| DATA_SET_DESCRIPTION |
Data Set Overview
=================
This dataset contains tables of raw readings and reduced data from
all six runs on 01 August 1971 of the Lunar Self-Recording
Penetrometer (LSRP) on the surface of the Moon for the Apollo 15
Soil Mechanics experiment. Supporting documentation includes
digitized scans in JPEG and PDF format of the original LSRP soil
mechanics dataset on microfilm, videos and transcripts of the LSRP
as it was operated on the Moon, diagrams and maps of the experiment
areas, and photography of the Apollo 15 Station 8 where the experiment
was performed.
All six Apollo 15 penetrometer runs were done near a 40 cm deep trench
dug by the astronaut at Station 8 which was next to the ALSEP site
which was centered at 26.1341 degrees North latitude, 3.6298 degrees
East longitude, roughly 110 meters West-North-West of the lunar
module. The runs were performed near the end of second EVA
(extra-vehicular activity) on 01 August 1971. The flight unit S/N
2003 and lunar drum S/N 2002 were used for all runs. The drum was
returned to Earth and the etchings made by the penetrometer were read
and recorded on hand-written charts by the investigators. Copies of
the charts were sent to the National Space Science Data Center
(NSSDC), where they were microfilmed and archived. For more
information about the experiment see the Chapter 7 of the Apollo 15
Preliminary Science Report, which is provided in the DOCUMENT
directory.
Data
====
The raw readings and reduced data from each of the six runs of the
penetrometer are provided as fixed-width ASCII text tables and are
reproductions of the lunar penetration data reduction charts, in the
handwritten LSRP report, which were taken from the penetrometer drum
returned to Earth. (The handwritten report was scanned from the
microfilm archived at the NSSDC.) The tables are named in the form
A15_SMSS_71_M016935_nnn.TAB, where A15 denotes Apollo 15, SMSS is for
soil mechanics, 71 is the year of data acquisition, M016935 is the
microfilm reel, and nnn is the sequential frame number corresponding
to a page that contained the data chart in the report. Each table
(*.TAB) is accompanied by an ASCII text file (*.TXT) that provides
the header records for that data chart. Each table and header
combination is described by a detached PDS label.
The header records contained in the *.TXT file for a data table
give the mission, date, flight unit, lunar drum, index number (from 2
to 7 and designating penetrometer runs 1 to 6), and notes on the cone
or plate used. The columns in the data records of a table give
the drum load (the angle of deflection of the stylus on the drum) in
degrees/minutes, the drum load in decimal degrees, the drum
circumference deflection in millimeters (decimal degrees multiplied
by .5542), the load in Newtons (calculated from a calibration curve),
and the stress in Newtons per square centimeter (load divided by the
cone or plate base area). This is the value plotted for stress on
the plots. A second set of columns starts with a column labeled
initial drum depth/final in cm and gives a running total of the drum
reading. The next column, delta Drum Depth Reading in cm gives the
difference between the current drum depth reading and the previous
value. The next column, penetration depth in cm, is the drum depth
reading multiplied by 31.5 (index 2, Apollo 15). On some tables
there is a final column, headed '+correction add 3.75', which is the
previous column with a 3.75 cm correction added. This is a correction
for the additional length of the cone attached to the bottom of the
penetrometer rod on Apollo 15.
The six penetrometer runs and associated tables in the DATA directory
are provided below. Times in brackets are values listed in the
Apollo Lunar Surface Journal (ALSJ at http://history.nasa.gov/alsj/)
followed by conversion from Mission Elapsed Time (MET) to UT. The runs
started roughly at 148:21:10 MET according to ALSJ which has all times
approximately 6 minutes earlier than the times listed in the notes.
