Satellite Overpass Closest Approach Predictor

The errors of these predictions grow beyond the first 2-3 days, and this website should be checked daily for the updated predictions based on current TLEs. Under normal conditions, the CloudSat grountrack will repeat withing +/-20 km cross-track every 16 days. Orbit maneuvers to keep CloudSat in formation with the A-Train (i.e. that maintain the 16-day repeating groundtrack) are performed every few days which will alter the predictions. Again, this website should be checked daily. Website users should check the lat/lon recorded for their site and notify us of any changes or errors. The predictions are based on a single point at this lat/lon, and do not account for an extended site. For all these reasons, we strongly advise that ground-based radio astronomy sites operation at/near 94 GHz not be pointed at the zenith at any time that CloudSat is predicted to pass over the sight with an elevation angle >80 degrees.
Satellite Name
Min Satellite Elevation to report
Max Distance (km) to report
Orbit time step increment to use:
   2   4   8   10   seconds
smaller value = more accuracy = longer compute time (may take upto 1 min to process)

Enter a Ground Site Location Lat/Lon
     Longitude (East+) 
report error or add site lat/lon

Welcome to NASA Langley's satellite overpass closest approach predictor. This tool calculates 16 day closest approach estimate of a spacecraft to a ground site location.


The software to calculate closest approach estimates was written by Donald P. Garber.
Responsible NASA Official:   Louis Nguyen   Last updated Jul 06, 2005    Feedback on Langley Products and Services