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Galileo Dust Detections: 1990-1992 (PDS)

NSSDCA ID: PSSB-00006

Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)

Time span: 1989-12-31 to 1992-12-28

Description

This data set is comprised of results of dust particle detections by the Galileo spacecraft from 1990 through 1992. It contains the information from the spacecraft instrument as received on Earth, information about the location and pointing direction of the spacecraft, and the physcial properties determined from the data analysis. The data include:

1) galddust.tab - An ASCII table of detector response data and derived quantities from the Galileo dust detector as well as spacecraft geometry information.

2) galdcode.tab - An ASCII table of values for codes found within the galdust.tab dataset.

3) galdcalb.tab - An ASCII table of laboratory measurements of detector rise times and charge to mass ratios as a function of impact velocity for different impacting materials. This calibration data is used to relate instrument responses to physical properties of the impacting dust particles.

4) galdarea.tab - An ASCII table of the area of the dust detector exposed to particles as a function of their speed and direction relative to the detector axis.

The data received from the spacecraft are used for determining the location and orientation of the spacecraft and instrument. Given are the SPACECRAFT SOLAR DISTANCE, ECLIPTIC LONGITUDE, ECLIPTIC LATITUDE, SPACECRAFT EARTH DISTANCE, ROTATION ANGLE, DETECTOR ECLIPTIC LONGITUDE, and DETECTOR ECLIPTIC LATITUDE.

Data received from the dust detector are given in an integer code format. Some of the integer codes represent a range of values within which the data could fall (e.g. ION AMPLITUDE CODE), some may represent a specific value (e.g. ION COLLECTOR THRESHOLD), and others, a classification based upon other integer codes (e.g. EVENT CLASS).

The instrument data consists of cataloging information, instrument status, instrument readings at time of impact, and classification information. The cataloging information includes the SEQUENCE NUMBER (impact number), DATE JULIAN (time of impact), and SECTOR (the pointing of the instrument at time of impact). The instrument status data are the threshold levels of the detectors and the CHANNELTRON VOLTAGE LEVEL.

The instrument readings are the amplitude codes of the detectors on-board the instrument, the rise time integer codes of the charge level rise times of the detectors, the integer code representing the difference in starting times of the ion signal and the electron signal, and coincidences between the electron and ion signals, and between the ion and channeltron signals.

The classification information is used to assist in classifying an event into probable impact and non-impact categories. There are three variables used in classification: EVENT DEFINITION which records which detectors begin a measurement cycle, ION AMPLITUDE RANGE which is the classification of the ION AMPLITUDE CODE into 6 subranges (used with EVENT CLASS) and EVENT CLASS which categorizes events into a range of probable impacts to probable non-impacts.

The PARTICLE SPEED and PARTICLE MASS and their corresponding error factors are determined from the instrument and calibration data given in galddust.tab and galdcalb.tab, respectively.

ION RISE TIME, ELECTRON RISE TIME, ION CHARGE MASS RATIO, and ELECTRON CHARGE MASS RATIO were measured for iron, glass, and carbon particles of known mass and impacting at known speeds. Since the composition of particles striking the Galileo spacecraft is unknown, logarithmic averages of the above values are used to infer the particle speed and mass from the instrumental measurements.

The data contain different levels of processing. Some processing is done at the time of the impact observation. This processing categorizes the detector responses to transmit the data efficiently back to Earth. On Earth, the data are fit to calibration curves to determine the speed and mass of the impacting particle.

The data has been processed and validated through the Planetary Data System (PDS). This data is available on-line at the Dust Subnode of the PDS Small Bodies Node on the WWW at:

http://dorothy.as.arizona.edu/DSN/

Alternate Names

  • PDS GO-D-GDDS-5-DUST-V1.0
  • GO-D-GDDS-5-DUST-V1.0

Discipline

  • Planetary Science: Small Bodies

Old NSSDCA ID

  • 89-084B-09A

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Carol NeeseData ProviderPlanetary Science Instituteneese@psi.edu
Dr. Eberhard GruenGeneral ContactMax-Planck-Institut fur Kernphysikeberhard.gruen@mpi-hd.mpg.de

Selected References

  • Gruen, E., et al., Three years of Galileo dust data, Planetary Space Sci., 43, No. 8, 953-969, doi:10.1016/0032-0633(94)00234-I, Aug. 1995.
  • Gruen, E., et al., Reduction of Galileo and Ulysses dust data, Planetary Space Sci., 43, Issue 8, 941-951, doi:10.1016/0032-0633(94)00232-G, Aug. 1995.
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