As was the case for the Alouette satellites, RCA Ltd. of Montreal was the prime contractor for both ISIS 1 and 2.
[2] ISIS 1 (1969-009A) was launched at 6h43 UTC[3] on January 30, 1969, by a Delta rocket at the Western test range at Vandenberg AFB in California.
ISIS 2 (1971-024A) was launched at 2h53 UTC[5] on April 1, 1971, on a Delta rocket also from the Western test range at Vandenberg AFB in California.
The main difference was the addition of two experiments designed to study atmospheric optical emissions, including a photometer.
[7] James Gosling wrote some of the software to analyze data from ISIS 2, as a high school student working for the University of Calgary physics department.