildly ionized state.) PET measures relativistic electrons also in the 1-30 MeV range, which have important effects on the mesospheric/stratospheric chemical composition. All data acquisition and processing are coordinated through the Project Office at the University of Maryland; the Project Scientist is Glen Mason.

By early 1995, NSSDC expects to disseminate the 30-sec averages of count rates and fluxes from many mass/energy channels (2.1 GB/year) and similar data averaged over the polarcap during each pass (15 MB/year). The first installment will cover July 1992–July 1993. These are written at the project office in self-documenting SFDU/CDF format. They will be available on NSSDC's nearline NDADS mass store system for downlinking either in CDF format or as a generically transformed ASCII version. For redundancy, the original ASCII version of the data (5.7 GB/year) that formed the input to the SFDU/CDF version also will be archived at NSSDC.

NSSDC has been archiving the high-resolution level-1 data (Master Data File) in the Caltech-created Tennis format, provided by the project office on rewritable optical disks, as one file per day and about 10 days per disk. A library of Tennis routines (VMS) and the first version of a data description report have also been received. However, distribution of the disks will be delayed until NSSDC finishes reviewing the disks for completeness and makes the accessing software and user guide as easy to use and understand as possible. For the interim, the project office at the University of Maryland will support reasonable access requests to this data level.

For more information about the status of SAMPEX data at the NSSDC, please contact the author via Internet at sardi@nssdca.gsfc.nasa.gov.

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Author:Miranda Beall
Curators: Erin Gardner and Miranda Beall
Responsible Official: Dr. Joseph H. King, Code 633
Last Revised: 21 Nov 1996 [EDG]