SCISAT-1 is a Canadian satellite designed to make observations of the Earth's atmosphere. Its most important instrument is an optical Fourier transform infrared spectrometer. This device records the spectrum of the Sun, as sunlight passes through the Earth's atmosphere, and makes an analysis of the chemical elements of the atmosphere possible.

SCISAT is a relatively small satellite weighing 150 kg or about 330 pounds. It is partly drum shaped with a diameter of about five feet and a depth of about five feet also. Its design, launch and use were coordinated by the Canadian Space Agency. The main contractor was Bristol Aerospace of Winnipeg, Manitoba.

SCISAT orbits through the Earth's shadow 15 times per day, profiting from the occultation of the Sun to make a spectrographic analysis of the structure and chemistry of those parts of the upper atmosphere that are too high to be reached by balloons and airplanes and too low to be visited by orbiting satellites. This kind of analysis can help understand the depletion of the ozone layer and other upper atmosphere phenomena.

SCISAT was placed in low Earth orbit, or LEO, by a Pegasus rocket launched from a carrier aircraft on August 12, 2003. It is expected to operate for two to five years.

The University of Waterloo, the University of Toronto, and several other Canadian universities collaborated in the design of the experiments, and in several aspects of the testing of the satellite.