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

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

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 an ...

over one complete

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

. 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 w ...

, 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 Explore ...

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

Montreal Montreal ( ; officially Montréal, ) is the List of the largest municipalities in Canada by population, second-most populous city in Canada and List of towns in Quebec, most populous city in the Provinces and territories of Canada, Canadian ...

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 towards 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 on January 30, 1969 by a

Delta rocket Delta is an American versatile family of expendable launch systems that has provided space launch capability in the United States since 1960. Japan also launched license-built derivatives ( N-I, N-II, and H-I) from 1975 to 1992. More than 300 ...

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 th ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. Unlike the Alouette satellites, the 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 UTC 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, ph ...

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

Aurora Borealis An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of br ...

as seen from above.

James Gosling James Gosling (born May 19, 1955) is a Canadian computer scientist, best known as the founder and lead designer behind the Java programming language. Gosling was elected a member of the National Academy of Engineering in 2004 for the conceptio ...

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

University of Calgary The University of Calgary (U of C or UCalgary) is a public research university located in Calgary, Alberta, Canada. The University of Calgary started in 1944 as the Calgary branch of the University of Alberta, founded in 1908, prior to being ins ...

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