Some 13,800 Alouette and ISIS analog telemetry tapes were selected from 100,000 tapes available (as of March, 1996) in Canada and were shipped to Goddard for analog-to-digital (A/D) transformation and archival in the NSSDC. Since that time all but approximately 4000 selected ISIS 1 and 2 tapes have been destroyed. These tapes will be saved in Canada for a period of 5 years in anticipation of possible processing. The tapes shipped to Goddard were selected in order to obtain global coverage and to accommodate requests to address subjects and time periods of special interest.
Approximately 8,000 ISIS 2 telemetry tapes were selected so as to obtain global coverage. The selection included data from 24 telemetry stations from the years 1972 - 1984 with most tapes corresponding to the years 1973 - 1984. The stations are listed in Table 1 and their global location is shown in Fig. 1. Only 2 stations were chosen during 1972 (because of the good coverage on 35 mm film in 1972) and only 6 stations included coverage after 1979 (because of the low rate of data collection after 1979).
The tapes were selected from an estimated 30,000 or more that were available from these stations during the 1973 - 1984 interval. Typically, 80 tapes/year were specified with the plan that 20 consecutive tapes, centered on each of the equinoxes & solstices, would be selected. In some cases a larger number was requested to obtain additional coverage to accommodate special requests received as described below:
John Craven recommended consideration of the following intervals based
Aug 1981 - Feb 1983: duration of DE-2 mission
Sept 1981 - Feb 1982: northern DE-1 auroral images
Mid 1983 & mid 1986 southern DE-1 auroral images
Roland Tsunoda recommended:
obtaining data over the equator near Kwajalein
obtaining data over Alaska in conjunction with Chatanika radar operations (starting in summer 1972?) with particular interest in the 1973 & 1974 equinoxes)
The above requests resulted in additional tape allocations (above 80/yr) during selected years from 5 mid-to-high latitude telemetry stations.
In addition to the approximately 8,000 ISIS 2 tapes selected above for global coverage, over 4,000 additional Alouette 2, ISIS 1 and ISIS 2 tapes were requested to address subjects and time periods of special interest, i.e., for investigations of sounder-stimulated plasma wave & instability phenomena, natural wave emissions, trans-ionospheric propagation, mixed -mode operation, low power (100 W) sounding, successful rendezvous' operations, ISIS 1 operations during the duration of the DE-2 mission and during DE-1 auroral images,
The above request was matched with the available tapes in the Public Archives of Canada and the available tapes were shipped to the GSFC. The distribution of the telemetry tapes among the four Alouette/ISIS topside-sounder satellites was the following:
ALOUETTE 1: 2
ALOUETTE 2: 1562
ISIS 1: 4255
ISIS 2: >7689
(ISIS 2 contains an additional unknown number from the station at Brazzaville, Congo)
Table 1. List of station for which tapes were received.
Fig. 1 Station location on worldmap.