Data Set Overview

This data set contains data that is useful for determining the major and minor elemental composition of Martian soils, rocks, and other geological materials that the rover encountered. The EDR data products are raw uncalibrated data reconstructed from telemetry data products and formatted according to the APXS EDR Software Interface Specification. Meta-data acquired from the telemetry data headers are used to populate the PDS label. There will not be multiple versions of an APXS EDR.

Processing

The Committee On Data Management and Computation (CODMAC) data level numbering system is used to describe the processing level of the EDR data product. APXS EDR data products are considered CODMAC Level 2 or Edited Data (equivalent to NASA level 0) products. The EDR data files are generated from Level 1 or Raw Data, which are the telemetry packets within the project specific Standard Formatted Data Unit (SFDU) record.

The APXS EDR data products were generated by the MIPL (Multimission Image Processing Laboratory) at JPL under the Operations Product Generation Subsystem using the telemetry processing software, mertelemproc. If telemetry packets are missing during the initial downlink from the rover memory, partial data sets will be created and the missing data will be filled with (zeroes). The data will be reprocessed after all data are received and the original version will be overwritten.

The APXS memory is maintained by a battery, and in theory, retransmits from the APXS memory could be commanded. In this instance, a new data product will be created, because there will likely be subtle and potentially useful changes in the data when a retransmit from the APXS memory is commanded.

Data

Each APXS EDR consists of two files. The first file is an ASCII formatted detached PDS label. The second file is a binary data file. The APXS EDR data file is a copy of what was in the APXS memory buffer. That is, the EDR consists of unprocessed experiment data stored in binary format. The APXS EDR contains energy spectra in units of counts and temperature values. Temperatures are derived from the two temperature sensors. There are two types of APXS spectra in each measurement: one x-ray, and two alpha spectra. The energy scale is divided into discrete channels with 256 channels for the alpha spectra and 512 channels for the x-ray spectra. The instrument holds data for the twelve most recent measurements in memory. When a new measurement begins, the oldest one is discarded. Each spectrum has a unique identifier. There are also 2 Kbytes at the end of the APXS EDR data file that are transferred from the instrument's internal RAM. This 2 Kbyte section of RAM is used for instrument engineering data.

Software

A reader program, called apxs2asc will be available to convert the APXS EDR binary format data into ASCII format. This reader will be archived with the EDR data products. The ASCII format data can be imported into spread sheet and plotting programs.

PDS labeled tables can be viewed with the program NASAView, developed by the PDS. NASAView is available in versions that run on SUN/SOLARIS, WINDOWS, and LINUX operating systems. NASAView can be obtained from the PDS web site.

Media/Format

The data set will be initially delivered and kept online. Upon Mission completion, the APXS EDRs will be delivered to PDS on DVD as part of the complete MER EDR data set.

Data Set Overview

This data set contains data that is useful for determining the major and minor elemental composition of Martian soils, rocks, and other geological materials that the rover encountered.

Processing

The Committee On Data Management and Computation (CODMAC) data level numbering system is used to describe the processing level of the EDR data product. APXS x-ray data products are considered CODMAC Level 2 or Edited Data (equivalent to NASA level 0) products.

The APXS x-ray data products were generated by the Max Planck Institute for Chemistry, Mainz, Germany. The x-ray spectra were extracted from the binary EDR files and converted to ASCII. Any spectra that remained in the instrument's memory from previous analyses were removed from the data product.

Data

Each APXS oxide abundance data file is a table. Columns are variable length and are delimited with commas. Each row is terminated with a carriage return and line feed character.

Data Set Overview

This archive contains oxide abundance data derived from X-ray analyses of the MER APXS (Alpha Particle X-Ray Spectrometer) Reduced Data Record (RDR) products. A description of the data analysis procedure and interpretation of the results can be found in Gellert, R., et al. (2006), Alpha Particle X-Ray Spectrometer (APXS): Results from Gusev crater and calibration report, J. Geophys. Res., 111, E02S05, doi:10.1029/2005JE002555 [GELLERTETAL2006], and in Ming, D.W. et al. (2008), Results of the Alpha Particle X-Ray Spectrometer from Cumberland Ridge to Home Plate, J. Geophys. Res., 113, E12S39, doi:10.1029/2008JE003195 [MINGETAL2008].

Processing

The Committee On Data Management and Computation (CODMAC) data level numbering system is used to describe the processing level of the oxide abundance data product. The products are considered CODMAC Level 5, Derived Data equivalent to NASA level 3.

The APXS oxide abundance data products were generated by the MER APXS Team. A nonlinear least squares algorithm was used to derive peak areas of characteristic element lines from APXS summed spectra. Peak areas were converted into element or oxide concentration using instrument calibration tables. Details of data processing and calibration are given in Gellert et al. 2006. The data were derived from APXS reduced data records (RDRs) from both rovers.

Data

Each APXS oxide abundance data file is a table. Columns are variable length and are delimited with commas. Each row is terminated with a carriage return and line feed character.