NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

Mass Spectrometer

NSSDCA ID: 1978-086C-01

Mission Name: Venera 12 Descent Craft
Principal Investigator:Dr. V. G. Istomin


The object of this experiment was (1) the detection and determination of the relative concentrations of Noble gases in the Venusian atmosphere, (2) determination of the isotopic composition of the Noble gases, and (3) detection of small amounts of such materials as ammonia, methane, and sulfur-containing compounds. The mass spectrometer was of the radio-frequency type with a range of 11-105 atomic mass units. The resolution (M/delta M) at 10% of peak amplitude was about 35. The volume sensitivity limit for molecular nitrogen was 0.2%, for molecular oxygen 0.05%, for inert gases 1-5 ppm, and for methane 5 ppm. The mass spectrometer cycled approximately every 8 s and acquired a total of 176 spectra (Venera 11 + 12). The instrument was operated in five gain modes: 0.1, 1, 10, 100, and 1000. The experiment was active during the Venusian descent, from altitudes of 23 km to 1 km above the surface. A source of systematic errors in the determination of minor atmospheric components such as nitrogen and argon was the error in the composition of the preflight model gas mixtures. The systematic error is estimated at about 20%. The instrument was described in Grechnev, K. V. et al. ,1979, Cosmic Research, Consultants Bureau, New York, v. 17, pp. 575-580 (Kosmicheskie Issledovanija, 1979, v. 17, n. 5, pp. 697-702).

Alternate Names

  • Venera12DescentCraft/MassSpectrometer

Funding Agency

  • Unknown (U.S.S.R)


  • Planetary Science: Fields and Particles

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. V. G. IstominPrincipal InvestigatorInstitut Kosmicheskich Issledovaniya (IKI)
[] NASA Logo -