Instrument Information
IDENTIFIER urn:nasa:pds:context:instrument:gp.gpms::1.3
NAME Mass Spectrometer for Galileo Probe
TYPE Mass Spectrometer
DESCRIPTION The Galileo Probe Mass Spectrometer (GPMS) measured the chemical and isotopic composition in the atmosphere of Jupiter, including the vertical variations of the constituents. The measurements were performed by in-situ sampling of the ambient atmosphere in the pressure range from approximately 0.5 to 21 bars. In addition, batch sampling was performed for noble gas composition measurement and isotopic ratio determination, and for sensitivity enhancement of non-reactive trace gases. The instrument consists of a gas sampling system that is connected to a quadrupole mass analyzer for molecular weight analysis. In addition two sample enrichment cells and one noble gas analysis cell are part of the sampling system. The mass range of the quadrupole analyzer is from 2 amu to 150 amu. The maximum dynamic range is 1.E8. The detector threshold ranges from 10 ppmv for H2O to 1 ppbv for Kr and Xe. It is dependent on the instrument background and ambient gas composition because of spectral interference. The threshold values are lowered through sample enrichment by a factor of 100 to 500 for stable hydrocarbons and by a factor of 10 for noble gases. The gas sampling system and mass analyzer were sealed and evacuated until the measurement sequence was initiated when the Probe entered the upper atmosphere of Jupiter. The instrument weights 13.2 kg and the average power consumption is 13 W. Since the probe is not pressurized the instrument is enclosed by a pressurized housing made of titanium to save weight. Pressurization (~1 atmosphere of N2) prevents corona, condensation, and collapse of the electronics package during the descent. The instrument followed a pre-programmed sampling sequence of 8192 steps with a sampling rate of two steps per second.
MODEL IDENTIFIER
NAIF INSTRUMENT IDENTIFIER
SERIAL NUMBER not applicable
REFERENCES Niemann, H.B., D.N. Harpold, S.K. Atreya, G.R. Carignan, D.M. Hunten, and T.C. Owen, Galileo Probe Mass Spectrometer experiment, Space Science Reviews volume 60, pp 111-142, 1992

Niemann, H.B., S.K. Atreya, G.R. Carignan, T.M. Donahue, J.A. Haberman, D.N. Harpold, R.E. Hartle, D.M. Hunten, W.T. Kasprzak, P.R. Mahaffy, T.C. Owen, N.W. Spencer, and S.H. Way, The Galileo Probe Mass Spectrometer: Composition of Jupiter's Atmosphere, Science 272, pp 846-849, 1996