ISIS 1 and 2 ("International Satellites for Ionospheric Studies") were the third and fourth in a series of Canadian

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

s launched to study the

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...

over one complete

solar cycle The Solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a periodic 11-year change in the Sun's activity measured in terms of Modern Maximum, variations in the number of observed sunspots on the Sun ...

. After the success of Canada's

Alouette 1 ''Alouette 1'' is a deactivated Canadian satellite that studied the ionosphere. Launched in 1962, it was Canada's first satellite, and the first satellite constructed by a country other than the Soviet Union or the United States. Canada was ...

, Canada and the United States jointly sent up three more satellites in the ISIS program. The first was named

Alouette 2 Alouette 2 was a Canadian research satellite launched at 04:48 UTC on November 29, 1965, by a Thor Agena rocket with Explorer 31 from the Western test range at Vandenberg AFB in California. It was (like its predecessor ''Alouette 1'', and Exp ...

(after originally being named ISIS-X). As was the case for the Alouette satellites, RCA Ltd. of

Montreal Montreal is the List of towns in Quebec, largest city in the Provinces and territories of Canada, province of Quebec, the List of the largest municipalities in Canada by population, second-largest in Canada, and the List of North American cit ...

was the prime contractor for both ISIS 1 and 2. A third satellite, ISIS 3, was scheduled for construction, but when the government's focus shifted toward communications satellites, it was cancelled in 1969. The funds were instead used to produce the

Communications Technology Satellite The Communications Technology Satellite (CTS), known as Hermes, was an experimental high-power direct broadcast communications satellite. It was a joint effort of Canadian Department of Communications, who designed and built the satellite, NASA w ...

(also known as Hermes), which was launched in 1976.

ISIS 1

ISIS 1 (1969-009A) was launched at 6h43

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

on January 30, 1969, by a

Delta rocket The Delta rocket family was a versatile range of American rocket-powered expendable launch systems that provided space launch capability in the United States from 1960 to 2024. Japan also launched license-built derivatives (N-I (rocket), N-I, N ...

at the Western test range at

Vandenberg AFB Vandenberg Space Force Base , previously Vandenberg Air Force Base, is a United States Space Force Base in Santa Barbara County, California. Established in 1941, Vandenberg Space Force Base is a space launch base, launching spacecraft from the ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. Unlike the Alouette satellites, ISIS had complex navigational equipment and a tape recorder to record some experiments when they were out of communications range and play back the results when the satellites came over Canada again. Some other experiments were not recorded but data was sent in over several stations around the globe. In total it conducted 10 experiments.

ISIS 2

ISIS 2 (1971-024A) was launched at 2h53

on April 1, 1971, on a

also from the Western test range at

. Due to budget constraints, the design of ISIS 2 was largely similar to that of ISIS I. The main difference was the addition of two experiments designed to study atmospheric optical emissions, including a

photometer A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, ...

. This allowed images to be taken for the first time of an

Aurora Borealis An aurora ( aurorae or auroras), also commonly known as the northern lights (aurora borealis) or southern lights (aurora australis), is a natural light display in Earth's sky, predominantly observed in high-latitude regions (around the Arc ...

as seen from above.

James Gosling James Arthur Gosling (born 19 May 1955) is a Canadian computer scientist, best known as the founder and lead designer behind the Java (programming language), Java programming language. Gosling was elected a member of the National Academy of E ...

wrote some of the software to analyze data from ISIS 2, as a high school student working for the

University of Calgary {{Infobox university , name = University of Calgary , image = University of Calgary coat of arms without motto scroll.svg , image_size = 150px , caption = Coat of arms , former ...

physics department. On March 13, 1984, both ISIS 1 and ISIS 2 were loaned to Japan's Communications Research Laboratory, which continued to operate the satellites until 1990, when they were shut down due to deterioration of battery capacity.

External links

ISIS program from the Canadian Space Agency

ISIS-I
at NSSDC (1969-009A)
ISIS-II
at NSSDC (1971-024A)

References

{{Orbital launches in 1971 Satellites orbiting Earth Satellites of Canada ISIS 1 ISIS 2 Geospace monitoring satellites

ISIS 1

ISIS 2

See also

External links

References