NSSDCA ID: 1969-051A-04
Mission Name: OGO 6The primary objective of this experiment was to study, by obtaining appropriate direct in situ composition measurements, the variation of the concentrations of the major constituents (nitrogen, oxygen, helium, and hydrogen) of the earth's neutral upper atmosphere during changing solar and magnetic activity as a function of time and location. The spectrometer system consisted of a quadrupole analyzer, in which mass separation occurred within a direct current and a radio frequency electric field, an enclosed dual-filament electron bombardment ion source, an electron multiplier, supporting electronics for operating the analyzer and source, and a break-off device for exposing the evacuated mass spectrometer to the atmosphere after the spacecraft achieved orbit. Oriented continually into the orbit plane, the spectrometer's entrance aperture normally faced into the direction of motion. Entering gas particles interacted with the surfaces of an antechamber before being ionized by a 90-V electron beam, after passing through electric fields, the selected ions struck the first dynode of a multiplier. The resulting multiplier output pulses were counted, and the measured count was proportional to the number density of the selected mass in the antechamber. This versatile experiment was designed to operate in any one of three modes, depending on the command given. In mode C the spectrometer was tuned to a particular neutral species mass and measured its concentration only. In the other two modes, both pretuned stepping and mass sweeping approaches were used. The experiment was automatically placed in mode A each time it was turned on, and the bulk of the transmitted data was obtained in mode A. Here, the analyzer was fixed tuned sequentially to the masses of principal interest, 2, 4, 16, 28, and 32. There were 28 stepping sequences, each lasting 9.2 s. In addition, there were two sweeping sequences, each of 55.2-s duration, so that a complete measurement cycle lasted 368 s. In the sweeping mode, the analyzer was tuned over the mass ranges 2 to 1.2, 4 to 2.2, 16 to 9, 28 to 15.5, 32 to 18, and 45 to 25.3 atomic mass units. A complete measurement cycle in mode B also took 368 s and consisted of six sweeping sequences and four stepping sequences. More details can be found in D. R. Taeusch et al., "Neutral composition variation above 400 km during a magnetic storm," J. Geophys. Res., v. 76, n. 34, pp. 8318-8325, 1971. NSSDC has all the useful data that exist from this investigation.
Mass: 4.8 kg
Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. George R. Carignan | Other Investigator | University of Michigan | carignan@engin.umich.edu |
Mr. Dan N. Harpold | Other Investigator | NASA Goddard Space Flight Center | dharpold@paf.gsfc.nasa.gov |
Mr. David R. Taeusch | Other Investigator | University of Michigan | |
Dr. Carl A. Reber | Principal Investigator | NASA Goddard Space Flight Center | reber@skip.gsfc.nasa.gov |