Each NOAA and DMSP satellite provides global microwave coverage of the earth's atmosphere and surface every 12 hours. This is accomplished with a set of approximately seven ascending and descending passes as shown in both the animation and 12-hour NOAA-15 composite. A pass (swath) is referred to as ascending when the satellite travels from south to north, and descending when the satellite travels from north to south.

Most locations on the earth will be viewed a minimum of twice daily by each satellite - once during an ascending pass and once by a descending pass. Coverage at high latitudes however, is more frequent due to an overlap in the coverage for consecutive orbits.

NOAA and DMSP spacecraft produce routine global coverage by placing each into sun-synchronous near-polar orbits, between approximately 830 and 860 km above the earth's surface. Sun-synchronous means that the satellite remains fixed with respect to the sun with the earth rotating under the satellite. Notice that in the above animation, the satellite passes northward across the equator at the same local time, shortly after sunset, with each orbit.

To remain sun-synchronous, each orbit is completed in approximately 101 minutes. During this time the earth rotates 25.59 degrees, meaning that the satellite views a different portion of the earth during each orbit. After 24 hours, approximately 14 orbits, the POES spacecraft returns to its starting location.