NSSDCA ID: PSFP-00483
Availability: Archived at NSSDC, accessible from elsewhere
Time span: 1978-12-05 to 1992-10-07
This description was generated automatically using input from the Planetary Data System.
orbits time 1 1978-12-05T15:06:25.000Z 645 1980-09-10T17:30:20.000Z 4710 1991-12-29T00:40:49.000Z 5055 1992-10-07T19:50:29.000Z The data reduction process has been described in Kasprzak et al. (1987). The method used to reduce the data assumes cylindrical symmetry of the ion source. In actual fact, the source is asymmetrical in its angular response (Guenther, 1989). This can introduce as much as a factor of 2 scatter in the data. No simple solution has been found for modeling this asymmetry since the actual ion drift vector is unknown. The minimum energy of an ion detectable by the ONMS in this ion mode is 35.9 eV. The maximum transmission is assumed to occur about 10 V above this value. On the nightside of Venus the spacecraft potential is negative and the most probable ion energy is near 40 eV. The ion species regularly monitored include: He+, N+, O+, N+ and/or CO+ and CO2+. Because of the paucity of data at other mass numbers only mass 16 (atomic oxygen) has been reduced to a flux and number density. As part of the reduction process the angle in the ecliptic plane of the apparent ion flow in spacecraft reference frame has been deduced. The flux values are estimated in the spacecraft reference frame relative to spacecraft ground. The density is computed from the flux by dividing it by a speed corresponding to 40 eV. No correction has been applied to the angle, density or flux in order to remove the effect of spacecraft velocity. The dataset fields are: VARIABLE COMMENT -------------------------------------------------------ORBIT Orbit number MASS Mass number of species 4 He+ 12 C+ 14 N+ 16 O+ 28 CO+ and/or N2+ 30 NO+ 32 O2+ 44 CO2+ BTIME Beginning time -| BTPER Time from periapsis (sec) | BALTIT Altitude in (km) |-- START BSZA Solar zenith angle (deg) | BLAT Local solar time (hr) -| ETIME Ending Time -| ETPER Time from periapsis (sec) | EALTIT Altitude in (km) |-- FINISH ESZA Solar zenith angle (deg) | ELAT Local solar time (hr) -|
These data are available on-line from the Planetary Data System (PDS) at:
https://pds-ppi.igpp.ucla.edu/data/PVO-V-ONMS-5-SUPERTHERMALIONLOC-V1.0/
Questions and comments about this data collection can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Hasso B. Niemann | Data Provider | NASA Goddard Space Flight Center | |
Dr. Wayne T. Kasprzak | General Contact | NASA Goddard Space Flight Center | wayne.t.kasprzak@nasa.gov |