Data Set Information
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| DATA_SET_NAME |
VEGA1 DUST PARTICLE IMPACT DETECTOR DATA V1.0
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| DATA_SET_ID |
VEGA1-C-SP2-2-RDR-HALLEY-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : The SP-2 experiment on Vega spacecraft was intended for studying the spatial and mass distributions of dust particles in the cometary coma over the mass range 1.e-16 to 1.e-6 g. Covering such a broad mass range was made possible by using sensors of two types, namely, impact plasma and acoustic. The threshold sensitivity of the dust particle acoustic detector in terms of the transferred momentum is given by Pmin ~ 2x10**-5 gcm/s. Taking into account that the recoil momentum may exceed the particle momentum mV by 5 to 10 times, the minimum mass of recorded particles is < 3x10**-13 g. The measurement range n (> m)x3x10**-13 to ~ 2x10**-6 g is divided into 16 channels. With the relative width delta/m ~ 2.82, sensitive area S : 500 cm**2, accumulation time for one spectrum is 1 s, which corresponds to the spatial resolution ~ 80 km over the flyby trajectory. The counting rate of small mass particles is about 4095 1/s. The ionization detector is capable of recording particles with mass 3x10**-16 to 3x10**-11g. The number of channels is 6, with relative width delta/m : 10, sensitive area - 40 cm**2. The limit counting rate of small mass particles is ~ 65,500 1/s. The accumulation time for one spectrum is 1 s. The flyby trajectories of the Vega spacecraft in the cometocentric frame can be specified by the coordinates of the closest approach to the nucleus R0(R0x,R0y,R0z) and the components of the relative velocity V(Vx,Vy,Vz). The corresponding values for Vega1 and Vega2 were as follows: Vega 1: R0x : 7830 km; R0y : 2480 km; R0z : 3400 km; Vx : 28.64 km/s; Vy : -72.73 km/s; Vz :-12.95km/s; Vega 2: R0x : 7100 km; R0y : 2680 km; R0z : 2630 km; Vx : 30.53 km/s; Vy : -69.44 km/s; Vz :-11.88km/s; If the results of the dust flux measurements are referred to the time reckoned from the instant of closest approach, the corresponding distances to the cometary nucleus can be found as R:R0*sqrt(1 + (t/t0)^2), where the parameter t0 : R0/V. In the course of measurements the numbers of particle impacts with masses exceeding the channel threshold is counted in each pulse height channel at 1 second intervals along the trajectory: N(>m) : F(>m)*S*T : n(>m)*V*S*T, where n(>m) is the number density, F(>m):n(>m)*V the cumulative flux, S the effective sensor area (500 cm2 for the acoustic sensor and 28.57 cm2 for the impact plasma one), T:63/64s the accumulation time in each measurement. For the acoustic sensors, dead time corrections were introduced at channel count rate N(>m) > 50/s. For the fast impact plasma sensors such corrections were not needed. The SP-2 data from IKI (Dyachkov) are formatted into table containing 2092 records. Each record consists of 18 columns and contains time of measurement referred to one of closest approach, 5 columns of impact plasma sensor data, and 12 columns of acoustic sensor data.
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| DATA_SET_RELEASE_DATE |
3000-01-01T00:00:00.000Z
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| START_TIME |
1986-03-06T06:38:34.000Z
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| STOP_TIME |
1986-03-06T07:28:03.000Z
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| MISSION_NAME |
VEGA 1
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| MISSION_START_DATE |
1984-12-15T12:00:00.000Z
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| MISSION_STOP_DATE |
1986-04-01T12:00:00.000Z
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| TARGET_NAME |
HALLEY
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| TARGET_TYPE |
COMET
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| INSTRUMENT_HOST_ID |
VEGA1
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| INSTRUMENT_NAME |
DUST PARTICLE DETECTOR
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| INSTRUMENT_ID |
SP2
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| INSTRUMENT_TYPE |
ACOUSTIC SENSOR
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| NODE_NAME |
Small Bodies
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| ARCHIVE_STATUS |
ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
Confidence Level Overview: N/A
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| CITATION_DESCRIPTION |
Balebanov V.M., Skuridin G.A., Vorontsova E.V., Bassolo V.S. and A. V. Dyachkov, VEGA1 DUST PARTICLE IMPACT DETECTOR DATA V1.0, VEGA1-C-SP2-2-RDR-HALLEY-V1.0, NASA Planetary Data System, 1997
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| ABSTRACT_TEXT |
The SP-2 experiment on Vega spacecraft was intended for studying the spatial and mass distributions of dust particles in the cometary coma over the mass range 1.e-16 to 1.e-6 g. Covering such a broad mass range was made possible by using sensors of two types, namely, impact plasma and acoustic.
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| PRODUCER_FULL_NAME |
INTERNATIONAL HALLEY WATCH
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| SEARCH/ACCESS DATA |
SBN Comet Website
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