Data Set Information
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| DATA_SET_NAME |
PVO VENUS ELECT TEMP PROBE DERVD IONOPAUSE LOCATION VER 1.0
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| DATA_SET_ID |
PVO-V-OETP-5-IONOPAUSELOCATION-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
|
| DATA_SET_DESCRIPTION |
The Ionopause File. This file gives the orbit-by-orbit times andlocations of the ionopause crossings, which are evident as sharp gradientsin Ne at the top of the ionosphere. (These crossings always occur within 30minutes of periapsis, so they may be seen in the High Resolution Ne files).The ionopause and bow shock crossing times and locations are easilyidentified in the high resolution Ne measurements (Theis et al., 1980).These files contain the UT, altitude, latitude, SZA and local time of eachcrossing.On the dayside, the ionopause is taken (somewhat arbitrarily) at the levelin the steep gradient of the ionopause where Ne = 1x102 cm-3. On thenightside, the ionopause is selected at somewhat lower densities becausethe absence of spacecraft photoelectrons lowers the Ne measurementthreshold. In both cases, the intent is to identify the ionopause as thepoint where the first rise of Ne above the background density occurs. Ofcourse, the ionopause itself is not a point but is the extend region in whichthe ionopause density gradient occurs.
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| DATA_SET_RELEASE_DATE |
1993-10-01T00:00:00.000Z
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| START_TIME |
1978-12-05T03:07:34.817Z
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| STOP_TIME |
1992-10-07T07:46:27.000Z
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| MISSION_NAME |
PIONEER VENUS
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| MISSION_START_DATE |
1968-06-01T12:00:00.000Z
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| MISSION_STOP_DATE |
1992-10-07T12:00:00.000Z
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| TARGET_NAME |
VENUS
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| TARGET_TYPE |
PLANET
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| INSTRUMENT_HOST_ID |
PVO
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| INSTRUMENT_NAME |
ORBITER NEUTRAL MASS SPECTROMETER
|
| INSTRUMENT_ID |
ONMS
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| INSTRUMENT_TYPE |
QUADRUPOLE MASS SPECTROMETER
|
| NODE_NAME |
planetary plasma interactions
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| ARCHIVE_STATUS |
ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
The ionopause location is selected at that point in the steep gradient of theionopause where Ne crosses through the level of 1x102 cm-3. When thespacecraft is in darkness, the pe background is absent and the ionosphericNe is also much lower, so the ionopause is identified as the first rise in Neabove whatever background is present. The ionopause is identified by ahuman operator who views each high resolution Ne pass plot on aninteractive computer terminal. He selects the ionopause somewhatsubjectively as the time of the first rise above the background Ne, whichmay consist of magnetosheath plasma or photoelectrons. The 40 minutepass plots used for this purpose provide only a 5-10 second accuracy inthe crossing times. When irregularities or waviness in the ionopauseproduce several ionopause crossings, the outer most crossing is the onlyone identified.
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| CITATION_DESCRIPTION |
Theis, R. F., PVO-V-OETP-5-IONOPAUSELOCATION-V1.0, PVO VENUS ELECT TEMP PROBE DERVD IONOPAUSE LOCATION VER 1.0, NASA Planetary Data System, 1993.
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| ABSTRACT_TEXT |
The Ionopause File. This file gives the orbit-by-orbit times and locations of the ionopause crossings, which are evident as sharp gradients in Ne at the top of the ionosphere. (These crossings always occur within 30 minutes of periapsis, so they may be seen in the High Resolution Ne files).
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| PRODUCER_FULL_NAME |
DR. ROBERT F. THEIS
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| SEARCH/ACCESS DATA |
Planetary Plasma Interactions Website
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