Run 1 - Index 2 - A15A_SMSS_71_M016935_011.TAB
Adjacent to north end of trench using 0.5 square inch cone
18:01:15 UT [~148:21:10 MET (ALSJ) which corresponds to 17:55:10 UT]
Run 2 - Index 3 - A15A_SMSS_71_M016935_012.TAB
Bottom of trench, 0.5 square inch cone
18:03:30 UT [~148:22:20 MET (ALSJ), 17:56:20 UT]
Run 3 - Index 4 - A15A_SMSS_71_M016935_013.TAB
In rover tracks directly behind the rover, 0.5 square inch cone
18:04:25 UT [~148:23:36 MET (ALSJ), 17:57:36 UT]
Run 4 - Index 5 - A15A_SMSS_71_M016935_014.TAB
Adjacent to rover tracks, 0.5 square inch cone
18:05:15 UT [~148:24:16 MET (ALSJ), 17:58:16 UT]
Run 5 - Index 6 - A15A_SMSS_71_M016935_015.TAB
Bottom of trench, flat plate
18:06:30 UT [~148:26:38 MET (ALSJ), 18:00:38 UT]
Run 6 - Index 7 - A15A_SMSS_71_M016935_016.TAB
Outside of trench, 4 inches from side of trench, plate, causes edge
of trench to collapse
18:07:33 UT [~148:27:00 MET (ALSJ), 18:01:00 UT]
Known Problems with Penetrometer Runs
-------------------------------------
According to the Apollo 15 Preliminary Science Report [APOLLO15A1972]
the surface reference pad tended to ride up the shaft during the last
four penetrometer runs, so the precise depth of penetration for runs 3
through 6 is difficult to determine and is probably slightly less than
the measured value. Therefore the stress-penetration curves in these
cases give an upper bound on the depth of penetration for an applied
force of 111 Newtons.
Supplementary Information
==========================
The DOCUMENT directory contains supplementary information about the
Soil Mechanics experiment, including the following items.
Handwritten LSRP Report
-----------------------
In addition to the data tables, it is important to note that the
handwritten LSRP report includes hand-drawn plots and notes from the
experiment. The Stress versus Penetration plots give the stress in
Newtons per square centimeter versus the penetration depth in
centimeters on a linear scale. These are plotted from the data in
the lunar penetration data reduction tables found in the report and
in this dataset.
Additionally sets of handwritten notes in the handwritten LSRP
report give times and notes on the sampling locations and other
aspects of the sampling, including diagrams. The Post-Flight
Calibration plots give load in Newtons versus drum circumferential
deflection in mm. One line shows the deadweight load and a parallel
line shows the correction for the weight of the penetrometer. The
latter is the line used for the calibration. The plot is based on a
pair of post-flight calibration tables. The first table, 'load
calibration' gives the index number, the 'vert. scribe', which looks
to be the starting point of the drum rotation for a given index run,
and columns giving the load in kilograms and Newtons. All values
are given in degrees and minutes. The top value in a cell is the
actual reading and the lower value is the reading minus the vert.
scribe value, which would represent the drum deflection. The second
table, 'penetration calibration', gives the readings in cm for a
given position and index number. There is also a pre-flight
calibration plot which gives the load in Newtons versus the drum
circumferential deflection in mm with a 2 sigma error line on each
side of the calibration line.
Site Diagrams, Maps, and Images
-------------------------------
The DOCUMENT directory contains several diagrams and maps of the
experiment areas including high resolution images taken by the
Lunar Reconnaissance Orbiter Camera of the entire Apollo 15 area
and the landing site.
Videos
------
Index 2, 3, 4, and 6 runs were captured on video with audio and are
included in the DOCUMENT directory.
Photography
-----------
Still photos taken of or near the 40-cm trench of the experiment
are included in the DOCUMENT directory. Most of the photos apply
to index 2, 3, 4, 6, and 7 runs; one is a context view of the
ALSEP site of Apollo 15 Station 8.
Transcript
----------
A transcript of the recorded audio commentary as the astronauts
performed the experiment at Apollo 15 Station 8 is included in
the DOCUMENT directory.
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