| DATA_SET_DESCRIPTION |
Modification History
====================
Version 1 data volumes include volumes MS000 through LS029, released
Dec 2008. These volumes contain MET data collected May 2008
through June 2008, sols 0-29.
Data Set Overview
=================
The Phoenix Mars Lander arrived at 68.2184N, 234.2487E on May 25, 2008.
The PHX METEOROLOGICAL EDR DATA product contains unprocessed values of
pressure and temperature data. Each product is approximately 24 hours
(LMST) in duration, and was collected continuously over the entire mission
at a data rate of 2 sec.
The Data are organized into 'High Resolution' (2 sec) and 'Low
Resolution' (512 sec). There are three temperature sensors
along the vertical 1.0 m MET Mast (250, 500 and 1000mm), a
reference Platinum Resistance Thermometer (PRT) at the base, and a
pressure sensor on the Lander Deck on the Payload Electronic
Box. [TAYLOR2008]
The collection of High Resolution Data is determined by the setting
of P & T threshold values ranging from setting the thresholds to
zero (constantly triggering, creating continuous 2 sec data) to
essentially infinity (never triggering, creating no 2 sec data).
Owing to favorable transmission bandwidth, the unit was operated over
the entire mission in triggered (2 sec) mode.
The Data is organized by a unique identifier (Token) is keeping with
the other Phoenix instruments. The token for the PT was nominally
set each sol, when the PT instrument stopped recording to allow
for transfer of data to the Lander (and hence telemetry to Earth).
The token is provided as a 4 byte hex value.
Parameters
==========
Each EDR file contains time as the MET Frame count since instrument
power on (1 count is 2 sec).
The MET P&T threshold was commanded each sol, to trigger constantly,
creating 2 sec data. The calibration constants used internally onboard
the unit were determined prior to launch, and outlined in the CCC report.
The pre-processed EDR temperature data for each of the three
thermocouples and the PRT were stored as a 16 bit value. For the
lower resolution 512 sec data the min, max and standard deviation
were also stored at 16 bit. All pressure values (avg, min, max, var)
are given as 32 bit values.
The temperature data is sent as a DN, which is converted in the MET
Ground Data Segment into values of Kelvin (EDR -> RDR), while the
pressure is send in units of PA.
The MET PT instruments were nominally operated 24 hours of each Martian
sol. Once each sol, the instrument was transitioned out of RECORD
to allow for transfer of data from MET flash to the Lander. Thus
there will nominally be a ~20 min gap each sol.
During surface operations the MET PT was operated continuously, with a
gap early in the mission (Sol 19/20) owing to a spacecraft event.
Smaller data gaps exist, from dropouts in telemetry, but these were often
recovered owing to use of the MET PT internal flash and data retransmits.
Processing
==========
The EDRs are essentially identical to the telemetry messages sent
from the MET-PT instrument to the Lander computer, converted to ASCII
and with the addition of a Lander timestamp (there is no onboard MET
clock, so the instrument relies on an internal Frame Count. Matching
of this frame count and the Lander clock are made using the MET GDS)
Commanded parameters, such as threshold values, are also added to the
EDR products.
Finally, the data were converted to PDS format, converting the
tab-delimited fields to fixed-width fields, and exchanging the
multiple packet headers for a single session header by the MET GDS.
Address: Cameron Dickinson
Dept. of Earth and Space Science Engineering
York University
4700 Keele St
Toronto, ON M3J 1P3
Phone: (416) 736-2100 X 23870
Email: cameron.dickinson@gmail.com
For science related questions about the data, please contact the
MET Instrument Science Team Lead:
Address: James Whiteway
Dept. of Earth and Space Science Engineering
York University
4700 Keele St
Toronto, ON M3J 1P3
Phone: (416) 736-2100 X 22310
Email: whiteway@yorku.ca
Data
====
All of the data in this data set are contained in ASCII tabular files
with detached PDS labels. Data is stored in a separate directory
relating to the sol in which the recording of data commenced (i.e.
data acquired from 003 10:00 local to 004 10:15 will be in the sol
3 directory)
Individual filenames are constructed as follows:
MS000EMH_00896227243_10CCM0.LBL
1: The first character will always be an 'M', representing MET
data.
2: The second character will be an 'S', signifying surface
data (versus 'C' for Cruise)
3-5: The next three characters provide the sol number of the data
file.
6-8: The next three characters describe the type of MET data,
EML - EDR MET LOW (Resolution)
EMH - EDR MET HIGH (Resolution)
RML - RDR MET LOW (Resolution)
RMH - RDR MET HIGH (Resolution)
RMC - RDR MET Corrected (Pressure Corrected Values)
RMA - RDR MET Ancillary (Pressure Sensor Temperatures)
9: Blank
10-20: SCLK - Spacecraft clock
21: Blank
22-25: Operations Token
26: Producer (M for MET Team)
27: Version
28: Period
29-31: Extension, LBL or TAB
The tabular files are formatted so that they may be read directly into
many database management systems (DBMS) or spreadsheet programs on
various computers. Each of the files contains two tables. The first
is the header table, and is only a single record in length. The
second table contains all of the data records for a session and varies
in length.
All fields in the tables are stored in columns of fixed width and are
right justified. The records are of fixed length; since the header
records are shorter than the data records, they have been padded with
blank spaces at the end of the record. The last two bytes of each
record contain the ASCII carriage return and line feed characters.
This allows the tables to be treated as fixed length record files on
computers that support this file type and as normal text files on
other computers.
The PDS labels are object-oriented. The object to which the labels
refer (the tables) is denoted by a statement of the form:
^object = location
in which the carat character ('^', also called a pointer in this
context) indicates that the object starts at the given location. For
an object located outside the label file (as in this case), the
location denotes the name of the file containing the object, along
with the starting record. For example:
^TABLE = 'MS013EML_00126907202_15C6M1.TAB'
indicates that the TABLE object is in the same directory as the
detached label file. (Records are counted starting at 1, not 0.)
The detached label files are stream format files, with a carriage
return (ASCII 13) and a line feed character (ASCII 10) at the end of
each record. This allows the files to be read by the MacOS, DOS,
UNIX, and VMS operating systems.
Software
========
The EDR/RDR tables can be displayed on UNIX, Macintosh,
and PC platforms as simple ASCII files, or using the PDS developed
program, NASAView. This software is freely available from the PDS
Central Node and may be obtained from their web site at
http://pds.nasa.gov/. For more information or help in obtaining
the software, contact the PDS operator at the following address:
Address: Planetary Data System, PDS Operator
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109
Phone: (818) 354-4321
Email: pds_operator@jpl.nasa.gov
WWW URL: http://pds.nasa.gov/
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