Data Set Information
DATA_SET_NAME GALILEO PROBE NEP RAW DATA SET
DATA_SET_ID GP-J-NEP-3-ENTRY-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : Description of nephelometer files in the data bank: This file describes the data obtained by the Galileo Probe Nephelometer during the descent into the Jupiter atmosphere on December 7, 1995. The total time of data acquisition was less than two hours before the destruction of the probe in the Jupiter atmosphere. The Nephelometer measured light scattering at 900 nm wavelength at five angles in order to determine properties of aerosol particles and clouds encountered during descent. References describing the instrument include: 1. Ragent, B., C. A. Privette, P. Avrin, J. G. Waring, C. E. Carlston, T. C. D. Knight and J. P. Martin, Galileo Probe Nephelometer Experiment, Space Science Reviews, 60, 179-201, 1992. [RAGENTETAL1992] 2. Ragent, B., D. S. Colburn, P. Avrin and K. A. Rages, Results of the Galileo Probe Nephelometer Experiment, Science, 272, 854-856, 1996. [RAGENTETAL1996] 3. Ragent, B., D. S. Colburn, K. A. Rages, T. C. D. Knight, P. Avrin, G. S. Orton, P. A. Yanamandra-Fisher and G. W. Grams, The Clouds of Jupiter: Results of the Galileo Jupiter Mission Probe Nephelometer Experiment, Journal of Geophysical Research, 103, 22891-22909, 1998. [RAGENTETAL1998] The data are in tabular form in ASCII format, and thus can be read easily by FORTRAN (or similar) programs. There are 21 files. Each starts out with a header in ASCII which describes the content of the columns and which a FORTRAN program should skip over before reading the data. The following are the 24 data files in the volume: File 1 - raw.dat Raw data. This is the hexadecimal information from the probe. A description of this file follows this table of contents. File 2 - ptz.dat Probe Descent Data. Pressure, temperature and altitude. File 3 - elecoffs.dat Electronic Offsets, Counts. An offset measurement made periodically. File 4 - srcalign.dat Source Monitors and Alignment Detector Readings, Counts. File 5 - tempvolt.dat Forward, Backward and Electronics Temperature Sensor Readings, in Degrees C, and Voltage Monitor, in Counts. File 6 - gain.dat Gain of 16 Degree Channel Electronics. File 7 - contam.dat Contamination Channel Readings, Counts. File 8 - scatter.dat Scatter Data, Counts. File 9 - fittemp.dat Fitted Temperature Profiles, Fitted to a Ninth Order Polynomial File 10 - xsec11.dat Cross Sections with No Adjustment of Baseline and Using Pre-Launch Calibration Data Extrapolated to Cover Out-of-Range Temperatures. File 11 - xsec12.dat Cross Sections with No Adjustment of Baseline and Using Both Pre-Launch Calibration Data and Post-Encounter Test Data to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 12 - xsec21.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number 14 (p : 0.510 bars) and Using Pre-Launch Calibration Data Extrapolated to Cover Out- of-Range Temperatures Experienced during Probe Descent. File 13 - xsec22.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number N:14 (p:0.510 bars) and Using Both Pre-Launch Calibration Data and Post-Encounter Test Data to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 14 - xsec31.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number 24 (p : 0.627 bars) and Using Pre-Launch Calibration Data Extrapolated to Cover Out- of-Range Temperatures Experienced during Probe Descent. File 15 - xsec32.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number N:24 (p:0.627 bars) and Using Both Pre-Launch Calibration Data and Post-Encounter Test Data to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 16 - xsec41.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number 60 (p : 1.345 bars) and Using Pre-Launch Calibration Data Extrapolated to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 17 - xsec42.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number N:60 (p:1.345 bars) and Using Both Pre-Launch Calibration Data and Post-Encounter Test Data to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 18 - xsec51.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number 69 (p : 1.621 bars) and Using Pre-Launch Calibration Data Extrapolated to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 19 - xsec52.dat Cross Sections with Adjustment of Baseline to Zero Both at Measurement Number N:69 (p:1.621 bars) and Using Pre-Launch Calibration Data and Post-Encounter Data Test to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 20 - xsec61.