NSSDCA ID: 2002-034A-03
Mission Name: CONTOURThe Neutral Gas and Ion Mass Spectrometer (NGIMS) will measure the abundance and isotope ratios for many neutral and ion species in the coma of each comet during the flyby. The objectives of this experiment are to gain an understanding of the abundances of simple species such as H2O, CH4, CO2, NH3, and H2S and considerably more complex molecules released by the comet.
NGIMS is a quadrupole mass spectrometer with two ion sources, an open ion source and a closed ion source. The open source minimizes gas/surface interactions by directly sampling gaseous species that have been formed into a beam by collimating apertures. It measures ambient particle density directly for all neutral species. The closed ion source uses ram density enhancement in an enclosed chamber to provide higher accuracy and sensitivity, but is not as precise for species which interact with the source walls. The quadrupole mass analyzer consists of four precision ground hyperbolic rods mounted in a rigid mechanical assembly. Three fixed frequencies in the 1 to 5 MHz range are selected to cover the mass range (1 to 300 amu). The dual detector system counts ions transmitted through the quadrupole anlyzer to produce a mass spectrum. The NGIMS is mounted on the side of the spacecraft directly behind the dust shield with the aperture pointed in the direction of flight.
Mass: 8.8 kg
Power (avg): 22.6 W
Questions and comments about this experiment can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Hasso B. Niemann | Co-Investigator | NASA Goddard Space Flight Center | |
Dr. Paul R. Mahaffy | Co-Investigator | NASA Goddard Space Flight Center | mahaffy@paf.gsfc.nasa.gov |
Mr. Jack E. Richards | Instrument Manager | NASA Goddard Space Flight Center | richards@pop900.gsfc.nasa.gov |