'Slight errors are magnified over time'

Mr. Wingo has now persuaded NASA to use the Deep Space Network to pinpoint ISEE-3's trajectory, to calculate the rocket burn required to put it on a path to Earth orbit. Dr. Farquhar's 1986 calculations were close, but not exact. Slight errors are magnified over time, and now the uncertainty is 20,000 miles, which means the spacecraft could be on course to splat into the moon.

—"Calling Back a Zombie Ship From the Graveyard of Space," by Kenneth Chang, The New York Times, A21, Sunday, June 15, 2014