NSSDCA ID: 1971-019A-09
Mission Name: IMP-IThis experiment was designed to measure the spectra and composition of solar and galactic cosmic rays and of magnetotail particles, to serve as a prototype of instruments to be flown on the deep space probes Pioneers 10 and 11, and to provide reference 1-AU data for comparison with the Pioneer data in gradient studies. The experiment consisted of a composition telescope (which failed approximately 10 days after launch), a second telescope (from which virtually all the useful data of this experiment were obtained), an electron current detector (electrons above 1.8 MeV plus protons above 21 MeV), and a fission cell (protons above 120 MeV). The latter two instruments were specifically included as prototypes of Pioneer instruments designed to measure very high fluxes of Jovian trapped particles. As such they were not optimized for measurements of the relatively low fluxes in the earth's radiation belt. The successful telescope consisted of six colinear sensors (five lithium-drifted silicon sensors and one CsI (Tl) scintillator) and an anticoincidence scintillator. This telescope had a look direction that was normal to the spacecraft spin axis and had an angular aperture between 48 and 64 deg (depending on coincidence mode considered). Coincidence mode rates (5.12 s accumulations, corresponding to protons in the ranges 0.5 to 10.6, 10.6 to 19.6, 29.3 to 66.7 and above 66.7 MeV) were obtained each 10.24 s. Pulse-height analysis (one event every 20.48 s) was used with these rates to study charge composition (up to Z of 8), isotopic composition ( for Z of 1 and 2), and electron fluxes. The spacecraft onboard computer was used to permit some of the objectives assigned to the composition telescope to be achieved through the smaller successful telescope. Except for the failure of the composition telescope, the experiment worked as planned throughout the spacecraft life.
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Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Ke-Chiang Hsieh | Other Investigator | University of Arizona | hsieh@cc.arizona.edu |
Mr. Satish Verma | Other Investigator | Louisiana State University | |
Dr. Glenn M. Mason | Other Investigator | University of Chicago | Glenn.Mason@jhuapl.edu |
Dr. Moises Garcia-Munoz | Other Investigator | University of Chicago | munoz@odysseus.uchicago.edu |
Dr. John A. Simpson | Principal Investigator | University of Chicago |