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number 117 (p : 3.603 bars) and Using Pre-Launch Calibration Data Extrapolated to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 21 - xsec62.dat Cross Sections with Adjustment of Baseline to Zero at Measurement Number N:117 (p:3.603 bars) and Using Both Pre-Launch Calibration Data and Post-Encounter Test Data to Cover Out-of-Range Temperatures Experienced during Probe Descent. File 22 - senstemp1.dat Sensitivities for each scatter channel, normalized to 1.000 at 15C, and extrapolated from pre-launch tests on the Flight Unit. File 23 - senstemp2.dat Sensitivities from pre-launch tests on the Flight Unit, normalized to 1.000 at 15 C, and modified using post-encounter data. File 24 - baseoffs.dat Baseline offsets versus temperature measured with the flight unit in the laboratory. File 1 description File 1 contains all of the Nephelometer data transmitted back during the encounter, in hexadecimal form. They were taken directly from the file NEP0701A.SDM, sent from the project office in July 1996. Column 1 has the line number. Each nephelometer frame is identified by a block of 20 lines beginning with the sync word EB 90 followed by the nephelometer frame number in hexadecimal format. Since a nephelometer frame is composed of data from 20 consecutive spacecraft frames, frame number zero contains data from lines 1 through 20, and the frame number for later data is obtained by the integer division of ( line number - 1 ) by 20. Useful data ended at line number 878, and two lines of zeros have been added to complete nephelometer frame 43. As an aid to understanding hexadecimal format, the following examples are shown: Hexadecimal frame numbers 9, A, F, 10, 1A, and 20 have the decimal equivalent 9, 10, 15, 16, 26, and 32. Column 3 contains the number 5 for A string data and 6 for B string data. The file NEP0701A.SDM contains both, and where they overlap, the data is identical, except for a few lines where it is obvious which choice should be made. This data set contains only A string data, because it is a complete set and where B string data exists there is no reason for preferring it over the A string data. Column 2 shows in decimal notation the probe minor frame number transmitted by the probe, cycling from 0 through 63. The minor frame number, and the date and time of transmission, are not essential to interpreting the nephelometer data, since the timing of the measurements is asynchronous with the time of transmission. The first minor frame with nephelometer data is minor frame number 1. Columns 5 through 10 are the Universal Time and date assigned to each minor frame. Columns 5 and 6 represent December 7, 1995. Columns 7 and 8 give the minute and hour, in that order, so that for example the numbers 7, 16 represent 2207 U.T. Columns 9 and 10 give the seconds and milliseconds. The first digit of column 10 generally increases by 1 for each line because the minor frames were transmitted at intervals of very nearly 4 seconds. After every 15 lines, column 7 is expected to increase by one, representing an addition of one minute. The remaining columns (11 through 15) contain the nephelometer data. Every twenty lines contains one nephelometer frame, the start of which is identified by a code word EB 90. The next two digits comprise the nephelometer frame number, supplied by the nephelometer clock, beginning with frame 0 at startup and ending at frame 43 (hexadecimal notation 2B). Since the data set is complete, the frame numbers are found where the index is 1, 21, 41, etc., with the frame number equaling (index - 1)/20. The first several words comprise the engineering data for the frame and they are followed by the words for the nephelometer measurements. In the hexadecimal printout, a frame contains 100 words of 8 bit length. To unpack the data, we have strung the words together to recover the original group of 800 binary bits, and then extracted the 10 bit nephelometer words along with the 8 and 2 bit housekeeping data. Rollover corrections had to be applied to some of the housekeeping data when the analog signals representing temperature, etc., exceeded the expected range of the analog to digital converter. The unpacked data, in counts, are shown in Files 3 through 8. File 2 relates the time of each measurement to the atmospheric pressure and temperature and the probe altitude as determined by the ASI experiment. Thus the data in the remaining files are labelled by atmospheric pressure in order to relate nephelometer findings to the atmospheric environment. Files 9 through 21 are cross sections computed according to the parameters described in the headings. (See reference 3)
DATA_SET_RELEASE_DATE 1996-12-08T00:00:00.000Z
START_TIME 1995-12-07T07:04:00.000Z
STOP_TIME 1995-12-07T10:04:00.000Z
MISSION_NAME GALILEO
MISSION_START_DATE 1977-10-01T12:00:00.000Z
MISSION_STOP_DATE 2003-09-21T12:00:00.000Z
TARGET_NAME JUPITER
TARGET_TYPE PLANET
INSTRUMENT_HOST_ID GP
INSTRUMENT_NAME GALILEO PROBE NEPHELOMETER
INSTRUMENT_ID NEP
INSTRUMENT_TYPE NEPHELOMETER
NODE_NAME Planetary Atmospheres
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : Because the instrument deteriorated in the hot internal probe environment near the end of descent, valid data may have been obtained only for the first 35 to 40 min of descent, corresponding to an ambient pressure of ~10 to 13 bars.
CITATION_DESCRIPTION Citation TBD
ABSTRACT_TEXT This data set describes the data obtained by the Galileo Probe Nephelometer during the descent into the Jupiter atmosphere on December 7, 1995. The total time of data acquisition was less than two hours before the destruction of the probe in the Jupiter atmosphere.
PRODUCER_FULL_NAME DAVID COLBURN
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