Space Station Orbit Tutorial

FACT 2: With each orbit taking 90-93 minutes, there are approximately 16 orbits per day (24 hours). The exact number of orbits per day is usually less than 16 (generally 15.5 to 15.9 orbits/day) depending on the altitude of the ISS. Each orbit shifts to the west by approximately 22.9° of longitude (measured as the position where the orbit crosses the equator).

Figure 2. Example of two consecutive orbits (daylight only shown) the first orbit is in red and the second in yellow. Arrows show the travel direction of the spacecraft.

Figure 3. Daylight tracks for 16 consecutive orbits (about one day). The part of orbit 16 overlaps into the next day is during darkness and is not shown here. The first daylight orbit of the next day, number 17, is shown in red.





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